ML20217B600
| ML20217B600 | |
| Person / Time | |
|---|---|
| Issue date: | 04/15/1998 |
| From: | Camper L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Combs F NRC |
| References | |
| IEIN-94-017, IEIN-94-17, IEIN-96-066, IEIN-96-66, NACMUI, NUDOCS 9804230091 | |
| Download: ML20217B600 (2) | |
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UNITED STATES j) j NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. 20655-0001 49
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April 15,1998 MEMORANDUM TO: Frederick C. Combs, Chairman Generic Assessment Panel FROM:
Larry W. Camper, Chief
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Materials Safety Branch d Division of Industrial and Medical Nuclear Safety, NMSS i
SUBJECT:
SUGGESTED NRC OPTIONS FOR ADDRESSING ISSUES RELATED TO SR-90 EYE APPLICATOR CAllBRATIONS, INCLUDING ACMUI RECOMMENDATIONS ON THIS ISSUE During the meeting of the Advisory Committee for the Medical Use of isotopes (ACMUI) on March 1,1998, a summary of the Sr-90 eye applicator misadrninistrations that have been reported to NRC since the ACMUI last discussed this issue in November of 1993 was presented along with the issuance of two information notices (ins) distributed to licensees on this issue. This was followed by a presentation from Dr. Chris Soares of the NationalInstitute of Standards and Technology (NIST) on problems related to calibration of these devices. This latter presentation included a summary of the NIST data on observed calibration errors and source non-uniformities in these devices. At the conclusion of these presentations a list of seven possible recommendations / options were presented to the ACMUI for their consideration After some discussion the ACMUI recommended that NRC take the following two actions from the presented list of seven options:
1.
Issue an IN recommending all Sr-90 eye applicators be recalibrated to present standards, and, i
2.
Issue another IN discussing proper corrections to the dose rete from these devices due to radioactive decay.
To a considerable extent the ACMUI recommendations can be interpreted as recommending the reissuance on NRC ins 94-17, which suggested recalibrations under certain conditions, and 96-66, which presented an extensive discussion of calibration errors related to improper corrections for radioactive decay and presented licensees with both proper equations and tables for decay correcting the dose rates oitheir Sr-90 eye applicators.
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O g._ h5-67641/W CONTACT:
Robert L. Ayres, NMSS/IMNS j p) Nf ( I4 g, (301) 415-5746 g
A 9804230091 980415 PDR ADVCM NACM pp 4 NRC FILF CENTER CDPV a
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Fred: rick C. Combs 2
f Considering that the recommended information has already been provided to licensees by the issuance of two earlier ins, it is questionable whether the issuance of an new IN will accomplish the desired result, namely, halting or substantially reducing the continued use (and resultant multiple misadministrations) of improperly calibrated Sr-90 eye applicators by licensees. I i
would recommend that other alternatives be explored to address this ongoing problem. To be truly effective, NRC's response to this ongoing problem should be one that provides a high degree of confidence that all of these devices, that are actively being used to treat patients, are properly calibrated.
One approach would be to conduct a survey the calibration accuracy of alllicensees Sr-90 eye applicator by making timed exposures to a sample of radiochromatic film supplied by either NRC or a designation national calibration laboratory, such as, NIST or one of the Accredited l
Dosimetry Calibration Laboratories (ADCL). This could be done by either: (1) sending a sample radiochromatic film to each licensee, with instructions for exposing the film and returning it the calibration laboratory; or, (2) providing NRC inspectors with the appropriate radiochromatic film samples and having them perform the exposures and shipments of the films to the calibration laboratory. I would favor the latter approach, as this would most likely reduce the variabilities, and related variations in dose rate assessments, that could be anticipated if individuallicensees were to make these film exposures. In addition to providing a measure of the overall or average dose rate for each device, this type of measurement also provides a I
measurement of the spacial distnbution of the Sr-90 activity over the active surface of the l
source. This may be as important as determining the average dose rate from these sources as it has been well established that a number of these sources have very poor spatial homogeneities in dose rates. This survey could be done under contract with at least two national calibration laboratories at an estimated cost of $600.00 per source measurement.
If this approach were taken, a number of other related issues must be resolved. Namely, action level values for maximum calibration errors, inhomogeneity limits, actions to be taken for sources exceeding action levels, and responsibility for paying costs of the survey. In regard to the latter item, either the NRC could assume the costs of contracting with one of the two available national calibration laboratories or the individual licensees could be assessed the costs through license fee increases or a one time charge. If the NRC assumed to costs, these costs could approach revenue neutrality considering most of the present costs responding to the recurring multiple patient misadministrations would be expected to be reduced or completely eliminated, at least over the short term.
Another approach would be to require, either by order or amendment of 10 CFR Part 35, all licensees to have their devices calibrated by one of the available national calibration laboratories. This option would have the greats overall cost impact on individual licensees.
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