ML20041G470
| ML20041G470 | |
| Person / Time | |
|---|---|
| Issue date: | 03/15/1982 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Calene J DAVID GRANT, USAF MEDICAL CENTER, TRAVIS AFB, CA |
| References | |
| NUDOCS 8203220347 | |
| Download: ML20041G470 (2) | |
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a MAR 151982 CONFIRMATORY ACTION LETTER License No. 04-07840-02(RS)
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Department of the Air Force
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David Grant USAF Medical Center NECEfp6D' Travis Air Force Base, California 94535 0
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Attention: Colonel James Calene 6
Deputy Conmander and Director estawy of Hospital Services
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Subject:
License No. 04-07840-02 This refers to the telephone conversations held on March 9 and 10,1982 between Mr. David D. Skov of this office and Dr. Bernard Tatera, Medical Physicist, concerning the radiation output from the licensee's AECL Model Theratron-80 (serial number 312) teletherapy uni', which was discussed with you and' other members of your staff at the conclusion of the NRC inspection on February 24, 1982.
As a part of the inspection conducted by Mr. Skov on February 23-24, 1982, the teletherapy unit radiation output was determined to be in error by 5.8 percent based upon a comparison between the NRC measured output and i
those values determined by the licensee. As a result of the telephone conversations between Mr. Skov and Dr. Tatera, it is our understanding that you will take immediate action with regard to calibration of the licensee's dosimetry system and to a change in the teletherapy unit calibration procedures which are described in detail as follows:
1.
The licensee's Victoreen electrometer and chamber will be submitted as soon as possible for recalibration at the AAPM accredited I
Regional Calibration Laboratory (RCL) at M. D. Anderson Hospital.
Houston, Texas.
2.
In the interim period between the date of this letter and the date of return of the licensee's Victoreen instrument and the assignment of a new calibration factor, the clinically used radiation output of the licensee's teletherapy unit, as determined from full cali-bration measurements, will be based upon the use of a different
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electrometer-chamber system which has been calibrated within the previous two years by an accredited RCL.
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3.
When performing full calibration and spot check measurenents of the teletherapy unit radiation outpt't, the licensee will use'a vertical stand and clamp to hold and support the measuring instrument which is sufficiently stable to prevent excess vibration and which will allow the precise positioning and alignment of the chamber to an accuracy within + 1 n:a w!th respect to the intended point of measurement.
4.
When performing full calibration and spot check measurements' of the 3
teletherapy unit radiation output, the licensee will detenaine by a nonoptical method, the distance from the cobalt-60 source to the measuring instrument, using as a reference point, a rigid mechanical surface such as the collimator or other appropriate part of the teletherapy unit source head. A ruler or a rigid mechanical front pointer will be used as the distance indicator which will permit the distance to be measured with an accuracy and reproducibility of measurement to within + 1 mm.
5.
The teletherapy unit timer error, as determined by the licensee during full calibration and spot check measurements, will be measured and calculated to a three decimal place accuracy.
The timer error, without any rounding off of its numerical value, will be incorporated into the calculation of the teletherapy unit radiation output. -The timer error value will be recorded on all full calibration and monthly spot check measurement records.
6.
Monthly spot check measurements of the radiation output will indicate the difference between the measured and anticipated output, expressed as a percentage of the anticipated output based-on physical decay of the values obtained from full calibration.
If our understanding of the planned actions 'as described above is not in accordance with your planned corrective actions, please contact this office innediately.
Sincerely, m!g'nd egnta tz a,11. Enge M R. H. Engelken Regional Administrator r
COMFIRMATORY ACTION LETTER
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