ML23198A203

Public Meeting on Information Request-Draft Regulatory Guide 8061, July 20, 2023

ML23198A203
Person / Time
Issue date:	07/20/2023
From:	NRC/NMSS/DMSST/MSEB
To:
References
Download: ML23198A203 (56)

Text

Public Meeting on Information Request Draft Regulatory Guide 8061, Release of Patients Administered Radioactive Material.

July 20, 2023

Welcome and Logistics

Background

Overview of Proposed Changes (Patient Perspective)

How to Prepare and Submit Comments Question and Answer Session Overview of the Modifying Factors and Examples of Calculations Question and Answer Session

Logistics

• Meeting is being transcribed

• Keep the line muted until you intend to speak

• Raise hand button in Teams (*5 on phone)

• Unmute button in Teams (*6 on phone)

• Chat feature available

• Presentation slides shown on the Microsoft Teams screen and in ADAMS at ML23198A203

• Phone attendees should email Brian.Allen3@nrc.gov for attendance 3

Purpose

• Provide an overview of the proposed changes to the NRC Regulatory Draft Guide (DG)-8061, Release of Patients Administered Radioactive Material, to help the public prepare comments on the guide

• Share the different methods by which you may submit comments on the DG

• The NRC is not seeking comments at this meeting.

• Comments should be submitted according to the instructions in the FRN (88 FR 38407) by August 20, 2023.

4

Opening Remarks Kevin Williams Division Director Division of Materials Safety, Security, State, and Tribal Programs

Background

Katie Tapp, PhD Medical Physicist Medical Radiation Safety Team

NRC Policy on Medical Use of Radioactive Materials

• The Nuclear Regulatory Commission (NRC) will regulate the uses of radioactive material in medicine as necessary to provide the radiation safety of workers and the general public.

• The NRC will not intrude into medical judgements affecting patients, except as necessary to provide for the radiation safety of workers and the general public.

Patient Release Regulations (10 CFR 35.75)

• 10 CFR 35.75 allows the licensee to release from its control any patient who has been administered radioactive material if the total radiation dose to any other individual from exposure to the released patient is not likely to exceed 5 mSv (500 mrem).

• Licensees must provide written instructions to the patient to maintain doses ALARA if the exposure to any other individual is likely to exceed 1 mSv (100 mrem).

• Licensee must also provide specific instructions if the total effective dose equivalent to a nursing infant or child could exceed 1 mSv (100 mrem), assuming there was no interruption of breastfeeding.

Patient Release Regulations (10 CFR 35.75)

• The limits are for each patient treatment.

• The NRC regulations apply to the licensee, and not the patients.

• Regulatory Guide 8.39 provides guidance on how licensees can demonstrate they meet this requirement.

Evaluation of Regulatory Requirements for Patient Release

• In January 2018, the NRC completed an evaluation of its patient release program.

• Results were published in SECY-18-0015, Staff Evaluation of the U.S. Nuclear Regulatory Commission's Program Regulating Patient Release After Radioisotope Therapy

• Findings -

• The regulations are adequate to protect the public

• Guidance update is needed as methodology in the guidance can UNDERESTIMATE potential dose to a member of the public in some situations.

RG 8.39, Release of patients administered radioactive material, Revision 1

• Current version of patient release guidance

• Issued in April 2020 to include recommendations for:

• Pretreatment discussions

• Patient instructions to maintain doses ALARA

• Additional instructions provided to the NRC during public comments by the industry

• Patient acknowledgement of instructions

• The current draft did not include significant updates to these sections

General Overview of Proposed Changes Katie Tapp, PhD Medical Physicist Medical Radiation Safety Team

DG 8061, Release of patients administered radioactive material

• Proposed Draft Regulatory Guidance (DG) to update Regulatory Guide (RG) 8.39

• Proposed changes include

• Updated dosimetry methodology

• Updated breastfeeding cessation guidelines

• The NRC is requesting public comments until August 20, 2023 (88 FR 38407)

Baseline and patient specific release Two-tiered approach to release - baseline thresholds and patient specific release values Administered activity and measured dose rate baseline thresholds that licensees can use to release patients without gathering patient specific information.

