ML23226A087
| ML23226A087 | |
| Person / Time | |
|---|---|
| Issue date: | 07/20/2023 |
| From: | Allen B NRC/RES/DSA/RSAB |
| To: | |
| Allen B | |
| Shared Package | |
| ML23235A164 | List: |
| References | |
| NRC-2441 | |
| Download: ML23226A087 (118) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Information Meeting with Q&A Sessions on the Proposed Revision to Regulatory Guide 8.39 Release of Patients Administered Radioactive Material Docket Number: (n/a)
Location: teleconference Date: Thursday, July 20, 2023 Work Order No.: NRC-2441 Pages 1-117 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION
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INFORMATION MEETING WITH Q&A SESSIONS ON THE PROPOSED REVISION TO REGULATORY GUIDE 8.39 RELEASE OF PATIENTS ADMINISTERED RADIOACTIVE MATERIAL
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THURSDAY JULY 20, 2023
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The meeting started via Videoconference, at 12:00 p.m. EDT, Sophie Holiday, Senior Emergency Response Coordinator, facilitating.
PRESENT:
SOPHIE HOLIDAY, NSIR/DPR/CB BRIAN ALLEN, RES/DSA/RPB KATHERINE TAPP, NMSS/MSST/MSEB KEVIN WILLIAMS, NMSS/MSST CELIMAR VALENTIN-RODRIGUEZ, NMSS/MSST/MSEB DAVID HAMBY,RCD,NRC Contractor NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 ALSO PRESENT:
PETER CRANE RALPH LIETO KORESSA LEE MAX AMURAO PRASAD NETI JERRY THOMAS SCOTT FULLER BRYAN LEMIEUX ROXANNA KIMES STANLEY HAMPTON TIANLIANG GU HARRISON REDMAN NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 C-O-N-T-E-N-T-S PAGE Welcome and Logistics 4 Opening Remarks 10 Background 14 Overview of Draft RG 8.39 (Patient Perspective) 17 Q/A 34 Overview of the Modifying Factors and Examples of Calculation 46 Q/A 80 Closing Remarks 116 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 P-R-O-C-E-E-D-I-N-G-S 12:00 p.m.
MS. HOLIDAY: Good morning or good afternoon. And welcome to today's virtual public meeting to discuss the Proposed Revision No. 2 of the U.S. Nuclear Regulatory Commission's, or NRC as you will hear it referred to today, Regulatory Guide 8.39 Release of Patients Administered Radioactive Material, which provides licensees with methods that are acceptable to the NRC for the release of patients after medical procedures involving the administration of unsealed byproduct material such as radiopharmaceuticals or implants that contain radioactive material. My name is Sophie Holiday, and I am a senior emergency response coordinator here at the NRC.
It is my pleasure to serve as the facilitator for today's meeting. Before I launch into my remarks, I would like to inform you that for accessibility purposes, you may turn on closed captioning for this meeting by selecting the three dots on the top of your screen has the word, More.
From the drop-down menu depending on your version of Microsoft Teams, you can select Language and Speech or Accessibility to turn on live captions.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
5 The goals for today's meeting are to provide you with an overview of the proposed changes to the NRC's Regulatory Guide 8.39 which was initially published in the Federal Register on April 21st, 2023, for public comment as a draft Regulatory Guide DG-8061, Release of Patients Administered Radioactive Material. The purpose of this meeting is to support you in preparing comments for that draft guide, also to answer any clarifying questions that you may have, and to share the different methods by which you may submit your comments on the draft Regulatory Guide by the deadline of August 20th, 2023. Next slide, please. I see a comment in the chat. Can anyone not hear?
If anyone can please raise their hand if you can hear me, please let me know before I proceed.
Perfect. I see several hands. Thank you. For the individuals that are not able to hear, please check your audio settings. If you are on Microsoft Teams, you do this by going to Settings, Device Settings, and ensuring that you have selected the correct audio input. Thank you very much.
Okay. As you can see on this slide, we have our agenda. This meeting will have essentially two parts. First, we will hear presentations from NRC NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
6 staff which will provide a high-level overview of the proposed changes contained in the draft guide.
As the NRC staff understands, we may have many patients on the line. This part of the meeting will focus on changes that patients might see. The second part of the meeting which will begin no earlier than 1:30 p.m. Eastern Time will include a presentation that will provide a more technical focus on the proposed changes and example calculations.
I will facilitate a question-and-answer session after each presentation during which you may interact with the staff to ask any clarifying questions on the proposed revisions to the Regulatory Guide. Please note that I might defer some of the more technical questions until after we have completed the second session or second part of the meeting as many of those questions might be answered during that presentation. Next slide, please. So let's cover a few ground rules.
As I stated earlier, my introductory remarks, this is a completely virtual public meeting being held on Microsoft Teams. A link to the presentation slides can be found on the NRC's public meeting website as well as the ML accession number that you see here on the screen. Please keep in mind NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
7 that this meeting is being transcribed so that we can fully capture your questions and your feedback and to assist in the development of a meeting summary.
This summary will then be placed into the NRC's ADAMS or the Agency-wide Documents and Access Management System as a publicly available document approximately 30 days after the meeting concludes.
You can help us to get a clean recording and have a smooth meeting by ensuring that you are muting your telephones or your microphones on your devices when not speaking. Additionally, we ask that you minimize any background noise if you choose to speak and that when you do, you identify yourself and any group or organizational affiliation if applicable.
The NRC categorizes this meeting as an information meeting with a question-and-answer session so that attendees will have the opportunity to ask questions of the NRC staff or make comments about the topics discussed throughout the meeting. However, the NRC is not accepting any comments made at today's meeting as official comments on the proposed Regulatory Guide revision. Rather the comments will have to be submitted in writing to receive formal consideration.
We'll be going over the various ways you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 can provide your formal comments later on in the meeting. You may notice that our chat feature is open and accessible to those who have joined us via the Microsoft Teams application. If you encounter any technical issues during this meeting, you may post them in the chat so that I can assist you.
Alternatively, you can reach out to me directly via Teams or through email at Sophie, S-O-P-H-I-E, dot Holiday, H-O-L-I-D-A-Y, at NRC.gov for your technical difficulties. You may also post clarifying questions or comments into the chat. But we strongly encourage you to verbalize them so that they can be captured on the record and because they may be inadvertently missed if we have a large volume of comments in the chat.
Now I'd like to take a moment to introduce the panelists in attendance today. Dr. Katie Tapp, a medical physicist on the medical radiation safety team, will provide an overview of the proposed changes on the Regulatory Guide. Dr. David Hamby, a health physicist contracted by our Office of Regulatory Research, will provide an overview and examples of the different calculation methodologies.
And last but not least, Mr. Kevin Williams, Director of the Division of Material Safety, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
9 Security, State, and Tribal Programs within the Office of Nuclear Materials Safety and Safeguards at the NRC who I will now turn the meeting over for some of our opening remarks. Thank you. Kevin, the floor is yours.
Kevin, your microphone is muted. I'm afraid I can't hear you just yet. Can I have attendees please raise their hands if they're able to hear Mr. Williams? I do see a few hands. Oh, I see hands retracted. Perhaps, Mr. Williams, could you please speak up?
DR. TAPP: Sophie, this is Katie. Can you hear me?
MS. HOLIDAY: I can hear you, Katie.
Excellent. If you would please bear with us for a moment while Kevin exits and reenters the meeting. I apologize for the inconvenience and the slight delay.
While we wait for Mr. Williams to rejoin the meeting, I will also cover some of the items that you see here projected on the logistics screen. I will, of course, reiterate these when we enter into our question-and-answer session. Again, this meeting is being transcribed.
Please keep your lines muted until you intend to speak. When we do the question-and-answer NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
10 session, we will use the raise hand function. Teams will automatically put you into queue in the order in which you raise your hand.
For those that have joined us via telephone bridge line, you can utilize the raise hand feature by pressing star-5 on your phone. And then you can unmute your phone by pressing star-6 or the unmute button on Teams. I see Mr. Williams has rejoined. Can we see if your audio works?
Yes, Mr. Greg Fairchild, I do see your comment in the chat that the ability to unmute was removed. This is so that we can minimize any audio disruptions during the meeting. When you raise your hand, I will call your name and then unmute your microphones. I'm afraid I cannot hear you yet, Mr.
Williams.
MR. WILLIAMS: How about now?
MS. HOLIDAY: Absolutely.
MR. WILLIAMS: Okay, perfect.
MS. HOLIDAY: Loud and clear. Thank you very much.
MR. WILLIAMS: All right. Thank you. So thank you, Sophie, and welcome to everyone to the public meeting on the proposed changes to Regulatory Guide 8.39.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
11 DR. TAPP: Kevin, your mic went out.
MS. HOLIDAY: Mr. Williams, unfortunately your sound went out once more. Mr. Williams, unfortunately we can't hear you. Perhaps, Dr.
Celimar, you can provide opening remarks in lieu of Mr. Kevin.
DR. VALENTIN-RODRIGUEZ: Hi, Sophie. Can you hear me?
MS. HOLIDAY: Absolutely.
DR. VALENTIN-RODRIGUEZ: Good afternoon, everyone. And Kevin, if you are able to speak while I'm making the remarks, please feel free and I'll let you speak. Welcome, everybody, to this public meeting on the proposed changes to Regulatory Guide 8.39 as Sophie has indicated.
We always appreciate the interest that surrounds our patient release program and recommended
-- and Reg Guide 8.39. So we appreciate everyone taking time to attend this meeting today. Just as a bit of a background in 2018, the NRC staff conducted a review of a patient release program, and we recommended to the Commission that the Reg Guide be updated to ensure that our patient release regulatory limits would continue to be met by licensees that utilized the methodologies in our Reg Guide. At that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 time, the staff also recommended to the Commission that no regulatory changes to our patient release criteria were warranted. The Commission agreed with these recommendations and for the last several years the NRC has been conducting a phased revision to its Reg Guide 8.39, and that's the reason we are here today.
The last revision to the Reg Guide was published in April of 2020 which is the one that some of you your licensees are currently using. And at that time, we updated the patient release information to include example patient instructions. The latest proposed revision to the Reg Guide is currently out for public comment.
As Sophie indicated, the public comment period now closes on August 20th, 2023. And this proposed revision includes updated dosimetry equations, methodologies, and tables to assist licensees in calculating doses to members of the public from patients released after administration of radioactive material. The purpose of our meeting again is to provide information to you all, the public, including patients and licensees, to help prepare your comments on the proposed changes to the Reg Guide.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
13 We're not seeking comments at this meeting as Sophie stated. But we will consider all your comments that we received through the methods that staff will later indicate during the meeting and that have already been included in the Federal Register notice that we publish in April of this year. So, with that, Kevin, I don't know if you want to do any remarks. If not, I'll move it over to Dr. Katie Tapp for her presentation unless, Sophie, you have any other remarks before we get started.
MS. HOLIDAY: I do not. Please take it away, Dr. Katie Tapp.
DR. TAPP: Okay. You can move to the next slide. As Sophie had mentioned, the purpose of this meeting is to provide an overview of the proposed changes on the NRC's Draft Regulatory Guide 8061, Release of Patients Administered Radioactive Material to help the public prepare comments on the guide. In this meeting today, we will share different methods of which you may submit comments on the draft guide.
As Sophie mentioned, the NRC will not be seeking comments made at this meeting today. You must submit the comments and the methods mentioned in the Federal Register notice which is linked here and the comments should be submitted according with these NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
14 instructions by August 20th, 2023. Go to the next slide. And next slide. I'm going start by providing a background.
As Sophie mentioned, my name is Katie Tapp. I am a medical physicist in the medial radiation safety team at the Nuclear Regulatory Commission.
Next slide, please. It is the NRC's policy on medical uses of radioactive material to regulate these uses as necessary to provide the radiation safety of workers and the general public.
It is also the NRC's policy to not intrude into medical judgments affecting payments except as necessary to provide radiation safety to the workers and the general public. This means the NRC's regulations will not interfere with physician's judgment to treat a patient or how the physician wants to treat the patient using their medical knowledge.
However, as patients who administered radioactive material can expose others who are near them to radiation when they have radioactive material inside their body, it is the NRC's policy to ensure adequate protection of the workers and the general public.
Due to this, the NRC has developed regulations regarding when patients can be released from the hospital or licensee's control. When a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
15 patient stays inside the hospital, there's also regulations to make sure the workers are protected, and the general public are protected in the hospital.
But today we're talking about when a patient can be released from that control and go home. Next slide, please.
These regulations for patient release are contained in 10 CFR 35.75 which allows a licensee to release patients from his control when the total radiation dose to any other individual from the exposure to the released patient is not likely to exceed 5 millisieverts. The licensee must provide in written instructions to the patients to maintain the doses as low as reasonably achievable if the exposure to any other individual is likely exceed one millisievert. This regulation also states that licensees must also provide specific instructions if the total exposure to a nursing infant or child could exceed one millisievert assuming there's no interruption in breastfeeding. Next slide, please.
