国产NT-AD200型三维水箱射束扫描性能验证

目的:全面了解中国测试技术研究院NT-AD200型三维水箱的射束扫描精度与性能。 方法:以德国IBA公司Blue Phantom 2三维水箱为参照，分别使用NT-AD200型三维水箱与Blue Phantom 2三维水箱对美国瓦里安公司TrueBeam医用直线加速器进行6 MV光子线剂量学数据采集。测量源皮距为100 cm和不同射野大小条件下的百分深度剂量（PDD）曲线，比较分析各相同射野条件下不同深度的离轴比（OAR）曲线。 结果:与进口设备相比，在机械控制及易用性方面，NT-AD200还存在着一定的差距。在射束扫描性能方面，以Blue Phantom 2数据为基准，PDD建成区以外剂量偏差均值均小于1%，标准差小于0.3%，建成区最大剂量偏差出现在（3×3） cm2射野大小，为-5.23%±7.41%。OAR曲线80%射野大小范围内偏差均值均小于1%，标准差小于0.3%；80%~120%射野大小范围内（半影区）剂量偏差均值均小于1%，但标准差为0.51%~1.31%；120%射野大小范围以外NT-AD200型水箱的OAR比Blue Phantom 2水箱均偏大1%左右。 结论:NT-AD200型三维水箱与Blue Phantom 2三维水箱采集的剂量学数据有很好的一致性，射束扫描性能与进口设备相当。

Beam scanning performance verification of domestic NT-AD200 three-dimensional water tank

Abstract: Objective To comprehensively understand the beam scanning accuracy and performance of domestic NT-AD200 three-dimensional water tank (National Institute of Measurement and Testing Technology of China). Methods Blue Phantom 2 three-dimensional water tank (IBA Dosimetry GmbH) was used as reference. The 6 MV photon dosimetry data of TrueBeam medical linear accelerator (Varian Medical Systems, Inc.) were separately collected with NT-AD200 three-dimensional water tank and Blue Phantom 2 three-dimensional water tank. The percent depth dose (PDD) curves with source-to-surface distance of 100 cm and different field sizes were obtained, and off-axis ration (OAR) curves of different depths under the same field conditions were measured. Results NT-AD200 was inferior to imported equipment in terms of mechanical control and ease of use. For beam scanning performance, based on the baseline of BluePhantom 2, the mean dose deviation outside the PDD built-up area was less than 1%, and the standard deviation was less than 0.3%. The maximum dose deviation in the built-up area appeared in the irradiation field of (3×3) cm2, which was -5.23%±7.41%. The average deviation of the OAR curve within 80% of the field size was less than 1%, and the standard deviation was less than 0.3%. The mean dose deviation within 80%-120% of the field size (penumbra area) was less than 1%, but the standard deviation was 0.51-1.31%. The OAR of NT-AD200 water tank was about 1% larger than that of Blue Phantom 2 water tank at the outside of 120% of the field size. Conclusion The dosimetric data collected with NT-AD200 three-dimensional water tank and Blue Phantom 2 three-dimensional water tank have a good agreement, and the beam scanning performance of domestic NT-AD200 3D water tank is close to that of imported equipment.