The proposed revision provides updated guidance on how patient specific information can be used to demonstrate release would comply with regulations.

Exposure Pathways

• The equations provided in the DG consider external exposure and do not include internal exposure due to uptake by the individual other than the patient.

• Previous studies and NRC evaluation found potential intake by household members and other members of the public is negligible (less than a few percent) relative to external doses, when instructions are followed.

• Instructions and precaution recommendation were not updated in this DG as they were recently updated in the last revision.

Baseline Thresholds

• Added new radionuclides to the table, such as Lu-177.

• Used CONSERVATIVE assumptions to ensure all released patients are not likely to cause exposure to other individuals in excess of 5 mSv (500 mrem).

• Due to these CONSERVATIVE assumptions, licensees do not need patient specific information to release patients who have administered activity (or have measured dose rates) below values found in the tables.

Patient Specific Release

• If a patient has administered activity (or measured dose rate) above baseline thresholds, patient specific information is needed to determine if release can be authorized.

• Patient specific information is used to add realism to the conservative assumptions used to develop the baseline threshold values.

Patient Specific Release

• The proposed draft guidance recommends use of 4 modifying factors to change the baseline thresholds based on patient release information.

• Occupancy (FO)

• Geometry (FG)

• Attenuation (FA)

• Biokinetics (FB)

• Licensees can choose to use patient specific information for some factors while keeping conservative values for others

Occupancy Factor

• Occupancy factor is the amount of time an individual is near the patient while the radioactive material decays.

• The less time the individual is near the patient while the material decays, the less exposure they will receive.

• The baseline threshold assumes an individual is 1 meter away from a patient all the time.

• To determine a patient specific occupancy factor, patient specific information is necessary.

Geometry Factor

• The baseline threshold assumes:

o A conservative geometry where the source and individual exposed are points o That the patient and individual are always 1 meter away

• The geometry factor allows licensees to modify the likely exposure scenarios based on:

o Conversations with the patient to determine likely distance and geometry of exposure scenarios, and o Medical knowledge of where the radionuclide will travel inside the patient

Attenuation Factors

• Baseline threshold assumes no attenuation (shielding) or buildup between source and individual.

• Patient specific attenuation factor is dependent on the expected depth of the source in the body.

• Attenuation factors can be greater than 1.

• Licensees should use the most conservative attenuation factor for the radionuclide if they do not plan to determine patient specific attenuation factors as conservatism is being removed from other factors.

• The DG provides the most conservative values and graphs for licensees to select attenuation values if thickness is known.

Biokinetic Factors

• The baseline threshold conservatively assumes no biological removal of the radionuclide.

• Licensees can continue to use this conservative assumption when patients retention data is unknown.

• The DG provides guidance on how licensees can adjust for patient specific excretion (i.e., removal) for additional realism.

How to Prepare and Submit Comments

Tips for Preparing Comments

• Review the Commenters Checklist on Regulations.gov 25

Methods for Submitting Comments

• Regulations.gov: comment form Docket ID NRC-2023-0086 or

• Email: Rulemaking.Comments@nrc.gov or

• Mail: Secretary, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001 ATTN: Rulemakings and Adjudications Staff 26

Next Steps

• Public comment period ends: August 20, 2023

• NRC staff updates draft regulatory guide based on public comments and feedback prior to publishing final regulatory guide 8.39, Release of Patients Administered Radioactive Material.

27

Public Feedback and Questions WE ARE ON BREAK.

We will return at 1:30pm ET for the second part of the meeting.

PROPOSED PHASE 2 UPDATES TO REGULATORY GUIDE 8.39 ON PATIENT RELEASE: DOSIMETRY METHODOLOGY JULY 20, 2023

OVERVIEW Phase 2 revisions to Regulatory Guide 8.39 are intended to update the dosimetry methodology Proposed direction provides versatile, realistically-conservative dosimetry Basic activity thresholds with the ability, if necessary, to generate patient-specific values Thresholds are based on maximum dose equivalent limits found in 10 CFR 35.75 Through patient instruction & interruption, breastfeeding infants are protected to 1 mSv Emerging technologies are easily supported with the new methodology RCD RADIATION PROTECTION ASSOCIATES 31

WHATS DIFFERENT GIVEN PHASE 2 REVISIONS?