Therere some important points I want to point out about this regulation. First, this regulation applies to each patient treatment. Each patient treatment and the potential to expose other individuals is unique.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
16 So, the ability to release a patient and the way licensees may release a patient might be different for the same treatment for different patients and could be different even for the same patient if they're treated at a different time. So, it's important to note that it's each patient treatment that this release calculation is being done by the licensee. Second, this regulation applies to the licensee and not the patient.
It is the licensee's responsibility to ensure that they're in compliance with the NRC's regulations. The physicians who are authorized to use radiopharmaceuticals are required by the NRC to have training and radiation safety. As we will discuss later, in some cases, licensees may need to ask patients a question regarding their plans after treatment.
When licensees or physicians are doing this, they might be asking questions to perform these calculations that we'll be discussing to determine the maximum likely exposure to other individuals to ensure that they can release the patient in compliance with this regulation. For a licensee to perform the appropriate calculation, truthful and complete answers are necessary. Finally, this regulatory guide provides NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
17 guidance on how licensees can demonstrate they meet this requirement.
This is a regulatory guide that will be updated, Regulatory Guide 8.39, that we'll be discussing today. The regulation for the dose limits that I discussed previously are not changing at this time. We are only discussing the changes to the regulatory guide which is guidance to licensees and how they can demonstrate they meet this requirement.
Next slide, please.
As I just stated, the regulation is not changing at this time. In January of 2018, the Nuclear Regulatory Commission completed an evaluation of the entire patient release program. This evaluation looked at both the regulation and the guidance.
The results were published in the staff evaluation of the program's regulations for patient release after radioisotope therapy which can be found on the QR code listed here or on the NRC's public website. This evaluation found that the regulations are adequate to protect the public. However, this evaluation did find that the guidance contained in the regulatory guide we're discussing today needed to be updated because the methodologies in this guidance can NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
18 underestimate potential doses to members of the public in some unique situations such as long public transportation rides or when a patient is in close proximity to others for a long period of time immediately following release.
This is the reason we're updating the regulatory guide at this time. Next slide, please.
During this evaluation that I just mentioned that concluded in 2018, we were already working on Revision 1 to the regulatory guide which was issued in April 2020. This revision updated the regulatory guide to include recommendations for licensees to have pre-treatment discussions with patients to ensure that the licensees knew what the patients' plans were following release and to ensure patients could follow any necessary instructions following the release to ensure compliance with the regulations.
This revision that was published in 2020 also included example patient instructions to maintain doses as low as reasonably achievable, additional example instructions provided to the NRC during public comment periods, and patient acknowledgment that instructions were given. As I stated before, every treatment and patient release is different. So, the instructions and precautions contained in the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
19 regulatory guide are just examples and individual patient instructions may vary.
For any patients listening in, it is important that you talk to your healthcare providers if you have any questions on your specific instructions as well as if you're on this call, you know about the regulatory guide. You can ask questions on why yours may differ from the examples.
As I said, every situation is unique, and your healthcare providers can provide you the answers that you need for your situation.
Since this section was updated in Revision 1, the current draft did not include significant updates to these sections. Next slide, please. Now I'm going to move into the general overview of the proposed changes that are currently in the draft guide that we're discussing today. Next slide, please. The proposed revisions in the regulatory guide were published under Draft Guide 8061 entitled Release of Patients Administered Radioactive Material.
The proposed changes in this draft guide included updates to the dosimetry methodologies that licensees can use to demonstrate compliance with the dose limits in 10 CFR 35.75. In addition, the proposed changes included updating breastfeeding NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
20 cessation guidelines. This proposed revision was published in the April 21st Federal Register notice, and the NRC is currently requesting public comments on this revision until August 20th.
I'll discuss how to submit comments later in the presentation. Next slide, please. The dosimetry methodology proposed in the draft guide contains two-tiered approach to release, baseline thresholds, and then how the licensee can calculate patient-specific release values. This is similar to the methodology contained in the current revision of the Reg Guide that contains tables of baseline values and then recommendations on how to do patient-specific release values later.
The first baseline thresholds proposed in the draft guide provides tables of administered activities and measure dose rates, baseline threshold values that licensees can use to release patients if their administered activity or measured dose rates are below these values. Licensees can use these tables to release patients without gathering patient-specific information. Second, the patient release-specific values contained in the draft guide provides updated guidance on how patient-specific information can be used to demonstrate release and comply with the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 regulations. Next slide, please.
The equations provided in the draft guide consider external exposure and do not include internal exposure due to uptake of radioactive material by the individual other than the patients. The reasons for this is previous studies described in the NRC's evaluation I mentioned earlier that was concluded in 2018 found that the potential intake by household members and other members of the public is negligible or less than a few percent relative to the external dose rates, especially when the instructions by the healthcare provider are followed. As I mentioned earlier, the instructions, precaution recommendations and examples were not updated in the draft guide as they were recently updated in the last revision. Next slide, please.
As I mentioned earlier, the tables of the baseline administered activity and measured dose rates were in the previous revision of the reg guide.
However, the proposed draft guide has made changes to these tables. First, the draft guidance has added new radionuclides that are now being used in medicine such as Lutetium-177.
Additionally, the assumptions used to develop these values are clearly defined so new NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 emerging radionuclides can be added in the future.
Next, the assumptions used in the draft guidance have changed. While the values have always been conservative for most patients, the assumptions were updated to be even more conservative to ensure that all releases are not likely to expose others in excess of 5 millisieverts.
Due to these conservative assumptions, licensees do not need patient specific information to release patients who have been administered activity or have measured dose rates at values below those found in the tables. Next slide, please. If a patient does have administered activity or a measured dose rate above the baseline thresholds, patient-specific information is needed to determine if a release can be authorized. Due to the overly conservative assumptions used to develop these baseline thresholds to ensure all patients can be released using those values, most patients can be released at values higher than the baseline threshold values.
It is just that licensees will need to gather patient-specific information to add realism to demonstrate the compliance and that the release is in accordance with the regulations. Next slide, please.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 I'm now going to cover the patient -- quickly cover the patient-specific modifying factors that are in the draft guidance. In the latter session this afternoon, Dr. Hamby will discuss these more in detail with more technical background and provide examples of how these can be used.
I'm now just going to cover them at a higher level. The proposed draft guidance recommends use of four modifying factors to change the baseline thresholds based on patient release information.
These modifying factors are the occupancy factor, the geometry factor, attenuation factor, and biokinetic factor.
By using these modifying factors, licensees can change the baseline threshold values to make patient-specific values for each treatment. The licensees can release the patient if the administered activity or measured dose rate is below these patient-specific values. Licensees can choose to use patient-specific information to modify some of these factors while keeping conservative values for others if the administrative activity is below the calculated specific values based on these modifying factors that they're changing.
Many patients will be able to be released NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
24 using patient-specific information for some of these factors while using the most conservative values for others. However, the proposed draft guidance provides guidance for when licensees need to change all four factors or when they need to add more realism as the regulations applies to every release. And as I mentioned earlier, every release is unique.
In a later session today, as I mentioned, Dr. Hamby will provide more details and examples of how you can use these values to change the patient release baseline thresholds. And I'll cover each factor individually as an overview. The first modifying factor is the occupancy factor.
The occupancy factor is the amount of time an individual is near the patient while the radioactive material decays which is when the individual near a patient will be exposed. The less time the individual is near a patient while the material decays, the less exposure they will receive.
The baseline threshold assumes that an individual is one meter away from a patient at all times.
This means that this individual is near this patient 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day at one meter away. To determine a patient's specific occupancy factor, patient-specific information is necessary. A licensee NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 can gather this information from talking with a patient or a patient's family to determine what their plans are after treatment.
These questions could include what the patient plans to do, where they plan to go, who lives with them and how they spend their time, where they work, and potentially sleeping arrangements. The amount of time with which is the licensee is asking a patient for their plans after treatment depends on the treatment and potentially depends on the medical factors of the patient as the amount of time which the patient retains the activity inside their body is dependent on the treatment and the patient's body.
The depth of the questions which the licensee asks is also dependent on the treatment in patients.
In many cases, licensees can demonstrate compliance by confirming a patient does not plan to spend a significant amount of time, for example, eight hours a day near another individual. However, in other cases, the licensee may need or want more realism to demonstrate compliance and may ask more detailed questions. Licensees need complete and accurate information to perform their calculations to ensure those around you are adequately protected and to ensure that they're in compliance with the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
26 regulation.
If you are a patient and are being asked questions and have concerns about why they want this information, it is important to ask your healthcare provider why they're asking these questions and how the information may be used. Next slide, please. And next slide, please. The next factor I'm going to talk about is the geometry factor. The geometry factor is the factor regarding the geometry an individual is exposed to a patient as a patient who's farther away from the individual will have less exposure.
So, the closer you are to someone with radioactivity, the closer you are to the source, the more exposure you'll have. The baseline threshold conservatively assumes that the source individuals are exposed are points. This is a conservative assumption used for two reasons.
First, the individual being exposed is not a point but a person. They have volume. The conservative assumption used in the baseline assumes these two points are one meter away.
However, because a person is a volume, the point that's closest to the person is going to be at one meter. But you're farther away part like your legs will actually be farther away from the patient NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
27 and will receive less exposure. In addition, many radionuclides do not accumulate as a point inside a patient but instead spreads out throughout the patient's body.
Therefore, the draft regulatory guide provides tables which licensees can use to modify these assumptions that are used in the baseline to account for more realistic exposure scenarios based on medical knowledge of where the material is going in the body or knowledge about who the patient is going to spend their time around. The baseline threshold also assumes the patient and individual are one meter away for the entire time that the radioactive material is decaying and leaving the patient's body. As you can hear, that is related to the occupancy factor that I just discussed.
And the draft guide recommends if the occupancy factor is being updated that the licensee either confirm the conservatism in the geometry factor or make patient-specific geometry factors as well.
Similar to the occupancy factor, licensees can modify the geometry factor based on conservatisms with a patient or the patient family to determine what activities they plan to do after treatment. In addition, they may use conservatisms to determine if NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 the patient will be near a young child as a young child will have a different geometry than an adult who's been exposed.
The licensee may also use medical knowledge of where the radionuclide inside the patient to modify this factor. Next slide, please. This next slide shows the draft guidance example questionnaire that licensees could use to gather information to determine the occupancy factor and part of the geometry factor. As you can see in the questionnaire, the licensee is asking questions such as what mode of transportation the patient will be using.
This is an important question because the amount of radionuclide inside a patient's body is going to be highest immediately after administrationand some transportation such as public transportation has patients in close geometry.
Second, this questionnaire has guided open-ended questions in number three so patients can describe their unique scenarios.
The NRC has recommended open-ended questions instead of specific questions as we know that we could never capture all scenarios in an example that can occur for all patients. Third, the questionnaire asked about unique patient plans to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
29 ensure that licensee includes them in their calculations if necessary. The licensee just asked about what do you normally do and not what are your unique plans after treatment. They may miss something.
Fourth, the questionnaire is to ensure that the licensee considers any radiation safety issues if the patient is incontinence or has many radionuclides are excreted in urine. So, the licensee may need to consider how waste is handled if a patient is incontinent and consider dose to other individuals if any individual helps the patient with this waste.
Fifth, the questionnaire is to ensure that the patient is able and willing to follow instructions.
The draft guidance does state licensees have an option to use the instructions to modify occupancy and geometry factors if the patient is able and willing to follow instructions. For example, a patient might normally spend 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> close to their spouse. But following discussions and a conversation with the medical team, they agree to spend only 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> with their spouse for the few days necessary after treatment.
The medical team can then use the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> in this occupancy factor as part of their occupancy NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 factor calculation if the patient agrees that they're able and willing to follow this instruction. It is important to discuss this specific scenario with your healthcare team because sometimes there might be different ways to go about this for release. That is why the draft guide gives so many options if there are so many different methods because each treatment is unique and, we know each patient's ability to follow instructions are unique.
So, if you're unable to follow the instructions that are being proposed, talk to your licensee. There may be other ways to go about the release and for them to do the calculation. The final question is to discuss other issues that might prevent a patient from complying with radiation safety instructions as provided.
As I mentioned, it is important to ask questions if you do not understand something in your instructions or if you need any help from your healthcare team. There're no examples that we can provide in a regulatory guide that can help for every scenario out there because we know there're many differences in patients and patient situations. Next slide, please. Now we're going to quickly cover the final two modifying factors.
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31 These are not ones that patients are going to see being changed much because they're based more on the medical knowledge of the patient and where the material goes in the body and how it leaves the body.
So, I'll just quickly provide an overview. These will be discussed further in the next presentation and shown how they can be used by licensees to demonstrate compliance for release.
The first factor I'll cover here is the attenuation factor. This accounts for the shielding and the build-up of radioactivity between the source and the individual. The patient-specific attenuation factor is dependent on the expected depth of the material inside that patient's body.
The attenuation factors can be greater than one due to build-up of the radioactivity. And licensees should use the most conservative attenuation factor for radionuclides if they do not plan to determine specific attenuation factors because the conservatism is being removed from other factors. So, if a licensee is modifying the occupancy factor and the geometry factor, they should use the most conservative factor, even if it's greater than one.
