ASSESSMENT OF EFFECTIVE DOSE TO STAFF IN BRACHYTHERAPY

The aim of this paper is to investigate the problem of monitoring effe ctive dose to hospital staff who are involved in the treatment of tumo rs using sealed sources placed inside the body (brachytherapy). In add ition, the use of an unsealed source to treat the thyroid was also con sidered, Radiation distributions produced by both sealed sources commo nly used in brachytherapy (I-192, Cs-137, Ra-226) and an unsealed sour ce used in the treatment of the thyroid (I-131) were used to irradiate a Rando phantom. The brachytherapy treatments of esophageal and gynec ological carcinoma were simulated, The Rando phantom was loaded with l ithium fluoride thermoluminescent dosimeters at positions correspondin g to a number of radiosensitive organs. Film badges and electronic per sonal dosimeters were attached to the Rando phantom at various anatomi cal sites. The Rando phantom was positioned adjacent to the patient at an angle of 90 degrees to the longitudinal axis of the patient, Irrad iations were performed with and without a portable lead screen used on the radiotherapy wards, Effective dose was estimated for each simulat ed radiotherapy treatment and compared with the personal monitor readi ngs, The data were used as a basis for the provision of advice on the wearing of the film badge dosimeters and the design of portable lead s creens, The data also permitted a comparison between the two types of dosimeter when used for personal monitoring in brachytherapy.