IEEE - ANSI N449.1
Procedures for Periodic Inspection of Cobalt - 60 and Cesium - 137 Teletherapy Equipment
|Publication Date:||1 January 1978|
(This Foreword is not a part of ANSI N449.1-1978, Procedures for Periodic Inspection of Cobalt - 60 and Cesium - 137 Teletherapy Equipment.)
These guidelines for inspection of teletherapy equipment are the product of Subcommittee N44.2, and its original draft of 1973 was written by Peter Veerling. Priority for the attention of N44.2 on this subject of periodic inspection was suggested by the Bureau of Radiological Health (BRH) of the United States Department of Health, Education and Welfare. For those several early years of N44.2 the BRH was the sponsor of the subcommittee and some of the most productive work on this standard (ANSI N449.1-1978) was done at meetings in BRH headquarters. Urgency for promulgation of standards for periodic inspection of teletherapy apparatus was stimulated by a fatality occurring when a patient was crushed by a cobalt teletherapy whose deficiency might have been corrected by appropriate maintenance and inspection. It is a tribute to teletherapy apparatus, in general, that few serious accidents have been reported with such machines which became the "conventional radiotherapy devices" of the 1950's, 1960's and even the 1970's.
Complacency can follow decades of safe and dependable use of cobalt and cesium teletherapy machines, and this maintenance guide is designed to avoid accidents and inaccuracies of output.
When the BRH deemed it in conflict with their bureau to continue sponsorship of N44.2, the subcommittee on standards for radiotherapy equipment IEEE took on the task of continued sponsorship of N44.2, and the task of completion of this maintenance standard by obtaining final approval by formal balloting.
Members of N44.2 assisted Peter Veerling in their numerous reviews and meetings, but the brunt of the work in developing N449.1 was borne by Peter Veerling, himself. Consensus and suggestions of overlapping pertinent standards from other national and international agencies were supplied by members of the subcommittee.
N44.2 aimed its efforts toward supplying useful information on periodic inspections of teletherapy apparatus to users (physicians and physicists), manufacturers, and regulators (for example, BRH). During the multiple meetings and discussions on safety for teletherapy, the increase in numbers of linear accelerators was recognized, and the importance of promulgating standards for these complex devices was noted. But the relatively simpler job of establishing standards for cobalt teletherapy machines was elected because of the need for such a standard, and also to afford a prototype standard for subsequent promulgation of similarly needed guides for linear accelerators.
The membership of the Committees, Subcommittee and Working Group at the time of approval of this standard were as listed below.
This guideline provides suggested procedures for the inspection of cobalt-60 and cesium-137 teletherapy equipment which may identify and quantify malfunctions or maladjustments of the safety and radiation defining components. This guideline is a companion document to ANSI N449-1974 ,1 which specifies tests and suggested frequencies for the inspection and maintenance of teletherapy equipment.