Finally, the draft guide provides the most conservative values and graphs that licensees can use NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
32 to select these values without doing their own calculation or to find the most conservative value.
Next slide, please. The final modifying factor is a biokinetic factor. In the baseline threshold values, the assumption assumes that there is no removal of the radionuclide from the patient's body.
This is highly conservative as most radionuclides are quickly removed from the patient's body through excreta. Licensees continue to use a conservative assumption when a patient's retention data is unknown. However, if the licensee wishes to use patient-specific values, the draft guidance provides guidance on how licensees can adjust for patient-specific excreta removal for additional realism. Next slide, please.
Next, I'll quickly discuss some tips on how to prepare and submit comments. Next slide.
First, one can look and use this website here that's provided in these comments that gives commenters a checklist. This is a generic commenter's checklist that we use for all requests for comments from the NRC. And it provides good tips for submitting effective comments.
Some important points from this commenter's checklist is --. Please feel free to reach NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
33 out to us if you have any questions on the draft guide. It is important that you read and understand the document that you're commenting on. We recommend that the comments be concise but support your claim.
It is really important that you don't worry about the length of your comments. Every comment is important to us. So, if you just want to comment in one section of the Reg Guide, that is fine.
And there's no maximum length on comments.
So, one can have a small comment or a big comment.
They'll both be coming into us and be used by the technical staff here as we're updating the guidance.
And one additional final comment is that the comment process is not a vote. There are varying opinions on comments. And one well supported comment is just as influential as other comments from thousands of letters.
So, we do take all comments seriously, and we will look at all of them. Next slide, please.
This slide discusses the methods for submitting comments. The comments can be submitted on regulations.gov in the comment form, link this slide under Docket ID NRC-2023-0086.
You can also email rulemaking.comments@nrc.gov or mail to the Secretary NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
34 with the address in the Federal Register notice. Next up, please. As I mentioned earlier, the public comment period ends on August 20th, 2023. And what we'll do after that is the NRC will look at these comments. We'll evaluate these comments as we are working to publish the final update to the Regulatory Guide 8.39. Next slide, please. And now I'll turn it over to Sophie --
(Simultaneous speaking.)
DR. VALENTIN-RODRIGUEZ: Thank you.
MS. HOLIDAY: Excellent. Thank you, Dr.
Tapp, for your very informative presentation. We have allotted approximately 30 to 40 minutes for this question-and-answer portion of the meeting. This is your opportunity to ask clarifying questions of the NRC staff present today.
As I stated earlier, please note that I might defer some of the more technical questions until after the second presentation that Dr. David Hamby will give to us as many of those questions might be answered during his presentation. Again, the NRC is not accepting any comments made at today's meeting as official comments on the proposed regulatory guide revision. Rather, comments will have to be submitted in writing to receive formal consideration through the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
35 various methods that Dr. Tapp, excuse me, just mentioned.
To ask a question, please utilize the raise hand feature on Teams. The icon looks like this, a raised hand. Or you may dial star-5 on your telephone if you've joined us via telephone.
Teams will automatically put you into the queue in order of your hand raising. This is not something that I do on my own. This is to help us facilitate a democratic, if you will, selection for those who have raised their hands.
Once I had called your name, I will unmute your microphone. Again, if you are on the audio bridgeline, you will have to dial star-6 to unmute your microphone. Once you're unmuted, you are free to ask your question. To ensure that everyone is given an opportunity to ask questions or make comments should they have any, we request that you ask only one question at a time.
If there are no additional questions or time permits, we will take your additional questions.
As a kind reminder, please state your name and your affiliation as this meeting is being transcribed. So, at this time, are there any questions or comments from those that are attending the meeting?
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36 Excellent. Mr. Peter Crane, I see your hand raised. Give me one moment to unmute your microphone. Mr. Crane, your hand went down. Did you still have a comment or question?
Mr. Crane, I have promoted you to presenter. You may unmute your microphone.
MR. CRANE: Okay.
(Simultaneous speaking.)
MS. HOLIDAY: Please identify yourself for the record.
MR. CRANE: Can you hear me now?
MS. HOLIDAY: Absolutely.
MR. CRANE: Can you hear me now? Yes?
MS. HOLIDAY: I can.
MR. CRANE: Okay. Thank you. My name is Peter Crane. I am the NRC Council for Special Projects, retired. I followed this issue for many, many years.
I'd like to say at the outset that I have rarely -- and this is in 48 years of observation --
heard a briefing as good as the one Katie just gave for its completeness, its clarity, and its being pitched to all kinds of listeners. So, I think that's great. Doesn't mean I don't have problems with the guidance, but I'll put those in a comment.
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37 What I wanted to ask is, is the reason that the guidance does not include citations to the two regulatory information summaries that were issues in 2008 and 2011? The first one which asked doctors to consider hospitalizing patients with young children at home and acknowledging that the patient release rule reflected insufficient concern for internal dose and the one in 2011 strongly recommending that doctors not send patients to hotels, question mark. That's my question.
DR. TAPP: Thank you, Mr. Crane, for the compliment. It was really focus of this meeting today to make sure we reach out to everybody as we do want comments from all members of the public. For your questions, the first was the information notice. I believe Revision 1 removed the links to those generic communications when they updated the precautions and the instructions because at that time, we rolled in the instructions from the generic communications that went with the public comment period on that direct guidance.
So those were looked at that Revision 1 time frame and they were rolled into the document as applicable. If you find during your review of these documents and the current revision and if there's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
38 something, a generic communication that you think that we should go back and review or go back and refer, I'd recommend that be in a comment. But the reason that was removed is they were reviewed in Revision 1. And then the team that worked on that revision updated the guidance, including the information there.
MR. CRANE: Thank you. I will do so.
I've made this comment repeatedly, and I've never heard it addressed. But I'll try again. So, thanks and I'll move on.
DR. TAPP: Thank you.
MS. HOLIDAY: Thank you for your comment and your question, Mr. Crane.
MR. CRANE: Thank you, Sophie.
MS. HOLIDAY: All right. At this time, is there anybody else that has a question or a comment?
If you would please raise your hand by pressing star-5 on your phone or using the icon raise hand on Microsoft Teams.
Mr. Ralph Lieto, I see your hand raised.
Please give me one moment. Mr. Lieto, your microphone is unmuted. Please identify yourself for the court reporter.
MR. LIETO: My name is Ralph Lieto. I'm a medical physicist and from the state of Michigan, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
39 retired. I've been following the issue for a long time.
I have a question for clarification for Katie. Regarding the statement you said about the baseline issue is no biological elimination. Does that mean, say, for I-131 therapy patients, sodium iodine 131 therapy patients, if you want to apply biological elimination, you have to determine that for each specific patient?
DR. TAPP: I think --
MR. LIETO: I probably just should clarify that a little bit. In light of the fact that there have been established values for classes of those patients, specifically hyperthyroidism and cancer patients. But that's for a class, okay, not specific.
Are you saying that those values are no longer necessarily valid and have to be determined specifically for those therapy patients?
DR. TAPP: Thank you for your question, Mr. Lieto. So the baseline values as you mentioned are radionuclide-specific, not radiopharmaceutical specific. So they do not include any biokinetics.
They assume that everybody retains the material inside their body. The patient specifically values, though, can be modified using biokinetic NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
40 models. And Dr. Hamby will talk about some examples of that.
As you mentioned, the values for radioactive iodine, those values can be used by licensees in situations. But as the draft guidance recommends, provides details when using established values. So double check and make sure there's not unique patient factors.
So, if that wording is not clear, I think a comment coming in would be helpful. But biokinetics can still be modified in patient-specific values. And then the licensee could then still use the conservative values for the other three modifying factors, if that makes sense.
MR. LIETO: Actually, I think you muddied the waters a little bit more because what you're saying is that I can understand if you have values that you want to apply more conservatively for a specific patient. But I'm just talking about a category of patients. Let's just take I-131 therapy patients being treated for cancer and that there's a set of biokinetic values that have been used for decades and in NCRP-155. Why isn't that just being put in as the baseline value for those types of patients?
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41 DR. TAPP: Yeah, and that's a good question. At this time, the draft guide has the baseline values using the retention as 100 percent keeping the patients in. But if someone would like to update that, the Reg Guide does not preclude grouping patients or grouping for a specific drug if that's applicable for that treatment for the patient-specific values.
But as I mentioned, the tables are radionuclide specific. So, at this time, all of them are assuming biokinetics of one. I think there will be an example later. So, if you're able to hang on to this afternoon, maybe the example will help.
MR. LIETO: Thank you.
DR. TAPP: Thank you.
MS. HOLIDAY: Thank you for your comment, Mr. Lieto. Before I move to the next person who has their hand up, Dr. Tapp, I'd like to highlight that there was a comment submitted or a question submitted into the chat. Ms. Korressa Lee, would you like to unmute your microphone so that you can verbalize your comment?
Alternatively, I can verbalize it for you if you do not wish to do so. At this time, I will go ahead and promote you. Ms. Korressa?
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42 MS. LEE: Yes, thank you, Sophie and the presenter. I was just wondering if this with the conservative values when the draft came out, are you anticipating a trend towards less outpatient releases, especially since it's probably Lutetium 177?
DR. TAPP: Yes, that's a good question.
The baseline values did decrease. But I believe that the draft guidance does provide more guidance on patient-specific values to modify the criteria. So, it's providing more guidance on how licensees can demonstrate release for patient specific.
So, I don't see changing the amount of outpatient procedures versus inpatient procedures based on this guidance. As I mentioned in the past, the regulation and the dose limit are staying the same. So, this is just a method for compliance with that regulation and giving a way for licensees to see documentation and examples on how they can perform patient-specific calculations and changes. So, it should not be changing the actual regulation itself.
MS. LEE: Thank you.
MS. HOLIDAY: Thank you, Ms. Korressa. At this time, I see that there is another hand raised, Max Amurao. If you would, please unmute your microphone and state your name and affiliation for the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
43 court reporter. Please proceed.
MR. AMURAO: Thank you for the opportunity. My name is Max Amurao. I am a medical physicist and a service radiation safety officer in the state of Missouri.
My question is in terms of potential timelines for implementation. Should changes, maybe wholesale or part of these revisions, be approved?
Could you comment on the timeline for implementation, particularly for agreement states? Thank you.
DR. TAPP: Good question. I'll start with the NRC. So this is updates to a regulatory guide.
So, when a regulatory guide is updated, the other regulatory guide is then sunsetted.
So, it is not changes to the regulations.
It is the change to the regulatory guide. So, when it would be updated, the regulatory guide would supersede the one in the past.
Licensees are always the ones responsible to demonstrate compliance with the regulations. So, assuming they're in compliance with the regulation, that's what the focus will be. And that will maintain.
For the states, it would be up to the states to adapt guidance. So, I can't speak to the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
44 agreement states if they would immediately use this guidance and refer to it when the NRC does or if they would modify their own guidance. Many states have their own patient release guidance out there. And some even have regulations that are recommendations beyond what the NRC has here. So that would be a question for the state of which you're located, what their plans would be based on the guidance.
MS. HOLIDAY: Thank you, Max Amurao, for your question and comment. Does anybody else have a question or comment at this time? If so, please utilize the raise hand function on Microsoft Teams or dial star-5 on your telephone.
Dr. Tapp, at this time, I do not see any hands raised or any comments in the chat. I will wait just another minutes to see if we have any other individuals that would like to provide feedback or ask a question. Okay. Well, it appears that there are no more questions.
This will conclude the question-and-answer portion of this first part of the meeting. As previously stated, the deadline for submitting your comments on the proposed revision to Regulatory Guide 8.39 is August 20th, 2023. The NRC highly encourages electronic submission through the federal rulemaking NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
45 website, http://www.regulations.gov using the docket ID number, NRC20230086.
We caution you not to include any identifying or contact information in your comments submission that you do not what to be publicly disclosed. This is, of course, covered in the checklist that Dr. Tapp mentioned during her presentation. You may also submit your comments in writing via email to rulemaking.comments@nrc.gov.
That is R-U-L-E-M-A-K-I-N-G, dot C-O-M-M-E-N-T-S,
@nrc.gov or via email to the Secretary.
Please ensure that if you use either of those methods, you reference the docket ID number, NRC20230086. If you should need any further information, you may also contact any of the following individuals, Dr. Katie Tapp via email at K-A-T-H-E-R-I-N-E, dot T-A-P-P, @nrc.gov, Brian Allen via email at B-R-I-A-N, dot A-L-L-E-N-3, @nrc.gov, Rigel Flora via email at R-I-G-E-L, dot F-L-O-R-A, @nrc.gov, or Harriet Karagiannis at H-A-R-R-I-E-T, dot K-A-R-A-G-I-A-N-N-I-S, @nrc.gov. This information is also found in the Federal Register notice.
We are going to go on break. We will return for the second portion of the meeting at 1:30 p.m. Eastern. Please return if you'd like to hear the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
46 technical presentation. Otherwise, I thank you for your attendance during this first portion of the meeting. Thank you.
(Whereupon the above-entitled matter went off the record at 1:03 p.m. and resumed at 1:30 p.m.)
MS. HOLIDAY: Good morning or good afternoon, depending on where you are joining us from.
