Information Notice 2003-12, Problems Involved In Monitoring Dose to Hands Resulting from Handling of Radiopharmaceuticals

Problems Involved In Monitoring Dose to Hands Resulting from Handling of Radiopharmaceuticals

ML032320470
Person / Time
Issue date:	08/22/2003
Revision:	0
From:	Miller C L NRC/NMSS/IMNS
To:
Sherbini S, DeCicco J, Turner A
References
IN-03-012
Download: ML032320470 (7)

August 22, 2003

NRC INFORMATION NOTICE 2003-12:PROBLEMS INVOLVED IN MONITORING DOSETO THE HANDS RESULTING FROM THE HANDLING OF RADIOPHARMACEUTICALS

Addressees

All holders of 10 CFR Parts 32, 33, and 35 licenses.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to alertlicensees of potential difficulties that may be encountered when monitoring doses to the hands of workers involved in handling radiopharmaceutical This IN describes some of these difficulties, the work that is being conducted to resolve them, and interim guidance that NRC will adopt pending completion of this wor It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem However, suggestions contained in the IN are not NRC requirements; therefore, no specific action nor written response is required.Background:Handling of radiopharmaceuticals contained in syringes, vials, and other vessels exposes theworkers' hands to radiation doses that may, in the course of a year, approach a significant fraction of the regulatory limit on the shallow dose equivalent (SDE), which is the limit that normally applies to such exposure The practice has been, for many years, to monitor these doses using ring dosimeters worn on one or more fingers of one or both hands, depending on the details of the activity that produces the exposur The highest ring dosimeter reading is normally considered to provide a measure of the SDE received, and is used to show compliance with the applicable dose limit.During the past year or so, NRC inspectors have focused attention on this practice, and haveconcluded that, at least in some cases, the dosimeters may be underestimating the doses they are supposed to be measurin This conclusion was reached because the dose that must be assessed for the worker is the dose at the location of the highest exposure on the extremit When handling radiopharmaceuticals, it may happen that the location of the highest exposure is not the same as the location of the ring dosimeter, in which case the dosimeter will underestimate that dos This is particularly true when handling radioactive materials with the fingertips, thus creating a sharp dose gradient between the location of highest exposure, which is likely to be at the fingertip, and the location of the dosimeter, which is normally at the base ofthe finge Under these conditions, the dosimeter may not provide a sufficiently accurate measure of the SDE for purposes of showing compliance, and a correction factor may be warranted, in such cases, to adjust the dosimeter reading.In response to these findings, some licensees have undertaken some measurements in anattempt to estimate the value of such a correction facto It is clear that this factor will vary depending on the details of the handling activities, and this has been confirmed by the measurement The results obtained by the licensees, as well as those published in the professional literature, showed factors ranging from very close to 1 up to 2, or in some cases, higher values, with an average of roughly 1.2 - These factors were estimated using the ratio of the dose measured at the fingertip to that measured by the ring badg Based on these results and other considerations, some licensees have concluded that their activities are such that their dose measurements do not require a correction factor or, in effect, that the appropriate factor for them is 1.This situation has been complicated by the change in the SDE limit, which became effective inJune 200 The SDE limit has remained numerically the same, namely 0.5 Sv (50 rem) per year to the extremitie However, whereas the old rule required that the dose be averaged over an area of 1 cm2 of skin, the new rule requires that the dose be averaged over a skin area of 10cm2 (10 CFR 20.1201(c)). The effect of this change has been two-fol For uniform, or nearlyuniform, exposures, over the extremity, the effect is negligibl However, for situations involving high dose gradients, which is the case when handling radioactive materials with the fingertips, the new rule results in an assessed dose that may be lower than would have been assessed under the old rule, the extent of the reduction depending on the details of the exposur This in turn means that any correction factor that may have been applied to the ring badge reading under the old rule is most likely to be closer to 1 under the revised rul The second effect of the rule change is that it now defines the limit in terms of a quantity that isnot directly measurable, without specialized measurement techniques, under conditions of high dose gradient Under the old rule, measuring the dose at the point of highest exposure, such as at the fingertips, by placing a dosimeter at that location, provided a fairly good approximation of the dose averaged over an area of 1 cm2 , even in the presence of a high dose gradient. However, such a measurement does not provide a good estimate of the dose averaged over an area of 10 cm The required dose must now be measured using special measurementtechniques, or calculate Such measurements or calculations enable estimation of any correction factors that should be used with finger ring dosimeters, to permit reasonably accurate estimation of the required SD It should be noted that this is not an unusual situation in applied dosimetry, but only one that is made somewhat more than usually difficult because of the relatively large area over which the dose must be averaged.Discussion:NRC and the radiopharmaceutical industry are currently conducting studies and measurementsdesigned to provide estimates of the appropriate correction factors that should be used with ring dosimeters to enable accurate assessment of the SD It is expected, as a result of the revised SDE limit, that these correction factors will be close to unity, but may be sufficiently different to warrant their routine use in assessing the SD Until this work is completed, and licensees are notified of its results and conclusions, NRC will accept the reading of the finger ring dosimeter, without application of a geometry correction factor, as being sufficiently accurate to provide a direct indication of the SDE received by the worker provided the ringdosimeter is worn on the finger that is expected to receive the highest dos NRC will reconsider this approach, and licensees will be notified of the new guidance, when the ongoing work to resolve this matter is complete In the interim, licensees are reminded of the regulatory requirement to keep doses As Low As is Reasonably Achievable (ALARA) to ensure that, even if the appropriate correction factor is found to be higher than 1, the worker will nevertheless be adequately protected, and the SDE limit will not be exceeded.This notice requires no specific action nor written respons If you have any questions aboutthe information in this notice, please contact one of the technical contacts listed below or the appropriate regional office./RA/ Patricia K. Holahan, forCharles L. Miller, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and SafeguardsTechnical Contacts:Sami Sherbini, NMSSAnita Turner, Ph.D., NMSS(301)415-7853(301) 415-5508 Sxs2@nrc.govAlt@nrc.gov Joseph DeCicco, NMSS(301) 415-7833 Jxd1@nrc.gov

