Dose monitoring of health care workers occupationally exposed to ionizing radiation in Mansoura university hospitals

ABSTRACT

This study aims at evaluating the efficacy of radiation safety in Mansoura University Hospitals [MUHs] and to establish practical dose constraint [DC] for medical application. The study has been conducted upon health care workers [HCWs] occupationally exposed to ionizing radiation in various diagnostic and therapeutic activities in six health premises of MUHs. Four medical applications [radiotherapy, nuclear medicine, general radiology and interventional radiology] and five specialties [medical doctors, physicists, technicians, nurses and non-classified personals] were accounted. Doses were measured on a quarterly basis using thermoluniscent dosimeters [TLD-badges], while pocket dosimeters were used whenever TLD was not available. The annual doses were collected to build up a data base for years 1994-2005. The results show that TLD-badges were used in best situation in Oncology and Nuclear Medicine Dept. to cover less than one third of the exposed HCWs. The occupational doses showed a highly significant difference [p<0.0001] depending on the field of medical application. It is found that HCWs in radiotherapy were exposed to an average annual dose of 1.36 +/- 0.61mSv/y. For interventional radiology, the mean annual dose was found 2.25 +/- 2.47mSv/y unlike that of general radiology 1.07 +/- 0.65mSv/y. The largest sources of occupational exposure came from fluoroscopic radiology .equipments [1.76 +/- 0.92mS/y] followed by Cobalt-60 teletherapy machine [1.12 +/- 0.72mS/y]. The study showed that about 90% of HCWs received doses less than 2mSv/y and only 1.39% reported doses 5mSv or above. Dose constraint level can be set at 2mSv/y in premises of MUHs that may be considered achievable ceiling value referring to acceptably applied practices rather than optimized ones