Welcome back to today's virtual public meeting to discuss the proposed revision to the U.S. Nuclear Regulatory Commission's Regulatory Guide 8.39, Release of Patients Administered Radioactive Material. During the first part of this meeting, Dr. Katie Tapp provided a high-level overview of the proposed changes contained in the draft guide.
We are now getting ready to begin the second part of the meeting where Dr. David Hamby will give a presentation with a more technical focus on the proposed changes and example calculations. Similar to the first portion of the meeting, we will hold a question-and-answer session after Dr. Hamby finishes his presentation. At this time, let's do an audio check. Dr. Hamby, could you please say something?
DR. HAMBY: Yes, can you hear me?
MS. HOLIDAY: Yes, excellent. And if you're --
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47 DR. HAMBY: Great.
MS. HOLIDAY: -- ready to, you can go ahead and take control of the screen sharing.
DR. HAMBY: Okay. So hopefully, we've done this enough now that that all worked. But you never know.
MS. HOLIDAY: I can see your slides.
DR. HAMBY: Yeah, you never know. I'm David Hamby. I am the principle for RCD Radiation Protection Associates. And we've been working -- a team of us have been working with the NRC for a couple of years on this project.
So, I'm going to give an update on these phase 2 changes, the dosimetry methodology. I think one thing to keep in the back of your mind is that this is guidance that we're providing. And I certainly can't speak for the NRC. I don't work for them other than being a consultant.
But I certainly can't speak legally and for the NRC. But it's my thinking anyway that this is guidance. It doesn't tell you this is the way you must do patient release, but it provides a way -- I think it provides a fairly quick way.
The first time you go through these exercises, it might take a little bit of work. But NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
48 after that, I think it would be a pretty quick way of doing patient release. It's going to make sure that no one, no bystander -- innocent or otherwise, no bystander is receiving a dose greater than 5 millisieverts from the release patient.
And the method doesn't calculate dose, per se. But it does calculate an administration threshold that will assure that 5 millisieverts isn't exceeded.
So, we'll get into it here.
So as an overview of the presentation, we're talking about the revisions. We hope that the proposed direction provides something that's versatile and realistically conservative dosimetry, dose estimates. We think that the basic activity thresholds have been generated to produce -- well, with basic activity thresholds, you can generate patient-specific values if administration -- activity administrations are higher than what the basic thresholds show.
Thresholds are based on maximum individual dose limits as Dr. Tapp pointed out, dose limits found in 10 CFR 35.75. And with patient instruction and interruption of breastfeeding, if necessary, infants are protected to a millisievert. And we also think that the new method provides support for emerging NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
49 technologies.
We think it's something that can be moved into very quickly for emerging technologies. Kind of at the 30,000 foot level, what's different? And I think what you'll see is once you get into there's not a lot of difference in the method per se, except like I said, you're calculating thresholds, administered activity thresholds rather than actually dose.
But as the first major bullet says, if the administered activity is less than what's in Table 1, what's in the new Table 1, then there's no change for the licensee. The patient can be released and as it is now as the current version. If the activity --
administered activity is greater than what's in Table 1, then it provides a method or require the licensee to do a little bit of work and we hope not a lot of work.
But the licensee has some options then if the administered activity is greater than the threshold. One of these four things, the licensee can calculate -- I'm sorry, can look at measured dose rates or measure the dose rate and look at those in Table 2. Does rate values are provided.
And if the measured dose rate is less than what's in Table 2, the patient can be released. Or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
50 released activity -- retained activity can be used instead of administered activity as is similar now.
The licensee can calculate patient-specific thresholds to determine patient release which is kind of what I'm going to focus on today or calculate a hold time prior to patient release.
And I'll go through an example that shows a whole-time calculation. If the patient is breastfeeding, then there's another step that must be followed. The guidance suggests following certainly.
But then the regulation says that the infant must be protected to one millisievert.
But if the administered activity is less than thresholds found in Table 3 which is for breastfeeding, there's no change for the licensee.
But again, if that administered activity is greater than those thresholds, then the licensee should calculate interruption times and then advise the patient accordingly, of course. So go through each one of these examples that will kind of touch on this.
This is a lot of information, and I don't mean for you to look at numbers and compare numbers necessarily. I will do a little bit of that here in a second. But what's happening, the table on the left is the current table, Columns 1 and 2 of Table 1.
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51 And those are all of the nuclides that are listed currently in that table. When we notice is that a couple of them, P-32 for example, Strontium-89, those have no values. That's because they are pure beta emitters.
And the only external radiation that someone might be exposed to is the Bremsstrahlung that is created. So, we have included Bremsstrahlung calculations in the table that's on the right-hand side. That's one thing.
There are things that are included here.
And the table on the right is a proposed table.
Someone's mic is open. But anyway, there's a table --
the table on the right-hand side is the new proposed values.
And for the most part, those values are similar. The ones that you -- if you start looking at and comparing -- again, like I said, I'll do that in a second here. But if you start comparing numbers, you may see some that are about a factor of 4 different, and that factor of 4 relates to an occupancy of 25 percent which is kind of in the current method which we have removed to give more realism. And I'll talk about that specifically.
If we compare these two tables from what's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
52 current and what's proposed and we pick out a few values to look at. First, I want to look at the item 131 value. And this is a value that is a factor of 4 different.
And that is because of the assumption of 25 percent occupancy in the current values that has gone away, that has been removed. But we think we give a good example or a good method of determining this without just saying a flat 25 percent. The methodology is going to assume -- like I said, the methodology is going to assume 100 percent occupancy for conservatism.
But then the licensee can make a better estimate of that occupancy from Table 1. Another example I point out down here for Tc-99m, you see those numbers are roughly the same. And that's because the 25 percent occupancy does not apply to Tc-99m because it has a half-life greater than a day as in current. So those are roughly the same number.
Lutetium 177, that is new. That's not in current guidance. So there's a new one. And I have note there saying that 52 -- we've gone from 22 nuclides up to 52 nuclides. So, trying to be much more inclusive of what's emerging and what's in the current technology.
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53 And then we also added factors for pure beta emitters. So, show a couple of Strontium and Yttrium values there that are not in current guidance.
So, the way this threshold framework works is you can imagine this line here starting at zero seeing the dose to the bystander on the left side would start at zero dose and increases to the right.
And it increases up to a point of 5 millisieverts to the maximum bystander. And this maximum bystander is someone that will be estimated based on the survey that Dr. Tapp was talking about, the survey that the position would have with the patient to determine kind of characteristics of what the patient anticipates doing after release. So, we try to estimate who was the maximum bystander and then make sure that does -- the does to that person doesn't exceed 5 millisievert.
So, on this dose line, we have kind of a 0.5 millisievert. We also have a -- sorry, for this 5 millisieverts, we have -- if we can show that the does to the bystander -- the maximum bystander is less than 5 millisieverts as is shown here with the green, then release is authorized. If the dose is shown to be greater than 5 millisieverts by this method or by comparison to administered activity, then release is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
54 not authorized.
And so more things need to be done by the licensee to see if release is authorized under the specific characteristics of the patient. These values come from Column 1 of Table 1, and these are the basic thresholds for patient release. And as long as the administered activity is less than that number in Column 1 of Table 1, then release would be authorized.
The other threshold here that we're going to talk about is one millisievert to the bystander.
And this is the threshold where instruction is required. And so, this is Column 2 of Table 1 where it's the basic threshold for instruction.
And so, if that value in Column 2 is exceed but the Column 1 value is not exceeded, for example, so somewhere in between those two values, the patient can be released but must be given instruction for maintaining ALARA. And I'm going to talk a little bit more about that in an example here soon. So below one millisievert, there is essentially no regulatory action.
I think the majority of you -- of the licensees anyway -- would probably document this anyway even though there's not a regulatory need if you can show that it's less than one millisievert.
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55 But I'm sure the documentation would be occurring.
There might even be an option given to the patient in this case, but not necessary.
If the dose is between one millisievert and 5 millisievert, then ALARA instructions would be provided to the patient. And then above 5 millisieverts, alternative methods must be onto to determine whether or not release can occur. So, Example No. 1, a very basic example and called here like a baseline release, so this first example says a 56-year-old male is administered 1.3 gigabecquerels of Y-90 microspheres.
So, this is a pure beta emitter. So the current release and instruction thresholds are not existent. So, from the proposed Table 1, we see that the basic activity thresholds are 34 gigabecquerels for release. That relates to 5 millisieverts.
And then 6.8 gigabecquerels for instruction relating to one millisievert. If we put these on our threshold line here, you can see there's where the 34 falls. The 6.8 falls there. And obviously, our administration is less than both of them.
So, release is authorized. There's no regulatory action needed, a very simple case. As long NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
56 as the number is less than the two thresholds, there is no regulatory action needed. So, this is the most basic case.
So obviously, the next examples, we'll get into a little bit more detail here. If we're going to calculate a patient-specific threshold which is coming up in my next example and we would calculate it this way, this is the activity. The basic activity threshold has been exceeded from Table 1.
And so now the licensee determines that they want to calculate the patient-specific threshold.
And so, the patient specific threshold as Dr. Tapp talked about is modified. You're taking the threshold from Table 1 and you're modifying that value.
So, in the equation that you see there, the letter Q is representing the factor from Table 1, the basic threshold. And then you have four factors in the denominator. F sub-B is biokinetics. F sub-O is occupancy factor. F sub-G is the geometry factor.
And F sub-A is the attenuation factor.
And so, you basically take that value from Table 1. You divide it by the produce of those four factors. And you get Q prime. And the Q prime represents this new patient-specific threshold.
And then you can make the decision again.
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57 If the administered activity, for example, administered activity is less than Q prime, then you can be sure that the bystander -- the maximum bystander is not going to exceed a dose of 5 millisievert. So, in Example 2, we see here that we have a 75-year-old male who's administered 7.4 gigabecquerels of Lutetium 177.
From Table 1, we see that the basic activity threshold is 4.1 for release. And the basic activity threshold from Table 1 for instruction is 0.82. And now obviously here it's 7.4 is greater than both of those values.
And so, what this would say on the surface is if I only went by Table 2 and I only looked at the basic threshold, I would say I cannot release this patient. I have to do something else. And so, as the third bullet says, the licensee decides to calculate patient-specific thresholds.
So, Im going to take this value of 7.4 and Im going to modify it by those four modifying factors. And I believe actually in this example some of those factors are left at the most conservative level and others are actually calculated here. So, first factor is occupancy.
And so, the occupancy factor is determined NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
58 from the patient interview. And so, heres several bullets here and Ill read through them. But several bullets to talk about heres what the physician or the medical physicist has determined from the patient interview.
So, the patient says his spouse will drive him home after administration and he's going to sit in the back seat of the vehicle. He plans to sleep next to his spouse. Says he has a king-sized bed, and that can be important. The king-sized beg can be important because it allows for more separation.
He eats meals with his spouse, but the two are in close proximity for no more than about four waking hours of a day. Nobody else lives in the house, but his daughter plans to stop by for dinner a few days after treatment. He's retired and he can stay home for the first few days after treatment.
And he plans to go to the grocery store and go to church on the weekends. So, one thing to consider here is the half-life, the physical half-life of the radionuclide. And so, for Lutetium 177, it's nearly a week, a 6.7 day half-life.
So, what this means is that the medical physicist is going to be thinking in terms of a few weeks. What are the exposure -- potential exposed NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
59 people, the bystanders, over the first few weeks of this person -- for this person after release from the hospital? And so up in the small bullets up there, I've underlined people who are going to be exposed or could be exposed.
And so, I have spouse, daughter, groceries, and church noted. In reading all of this, what we see is that, yes, the daughter might stop by for dinner a few days after treatment. But the daughter is very likely not going to be the person who's exposed the most.
In reading through this and likewise, going to the grocery store, going to church on the weekends, those people will probably not be the maximum exposed individual, but the spouse will be.
And so, we consider the spouse and consider the characteristics of the spouse in the first few weeks.
And what's happening here according to the patient interview, we have about eight hours of sleep and about four hours of contact.
And so, eight and four obviously divided by 24 is 50 percent. So, we're going to assume conservatively -- conservatively assume the patient-specific occupancy factor is 50 percent. If the nuclide had a half-life that was very short, then we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
60 would be focused more -- and the patient interview would be focused more on what's going to happen with this patient for the first few hours, for example, if it's a really short half-life, for the first few hours after exposure or for the first day or two after exposure.
So, depending on the half-life of the radionuclide, we might change our focus here to the side who is probably the maximally exposed individual.
For the spouse, we'll use an occupancy factor --
assuming the spouse is the maximally exposed person, we'll assume an occupancy factor of 50 percent.
Geometry factor plays into this as well. And this consideration of geometry factor came out of a lot of the comments that came through to the NRC a few years ago about 8.39.
And that is that geometry really wasn't being considered. And the fact that a patient could be a source and the maximally exposed -- I mean, a point. And the maximally exposed person as a point, it's not realistic. So, what we did is we've gone a lot of the work for you in determining what happens if we assume, for example, that the patient is a point or the patient is a line, a line through the torso essentially.
