Ankara University, Department of Physics, Faculty of Science, 06100, Ankara, Turkey.
Hatay Mustafa Kemal University, Kırıkhan Vocational School, 31000, Hatay, Turkey.
Appl Radiat Isot. 2022 Sep;187:110340. doi: 10.1016/j.apradiso.2022.110340. Epub 2022 Jun 22.
Dosimetric measurements of the medical LINAC device using phantoms are an important procedure to determine the correct delivery dose on the target volume. The percentage depth dose values of RW3, SW557, ABS, epoxy, PRESAGE phantom materials obtained from a simulation program were compared with those experimentally measured with water phantom at 6 and 18 MV photon energy spectrums. The values of energy spectrums of photons were taken from the database of Elekta Synergy Linear Accelerator device and defined in GATE/Geant4 simulation program. The mean percentage dose differences for all these materials were compared with water phantom and the closest phantom material to water was determined as SW557 at 6 and 18 MV photon energies. The mass attenuation coefficients, the effective atomic numbers and electron densities of water-equivalent phantom materials and some selected human organs were found for both monoenergetic photons and 6, 18 MV photon energy spectrums using GATE simulation code. Furthermore, a new approximation method was developed to calculate the mass attenuation coefficient for the photon energy spectrums. There was determined to be good agreement between the numerical calculations of the approximation method and the simulation results, with a difference of less than 4% between them.
使用体模对医用 LINAC 设备进行剂量学测量是确定目标体积正确输送剂量的重要程序。从模拟程序中获得的 RW3、SW557、ABS、环氧树脂、PRESAGE 体模材料的百分深度剂量值与在 6 和 18 MV 光子能谱下用水体模实验测量的值进行了比较。光子的能谱值取自 Elekta Synergy 直线加速器设备的数据库，并在 GATE/Geant4 模拟程序中定义。将所有这些材料的平均剂量差异与水体模进行了比较，并确定在 6 和 18 MV 光子能量下与水最接近的体模材料为 SW557。使用 GATE 模拟代码，针对单能光子和 6、18 MV 光子能谱，找到了水等效体模材料和一些选定的人体器官的质量衰减系数、有效原子序数和电子密度。此外，还开发了一种新的近似方法来计算光子能谱的质量衰减系数。近似方法的数值计算与模拟结果之间存在良好的一致性，两者之间的差异小于 4%。
