| REVIEW ARTICLE |
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| Year : 2012 | Volume
: 35
| Issue : 3 | Page : 105-110 |
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Evaluation of internal hazards in medical cyclotrons
MR Iyer
Ex-BARC & Ex-IAEA; Consultant, Atomic Energy Regulatory Board, Mumbai, Maharashtra, India
Correspondence Address:
M R Iyer
Bungalow D4, Raj Kunj Society, Chembur, Mumbai 400074
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0972-0464.117663
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A large number of medical cyclotrons of various types and makes are now in operation in India and their number is ever increasing. A careful analysis of the various safety issues particularly in case of possible accidental conditions is required for a realistic evaluation of their impact. Apart from the external dose involved, internal dose issues under normal operation and in case of abnormal operational conditions such as target rupture, accidents, spills, etc., which are generally neglected also need evaluation. There is a need for carrying out worst scenario analysis and the possible dose consequences to the operating staff as well as the public due to releases through the stack. The paper carries out an analysis for a typical release of activity into the vault environment and the dose implications. Along with any measured air activity measurements in the vault of operating cyclotrons this would resolve the issue one way or other. During radio pharmaceutical processing a substantial fraction of the volatile positron emitting radiopharmaceuticals are released into the atmosphere. In some cyclotrons a provision of an air trap for holding the air is mentioned. Analysis of possible dose to a member of the public using typical release rates is also presented and shown to be not negligible. A short review of such analysis in literature is carried out to show that the possible internal dose consequences cannot be ruled out and need to be addressed to in the safety analysis of these facilities for regulatory controls. Methods for proper calibration of stack monitors are indicated. In case of location of medical cyclotrons in crowded areas replete with high rise buildings, it may be necessary "to insure engineered safety features to ensure zero discharges from the machines." |
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