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61 And then the bystander is a point, or the bystander could be a line for saying that all the organs of the torso, for example, are exposed equally.
And so, we did the calculations ahead of time. And what we've developed here is a table for a table of values for the geometry factor.
And what I want to point out is if you look in the right most column, it says, point to point, geometry factors. And if you look at one meter down in the left column, you look for one meter with a point to point and the geometry factor is one. And that's exactly what it should be because with the basic thresholds assume point to point, a point source and a point target calculations and at one meter.
And if that's still what you'd like to use, then the F sub-G is going to be one which also notice in this table is the values above that line above the one meter which means distances closer than one meter, you see the geometry factor can increase and can be greater than one. This is something you have to be cognizant of. This is kind of where the king-sized bed comes into play because the assumption that is made here is that even when the spouse -- even when the man and his spouse are sleeping together, they are still approximately only one meter away or up NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
62 to one meter away.
And this is because of the king-sized bed.
If they had said in the survey, for example, that they sleep together in a twin bed, then you know thats going to be very close. And so, the geometry factor has to change then for that kind of occupancy.
So, what's going to be assumed here going up to the bullets there at the top, the patient spouse is likely the maximally exposed individual. And it's assumed that on average exposures occur at approximately a meter. It's not a bad assumption.
We know that there's going to be times when it's closer and times when they're farther away.
But for the most part during that 50 percent occupancy, I think a meter is a good approximation.
We say the licensee chooses to assume the radiation source is a point. In this case, the Lutetium 177, we'll call it a point.
But the radiation dose absorbed by the spouse is better represented assuming a line receptor, assuming that the spouse is a line, and that line is representing the torso. And then from Table B1 that's in the draft, we look at modifying factor 0.87, the geometry factor. So, we are taking into account that the exposed individual is not a point but that the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
63 distance of separation is still one meter. And we call F sub-G 0.87.
And then for biokinetics and attenuation factors, we choose -- we the licensee chooses to go with the conservative values. So, this one in the first bullet says licensee chooses the most conservative biokinetic and attenuation factors. And second bullet, that means the biokinetic factor is one.
F sub-B is going to be 1 if conservatism is chosen for this factor. It's always going to be one because then that goes back to the basic assumption that there is no biological loss.
Radiological loss is considered, but there is no biological loss.
Then attenuation factors, it's determined for whatever reason. This licensee determines that we're just going to use the most conservative attenuation factor. And I have the curve here for Lutetium 177.
And what this curve shows on the Y axis is the attenuation factor. Then on the X-axis is tissue thicknesses between zero and 50 centimeters. And this is meant to be the tissue covering the source.
So, they're all standardized from zero to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
64 50 centimeters from thin patients to larger patients.
And so, if you have a good estimate of maybe where the source might be and how thick the patient is, then you can get a good estimate of attenuation factor.
And as Dr. Tapp talked about, the attenuation factor considers both attenuation and buildup of photons.
And so, this is why some of these factors are greater than one. It's because build up is greater than attenuation in the shallow thicknesses.
And so, what we see from this plot is that the attenuation factor maximum is about one and a quarter, 1.25.
And if we look at Table A1, we will actually see what the maximum value is. And we see in that table it is listed as 1.25 for Lutetium 177. So, the licensee decides I don't really want to go through extra work here. I'm just going to choose the maximum value.
And what the licensee can do is they can say I'm going to choose these most conservative values and go back to my calculation for the calculation of the patient-specific threshold. And if I don't need to do extra work here, I'm not going to do it. If I do need to do extra work, then I can come back to these values and sharpen the pencil and look for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
65 values or go to values that are more specific.
For example, I could estimate the tissue thickness and use a value that's more realistic then just using the maximum here. So, the licensee chooses these values. So, for this patient then, depending on their stated habits, plans, so forth, the release in instruction thresholds are -- so we put this through the calculation, and we see now that the release threshold -- patient-specific release threshold has increased from 4.1 to 7.5 because of the factors that we've chosen, because of the factors that we can justify for this patient.
F sub-B is one, F sub-O is 0.5, F sub-G, 0.87, and F sub-A, 1.25. And given those factors, the release threshold goes to 7.5. We do the same calculation essentially for the instruction threshold, and we get the instruction threshold increasing from 0.82 to 1.5.
Now as I was saying, we could go back and sharpen the pencil if needed. But we don't need to in this situation. Licensee doesn't need to sharpen the pencil here because 7.5 for the release threshold is about 7.4, and this says that I can release the -- I as the licensee can release the patient.
The last major bullet says the patient can NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
66 be released but must be provided those minimizing instructions because it is greater than the instruction threshold. And those instructions, the small bullet there, those instructions must be consistent with the state plans, the sleeping arrangement. So, the licensee should remind the patient that we are releasing you, but we're assuming that these things will happen.
The sleeping arrangements and not seeing anyone for long periods of time other than spouse, so forth. And so all of that must be reiterated with the patient to make sure that the patient does not expose someone to a value that's great than -- I'm sorry, doesn't expose someone to a point where 5 millisieverts could be exceeded. Because what this is saying is that if this threshold is 7.4 that we've calculated as saying with these specific stated plans, the maximum exposed individual, the spouse, is not likely to exceed 5 millisieverts with these plans.
And so that's why they need to be reiterated in the instructions. Okay. Third example, iodine administration and Ralph Lieto might -- this might answer some of your questions. So, in this one, we have a 46-year-old female who's administered 1.8 gigabecquerels of Iodine-131, sodium iodine.
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67 The proposed activity thresholds in Table 1, so the basic thresholds for iodine are 0.32 gigabecquerels and 0.63 gigabecquerels. And I just have a note there that says, recall the current -- the current release threshold is 1.2 which is a factor of 4 greater. Okay. So, because 1.8 is greater than both thresholds, the licensee decides to calculate patient-specific thresholds.
So, the licensee chooses to determine a value for each modifying factor. And then the questions of release obviously then are with the patient-specific thresholds that the licensee is about to calculate, is immediate release allowable and are instructions required? Basically, going to compare to the release and instruction thresholds calculated for this patient.
So first, biokinetics, so in this example, it says consistent with current. They will be one of the current guidance and several citations in the literature. The licensee assumes a double exponential retention model for elemental iodine, very similar to what's been done currently.
And so, uptake fractions, what the licensee has determined, and maybe the licensee has the wherewithal and the resources to do these NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
68 calculations and maybe they don't. And so, the guidance provides other ways of calculating F sub-B.
This is one of the more detailed ways I'd say.
So, uptake fractions from the literature, 0.2 and 0.8 for extra thoracic and thyroid components are assumed with effective half-lives of 7.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and 125 hours0.00145 days <br />0.0347 hours <br />2.066799e-4 weeks <br />4.75625e-5 months <br /> respectively. And so, I think this is what Ralph was talking about in terms of class of patient.
So, this is from citations in literature, maybe even the licensee has the resources to have a lot of data on file where they can say that this particular person is in this particular class and therefore, we can make these assumptions for this particular class.
Again, I can't answer for the NRC. So maybe the question should be asked again. But anyway, if there is a -- if you have the data, it would seem that data would be useful.
Third bullet, iodine has a radiological half-life of 192 hours0.00222 days <br />0.0533 hours <br />3.174603e-4 weeks <br />7.3056e-5 months <br />. Okay. So, the biokinetic modifying factor is essentially defined as the effective half-life divided by the radiological half-life. And so, in this case, the effective half-life is from these two components, from these two exponential components.
We have 20 percent of 7.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and 80 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
69 percent of 125 hours0.00145 days <br />0.0347 hours <br />2.066799e-4 weeks <br />4.75625e-5 months <br />. And we divide that by the radiological half-life. And we get a biological factor of 0.53.
So, this is going to be the biokinetics factor that we use for calculating patient-specific value. Occupancy, very similar to the previous one.
During the initial patient interview, the patient says she's going to drive herself to and from her apartment
-- her appointment, sorry.
So, she's going to drive herself. She'll sleep with her husband but will keep her distance otherwise. And in this case, maybe a reminder of what that means, keep your distance several meters away during the day, whatever would work.
But she's going to keep her distance, otherwise sleeping with her husband. She's retired, but her husband is still working. This is important because the husband will be out of the house during the day.
And then no other individuals live in their home. So, this one seems fairly straightforward that the husband is going to be the maximally exposed individual. And with the eight hours of sleep and a 24-hour day, 0.33 is the occupancy factor.
So, in this case, it's fairly NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
70 straightforward with her arrangements and we'll still use an occupancy factor of 33 percent. The geometry factor similar to the previous one, the patient is administered Iodine-131. The bulk of the radionuclide is expected to concentrate in the thyroid.
And so that's how we're justifying basically a point source, the point source in the thyroid. The basic threshold assumes the point-to-point geometry at a meter for this case. For this patient that we're going to assume a point source in the thyroid but then a line receptor like we did in the previous example, torso with a maximum bystander.
And then again, we see an F sub-G of 0.87.
And then the attenuation factor, we look at the -- we can look in Table -- was it Table A1, I think? We can look in Table A1 and we can see what the maximum value is. And from this plot, we can see the maximum value looks like it's about 1.02 or something like that.
Or what we can do is we can actually try to determine what F sub-A should be for the given situation. And so, we've said that the Iodine-131 concentrates generally in the thyroid. And we're going to estimate -- as the licensee, we're going to estimate that about two centimeters of tissue is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
71 overlaying the thyroid to the front.
So, we're going to assume 2 centimeters.
And if we look at 2 centimeters that the attenuation factor doesn't come off one. And so, we can justify an attenuation factor of one.
If the patient were larger, then we might justify attenuation factors less than one depending on that estimate. Recall F sub-A accounts for both attenuation and buildup. And so, we have F sub-A is equal to one in this example.
All right. So, the patient-specific thresholds, again, like we did previously, here's administration of I-131. The release threshold patient specific goes from 0.32 to 2.1. And you can see that we have the biological factor 0.53, the occupancy 0.33, geometry 0.87, and F sub-A of one.
So, we go from 0.32 to 2.1 for the release threshold, patient-specific, and a patient-specific instruction threshold of 0.41.
Recall we had a 1.8 gigabecquerel administration. So, with this, we can release the patient. And again, minimizing instructions, reiterating to the patient what they have told you in the interview, keep up with what you said is going to occur. And we can be pretty certain then that the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
72 maximum bystander will not exceed a dose of 5 millisieverts.
Okay. Example 4, now this is getting into a whole time. So, let's suppose we do the calculations. The basic thresholds are exceeded. We do calculations, sharpening the pencil as much as we can for the patient-specific thresholds and the administered activity is still in excess of those values.
So that says one of the options here would then be we've got to hold the patient for a certain amount of time. And basically, what we're doing with the hold, we're allowing for radiological decay and we're allowing for biological loss in the meantime.
So, first bullet says we're going to use the previous example. But we're going to change the administered activity to 2.3 gigabecquerels. All right.
And I'm changing that purposefully because I know with the release threshold is the second bullet there. And I'm going to assume that we've sharpened the pencil as much as we can there with that value.
And so, we don't have a lot of choice here.
But we have administered activity of 2.3 and the release threshold is 2.1. So, saying while we can't release this patient, but for how long do we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
73 have to hold them? So, all of this obviously is set up so that I have to hold the patient.
Third bullet says retention data for this patient indicates that about 70 percent of a pre-treatment administration is retained in the patient's body after 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. So, we give a pre-treatment of Iodine-131 to see how its going to behave in the patients body. Maybe we do a measurement with instrumentation.
We do a measurement, and then 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> later we do another measurement. And we see that about 70 percent of the activity is still there.
Okay. Ive made up these numbers.
So, we do that. And then we say using Equation 11 in the specific section and page there, using this Equation 11, we're going to calculate a hold time. And what you see here is that the hold time relies on four values, and those four values are given in the problem.
So, the four values are the 48-hour time between measurements, okay, divide by the natural log of 0.7 which is the 70 percent remaining and then multiplied by the ratio of the natural log of 2.1 which is the release threshold over 2.3 which is the administered activity. I do that calculation. I get NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
74 an answer of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
So, this patient would need to be held for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if all these things were true. Last example I think I have, so this example says, what if the patient is breastfeeding? All right. So, we have a 26-year-old female who is administered 0.04 gigabecquerels of Zirconium-89.
Table 1 indicates the basic threshold of 0.26. And the basic thresholds of 0.26 which is for release and 0.052 which is for instruction. And so, what we do, again, we're going to place those on this.
We can do this mentally by now, of course.
But we place the 0.04 on this chart essentially and we say, yeah, it's less than. So, we can release this patient.
But then the patient tells us they're breastfeeding, hopefully not that close in time.
Hopefully, they've told us this ahead of time. But we can say, okay, the patient themselves can be released.
But since they're breastfeeding, we need to check to be sure that the infant who is being fed is not going to exceed one millisievert. And if they are, then we need to calculate a time for interrupting breastfeeding. So, we go to Table 3.
And Table 3 is the breastfeeding activity NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
75 thresholds. And we see down at the bottom of Table 3, we see Zirconium-89. And we see that 5 millisieverts or the 5 millisievert, Column 1, 0.01 gigabecquerels, and then for Column 2 for one millisievert, we see 0.002.
