Wang N, Ghebremedhin A, Simpson R, Patyal B
Loma Linda University Medical Center, Loma Linda, CA.
Med Phys. 2012 Jun;39(6Part13):3758. doi: 10.1118/1.4735302.
To perform the annual QA of proton gantry with a robotic table.
A new proton gantry with robotic table has been commissioned and is being used in clinic for patient treatment. The gantry is equipped with a robotic table with 6-degrees of freedom and dual cardinal angle KV imagers for patient registration. The system allows direct movement from one beam location to another without additional image registration, which effectively reduces portal setup time and increases treatment efficiency. The annual QA has four main components: Beam parameter checks included proton depth dose, output, linearity, modulation factor, field size factor, effective source distance, compensator gap factor, and monitor unit comparison between model calibration and physical measurements for every energy. Mechanical checks included gantry and robotic table isocenter, gantry and robotic couch isocentricity, and mechanical movement of fully loaded couch and corresponding digital readout. Imaging system checks included proton, X-ray beam, laser and image receptor alignment, image quality of KV imagers, and image registration accuracy. The last were the system safety checks. Methods used to perform these checks, especially those pertaining to robotic positioner will be discussed.
The new proton gantry and robotic table had the isocentric accuracy of about 1 mm. The accuracy of mechanical movements of the robotic table was within 1mm/0.5 degree in the clinical motion range. The accuracy of proton outputs determined by IAEA TRS 398 protocol was within +/-2% and the consistency of beam range for all clinical energies at cardinal gantry angles was within 1mm.
The results of the gantry annual QA demonstrate that the machine satisfies the highest standards of quality assurance for proton radiation treatment. The annual QA verifies the proton output, robotic table movement accuracy, image registration and safety of the machine and thus increases our confidence level in the uncertainties of daily proton treatments.
使用带有机器人治疗床的质子治疗机架进行年度质量保证（QA）。
一台配备机器人治疗床的新型质子治疗机架已投入使用，并正在临床中用于患者治疗。该机架配备了具有六个自由度的机器人治疗床和用于患者定位的双主角度千伏成像仪。该系统允许直接从一个射束位置移动到另一个位置，无需额外的图像配准，从而有效减少了射野设置时间并提高了治疗效率。年度QA有四个主要部分：射束参数检查包括质子深度剂量、输出剂量、线性度、调制因子、射野尺寸因子、有效源距、补偿器间隙因子，以及每种能量下模型校准与物理测量之间的监测单位比较。机械检查包括治疗机架和机器人治疗床的等中心、治疗机架和机器人治疗床的等中心性，以及满载治疗床的机械运动和相应的数字读数。成像系统检查包括质子、X射线束、激光和图像接收器的对准、千伏成像仪的图像质量以及图像配准精度。最后是系统安全检查。将讨论用于执行这些检查的方法，特别是与机器人定位器相关的方法。
新型质子治疗机架和机器人治疗床的等中心精度约为1毫米。机器人治疗床在临床运动范围内的机械运动精度在1毫米/0.5度以内。根据国际原子能机构（IAEA）TRS 398协议确定的质子输出精度在+/-2%以内，并且在主治疗机架角度下所有临床能量的射束范围一致性在1毫米以内。
治疗机架年度QA的结果表明，该机器满足质子放射治疗质量保证的最高标准。年度QA验证了质子输出、机器人治疗床运动精度、图像配准和机器安全性，从而提高了我们对日常质子治疗不确定性的信心水平。
