Experimental research of dose distribution and protection for mobile intra-operative radiotherapy accelerator in operating room / 中华放射医学与防护杂志

ABSTRACT

Objective To study the dose distribution characteristics formobile intra-operative radiotherapy accelerator (Mobetron) in an operating room,and to provide basic data for developing appropriate radiation protection measures and protection standard.Methods For most commonly used electron energy 9 MeV,TLD dosimeters were placed at 50,100,150 and 200 cm high plane,respectively.For each plane,the measurement points were selected at every 50 cm from the central axis at every 45° at eight different directions.Also different electron energies,such as 4,6,9 and 12 MeV,were taken into consideration at the plane at 100 cm height.After 10 Gy with a dose rate of 10 Gy/min were delivered,the TLD dosimeters were used to read out the data.Results For 9 MeV,at the phantom plane(100 cm high plane),the average doses were 169,756,395 and 241 μSv at 50,100,150 and 200 cm from the central axis,respectively.Themaximum deviation between the doses at 50 cm from the central axis in different angles and their average values were 9.1％.In the identical angle,the average doses of 50,100,150 and 200 cm high planes at the distance of 100 cm from central axis were 527,756,570 and 141 μSv,respecitvely.For the energies of 4,6,9 and 12 MeV,the average doses were 573,486,689 and 781 μSv at 100 cm from the central axis at 90° of 100 cm high plane.Conclusions For the same energy,the dose values at different directions were decreased by the minus exponential function law with the distance.The doses were uniformly distributed at different directions at the same distance from the central axis.The doses on the plane of 100 cm height were much higher than those at other heights,and the dose values were increased with the election energy.