And we look back up at our example which is 0.04 gigabecquerels administered. And we see that we exceed both those values. Okay. So, with the administration of 0.04 to the mother, there's a very likely chance that the infant will exceed one millisievert.
So, we have to do a little bit more work here. So, Table 3 provides the thresholds, again, 0.01 and 0.002. And the administration of 0.04 and an effective half-life determination of 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> for the patient that we could do the is in a similar fashion as the previous problem.
This patient instructed to interrupt breastfeeding for 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br />. So, you see the equation is given in the guidance. And we have the effective half-life, 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br />. And then we have the ratio of natural log of 0.04 which is the administration divided by 0.002 which is the instruction threshold.
And we use that instruction threshold because we are protecting to one millisievert. And NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
76 that gives us 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br />. So about 10 days, we're going to ask the female patient to not breastfeed for 10 days and to pump and discard the milk.
Some questions will come up, can -- some questions may come up. Can I save the milk and use it later? And in this case, the answer would be no, get rid of it. You need to do something else.
So, this is a calculation then of breastfeeding interruption. So, I have two remaining slides. And the reason I wanted to show you these slides was to show that there are alternative methods, first of all, alternative methods for determining F sub-B.
We have a table, or we have a plot in the guidance. And this plot is meant to be generalized and conservative. And you see on the Y-axis is the percent retained activity or dose rate if we're doing a measurement.
So, percent retained activity and then the X-axis is time administration as number of half-lives.
We had to do the X-axis, we had to do it this way so that we could make this plot generic for all radionuclides. And so, you see on there, there's nothing specific about a radionuclide other than the X-axis being relative to the number of half-lives --
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77 physical half-lives.
So, looking over the second bullet, it says, for example, if pre-treatment measurements indicate -- this is from the previous example. If pre-treatment measurements indicate 70 percent retention 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after administration of iodine which has a 192-hour physical half-life. So, we have the Y-axis is going to be the 70 percent.
You see there's the red line -- the red dashed line drawn there at 70 percent. And the X-axis is going to be 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> divided by 192 hours0.00222 days <br />0.0533 hours <br />3.174603e-4 weeks <br />7.3056e-5 months <br /> which gives us a relative number of half-lives. And that number of half-lives is 0.25.
And so, we have a line there. And so, where those two intersect, we're going to go to the line that is above that intersection. And so, the line in this case that is above that intersection is that orange line, burnt orange line.
And that burnt orange line relates to an F sub-B of 0.8. So, if we were to use this generalized conservative method, we could use a value for F sub-B of 0.8. When we did the calculation, I believe this was the problem, we did the calculation more closely and we got an F sub-B of 0.53.
It doesn't mean that one or the other is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
78 wrong. What it means is it's just kind of a level --
almost maybe a level of commitment in terms of how sharp do I need this pencil to be or how sharp do I want this pencil to be in terms of determining ability to release. The next one is just talking a little bit more about the occupancy factor.
There's a lot of text here. But basically, the bottom line is that for occupancy factor, there's a place in the guidance where it talks about basically calculating segments of occupancy factor. So, let's see.
If you look down to the -- one, two, three, four, five -- fifth bullet, it says occupancy can be segmented into F sub-1 for short-term exposure and F sub-2, long-term exposure. And then you sum them. Just add them together to get the full occupancy.
So, what this allows is that if you have a short-lived radionuclide, either short physical half-life or short biological half-life, you can estimate occupancy more closely if you consider the two time periods. So, there's information in the guidance about how you might consider that. The occupancy in the first time period might be close to zero and the occupancy in the second time period might be longer or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
79 vice versa, depending on the characteristics of the exposure and who that exposed individual is and so forth.
Bottom bullet says F1 and F2 are essentially fractions of time spent in close contact, modified by the expected loss of radioactive material during those times. That's essentially what is being done here is if the material is being lost from the body or decayed rapidly, then you might want to consider this idea of the segmenting of the occupancy factor, just a side note. So, to summarize -- last slide.
To summarize, patient release is authorized if radiation dose to any other individual is likely not to exceed 5 millisievert. Written instructions must be provided if doses are likely to exceed one millisievert. So, we've presented the updated methodology for guidance.
Updated breastfeeding interruption cessation guidelines allows for patient-specific exposure situations considering biokinetics, occupancy, geometry, attenuation which are all factors that were mentioned in previous comments a couple years ago. Previous comments about these factors should be considered and we did. And then easily NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
80 updated for emerging technologies. So, with that, I will release the screen and turn it back over to you, Sophie.
MS. HOLIDAY: Thank you, Dr. Hamby, for your presentation. We have allotted approximately 30 to 40 minutes for the question-and-answer portion of this meeting. Again, the is your opportunity to ask any clarifying questions that you may have for Dr.
Hamby or any of the NRC staff that are here today.
And a reminder that again we are not accepting any comments provided today as official comments on the proposed regulatory guide revision.
Rather, comments will have to be submitted in writing to receive formal consideration. To ask a question or provide feedback, please utilize the raise hand feature on Microsoft Teams. Icon looks just like this.
If you've joined us on the telephone bridge line, you can dial star-5 to raise your hand.
Teams will automatically put you into queue in the order of hand raising. Once I have called your name, I will unmute the microphone.
If you are on the audio bridge line, you'll have to dial star-6 to unmute your microphone yourself. To ensure that everyone has been given an NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
81 opportunity to ask their questions, we ask that you only ask one question at a time. If there are no additional questions or time permits, we will take your additional questions.
For the transcribing, we ask that you state your name and your affiliation if applicable.
At this time, if you have any questions, please raise your hand now. Prasad Neti, I see your hand raised.
One moment, please.
Prasad, your microphone has been unmuted.
Please identify yourself for the court reporter and proceed. Prasad, you'll have to unmute your microphone. You have the ability to do that on your end now.
MR. NETI: Can you hear me now?
MS. HOLIDAY: Yes, we can hear you now.
MR. NETI: Hi, Prasad. Thank you, first of all, for giving me the opportunity. Thank you.
I'm Prasad, Neti, Radiation Safety Officer, Rutgers University Newark campus.
So, I have a simple question. First let me thank Dr. Hamby for a beautiful generic presentation of calculating all the parameters in the denominator. But I do have a question.
These denominators are fractions are for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
82 standard site, right? However, even for the larger patient, there is a factor attenuation buildup is folded in there. But I do have a question related to I-131 versus beta emitter.
If you have a larger patient as a point source compared for Iodine-131 with 364 compared to a technetium which is a beta emitter. Does the body shield automatically in the attenuation factor? Or does the body size matter on the person of the uptake in the case of Iodine-131?
DR. HAMBY: Do you want me to do that, Katie?
DR. TAPP: Sure, go ahead.
DR. HAMBY: So, for the beta emitters, actually for any electron emitter, whether it's a photon emitter or not. But if it's emitting electrons, all of those electrons are considered in Bremsstrahlung calculation. So every nuclide will have some -- well, most every nuclide will have some Bremsstrahlung component, first thing.
The factors for attenuation or the F sub-A, the attenuation factor with buildup and so forth, yes. All of the photons that are created go through that calculation as well. I hope that -- does that get what you're asking?
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83 MR. NETI: Yes, that's correct. But another question -- it's not another question. It's the same question. Does the larger patient uptake varies with the size? Or the thyroid size remains the same?
DR. HAMBY: Oh, okay, yeah. Uptake, biological loss is not size dependent.
MR. NETI: Thank you.
MS. HOLIDAY: Thank you for your question, Prasad.
DR. HAMBY: Well, yeah, let me just throw on. It's not size dependent in the examples I showed.
If you have data that show size dependence, then I would say you could use that as your justification --
as part of your justification for the modifying factor.
MR. NETI: Thank you.
MS. HOLIDAY: Thank you, Dr. Hamby. Mr.
Crane, I see that your hand is raised. One moment, please. Mr. Crane, please go ahead and unmute your microphone.
MR. CRANE: Thank you. Thank you, Dr.
Hamby. That's been extremely informative and clearly reflects great responsibility and thought. And Sophie will tell you my reputation at the NRC is not that of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
84 a flatterer. It rather goes on the other side.
Sophie is grinning which will tell you what that means.
My concern -- well, to explain where I'm coming from, I'm a 50-year survivor of thyroid cancer.
And in my day, I had about 25 gigabecquerels of Iodine-131. And I have stayed very close over the years to the problems experienced in the real world by today's thyroid patients, many of whom are women of childbearing age, many with children. And their concern has to do with things like the child who creeps -- and plops down with a thyroid very close to their own.
My question is, are you confident that this reflects actual practice in the real world given that it's voluntary on the part of licensees, whether they comply with this Reg Guide. And it's then voluntary on the party of patients, whether they follow the instructions. And we've seen with COVID that telling people to do something and having them do it aren't necessarily the same thing. Do you care to offer your thoughts?
DR. TAPP: I'll start with this. And then, Dr. Hamby, if you want to add something. The baseline is allowing for the conservative assumption.
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85 And then what the proposal is, is the licensee has to go out and ask these questions.
So, the current draft is asking licensees to reach out more to patients to get these patient-specific values. As you know in the geometry factor, there's allowances to change it to the patient -- for the member being exposed to be aligned. But if you look at the draft guidance if we know that the child is one to be exposed more so, it's going to be your maximum exposed bystander.
You may then appoint maybe an approximation or better conservatism if it's a small child. We also are adding geometry factors. If you're holding a child, the recommendation now is to use a closer geometry factor based on those children.
So, this guide is trying to capture some of those scenarios that you're brining up with the children and the house and asking those questions.
Who is in your house? Having that open ended dialogue to try to open up a little bit more to find out what is the scenario for this patient and the patient's family and their maximally exposed person that's in there, opening it up for children.
So, I think the guidance is reaching out more and showing that it is the NRC's expectation that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
86 licensees ask these questions to modify these baseline values to account for children or different scenarios that are out there. As I mentioned at the beginning, the regulation has not changed. So still it is the onus on the licensee to demonstrate that every release, it is not likely that someone is going to be exposed to greater than 5 millisieverts.
So that stays the same. But we're showing that our expectation that each release is adequately justified and demonstrated that they're in compliance.
I think that's one of points of this Reg Guide. If you feel like it's not going far enough, comments are greatly appreciated.
MR. CRANE: I'm sorry. I certainly will comment. But my question is this. What's your level of confidence that this actually going to happen?
Because when you have, for example, ahead of the ACMUI saying we whisk them out the doors reflecting that they just don't do it in many cases. What makes you think that suddenly they will start doing so?
DR. TAPP: I do think that this draft guidance, one of the purposes is to demonstrate that it is the NRC's expectation that each patient release is demonstrated that it is in compliance with that regulation. It's not a generic grouping but as each NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
87 patient release. And that's where the baseline values went up, so we don't underestimate in some situations like a child being held or public transportation as we accounted in that SECY paper, in that evaluation. So, the guidance is showing that it is the NRC's expectation. And it is the regulation that each release is in accordance with this regulation.
MR. CRANE: Okay. Thank you.
MS. HOLIDAY: Thank you, Mr. Crane.
MR. CRANE: I'd be curious to hear Dr.
Hamby's take on that, very interested.
DR. HAMBY: So my take -- this is very politically charged, I think. But my take is I think it is the licensee's responsibility to tell the patient what will happen if you don't adhere to our instructions. If you allow that child to climb up on your neck, the child is going to get extra radiation dose that could be harmful to them. And I feel like the burden falls to the licensee to make sure they explain it to the patient very clearly.
MR. CRANE: Thank you.
MS. HOLIDAY: Thank you, Mr. Crane. And thank you, Dr. Hamby and Dr. Tapp. I do see a comment in the chat. I will pose the question as the individual does not have access to a microphone.
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88 We have a question from Matthew Hall, medical physicist at NARPS Incorporated, Chicago, Illinois. Why did initial Reg Guide version tabulate values for Yttrium-90? That isotope was removed from subsequent versions. But now Yttrium-90 table values have been added back to this revision. What are the internal inner thoughts on this isotope?
DR. TAPP: That is a good question.
Unfortunately, I do not have the historical knowledge going back all the way to the previous revision, 1997 version of the Reg Guide and why it was removed at the time. I think at the time there was an expectation that the Bremsstrahlung was going to cause exposures likely over one millisievert to require the instructions.
If I go back to the history knowledge, they didn't believe it hit that first level of threshold. At this time, we know there's merging radiopharmaceuticals. Activities are getting higher for these radiopharmaceuticals.
And we had the capability to calculate the Bremsstrahlung exposures. So, we did add it back at this time going back into it captures all these new radiopharmaceuticals coming out. If something does trigger a threshold, it is in there now and people can NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
89 use that. And I think that's important to know is there's definitely been changes from '97 to now when considering radiopharmaceuticals.
MS. HOLIDAY: Thank you, Dr. Tapp. And thank you for your question. I see a hand raised from Jerry Thomas. Jerry, if you would, please unmute your microphone and identify yourself and your affiliation if applicable.
Jerry, I'm afraid we can't hear you. If you would please unmute your microphone. Okay.
