Abstract
The irradiation characteristics for a plate source of 90Sr 222GBq (6Ci) were examined with the blue cellophane dosimeter and the thermoluminescence dosimeter. The 90Sr source used has the active area of 35×20mm2 and the surface concentration of 31.5 GBq (0.85 Ci) /cm2.
The high dose rate of 1.1 kGy (1.1×105 rad) /h was obtained at the distance of 5 cm from this source. At that time, the isodose curve determined by the blue cellophane was similar to a circle. The peak in depth dose curve was fairly displaced to the shallow direction in comparison with that obtained from the irradiation with an electron beam accelerator (2 MeV) . The calculated dose rate attains to 800 kGy (8.0×107 rad) /h at the distance of 5cm from the source when the infinite plate source with the maximum surface concentration (1.51 TBq (40.7 Ci) /cm2) is placed on a plane.