If the administered activity (A0) is less than the basic activity threshold appearing in Table 1:

o there is no change for the licensee If, however, A0 is greater than the activity threshold listed in Table 1, the license should select one of the following options for patient release:

o release the patient based on measured dose rates (Table 2);

o release the patient based on retained activity instead of administered activity; o calculate patient-specific activity thresholds to determine patient release; or o calculate a hold time prior to patient release.

For a breastfeeding patient o if A0 is less than the revised breastfeeding threshold (Table 3), there is no change for the licensee o if, however, A0 is greater than the breastfeeding threshold, the licensee should calculate a breastfeeding interruption time and advise the patient accordingly RCD RADIATION PROTECTION ASSOCIATES 32

COLUMN 1 COLUMN 2 RADIONUCLIDE Patient Release Threshold Instruction Threshold I-124 0.20 5.4 TABLE 1 I-125 I-125 implanta 0.074 0.084 Ag-111 At-211 Au-198 2.0 2.3 (GBq) 4.4 17 0.88 (mCi) 120 460 24 (GBq) 0.88 3.3 0.18 (mCi) 24 89 4.9 Bi-213 210 5,700 41 1,100 COLUMN 1 I-131 COLUMN 2 0.32 C-11 8.6 68 1,800 14 380 C-14b 0.0014 0.038 0.00028 0.0076 ACTIVITY AT OR BELOW In-111 DOSE RATE AT 1 METER, AT OR 0.64 Cr-51 17 1.1 30 0.23 6.2 WHICH PATIENTS MAY BE BELOW WHICH Ir-192 PATIENTS MAY 0.015 Cs-1310.41 Cs-131 implanta 1.1 1.1 30 30 0.21 0.23 5.7 6.2 RELEASED BEIr-192 implantba RELEASED 0.016 Cu-640.43 9.7 260 1.9 51 Cu-67 3.7 100 0.75 20 RADIONUCLIDE (GBq) (mCi) (mSv/h) Lu-177 (mrem/h) 4.1 Dy-165 110 320 8,600 65 1,800 Ag-111 19 520 0.08 N-13 8 140 3800 Er-169b 130 3,500 26 700 F-18 13 350 2.5 68 Au-198 3.5 93 0.21 O-15 21 680 18,000 Ga-67 2.1 57 Several radionuclides 0.42 11 Ga-68 22 590 4.4 120 Cr-51 4.8 130 0.02 P-32b 2 9.2 Ho-166b 250 26 700 have been added 5.2 140 Cu-64 8.4 230 0.27 P-33b 27 64 I-1231,700 6.7 180 1.3 (from 22 to 52) 35 I-124 0.20 5.4 0.041 1.1 Cu-67 14 390 0.22 Pd-103 22 0.27 I-125 7.3 0.074 2.0 0.015 0.41 Ga-67 8.7 240 0.18 Pd-103 implanta18 I-125 implanta 0.084 2.3 Threshold decreases from 0.017 0.46 0.39 I-131 11 0.32 8.6 0.063 1.7 I-123 6.0 160 0.26 Ra-223 26 0.27 In-111 7.3 0.64 17 1.2 GBq to 0.32 GBq (a 0.13 3.5 Ir-192 0.015 0.41 0.0030 0.081 I-125 0.25 7 0.01 Rb-82 1 960 26,000 Ir-192 implanta 0.016 0.43 factor of 4) because the 0.0033 0.089 I-125 implant 0.33 9 0.01 Re-186 1 6.2 Lu-177 170 4.1 110 0.82 assumption of 25% occupancy 22 N-13 140 3800 28 760 I-131 1.2 33 0.07 Re-188b 7 16 O-15 430 680 18,000 140 3,800 In-111 2.4 64 0.2 P-32b for nuclides with T > 1 day Ru-106b 20 9.2 250 1.8 49 r 180 P-33b4,900 64 1,700 13 350 Ir-192 implant 0.074 2 0.008Ru-106b implanta 0.8 200 Pd-103 5,400 0.27 7.3 has been removed 0.055 1.5 Pd-103 implanta 0.39 11 0.077 2.1 P-32c c c c Sc-47 c 3.1 Ra-223 84 0.27 7.3 0.054 1.5 Pd-103 implant 1.5 40 0.03 Se-75 3 0.0080 Rb-82 0.22 960 26,000 190 5,100 At this stage of the methodology, Re-186 6.2 170 1.2 32 Re-186 28 770 0.15 Sm-153 15 6.8 Re-188b Ru-106b 180 16 180 430 4,900 3.1 100% occupancy is assumed 37 84 1,000 Re-188 29 790 0.20 Sn-117m 20 0.29 7.8 Ru-106b implanta 200 5,400 550 15,000 Sc-47 11 310 0.17 17 Sc-47 3.1 84 for all radionuclides 0.62 17 Sr-89b 3.3 Se-75 89 0.0080 0.22 0.0016 0.043 Se-75 0.089 2 0.005 0.5 Sr-90b 0.055 Sm-153 1.5 6.8 180 1.4 38 Sm-153 26 700 0.3 30 Sn-117m 0.29 7.8 Pure beta emitters 0.058 1.6 Tc-99m 30 Sr-89b 810 3.3 89 0.66 18 Sn-117m 1.1 29 0.04 4 Sr-90b 0.055 1.5 have been added 0.011 0.30 Tl-201 1.2 Tc-99m 32 30 810 6.1 160 Sr-89c c c c c (bremsstrahlung) 28 760 Xe-127 0.073 Tl-201 2.0 1.2 32 0.23 6.2 Tc-99m 0.58 58 Xe-127 0.073 2.0 0.015 0.41 Tl-201 16 430 0.19 Xe-133 19 2.1 Xe-133 57 2.1 57 0.42 11 b Y-90b 34 920 6.8 180 Yb-169 0.37 10 0.02 Y-90 2 34 Yb-169 920 0.094 2.5 0.019 0.51 Yb-169 0.094 Zr-89 2.5 0.21 5.7 0.042 1.1 Zr-89 0.21 5.7 RCD RADIATION PROTECTION ASSOCIATES 33