Jerry, I'm afraid I don't hear you. I'm going to move to the next person if you're able to unmute after, then we can proceed with your question or comment.
Scott Fuller, I see that your hand is raised. If you would, please unmute your microphone and state your name and affiliation for the court reporter.
MR. THOMAS: This is Jerry. I found it.
I'll wait for my turn.
MS. HOLIDAY: Excellent. Scott Fuller, if you would go ahead and proceed and then we'll take Jerry Thomas after you. Oh, dear. Well, let's jump back to Jerry. Jerry Thomas, please unmute.
MR. THOMAS: I have to figure out where the icons are. Apologize to everyone. My name is Jerry Thomas. I'm a medical physicist and radiation NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
90 safety officer in the state of Kansas.
When you were doing the draft for providing calculation guidance, these Reg Guides are used broadly by people that have varying degrees of experience and expertise. Was there any consideration given to provide calculation release guidance for people that have special medical conditions in addition to what they're being treated for, specifically a patient that's undergoing dialysis?
DR. TAPP: Hi, Jerry. That's a good question. It has been talked about. Unfortunately, at this time, we did not do a dialysis calculation in the background. It was not included in this first calculation. But it would be appropriate for comments. I do know with some of the new radiopharmaceuticals coming out that we are seeing a higher patient population with dialysis.
MR. THOMAS: We have a rather broad variation of patient types and medical conditions now with the newer treatments that are being proposed.
And I will submit comments. But my suggestion is, is that in addition to comments that are submitted, you may want to consider that for either this revision or the following revision.
DR. TAPP: Thank you.
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91 MS. HOLIDAY: Thank you, Jerry. Let's see. Scott, if you'd like to try to unmute your microphone one more time.
MR. FULLER: Hello, can you hear me?
MS. HOLIDAY: Yes, we can hear you.
MR. FULLER: Good. I appreciate this opportunity and recognize the efforts made. My question was just I started placing it in the chat but was just in regard to the fact that the ACMUI reviewed this draft in 2022 and made a number of recommendations. And I'd like to hear a comment back as to how the committee used these recommendations to modify the draft.
Specifically, they talked about the use of an occupancy factor of one being unrealistic for Tables 1 and 2. And then they also went on to indicate that the calculations seem to be overly complex for many of the facilities where these treatments are happening and that a simplified equation should be considered. So, if you could just speak to were those comments considered and why were they dismissed in the current version of the regulatory guide that's out there. Thank you.
DR. TAPP: Thank you for your question.
The ACMUI's comments were considered by the working NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
92 group that worked on the draft. As for the occupancy factor, that comment is correct that they did recommend use of the 0.25 occupancy factor for radionuclides with a half-life of greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or what is in the current version.
And the working group felt to keep it at the one for now which is the more conservative value based on the evaluation that was done in 2018 that found that that assumption can something underestimate exposure in certain scenarios such as public transportation in addition to co-sleeping as the NCRP Report 55 mentions. In addition, the ACMUI did recommend that a simpler modifying factors be used.
And if you noticed there is changes between the report that the ACMUI did receive and then the draft report that's out for comment.
It was focused on adding more talk on using conservative modifying factors in combination with the patient release factor. So, if a patient release calculation was done, one could modify maybe one or two of those factors but then choose to use the most conservative factors for the other factors.
There is an ACMUI response memo that goes through each recommendation individually and provides the working groups and the NRC's comments on that.
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93 It is important to note that that discussion that's out for public comment now is a draft and now we're receiving the general public's comment in addition to the ACMUI. And ACMUI will also have another chance to review the document and provide comments to the NRC staff before that final version is open. So, it is important. This is the draft, and we're looking for all comments on it and then the final version.
MR. FULLER: Thank you.
DR. TAPP: Thank you.
MS. HOLIDAY: Thank you, Scott. And thank you, Dr. Tapp. Bryan Lemieux, I see that your hand is raised. If you would, please state your name and affiliation and proceed with your comment or question.
MR. LEMIEUX: Bryan Lemieux, I'm a medical health physicist in Kentucky asking on my own behalf questions. So I guess for the first question, and I'll raise my hand again later, has to do with the concept it did not carry over from NCRP 155 on how to do the sort of release calculations. NCRP 155, I think, as a lot of people consider it to be, like, a really good approach.
And what was presented in this guidance, it's a very good technical approach. It's certainly a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
94 vast improvement, I think, over 8.39 in terms of accounting for different scenarios and laying out really all sorts of things that really need to be considered by licensees. And so I think that's a noble improvement there.
But one thing that didn't carry over --
well, it has its issues which I'll ask questions about later and I'll comment later in the comment period.
But I didn't see anything -- and this came up in Scott's comments about the occupancy factor, the idea of occupancy combined with variable index distance.
And I didn't see that really because it's not that the occupancy factor I think of 0.25 was really the problem with the sleeping in the -- it was the index distance that really was the problem.
And it appears in the methodology that was proposed here. It's kind of like you had your geometry factor but then you didn't account for variable index distance with geometry factor to do that. So I'm curious as to why the NCRP 155 approach wasn't sort of just adopted, at least for those types of issues because it seems to make so much more sense and it's so much easier to understand than this sort of, like, weird occupancy factor framework that sort of accounts for variable things, at least to my mind.
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95 So I guess that's my first question.
Like, what was the thinking there? Maybe that's something that could be considered or, like, a different revision or something. I don't know.
DR. TAPP: And thank you for your question. I think that would be a fair comment to reference the NCRP 155. I will say that was used as reviewed by the working group. And I know Dr. Hamby's team on their recommendations, they reviewed NCRP 155.
The four factors came out as generally an approach here. But I think a comment is to support using index factors could be looked at again if you wanted to submit that as a comment. I don't know if -
- Dr. Hamby, I saw you come off, if you wanted to add something.
DR. HAMBY: Yeah, there is mention in the guidance about the combination of F sub-0 or F such naught and F sub-G -- F sub-O and F sub-G. When determining who the maximally closed individual likely is, you may -- and this is kind of the way it's said in the guidance that a product of those two values would give a good indication. It would be, like, this indexing of geometry for occupancy.
If you have a potentially exposed person who might be the maximum person and they are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
96 consistently half a meter away but their time there is shorter than another person who is a meter away, you would want to consider that. And I think that's what's being talked about here is you want to consider that. So there is this -- I can't point to it because I don't have it up in front of me. But there is a place that I recall that F sub-O and F sub-G are talked about at least as being potentially dependent on each other. And so that is where --
MR. LEMIEUX: I think it'd have to be intrinsically dependent on each other, right?
DR. HAMBY: Well, yes. But once you determine who that maximum individual is, then the dependents -- I mean, then that's where the dependence is, right, in determining who that maximum individual is.
MR. LEMIEUX: What would you -- yeah, in determining who that maximum individual and what their dose is to figure out. In your methodology, you're calculating a limit instead of a dose --
DR. HAMBY: Correct, yeah.
MR. LEMIEUX: -- which is different than the way that we've all consistently previously thought about it. We're used to calculating a dose and not a limit --
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97 DR. HAMBY: Sure, absolutely.
MR. LEMIEUX: -- when we're doing the calculations.
DR. HAMBY: Absolutely. The regulation just states that you will not exceed 5 millisieverts.
And we're giving what we believe to be a fairly straightforward method of saying you will not exceed 5 millisieverts if the administered activity is below this number.
MR. LEMIEUX: And to clarify, NRC is going to -- has anticipated to adhere fairly strictly to the guidance. And licensees should in theory be able to adhere to say NCRP 155, other methods, correct?
DR. TAPP: So the guidance is -- a Reg Guide is one acceptable method to be in compliance with regulations. So NCRP 155 may be another acceptable means. We're not endorsing that, but I would -- licensees can demonstrate that if it shows compliance and they demonstrate they're using it correctly in the regulation, then the NRC's inspectors and regional staff would then -- it meets the regulation, it meets the regulation.
MS. HOLIDAY: Thank you, Bryan. Thank you, Dr. Tapp. And thank you, Dr. Hamby. Roxanna Kimes, I see that your hand is raised. If you would NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
98 please state your name and affiliation and proceed with your question or comment.
MS. KIMES: Katie just actually answered my question. So I can take my hand down.
MS. HOLIDAY: Excellent. Thank you, Roxanna. Stanley Hampton, I see that your hand is raised. If you would, please state your name and affiliation and proceed with your question or comment.
MR. HAMPTON: Hi, Stan Hampton. I'm with Eli Lilly and Company. And on the breastfeeding interruption tables where you list F-18, you only list it as FDG. There are certainly other F-18 diagnostic imaging agents, and the list will grow. If those imaging agents don't have the same distribution of FDG, how will we take that into account? Because they with be different distributions.
DR. TAPP: Yes, you are correct that the table in the Reg Guide does only list the radiopharmaceutical FDG. The importance of listing the radiopharmaceuticals is to show there are differences in the radiopharmaceuticals. So at this time, this is the table and the radiopharmaceuticals that the NRC has the values that we're proposing. And we don't have methods yet for radiopharmaceuticals coming out in the future to develop more at this time.
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99 So we'd have to -- the licensee would have to do their own calculations if they want to calculate for other radiopharmaceuticals and strike that scientifically justifiable.
MR. HAMPTON: Thank you.
MS. HOLIDAY: Thank you, Stan.
DR. TAPP: I was just going to comment licensees or manufacturers if the manufacturers do the calculations. Licensees could use those calculations.
Thank you.
MS. HOLIDAY: Thank you, Dr. Tapp. Mr.
Zoubir Ouhib, I see that you had is raised. Please unmute your microphone and state your name and affiliation.
MR. OUHIB: My name is Zoubir Ouhib. I'm a medical physicist in South Florida, Florida Atlantic University. My question actually is in the chat, but I'm just curious now.
Imagine an area that the patient is interviewed then says, okay, who do you live with?
Well, I have a husband and I have a pet, whatever that is, a cat or a dog, whatever. And they perhaps insist that they want to make sure that their pet is protected if they hear that there might be issues related to radiation. Is it that these rules don't NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
100 apply to animals or strictly human being, period? But on the other hand, what if the patient insists to have some guidance regarding that?
DR. TAPP: Thank you, Zoubir. So the regulations and the NRC policy is for protection of the public and workers so humans. Our regulations do not apply to animals. However, calculations can be used.
A point could be used for an animal. So if a licensee would like to calculate conservatively to an animal, they could use these calculations. In addition, there are tools from the NRC that can be used to calculate doses farther out if people would like to calculate out farther using MCNP, the licensee so be inclined and can will.
So licensees could use this and the numbers in a way. But the regulations do not apply to pets. They only apply to the humans.
MR. OUHIB: Thank you.
MS. HOLIDAY: Thank you, Zoubir. Thank you, Dr. Tapp. Tianliang, I apologize if I mispronounced your name. I see that your hand is raised.
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101 court reporter. Tianliang Gu, please unmute your microphone if you'd still like to provide a comment or ask a question. Okay. I cannot hear you. So before I go to the next raised hand, I would like to remind everybody if you joined us via telephone line --
MR. GU: Hello.
MS. HOLIDAY: Oh, yes. I can hear you.
MR. GU: Okay. Sorry, I forgot how to mute myself. I'm Tianliang Gu. I'm a physicist and also a radiation safety officer at UT Health at Houston.
So I have one question here because I'm used to the version of the 8 and 9. At Version 1, there's more, like, a true compatible model. That model is used for void or the cartilage. And I remember the highest recommended is about 100 mercurial for Iodine-131. But for the newest one the method to calculate because newest one recommend is pretty low dose for Iodine-131.
DR. TAPP: Sure. So if you're looking at Revision 1 of the Reg Guide, the actual tabulated values are not based on the biokinetics. That value is actually provided in an example. And they're doing biokinetic modeling.
The assumption used in Revision 1 is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
102 assuming in the tables -- assumes, like, or tables in the baseline is that 100 percent stays in. It's physical decay. So you can still use it if it's still scientific and works for the patient situation you're working with as long as you justify it.
And the draft is proposing methods to justify your biokinetic model that you choose. And it provides you the documentation that you need to have if you choose to use that value. So it can still be used if that's the recommended value.
The guidance also gives you ability to use other types of biokentic modeling if that works better for your patients. Or as we know, there's more radiopharmaceuticals coming out. It allows for those to come in and then for the licensees to choose the biokinetics that are appropriate for those new radiopharmaceuticals, if that makes sense.
MR. GU: Okay. That's great. So I can still use the kind of biokinetic model to calculate for specific patient, right? I mean, I have to put that in the release document and say we use this calculation, right?
DR. TAPP: Yes, you still need to document it in accordance with --
(Simultaneous speaking.)
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103 MR. GU: Okay, good.
MS. HOLIDAY: Thank you, Tiangliang, for your question. Bryan Lemieux, I see that your hand is raised again. If you would, go ahead and unmute your microphone.
MR. LEMIEUX: Thank you so much. Just one quick follow-up questions just on a totally different subject. So I was looking at the attenuation which the transmission modifying factors. I noticed Lutetium had a 1.25 as most conservative and the blanket instruction giving no additional information as you assume that that is the modifying factor, right?