Attachments:

List of recently issued NMSS Information Notices List of recently issued NRC Information Notices accurate to provide a direct indication of the SDE received by the worker provided the ring dosimeter is worn on the finger that is expected to receive the highest dos NRC will reconsider this approach, and licensees will be notified of the new guidance, when the ongoing work to resolve this matter is complete In the interim, licensees are reminded of the regulatory requirement to keep doses As Low As is Reasonably Achievable (ALARA) to ensure that, even if the appropriate correction factor is found to be higher than 1, the worker will nevertheless be adequately protected, and the SDE limit will not be exceeded.This notice requires no specific action nor written respons If you have any questions aboutthe information in this notice, please contact one of the technical contacts listed below or the appropriate regional office./RA/ Patricia K. Holahan, forCharles L. Miller, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and SafeguardsTechnical Contacts:Sami Sherbini, NMSSAnita Turner, Ph.D., NMSS(301)415-7853(301) 415-5508 Sxs2@nrc.govAlt@nrc.govJoseph DeCicco, NMSS (301) 415-7833 Jxd1@nrc.gov

Attachments:

List of recently issued NMSS Information Notices List of recently issued NRC Information NoticesCoordinated with OE and OGCG:\imns\sherbini\extin.wpdML032320470OFFICEIMNSEditorMSIBMSIBMSIBNAMESSherbiniEKrausMBailey jed forATurnerJDeCiccoDATE6/20/036/19/037/01 /036/20/036/20/03OFFICEIMNSIMNSOGCOSTPNAMETEssig mgb forCMillerSTreby NLOPLohaus jmp forDATE7/09/038/11/036/24/037/24 /03OFFICIAL RECORD COPY

______________________________________________________________________________________OL = Operating License CP = Construction PermitAttachment 1 LIST OF RECENTLY ISSUEDNMSS INFORMATION NOTICES_____________________________________________________________________________________InformationDate of Notice N SubjectIssuanceIssued to

_____________________________________________________________________________________2003-10Criticality Monitoring SystemDegradation at BWX Technologies, Inc., Nuclear Products Division, Lynchburg, VA08/04/2003All U.S. Nuclear RegulatoryCommission (NRC) licensees authorized to possess a critical mass of special nuclear material.2003-09Source Positioning Errors andSystem Malfunctions During Administration of Intravascular Brachtherapy07/16/2003All medical licensees.2002-31, Sup 1Potentially Defective UF6Cylinder Valves (1-inch)03/24/2003All U.S. Nuclear RegulatoryCommission (NRC) licensees authorized to possess and use source material and/or special nuclear material for heating, emptying, filling, or shipping 30-

and 48-inch cylinders of uranium hexafluoride (UF6).2002-36Incomplete or InaccurateInformation Provided to the Licensee and/or NRC By Any Contractor or Subcontractor Employee12/27/2002All materials and fuel cyclelicensees and certificate holders.2002-35Changes to 10 CFR Parts 71and 72 Quality Assurance Programs12/20/2002All holders of 10 CFR Part 71quality assurance program approvals and all 10 CFR Part 72 licensees and certificate holdersNote:NRC generic communications may be received in electronic format shortly after they are issued bysubscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following command in themessage portion:subscribe gc-nrr firstname lastname

______________________________________________________________________________________OL = Operating License CP = Construction PermitAttachment 2 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES_____________________________________________________________________________________InformationDate of Notice N SubjectIssuanceIssued to_____________________________________________________________________________________2003-11Leakage Found on Bottom-Mounted Instrumentation Nozzles 08/13/2003All holders of operating license orconstruction permits for nuclear power reactors, except those that have permanently ceased operations and have certified that fuel has been permanently removed from the reactor.2003-10Criticality Monitoring SystemDegradation at BWX Technologies, Inc., Nuclear Products Division, Lynchburg, VA08/04/2003All U.S. Nuclear RegulatoryCommission (NRC) licensees authorized to possess a critical mass of special nuclear material.2002-26, Sup 1Additional Failure of SteamDryer after a Recent Power Uprate 07/21/2003All holders of operating license orconstruction permits for nuclear power reactors, except those that have permanently ceased operations and have certified that fuel has been permanently removed from the reactor.2003-09Source Positioning Errors andSystem Malfunctions During Administration of Intravascular Brachtherapy07/16/2003All medical licensees.2003-08Potential Flooding ThroughUnsealed Concrete Floor Cracks06/25/2003All holders of operating licensesor construction permits for nuclear power reactors.2003-07Water in the Vent Header/ventLine Spherical Junctions06/24/2003All holders of operating licensesfor boiling water reactors (BWRs)

with a Mark I containment.Note:NRC generic communications may be received in electronic format shortly after they areissued by subscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the followingcommand in the message portion:subscribe gc-nrr firstname lastname