Department of Medical Physics, Hospital Universitario Ramón y Cajal, IRyCIS, Madrid, Spain.
Department of Radiology, Rehabilitation and Physiotherapy, Universidad Complutense de Madrid, Madrid, Spain.
J Appl Clin Med Phys. 2023 Sep;24(9):e14053. doi: 10.1002/acm2.14053. Epub 2023 May 29.
The CyberKnife quality assurance (QA) program relies mainly on the use of radiochromic film (RCF). We aimed at evaluating high-resolution arrays of detectors as an alternative to films for CyberKnife machine QA.
This study will test the SRS Mapcheck (Sun Nuclear, Melbourne, Florida, USA) diode array and its own software, which allows three tests of the CyberKnife QA program to be performed. The first one is a geometrical accuracy test based on the delivery of two orthogonal beams (Automated Quality Assurance, AQA). Besides comparing the constancy and repeatability of both methods, known errors will be introduced to check their sensitivity. The second checks the constancy of the iris collimator field sizes (Iris QA). Changes in the field sizes will be introduced to study the array sensitivity. The last test checks the correct positioning of the multileaf collimator (MLC). It will be tested introducing known systematic displacements to whole banks and to single leaves.
The results of the RCF and diode array were equivalent (maximum differences of 0.18 ± 0.14 mm) for the AQA test, showing the array a higher reproducibility. When known errors were introduced, both methods behaved linearly with similar slopes. Regarding Iris QA, the array measurements are highly linear when changes in the field sizes are introduced. Linear regressions show slopes of 0.96-1.17 with r above 0.99 in all field sizes. Diode array seems to detect changes of 0.1 mm. In MLC QA, systematic errors of the whole bank of leaves were not detected by the array, while single leaf errors were detected.
The diode array is sensitive and accurate in the AQA and Iris QA tests, which give us the possibility of substituting RCF with a diode array. QA would be performed faster than using the film procedure, obtaining reliable results. Regarding the MLC QA, the inability to detect systematic displacements make it difficult to confidently use the detector.
CyberKnife 质量保证 (QA) 程序主要依赖于使用放射色胶片 (RCF)。我们旨在评估高分辨率探测器阵列作为替代 CyberKnife 机器 QA 的胶片的方法。
本研究将测试 SRS Mapcheck（美国佛罗里达州墨尔本的 Sun Nuclear 公司）二极管阵列及其自己的软件，该软件允许进行三次 CyberKnife QA 程序测试。第一个测试是基于两个正交光束的几何精度测试（自动化质量保证，AQA）。除了比较两种方法的稳定性和重复性之外，还将引入已知误差以检查其灵敏度。第二个测试检查虹膜准直器场尺寸的稳定性（虹膜 QA）。将引入场尺寸的变化来研究阵列的灵敏度。最后一个测试检查多叶准直器 (MLC) 的正确定位。将引入已知的系统位移到整个叶片和单个叶片进行测试。
RCF 和二极管阵列的结果在 AQA 测试中是等效的（最大差异为 0.18 ± 0.14mm），显示出阵列更高的可重复性。当引入已知误差时，两种方法的表现均呈线性，斜率相似。关于虹膜 QA，当引入场尺寸变化时，阵列测量高度线性。线性回归显示在所有场尺寸下斜率为 0.96-1.17，r 值均高于 0.99。二极管阵列似乎可以检测到 0.1mm 的变化。在 MLC QA 中，阵列无法检测到整片叶片的系统误差，而只能检测到单个叶片的误差。
二极管阵列在 AQA 和虹膜 QA 测试中灵敏且准确，这使我们有可能用二极管阵列代替 RCF。QA 的执行速度将快于使用胶片程序，同时获得可靠的结果。关于 MLC QA，无法检测到系统位移使得难以自信地使用探测器。
