Abstract:Objective Pre-use dosimetric verification of 3D TPS (Three-Dimensional Treatment Planning System) was performed in the department so as to verify its effectiveness and security in the clinical application under normal conditions. Methods Dosimetric verification of the absolute dose was carried out to calculate the absolute dose of POI (Point of Interest) for the water phantom and compare it with the actually measured value. The relative deviation and passing rate for the tests were calculated according to the recommendation of Netherlands Commission on Radiation Dosimetry (NCS). The dosimetric verification of the relative dose was carried out to scan the Mapcheck and solid water so as to import the images to the TPS. The 2D dose distribution at the depth of 5 cm from the surface was calculated and compared with the actually measured result. Then, the passing rate for the tests was calculated according to the standard of AAPM TG119. Results For the dosimetric verification of the absolute dose, the POI whose relative deviation of the absolute dose was less than 1%, 2%, 3% and more than 4% occupied 33%, 84.5%, 95.3% and 2.3% respectively, which were all located in the high dose gradient area within the built-up area. For the dosimetric verification of relative dose, the test whose passing rate was greater than 99% and 98% accounted for 72.2% and 89% respectively with its lowest passing rate being 92.1%. Conclusion The verification result proved the intended effectivity and safety of 3D TPS in its clinical applications under normal conditions, which was worthwhile to be promoted. However, the physician and physicist should be highly aware of dosimetric abnormalities caused by the curved and tongue-and-groove design of leaves, which can lead to unnecessary radiation damage.
胡杰,董晓庆,陶建民,张莹,张颖,林清. 三维治疗计划系统使用前的临床剂量学验证[J]. 中国医疗设备, 2015, 30(3): 88-91.
剂量计算的准确性是三维治疗计划系统(TPS)最重要的一项性能指标,直接关系着患者的治疗效果。我科Pinnacle治疗计划系统剂量计算时使用的不是原始测量数据,而是由数学模型根据原始数据拟合的参数,如果参数拟合不对,则无法得出正确的计算结果。因此TPS安装、建模、调试后并不能立即投入临床使用,必须按临床实际可能使用的照射方式进行广泛的附加验收测试,这种测试已开展多年但方法不尽相同,笔者根据调强放疗计划验证的方法,进行了一系列的点绝对剂量计算准确性验证和平面剂量分布计算准确性验证,并将此作为TPS使用前的临床剂量学验证程序。. Pre-Use Dosimetric Verification of 3D TPS. China Medical Devices, 2015, 30(3): 88-91.