THRESHOLD FRAMEWORK Table 1 Column 2 Table 1 Column 1 Basic Threshold Basic Threshold for Instruction for Patient Release Dose to Bystander No Regulatory Provide Alternative Methods Action ALARA To Determine Release Instructions 1 mSv to 5 mSv to Bystander Bystander Release Authorized No Release RCD RADIATION PROTECTION ASSOCIATES 34

EXAMPLE 1: BASELINE RELEASE 56-year-old male administered 1.3 GBq of 90Y microspheres for the treatment of hepatocellular carcinoma Because this is a pure beta emitter, the current release/instruction thresholds are non-existent From proposed Table 1, the basic activity thresholds are 34 GBq (for release) and 6.8 GBq (for instructions)

Because 1.3 GBq is below both thresholds, the licensee is authorized to release the patient without dose-minimizing instructions 1.3 GBq 6.8 GBq 34 GBq Basic Threshold Basic Threshold for Instruction for Release Dose to Alternative Method Bystander No Regulatory Action ALARA Instructions 1 mSv to 5 mSv to Bystander Bystander RCD RADIATION PROTECTION ASSOCIATES Release Authorized No Release 35

CALCULATING THE PATIENT-SPECIFIC THRESHOLDS In the proposed method, if a patient cannot be released based on the basic activity thresholds (Q) found in Table 1, the licensee may want to determine patient-specific activity thresholds (Q)

To carry out this calculation, modifying factors for biokinetics (FB), occupancy (FO),

geometry (FG), and attenuation (FA) are determined The patient-specific threshold is calculated using:

