为了确保在1.5TMRI直线加速器中对患者进行辐射输送的准确性,实施与MR技术兼容的质量保证(QA)设备至关重要。章鱼4DMR,由PTW(弗莱堡,德国)旨在确保其探测器与每个光束段的方向一致和理想的对准。本研究的重点是调查OCTAVIUS探测器(OD)1500MR和OCTAVIUS1600MR在MR兼容的OCTAVIUS4D中使用时的探测器响应的基本特性。检查的特征包括短期重现性,剂量线性度,字段大小依赖关系,监控单元(MU)速率依赖性,每脉冲剂量依赖性,和角度依赖性。OD1500MR的评估还包括在不同的目标尺寸和解剖部位测量25个临床治疗计划,包括肝脏/胰腺,直肠,前列腺,肺,和淋巴结。用标准设置和5厘米的左偏移测量一个计划。OD1600MR不可用于这些测量。通过在软件中引入MU和位置移位来评估OD1500MR识别潜在错误的能力。
结果显示短期重现性没有显著差异(<0.2%),剂量线性度(<1%),字段大小相关性(字段大小大于5cm×5cm时<0.7%),MU速率依赖性(<0.8%),剂量/脉冲依赖性(<0.4%)和角度依赖性(标准偏差<0.5%)。&#xD;所有临床计划的测试均已成功完成。当采用全局的3%/3mm伽玛标准时,OD1500MR证明了与标准95%通过率的兼容性。和90%的合格率使用全局2%/2mm的伽马标准。检测器展示了测量具有5cm左偏移的治疗计划的能力。有了标准参数,γ试验对位置误差敏感,但需要对平均/中位剂量或点剂量进行附加试验,以检测小剂量差异.
To ensure the accuracy of radiation delivery to patients in a 1.5 T MRI-linac, the implementation of quality assurance (QA) devices compatible with MR technology is essential. The OCTAVIUS 4D MR, made by PTW (Freiburg, Germany) is designed to ensure consistent and ideal alignment of its detectors with the direction of each beam segment. This study focuses on investigating the fundamental characteristics of the detector response for the OCTAVIUS Detector (OD) 1500 MR and OCTAVIUS 1600 MR when used in the MR-compatible OCTAVIUS 4D. Characteristics examined included short-term reproducibility, dose linearity, field size dependency, monitor unit (MU) rate dependency, dose-per-pulse dependency, and angular dependency. The evaluation of OD 1500 MR also involved measuring 25 clinical treatment plans across diverse target sizes and anatomical sites, including the liver/pancreas, rectum, prostate, lungs, and lymph nodes. One plan was measured with the standard setup and with a 5 cm left offset. The OD 1600 MR was not available for these measurements. The capability of the OD 1500 MR to identify potential errors was assessed by introducing a MU and positional shift within the software. The results demonstrated no significant differences in short-term reproducibility (<0.2%), dose linearity (<1%), field size dependency (<0.7%for field sizes larger than 5 cm × 5 cm), MU rate dependency (<0.8%), dose-per-pulse dependency (<0.4%) and angular dependency (standard deviation<0.5%). All tests of clinical plans were successfully completed. The OD 1500 MR demonstrated compatibility with the standard 95% pass rate when employing a global 3%/3 mm gamma criterion, and a 90% pass rate using a global 2%/2 mm gamma criterion. The detector demonstrated the capacity to measure treatment plans with a 5 cm left offset. With the standard parameters, the gamma test was sensitive to position errors but required an addition tests of mean/median dose or point dose in order to detect small dose difference.