Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
J Appl Clin Med Phys. 2022 Aug;23(8):e13728. doi: 10.1002/acm2.13728. Epub 2022 Jul 21.
The purpose of this work is to evaluate the Standard Imaging Exradin W2 plastic scintillation detector (W2) for use in the types of fields used for stereotactic radiosurgery.
Prior to testing the W2 in small fields, the W2 was evaluated in standard large field conditions to ensure good detector performance. These tests included energy dependence, short-term repeatability, dose-response linearity, angular dependence, temperature dependence, and dose rate dependence. Next, scan settings and calibration of the W2 were optimized to ensure high quality data acquisition. Profiles of small fields shaped by cones and multi-leaf collimator (MLCs) were measured using the W2 and IBA RAZOR diode in a scanning water tank. Output factors for cones (4-17.5 mm) and MLC fields (1, 2, 3 cm) were acquired with both detectors. Finally, the dose at isocenter for seven radiosurgery plans was measured with the W2 detector.
W2 exhibited acceptable warm-up behavior, short-term reproducibility, axial angular dependence, dose-rate linearity, and dose linearity. The detector exhibits a dependence upon energy, polar angle, and temperature. Scanning measurements taken with the W2 and RAZOR were in good agreement, with full-width half-maximum and penumbra widths agreeing to within 0.1 mm. The output factors measured by the W2 and RAZOR exhibited a maximum difference of 1.8%. For the seven point-dose measurements of radiosurgery plans, the W2 agreed well with our treatment planning system with a maximum deviation of 2.2%. The Čerenkov light ratio calibration method did not significantly impact the measurement of relative profiles, output factors, or point dose measurements.
The W2 demonstrated dosimetric characteristics that are suitable for radiosurgery field measurements. The detector agreed well with the RAZOR diode for output factors and scanned profiles and showed good agreement with the treatment planning system in measurements of clinical treatment plans.
本研究旨在评估 Standard Imaging Exradin W2 塑料闪烁体探测器（W2）在立体定向放射外科中使用的各种场中应用的适用性。
在对 W2 进行小场测试之前，我们先在标准大场条件下对 W2 进行了评估，以确保其探测器性能良好。这些测试包括能量依赖性、短期重复性、剂量响应线性度、角度依赖性、温度依赖性和剂量率依赖性。接下来，我们优化了 W2 的扫描设置和校准，以确保高质量的数据采集。在扫描水箱中，使用 W2 和 IBA RAZOR 二极管测量了由锥形和多叶准直器（MLC）形成的小场的轮廓。使用这两个探测器获取了锥形（4-17.5mm）和 MLC 场（1、2、3cm）的输出因子。最后，使用 W2 探测器测量了 7 个放射外科计划的等中心剂量。
W2 表现出可接受的预热行为、短期可重复性、轴向角度依赖性、剂量率线性度和剂量线性度。探测器对能量、极角和温度具有依赖性。使用 W2 和 RAZOR 进行的扫描测量结果吻合良好，全宽半高最大值和半影宽度相差在 0.1mm 以内。W2 和 RAZOR 测量的输出因子最大差异为 1.8%。对于 7 个点剂量测量的放射外科计划，W2 与我们的治疗计划系统吻合良好，最大偏差为 2.2%。切伦科夫光比率校准方法对相对轮廓、输出因子或点剂量测量的测量结果没有显著影响。
W2 显示出适用于放射外科场测量的剂量学特性。该探测器在输出因子和扫描轮廓方面与 RAZOR 二极管吻合良好，在临床治疗计划的测量中与治疗计划系统吻合良好。
