Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
J Appl Clin Med Phys. 2020 Aug;21(8):65-72. doi: 10.1002/acm2.12915. Epub 2020 May 28.
To develop a practical method for predicting patient-specific collision during the treatment planning process.
Based on geometry information of the accelerator gantry and the location of plan isocenter, the collision-free space region could be determined. In this study, collision-free space region was simplified as a cylinder. Radius of cylinder was equal to the distance from isocenter to the collimator cover. The collision-free space was converted and imported into treatment planning system (TPS) in the form of region of interest (ROI) which was named as ROISS. Collision was viewed and evaluated on the fusion images of patient's CT and ROIs in TPS. If any points of patient's body or couch fell beyond the safety space, collision would occur. This method was implemented in the Pinnacle TPS. The impact of safety margin on accuracy was also discussed. Sixty-five plans of clinical patients were chosen for the clinical validation.
When the angle of couch is zero, the ROISS displays as a series of circles on the cross section of the patient's CT. When the couch angle is not zero, ROISS is a series of ellipses in the transverse view of patient's CT. The ROISS can be generated quickly within five seconds after a single mouse click in TPS. Adding safety margin is an effective measure in preventing collisions from being undetected. Safety margin could increase negative predictive value (NPV) of test cases. Accuracy obtained was 96.3% with the 3 cm safety margin with 100% true positive collision detection.
This study provides a reliable, accurate, and fast collision prediction during the treatment planning process. Potential collisions can be discovered and prevented early before delivering. This method can integrate with the current clinical workflow without any additional required resources, and contribute to improvement in the safety and efficiency of the clinic.
开发一种在治疗计划过程中预测患者特定碰撞的实用方法。
基于加速器龙门架的几何信息和计划等中心点的位置，可以确定无碰撞空间区域。在本研究中，无碰撞空间区域被简化为一个圆柱体。圆柱体的半径等于等中心点到准直器盖的距离。无碰撞空间被转换并以感兴趣区域（ROI）的形式导入治疗计划系统（TPS），命名为 ROISS。在 TPS 中将患者 CT 与 ROIs 的融合图像上查看和评估碰撞。如果患者身体或治疗床的任何点超出安全空间，则会发生碰撞。该方法已在 Pinnacle TPS 中实现。还讨论了安全裕度对准确性的影响。选择了 65 例临床患者的计划进行临床验证。
当治疗床角度为零时，ROISS 在患者 CT 的横截面上显示为一系列圆。当治疗床角度不为零时，ROISS 在患者 CT 的横断面上为一系列椭圆。在 TPS 中，只需单击鼠标一次，即可在五秒内快速生成 ROISS。增加安全裕度是防止漏检碰撞的有效措施。安全裕度可以提高测试病例的阴性预测值（NPV）。使用 3cm 安全裕度，100%真阳性碰撞检测的准确率为 96.3%。
本研究提供了一种在治疗计划过程中可靠、准确、快速的碰撞预测方法。可以在交付前尽早发现和预防潜在的碰撞。该方法可以与当前的临床工作流程集成，而无需任何额外的资源，有助于提高临床安全性和效率。
