Raghavi Sajjad, Sadoughi Hamid-Reza, Ravari Mohammad Ehsan, Behmadi Marziyeh
Department of Medical Physics, Faculty of Medicine, Semnan University of Medical Sciences, Semnan, Iran.
Department of Medical Physics and Radiology, Faculty of Paramedicine, North Khorasan University of Medical Sciences, Bojnurd, Iran.
J Med Signals Sens. 2024 Nov 5;14:31. doi: 10.4103/jmss.jmss_28_24. eCollection 2024.
Different dose calculation methods vary in accuracy and speed. While most methods sacrifice precision for efficiency Monte Carlo (MC) simulation offers high accuracy but slower calculation. ISOgray treatment planning system (TPS) uses Clarkson, collapsed cone convolution (CCC), and fast Fourier transform (FFT) algorithms for dose distribution. This study's primary goal is to evaluate the dose calculation accuracy for ISOgray TPS algorithms in the presence of a wedge.
This study evaluates the dose calculation algorithms using the ISOgray TPS in the context of radiation therapy. The authors compare ISOgray TPS algorithms on an Elekta Compact LINAC through MC simulations. The study compares MC simulations for open and wedge fields with ISOgray algorithms by using gamma index analysis for validation.
The percentage depth dose results for all open and wedge fields showed a more than 98% pass rate for points. However, there were differences in the dose profile gamma index results. Open fields passed the gamma index analysis in the in-plane direction, but not all points passed in the cross-plane direction. Wedge fields passed in the cross-plane direction, but not all in the in-plane direction, except for the Clarkson algorithms.
In all investigated algorithms, error increases in the penumbra areas, outside the field, and at cross-plane of open fields and in-plane direction of wedged fields. By increasing the wedge angle, the discrepancy between the TPS algorithms and MC simulations becomes more pronounced. This discrepancy is attributed to the increased presence of scattered photons and the variation in the delivered dose within the wedge field, consequently impacts the beam quality. While the CCC and FFT algorithms had better accuracy, the Clarkson algorithm, particularly at larger effective wedge angles, exhibited greater effectiveness than the two mentioned algorithms.
不同的剂量计算方法在准确性和速度上存在差异。虽然大多数方法为了效率而牺牲精度，但蒙特卡罗（MC）模拟提供了高精度但计算速度较慢。ISOgray治疗计划系统（TPS）使用克拉克森法、卷积叠加（CCC）和快速傅里叶变换（FFT）算法进行剂量分布计算。本研究的主要目标是评估在存在楔形板的情况下ISOgray TPS算法的剂量计算准确性。
本研究在放射治疗的背景下评估使用ISOgray TPS的剂量计算算法。作者通过MC模拟在Elekta Compact直线加速器上比较ISOgray TPS算法。该研究通过使用伽马指数分析进行验证，将开放野和楔形野的MC模拟结果与ISOgray算法进行比较。
所有开放野和楔形野的百分深度剂量结果显示各点通过率超过98%。然而，剂量剖面伽马指数结果存在差异。开放野在平面内方向通过了伽马指数分析，但并非所有点在跨平面方向都通过。楔形野在跨平面方向通过，但除克拉克森算法外，并非所有点在平面内方向都通过。
在所有研究的算法中，在半影区、射野外部、开放野的跨平面以及楔形野的平面内方向，误差都会增加。通过增加楔形角，TPS算法与MC模拟之间的差异变得更加明显。这种差异归因于散射光子的增加以及楔形野内所输送剂量的变化，从而影响了射束质量。虽然CCC和FFT算法具有更好的准确性，但克拉克森算法，特别是在较大有效楔形角时，比上述两种算法表现出更高的有效性。