=

RCD RADIATION PROTECTION ASSOCIATES 36

EXAMPLE 2: PATIENT-SPECIFIC RELEASE 75-year-old male administered 7.4 GBq of 177Lu vipipotide tetraxetan for the treatment of metastatic castration-resistant prostate cancer From proposed Table 1, the basic activity thresholds are 4.1 GBq (for release) and 0.82 GBq (for instructions) 7.4 GBq is above both thresholds, therefore the licensee decides to calculate patient-specific thresholds 0.82 GBq 4.1 GBq 7.4 GBq Basic Threshold Basic Threshold for Release for Instruction Dose to Bystander ALARA Alternative Method No Regulatory Action Instructions 1 mSv to 5 mSv to Bystander Bystander Release Authorized No Release RCD RADIATION PROTECTION ASSOCIATES 37

EXAMPLE 2: OCCUPANCY FACTOR During the initial patient interview, the patient states:

his spouse will drive him home after administration; he is sitting in the back seat of a private vehicle as normal, he plans to sleep next to his spouse (king-size bed) he eats meals with his spouse, but the two are in close proximity for no more than 4 waking hours in a day no other individuals live in the house, but his daughter plans to stop by for dinner a few days after treatment he is retired and can stay home for the first few days after treatment he plans to get groceries and go to church on the weekends Thus, over the first few weeks (6.7-day half-life), the maximally exposed individual is likely the patients spouse Assuming 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of sleep and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of contact, the CONSERVATIVE patient-specific occupancy factor is:

(8 + 4)

= = 0.5 24 RCD RADIATION PROTECTION ASSOCIATES 38

EXAMPLE 2: GEOMETRY FACTOR The patients spouse is likely the maximally exposed individual and it is assumed that exposures (on average) will occur at approximately 1 meter The licensee chooses to assume that the radiation source is a point, but that radiation dose absorbed by the spouse (bystander) is better represented assuming a line receptor From Table B-1 of the draft Regulatory Guide 8.39, this orientation results in a geometry modifying factor of:

= 0.87 RCD RADIATION PROTECTION ASSOCIATES 39

EXAMPLE 2: BIOKINETIC AND ATTENUATION FACTORS In this initial determination, the licensee chooses to use the most conservative biokinetic and attenuation factors in place of patient specific values Most conservative biokinetic factor is always: =1 Attenuation factors are radionuclide specific, and their maximum value can be found in Table A-1 of the draft regulatory guide This factor includes both attenuation and build up and, at times, can be greater than 1; the maximum value listed in Table A-1 for 177Lu is:

= 1.25 RCD RADIATION PROTECTION ASSOCIATES 40

EXAMPLE 2: PATIENT-SPECIFIC ACTIVITY THRESHOLDS For this patient, and depending on their stated plans, habits, etc., the release and instruction thresholds for an administration of Lu-177 are:

4.1

= = = 7.5

• *

• 1

• 0.5

• 0.87

• 1.25 7.4 GBq 0.82

= = = 1.5

• *

• 1

• 0.5

• 0.87

• 1.25 Recall, this patient received an administration of 7.4 GBq The patient can be released, but must be provided dose-minimizing instructions and those instructions must be consistent with stated plans, sleeping arrangement, etc. and ALARA considerations RCD RADIATION PROTECTION ASSOCIATES 41

EXAMPLE 3: IODINE ADMINISTRATION 46-year-old female administered 1.8 GBq of 131I as sodium iodide Proposed basic activity thresholds (Table 1) for 131I are Qrel = 0.32 GBq (release) and Qins =

0.063 GBq (instructions) recall, current release threshold is 1.2 GBq for 131I Because 1.8 GBq is greater than both thresholds, the licensee decides to calculate patient-specific thresholds The licensee chooses to determine a value for each modifying factor With patient-specific thresholds, is immediate release allowable?

Are instructions required?

RCD RADIATION PROTECTION ASSOCIATES 42

EXAMPLE 3: BIOKINETICS, FB Consistent with current guidance (Table B-1) and several citations in the literature, the licensee assumes a double-exponential retention model for elemental iodine Uptake fractions of 0.2 and 0.8 for the extrathyroidal 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 I-131 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 /> The biokinetic modifying factor can be calculated as a weighted sum of effective half-lives in the two components divided by the radiological half-life:

0.2 7.7 + 0.8 125

= = 0.53 192 RCD RADIATION PROTECTION ASSOCIATES 43

EXAMPLE 3: OCCUPANCY, FO During the initial patient interview regarding the treatment plan, the patient states o she will drive herself to/from her appointment; o she will sleep with her husband, but will keep her distance otherwise; o she is retired, but her husband is still working; o and no other individuals live in their home.