So assume the exposure rate or this equivalent rate is 1.25, the theoretical at that distance. So I was wondering if the team looked at any of the published literature on that because there was, for example, a paper published in physics that I was the co-author on where we looked at, like, something, like, 400 patients administered Lutetium for cancer treatment and looked at -- put those actual values are indexed to BMI. And so I'm just curious because it doesn't quite play out that way in the real world.
And so to find MCNP and theoretical point-NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
104 kernel calculation and looking at that and things like that, I'm wondering sort of if the real world complexity of the situation is going to translate well to the theoretical model calculation. And so I was just wondering if the team has evaluated that at all and spot checked any of that and sort of what the thoughts might be on that. So I'll just leave that there, and this was my question. Thank you.
DR. TAPP: Sure. And that's a good question. The conservative value of 1.25 is the conservative value when a licensee does not want to use or own attenuation factor and have the basis and the justification for that. If they have a basis and justification for it using a different attenuation factor, the guidance points out then the documentation they would have to have.
There's an example in the guidance on page B10 which talks about using a torso radius for widely distributed radionuclides. I had not compared that with the guidance document. So if that's a comment you want to provide against that example maybe, it's going to provide in.
But for a widely distributed radionuclide, that's the example we have in the guidance -- in the draft guidance. And the reason we did not go down NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
105 each radiopharmaceutical is there's a lot coming out as you know. So the guidance we kept is unique and generic.
As we know, the science is constantly adapting now which we're getting a lot of new uses.
So it's trying to keep it open for licensees to use things in the future as the science evolves with that.
Hope it helped.
MS. HOLIDAY: Thank you, Dr. Tapp. And thank you for your second question, Bryan. Okay. At this time, I do not see any other hands raised. I'd like to remind you if you've joined us by telephone bridgeline, you can hit star-5 to raise your hand that way.
Or if you're on the Microsoft Teams application, you can click the icon that looks like a raised hand. It says raise so that you can raise your hand. Mr. Crane, I see that your hand is raised.
Give me one moment, please. Mr. Crane, please go ahead and unmute your microphone.
MR. CRANE: Thanks. I'll be very quick.
Again, it comes back to real world. It's very refreshing in Dr. Hamby's presentation to see somebody actually say above this level, you can't release them because usually it's presented as this is how you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
106 release them. In the real world when you say you can't release them, what do you think happens then?
DR. TAPP: There is requirements in the regulations on what happens when a patient is kept in a hospital. We do see patients being kept -- retained in the hospital for the radiation safety. The most common example would be the children you see in the MIBG.
And I know people on this call probably have more experience with that than me. But we do have patients who are held in hospitals that the licensee has determined it isn't appropriate to release them. They cannot demonstrate compliance. So hospitals do have the ability if they're able to administer these radionuclides, they have a license to hold patients.
And there is regulations then for how to keep the workers and the public safe than at their institution. This guidance has been updated to include reference to the Guidance NUREG 1556 Volume 9 Revision 3 which includes the guidance then for licenses on how to manage patients and the radiation safety aspects when patients are maintained in a hospital for radiation safety purposes and cannot be released. So that has been added as a reference over NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
107 to make sure it is clear that those are linked together.
MR. CRANE: Okay. I'm referring only to iodine. This is my sole concern. But in the real world, there are lots of facilities out there that simply will not hospitalize patients in part because insurance won't pay for them -- won't pay for the coverage. My question is, what do you think happens then to the patient who's told we can't treat you, we won't treat you unless you want to pay out of pocket?
What happens then?
DR. TAPP: The regulations that licensees must demonstrate that that patient is unlikely to expose another individual to 5 millisieverts. So if they're in compliance, that's -- out of compliance, that is a different realm. This is the guidance, the draft guidance for showing how they can demonstrate that. And it does include whole time calculations for licensees to calculate how long they may need to hold a patient. And please provide your comments.
MR. CRANE: Will do. Will do.
DR. TAPP: Thank you --
MR. CRANE: Thank you, Katie.
DR. TAPP: -- Mr. Crane. Thank you.
MR. CRANE: Thank you, Sophie. Thanks.
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108 MS. HOLIDAY: Thank you. Thank you, Mr.
Crane. Okay. Out of respect for time, I see that we have two hands raised. If it's okay with the NRC staff, I will allow the last two hands to be raised and then we will move into closing portion.
Out of respect for everyone's time, I know this has been a long meeting. So with that being said, Harrison Redman, I see that your hand is raised.
If you would, please state your name and your affiliation for the court reporter.
MR. REDMAN: Hi, can you hear me?
MS. HOLIDAY: Yes, we can.
MR. REDMAN: Hi, my name is Harrison Redman. I am a health physicist with Stanford University, but my question and thoughts are my own.
I want to thank the presenters and thank you, Dr.
Hamby, for your wonderful work as always.
I joined this presentation a little bit late. And so I apologize if I am asking something that has already been addressed. But I'm wondering about if this new revision has guidance on protecting individuals of the public who are not family members but something like a hotel worker or a certain situation like let's say there is a service that is commonly used to transport individuals from a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
109 hospital.
In that situation, you would worry about the driver of a car potentially driving home multiple patients that might've had a treatment like this. And I know the regulations are a certain dose limit per patient. But I guess I'm just wondering if there's been consideration for service workers who might find themselves around these individuals more frequently than a family member who's only around one situation.
Thank you.
DR. TAPP: And thank you for your question. This project here is focusing on the draft regulatory guide which is focused on the regulation.
And as you stated, that is limited to 5 millisieverts per release.
So it is focused on a single patient being released. But it does -- in the questionnaire, it does open it up to ask about outside the household.
So public transportation is -- when it's a close geometry, it is asking about that because we have identified public transportation when you're in close proximity.
So in short, it's asking that the licensee look to find the maximum exposed bystander. So that's where the draft guidance is today. And I'm welcome NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
110 for comments on that. And as I mentioned, this is focused on how to show compliance with the current 35.75 which per release.
MR. REDMAN: Understood. Thank you.
DR. TAPP: Thank you.
MS. HOLIDAY: Thank you, Dr. Tapp. Thank you, Harrison, for your question. And our last comment today or question will come from Mr. Ralph Lieto. Mr. Lieto, if you would please unmute your microphone.
MR. LIETO: Okay. Thank you. Yes, I want to also thank NRC staff for putting on this webinar and Dr. Hamby's presentation which has been very enlightening. My question stems from a follow-up that Bryan Lemieux initiated. And that has to do with the factors that were used in the Appendices B and C as examples.
There's the attenuation factor and I think some biokinetic factors. What is the origin of those tables and graphs? It appears that there's a reference given in the Reg Guide, but this is only draft. And is there some type of peer review literature or source where this information comes from? And then I have just a comment after that.
DR. TAPP: Sure. So you are correct that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
111 the reference is contained in the regulatory guide.
That was done by the Office of Research's contract with Dr. Hamby and his group at RCD. That is draft because it is awaiting public comments.
So public comments is on this document.
But that is maintained draft until we finalize the project. And then there is references in that guidance out farther. So that is a publicly available draft guidance that is referenced. But it will all be finalized in one package.
MR. LIETO: And I'm sorry, Katie. I guess maybe I'm not understanding. So that draft guide --
or excuse me, that draft reference which is the only reference for the appendices, that is out for review and approval.
Is that going out to the peer reviewed literature? Is it being done by some contract group?
Because I know ACMUI didn't.
DR. TAPP: So that draft guidance is part of this package. So that is referenced to the regulatory guide, and changes in comments on the regulatory guide could impact that draft guidance. So it will be finalized with this report.
MR. LIETO: Okay. Because I think that's very important for everybody to realize that reference NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
112 is -- what you're saying is also part of this comment period and needs to be also addressed. Is that correct?
DR. TAPP: Yes, because that is the basis.
So comments on this report could impact that basis as well. So yes, that is our contracted support from RCD that supports this document.
MR. LIETO: Okay. And then my one comment is that during the presentation, it was often referred to that the medical physicist does this, the medical physicist does that in the calculation. Okay. And just a opinion, obviously it's going to be in my statement is that this draft guidance is very complex with respect to any expectation that an authorized user physician or technologist is going to be able to do all these types of calculational estimates for every therapy that they do. And I think the practicality and the realism of the implementation of this regulatory guidance is not taking that into account because this is not something as straightforward as the existing Reg Guide is nor as Bryan Lemieux pointed out, Reg Guide -- or excuse me, NCRP 155 which, again, my opinion is that should've been the basis for this and gone from making the tweaks there with the updated stuff on breastfeeding NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
113 and new radionuclides. So I appreciate the opportunity to comment.
DR. TAPP: Thank you for your comment.
MS. HOLIDAY: Thank you, Mr. Lieto. Okay.
I know that I said I was not going to allow any more questions after Mr. Lieto. But I did see one final hand raised. Michael Welling, you will be our very last question because we are very much so over time.
So Mr. Welling, if you would please unmute your microphone and state your name and affiliation for the court reporter.
MR. WELLING: Thank you, Sophie. Mike Welling, radiation safety officer at University of Virginia. My question is regarding the guidance itself. As this is a Compatibility C requirement for the agreement states, what is the plan between NRC and OAS regarding the feasibility as a Compatibility C to make their own decisions for this guidance document?
DR. TAPP: Sure. As you mentioned, this is a Compatibility C. It's guidance. The states will
-- they do have time to review the guidance. And this is discussed when guidances are in development.
And the NRC does work with the agreement states on those types of comments. And it will be worked through as we get the public comments and the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
114 working group works to finalize the document. Then the states will be brought in and discussed on the changes and discussions with the states will occur at that time.
I'm looking -- I don't know if the PM would like to speak anything on agreement states, compatibility. But one thing that is important just like the NRC's guidance is one of acceptable means and I think to demonstrate a requirement. So regulatory guides just provide that one mean and then there could be different means to demonstrate that requirement as being that. So --
MR. WELLING: Right. But as the prior OAS Compatibility Chairman, I just want to point out that so if the grievance case is assigned, they don't like the 1.0 and they leave it 2.1.2.5, whatever they decide, they have that choice. Therefore, we just set up a dichotomy of differences a patient release throughout the states cause confusion and heartache, all of our patients. So I would hope the NRC would realize that if you're going to use 1.0 and agreement states listen to reason and do not go 1.0, we're going to have a huge problem in the states with releasing patients.
DR. TAPP: Thank you for your comment.
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115 MS. HOLIDAY: Thank you, Mr. Welling. And thank you to everyone who has joined us today for a meeting, especially to you, Dr. Tapp and Dr. Hamby, for your presentations. I really want to express our gratitude for all of you that have stuck with us for the past three hours for your active engagement and your questions and your feedback to the NRC staff.
As I previously stated, the deadline for submitting your comments on the proposed revision to the regulatory guide is August 20th, 2023. This deadline has already been extended once, and we do not intend to extend it again. We encourage that you use electronic submission through the federal rulemaking website which is found on the previous slides.
You can also submit your comments via email to rulemaking.comments@nrc.gov or in writing via mail to the Secretary of the U.S. NRC. You should reference the docket ID number, NRC 20230086. If you could go to the next slide, please.
If you should need any further information, you may contact any of the individuals that are listed here on the slide, Brian Allen, Dr.
Katie Tapp, or Harriet Karagiannis, excuse me.
Lastly, as your facilitator for the meeting, I would appreciate it if you took the time to fill out our NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
116 public meeting feedback form which is found on the public meeting website. Your opinion on how this meeting went will help the NRC improve upon future meetings.
So please take a moment and let us know what you think. Without further ado, I would like to turn the meeting over to Dr. Celimar Valentin-Rodriguez who is the team leader for medical radiation safety team to close us out. Dr. Celimar?
DR. VALENTIN-RODRIGUEZ: Thank you, Sophie. And thank you, Dr. Hamby and to Dr. Katie Tapp for providing presentations today. And we especially would like to thank the members of the public, medical licensees, and everyone, all the other stakeholders who joined us today during this meeting.
I understand that there's a lot of interest. And as one of our attendees stated in the chat, this is a controversial and tough issue. So we are here to accept your comments.
Please submit your formal comments through the methods that Sophie stated, that Katie covered, and that are found in the Federal Register. We will take all those comments into consideration. This is not the last step towards the issuance of this Reg Guide.
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117 After we address comments and include and consider the comments we received, there will be an opportunity for the ACMUI to review again the draft final guidance before it is issued. And we will also be engaged in agreement states as well before finalization of the Reg Guide. So there's still some more to do on the Reg Guide.
And so again, please feel free to include your comments in regulations.gov or through the other methods. And I look forward to reading your comments.
And thank you for taking three hours of your time today to join us and provide your expertise and knowledge on this issue. So with that, Sophie, thank you so much, and I'll turn it back to you.
MS. HOLIDAY: All right. Thank you, Dr.
Celimar. That concludes today's meeting. Again, thank you so much for attending, and we look forward to receiving your comments. Have a wonderful rest of your day. Goodbye.
(Whereupon, the above-entitled matter went off the record at 3:15 p.m.)
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