Imae Toshikazu, Takenaka Shigeharu, Watanabe Yuichi, Aoki Atsushi, Matsuda Kanako, Sasaki Katsutake, Saegusa Shigeki, Nawa Kanabu, Nakagawa Keiichi, Abe Osamu
Department of Radiology, University of Tokyo Hospital, Tokyo, Japan.
Faculty of Health Sciences, Komazawa University, Tokyo, Japan.
J Appl Clin Med Phys. 2020 Dec;21(12):334-339. doi: 10.1002/acm2.13094. Epub 2020 Nov 12.
Using a plane-parallel advanced Markus ionization chamber and a stack of water-equivalent solid phantom blocks, percentage surface and build-up doses of Elekta 6 MV flattening filter (FF) and flattening-filter-free (FFF) beams were measured as a function of the phantom depth for field sizes ranging from 2 × 2 to 10 × 10 cm . It was found that the dose difference between the FF and the FFF beams was relatively small. The maximum dose difference between the FF and the FFF beams was 4.4% at a depth of 1 mm for a field size of 2 × 2 cm . The dose difference was gradually decreased while the field size was increased up to 10 × 10 cm . The measured data were also compared to published Varian FF and FFF data, suggesting that the percentage surface and build-up doses as well as the percentage dose difference between FF and FFF beams by our Elekta linac were smaller than those by the Varian linac.
使用一个平面平行的先进马克斯电离室和一叠水等效固体模体块，针对2×2至10×10 cm的射野尺寸，测量了医科达6 MV有 flattening 滤波器（FF）和无 flattening 滤波器（FFF）射束的表面剂量百分比和建成剂量，作为模体深度的函数。结果发现，FF和FFF射束之间的剂量差异相对较小。对于2×2 cm的射野尺寸，在1 mm深度处，FF和FFF射束之间的最大剂量差异为4.4%。随着射野尺寸增加至10×10 cm，剂量差异逐渐减小。还将测量数据与已发表的瓦里安FF和FFF数据进行了比较，表明我们的医科达直线加速器的表面剂量百分比、建成剂量以及FF和FFF射束之间的剂量百分比差异均小于瓦里安直线加速器的相应数据。