Thus, the maximally exposed individual is very likely to be her husband Assuming 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of sleep, the patient-specific occupancy factor is:

8

= = 0.33 24 RCD RADIATION PROTECTION ASSOCIATES 44

EXAMPLE 3: GEOMETRY, FG The patient has been administered I-131 as sodium iodide Thus, the bulk of the radionuclide is expected to concentrate in the thyroid (a point source)

Basic thresholds assume point-to-point geometry at 1 meter, but for this patient-specific case, the licensee assumes a point source (thyroid) and a line receptor (torso of the maximum bystander)

Again, from Table B-1 of the draft Regulatory Guide, this orientation results in a geometry factor of:

= 0.87 RCD RADIATION PROTECTION ASSOCIATES 45

EXAMPLE 3: ATTENUATION, FA Because the radioactivity is likely concentrated in the thyroid, the licensee estimates 2 cm of overlying tissue in that area of the body The figure to the left is a plot of the attenuation modifying factor (FA) as a function of thickness of overlying tissue for I-131 FA accounts for both attenuation AND photon buildup (weve seen that FA can exceed 1.0)

At a thickness of 2 cm, this patient-specific attenuation factor is 1.0

= 1.0 RCD RADIATION PROTECTION ASSOCIATES 46

EXAMPLE 3: PATIENT-SPECIFIC ACTIVITY THRESHOLDS For this patient, and depending on their stated plans, habits, etc., the release and instruction thresholds for an administration of I-131 (as NaI) are:

0.32

= = = 2.1

• *

• 0.53

• 0.33

• 0.87

• 1.0 1.8 GBq 0.063

= = = 0.41

• *

• 0.53

• 0.33

• 0.87

• 1.0 This patient can be released, but must be provided dose-minimizing instructions consistent with stated plans, sleeping arrangement, etc.

RCD RADIATION PROTECTION ASSOCIATES 47

EXAMPLE 4: CALCULATION OF A HOLD TIME Lets use the previous example, but change the administered activity to 2.3 GBq With a Qrel of 2.1 GBq, the patient must be held, but for how long?

Retention data for this patient indicates that about 70% of a pretreatment I-131 administration remained in the patients body after 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> Then, using equation 11 (Section 2.3, Page 17), the hold time for this patient is:

48 2.1

= ln = 12 ln(0.70) 2.3 RCD RADIATION PROTECTION ASSOCIATES 48

EXAMPLE 5: WHAT IF THE PATIENT IS BREASTFEEDING?

26-year-old female is administered 0.04 GBq 89Zr panitumumab for imaging Proposed Table 1 indicates basic release and instruction thresholds of 0.26 GBq and 0.052 GBq for 89Zr The patient can be released without instruction HOWEVER, the patient tells you they are breastfeeding 0.04 GBq 0.052 GBq 0.26 GBq Basic Threshold Basic Threshold for Instruction for Release Dose to Bystander No Regulatory Action ALARA Calculate Patient-Instructions Specific 1 mSv to 5 mSv to Thresholds Bystander Bystander Release Authorized No Release RCD RADIATION PROTECTION ASSOCIATES 49

COLUMN 1 COLUMN 2 5-mSv Breastfeeding Activity 1-mSv Breastfeeding Activity TABLE 3 RADIO-NUCLIDE PHARMA-CEUTICAL Requiring a Record l Threshold for Instructions l Breastfeeding Activity Thresholds (GBq) (mCi) (GBq) (mCi)

C-11 choline 2 60 0.5 10 Cr-51 EDTA 30 800 6 200 F-18 FDG 1 30 0.2 6 Ga-67 citrate 0.08 2 0.02 0.4 Ga-68 octreotate 9 200 2 50 MIBG 1 40 0.3 8 I-123 OIH 2 40 0.3 8 NaIa 0.002 0.05 0.0004 0.01 I-124 NaIa 0.00003 0.0008 0.000006 0.0002 OIH 0.1 3 0.02 0.6 I-125 NaIa 0.00007 0.002 0.00001 0.0004 OIH 0.08 2 0.02 0.4 I-131 NaIa 0.000004 0.0001 0.0000009 0.00002 In-111 octreotate 0.9 30 0.2 5 0.04 GBq is to be administered.

