Hsieh Emmelyn S, Hansen Katherine S, Kent Michael S, Saini Sanjeev, Dieterich Sonja
School of Veterinary Medicine, University of California, Davis, Davis, California.
Department of Surgical and Radiological Sciences, UC, Davis School of Veterinary Medicine, Davis, California.
Pract Radiat Oncol. 2017 Jul-Aug;7(4):e283-e290. doi: 10.1016/j.prro.2016.12.005. Epub 2016 Dec 24.
The purpose of this study was to determine if the Sun Nuclear PerFRACTION electronic portal imager device dosimetry software would be able to detect setup errors in a clinical setting and would be able to correctly identify the direction in which the setup error was introduced.
A 7-field intensity modulated radiation therapy (IMRT) treatment plan for a centrally located tumor was developed for 1 phantom and 5 canine cadaver heads. Systematic setup errors were introduced by manually moving the treatment couch by 1, 3, and 5 mm in each translational direction to assess stereotactic radiation surgery (SRS), IMRT, and 3-dimensional (3D) treatment tolerances after the initial alignment was performed. An angular setup error of 5° yaw was also assessed. The delivered treatment fluence was automatically imported in the PerFRACTION software and compared with the baseline fluence.
In the canine phantom, a 5-mm shift was undetected by gamma analysis, and up to a 2-cm shift had to be introduced for the gamma pass rate of 3%/3 mm to fall below a 95% pass rate criterion. The same 5-mm shift using 3% difference caused the pass rates for 2 fields to drop below the 95% tolerance. For each respective translational shift, the affected beam angles were consistent across the cadaver heads and correlated with the direction of translational shift. The best field pass rate, worst field pass rate, and average pass rate across all 7 fields was analyzed to develop clinical guidance on parameter settings for SRS, IMRT, and 3D tolerances.
PerFRACTION 2-dimensional mode successfully detected setup errors outside the systematic error tolerance for SRS, IMRT, and 3D when an appropriate analysis metric and pass/fail criteria was implemented. Our data confirm that percent difference may be more sensitive in detecting plan failure than gamma analysis.
本研究的目的是确定Sun Nuclear PerFRACTION电子射野成像设备剂量测定软件能否在临床环境中检测到摆位误差，以及能否正确识别引入摆位误差的方向。
为1个模体和5个犬类尸体头部制定了针对位于中心位置肿瘤的7野调强放射治疗（IMRT）治疗计划。在初始对齐后，通过在每个平移方向手动将治疗床移动1、3和5毫米来引入系统摆位误差，以评估立体定向放射手术（SRS）、IMRT和三维（3D）治疗耐受性。还评估了5°偏航角的摆位误差。将交付的治疗注量自动导入PerFRACTION软件，并与基线注量进行比较。
在犬类模体中，伽马分析未检测到5毫米的移位，对于3%/3毫米的伽马通过率降至95%通过率标准以下，必须引入高达2厘米的移位。使用3%差异的相同5毫米移位导致2个射野的通过率降至95%耐受性以下。对于每个相应的平移移位，受影响的射野角度在尸体头部之间是一致的，并且与平移移位的方向相关。分析了所有7个射野的最佳射野通过率、最差射野通过率和平均通过率，以制定关于SRS、IMRT和3D耐受性参数设置的临床指南。
当实施适当的分析指标和通过/失败标准时，PerFRACTION二维模式成功检测到SRS、IMRT和3D系统误差容限之外的摆位误差。我们的数据证实，百分比差异在检测计划失败方面可能比伽马分析更敏感。
