Morikawa K, Ishimatsu K
Hiroshima City Asa Hospital.
Radioisotopes. 1990 Mar;39(3):83-90. doi: 10.3769/radioisotopes.39.3_83.
Absorbed dose rates of photons are measured in the maze of a medical electron accelerator facility. Radiations in the maze include high energy recoiled electrons other than low energy reflected X-rays. An ionization chamber for low energy X-rays is used for measurement, and is put in a build-up cap thick enough to obstruct the recoiled electrons of which contribution to the chamber output comes sometimes equal to that of X-rays. Dose rates of capture gamma-rays in the maze are estimated applying the calculation of neutron dose equivalent rates reported in the preceding paper. It is proved that capture gamma-rays are dominant in the dose rates measured in the maze at 14 MV X-ray generation. The estimated absorbed dose rates of total photons including capture gamma-rays and reflected X-rays agree with the measured ones in the range from +10% to -27%.
在医用电子加速器设施的迷宫中测量光子的吸收剂量率。迷宫中的辐射包括除低能反射X射线之外的高能反冲电子。使用用于低能X射线的电离室进行测量，并将其置于足够厚的积累帽中，以阻挡反冲电子，反冲电子对电离室输出的贡献有时与X射线的贡献相当。通过应用前文报道的中子剂量当量率的计算方法，估算迷宫中俘获γ射线的剂量率。结果表明，在14MV X射线产生时，俘获γ射线在迷宫中测量的剂量率中占主导地位。包括俘获γ射线和反射X射线在内的总光子的估算吸收剂量率与测量值在+10%至-27%的范围内相符。