WBC 0.08 2 0.02 0.4 Lu-177 octreotate 0.4 10 0.08 2 N-13 Any 10 400 3 70 O-15 water 10 300 2 60 The activity thresholds for requiring Ra-223 dichloride 0.000002 0.00005 0.0000004 0.00001 Rb-82 chloride 10 300 2 60 a record and requiring instructions DISIDA 0.2 6 0.05 1 DTPA DTPA aerosol 50 100 1000 4000 10 30 300 700 are exceeded.

glucoheptonate 20 600 5 100 HAM 0.2 7 0.05 1 MAA 2 60 0.4 10 MAG3 40 1000 8 200 Tc-99m MDP 40 1000 9 200 MIBI 30 800 6 200 pertechnetate 0.5 10 0.1 3 PYP 0.7 20 0.1 4 RBC in vitro 50 1000 10 300 RBC in vivo 40 1000 8 200 sulfur colloid 0.5 10 0.1 3 WBC 0.8 20 0.2 4 Tl-201 chloride 2 50 0.4 10 Zr-89 panitumumab 0.01 0.3 0.002 0.07 RCD RADIATION PROTECTION ASSOCIATES 50

WHAT IS THE RECOMMENDED INTERRUPTION TIME?

Table 3 provides the breastfeeding thresholds for maintaining records and providing instructions:

QBlrec = 0.01 GBq QBlins = 0.002 GBq With an administration of 0.04 GBq and a patient-specific effective half-life determination of 55 h, this patient is instructed to interrupt breastfeeding for

= 1.44 *

• ln = 1.44

• 55 []

• ln 0.04 0.002 = 240 l

RCD RADIATION PROTECTION ASSOCIATES 51

ALTERNATIVE METHOD FOR DETERMINING FB Generalized and conservative approach for estimating the modifying factor for biokinetics For example, if pretreatment measurements indicate 70%

retention 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after administration of I-131 (192-hr physical half-life) y-axis = 70%

x-axis = 48/192 = 0.25 FB = 0.8 RCD RADIATION PROTECTION ASSOCIATES 52

DETAILED MODIFYING FACTOR FOR OCCUPANCY, FO FO is the fraction of time the maximum bystander is exposed to the patient Occupancy and geometry can be taken together to help determine the maximally exposed individual The occupancy factor can be as simple as that shown earlier, i.e., FO = 8/24 = 0.33 Or it can be more detailed depending on the importance of early and late exposure potential (e.g., a radionuclide with short and long loss components)

Occupancy can be segment into (F1) short-term exposure (e.g., the initial period) and (F2) long-term exposure (e.g., the instruction period and thereafter); F1 and F2 are summed if for the same bystander F1 and F2 are essentially the fractions of time spent in close contact with the patient, modified by the expected loss of radioactive material prior to and during that exposure period (Appendix B)

RCD RADIATION PROTECTION ASSOCIATES 53

SUMMARY

Patient release is authorized if radiation dose to any other individual is not likely to exceed 5 mSv Written instructions must be provided to maintain ALARA if radiation dose to any other individual is likely to exceed 1 mSv Updated release methodology was presented Updated breastfeeding interruption/cessation guidelines (providing 1 mSv protection to the infant/child)

Allows for patient-specific exposure situations with modifying factors for biokinetics, occupancy, geometry, and attenuation Easily updated for emerging technologies RCD RADIATION PROTECTION ASSOCIATES 54

Public Feedback and Questions Contact Information and Resources Brian Allen, RES Technical Lead and COR Brian.Allen3@nrc.gov Katie Tapp, NMSS Technical Lead Katherine.Tapp@nrc.gov Harriet Karagiannis, Project Manager Harriet.Karagiannis@nrc.gov NRC Patient Release Website 56