Protection design on occupational hazards in the radiotherapy place reconstruction and device renewal

[Objective]To understand the occupational hazards related to the radiotherapy place reconstruction and device renewal,determine the reasonable design of radiation protection. [Methods]A radiotherapy place to be reconstructed and a Truebeam accelerator,a Clinac accelerator,a192 Ir brachytherapy device to be installed in People's Hospital of Beijing University were enrolled as the research objects. The shielding levels of radiotherapy place were checked according to the national and international technical standards,such as GBZ / T 201. 1-2007,GBZ 121-2002,NCRP No. 151 and IAEA No. 47,to identify the possible occupational hazards,and draw up the design project of the radiotherapy place protective shield and safety facility. [Results]The occupational hazards to be protected in the radiotherapy place were resulted from the penetrative radiation of treatment equipment and the harmful gases induced by radiation. Based on keeping the original shield of radiotherapy place,the design projects of local shield and protection reconstruction were initially worked out in terms of the protective properties and the setting requirements of accelerator and brachytherapy device. Following the design project,the periphery radiation level of the radiotherapy place were estimated and they were less than the control value of dose rate,the annual effective dose received by radiotherapy staff from the corresponding concerned positions was lower than 2. 0 m Sv,and the annual effective dose received by the public was lower than 0. 1 m Sv. Ventilation design of the place reached the ventilation rate issued on the national standard,and the safety protection facilities met the control requirements to prevent potential exposure. [Conclusion]If the partial shielding reconstruction is performed on the basis of original radiotherapy place,either some space and money can be saved effectively,or better protection of occupation hazards can be accompanied confidently,but some attention should be paid on the problem of local shielding optimization.