Chattaraj Arghya, Selvam T Palani
Radiological Physics and Advisory Division, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai 400 085.
Homi Bhabha National Institute, Mumbai 400 094.
Radiat Prot Dosimetry. 2020 Jul 17;189(3):286-293. doi: 10.1093/rpd/ncaa041.
Applicability of pure propane gas for microdosimetric measurements at photon energies relevant in brachytherapy is studied using the Monte Carlo-based FLUKA code. Monoenergetic photons in the energy range of 20-1250 keV and brachytherapy sources such as 103Pd, 125I, 169Yb, 192Ir, 137Cs and 60Co are considered in the study. Using the calculated values of energy deposited in the sensitive region of LET-1/2 tissue-equivalent proportional counter filled with pure propane gas and tissue-equivalent propane gas, values of density scaling factor for the site sizes of 1 and 8 μm are obtained. The study shows that density of propane gas should be lowered by a factor of about 0.93 for 169Yb, 192Ir, 137Cs and 60Co sources for the site sizes of 1-8 μm. For 125I source, the density of propane gas requires a scaling of 0.93 for 1 μm site size, whereas for site sizes 2-8 μm, density need not be altered. 103Pd source does not require density scaling for site sizes 1-8 μm.
使用基于蒙特卡罗的FLUKA代码，研究了纯丙烷气体在近距离放射治疗相关光子能量下进行微剂量测量的适用性。该研究考虑了能量范围为20 - 1250 keV的单能光子以及近距离放射治疗源，如103Pd、125I、169Yb、192Ir、137Cs和60Co。利用填充纯丙烷气体和组织等效丙烷气体的LET - 1/2组织等效正比计数器敏感区域内沉积能量的计算值，得到了1和8μm位点尺寸的密度缩放因子值。研究表明，对于169Yb、192Ir、137Cs和60Co源，在1 - 8μm位点尺寸下，丙烷气体的密度应降低约0.93倍。对于125I源，在1μm位点尺寸下，丙烷气体的密度需要缩放0.93，而对于2 - 8μm位点尺寸，密度无需改变。对于103Pd源，在1 - 8μm位点尺寸下不需要密度缩放。
