Impact of detector selections on inter-institutional variability of flattening filter-free beam data for TrueBeam linear accelerators
Impact of detector selections on inter-institutional variability of flattening filter-free beam data for TrueBeam linear accelerators
复制标题
探测器选择对 TrueBeam 直线加速器平坦无滤波器光束数据机构间变异性的影响
DOI：
10.1002/acm2.12766
复制
发表时间：
2020
影响因子：
2.1
通讯作者：
Yamamoto T
中科院分区：
文献类型：
--
作者：
Tanaka Y;Akino Y;Mizuno H;Isono M;Masai N;Yamamoto T
本研究评价了影响TrueBeam™直线加速器（Varian Medical Systems，Palo Alto，CA，USA）的无平坦滤波器（FFF）射束特定参数的机构间变异性的探测器类型。从19家机构收集了24个射束数据集，包括用于Eclipse（Varian Medical Systems）治疗计划系统建模的百分比深度剂量（PDD）、偏心率（OCR）和输出因子（OPF）。尽管许多机构使用CC 13（IBA Dosimetry，Schwarzenbruck，德国）或PTW 31010 semiflex（PTW弗赖堡，弗赖堡，德国）电离室收集数据，但一些机构使用二极管检测器、金刚石检测器和具有较小空腔的电离室。OCR数据包括半影宽度、半高全宽（FWHM）和FFF光束特定参数，包括不平整度和斜率。用CC 13/PTW 31010电离室测量的数据与其它探测器测量的数据进行了比较。PDD数据表明，在比峰值深度更深的剂量下降区域，变化在±1%范围内。CC 13/PTW 31010探测器测量的OCR半暗带宽度明显大于其他探测器（P< 0.05）。特别是EDGE探测器（Sun Nuclear Corp.，墨尔本，佛罗里达州，美国）和microDiamond探测器（型号60019; PTW弗赖堡）在30 × 30 mm 2场的半影值远小于CC 13/PTW 31010探测器。CC 13/PTW 31010探测器和所有其他探测器的FWHM、不平坦度和斜率参数值之间没有差异。OPF曲线表现出小的变化，每个数据点的平均值的相对差异几乎在1%以内的所有字段大小。尽管半影区表现出依赖于探测器的变化，但所有其他参数均表现出微小的单元间变化，与探测器类型无关。
This study evaluates the type of detector influencing the inter‐institutional variability in flattening filter‐free (FFF) beam‐specific parameters for TrueBeam™ linear accelerators (Varian Medical Systems,Palo Alto, CA, USA). Twenty‐four beam data sets, including the percent depth dose (PDD), off‐center ratio (OCR), and output factor (OPF) for modeling within the Eclipse (Varian Medical Systems) treatment planning system, were collected from 19 institutions. Although many institutions collected the data using CC13 (IBA Dosimetry, Schwarzenbruck, Germany) or PTW31010 semiflex (PTW Freiburg, Freiburg, Germany) ionization chambers, some institutions used diode detectors, diamond detectors, and ionization chambers with smaller cavities. The OCR data included penumbra width, full width at half maximum (FWHM), and FFF beam‐specific parameters, including unflatness and slope. The data measured by CC13/PTW31010 ionization chambers were compared with those measured by all other detectors. PDD data demonstrated the variations within ±1% at the dose fall‐off region deeper than peak depth. The penumbra widths of the OCR measured with the CC13/PTW31010 detectors were significantly larger than those measured with all other detectors (P< 0.05). Especially the EDGE detector (Sun Nuclear Corp., Melbourne, FL, USA) and the microDiamond detectors (model 60019; PTW Freiburg) demonstrated much smaller penumbra values compared to those of the CC13/PTW31010 detectors for the 30 × 30 mm2field. There was no difference in the FWHM, unflatness, and slope parameters between the values for the CC13/PTW31010 detectors and all other detectors. OPF curves demonstrated small variations, and the relative difference from the mean value of each data point was almost within 1% for all field sizes. Although the penumbra region exhibited detector‐dependent variations, all other parameters showed tiny interunit variations regardless of the detector type.