Felefly T, Achkar S, Khater N, Sayah R, Fares G, Farah N, El Barouky J, Azoury F, El Khoury C, Roukoz C, Nehme Nasr D, Nasr E
Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, School of Medicine, Saint Joseph University, Beirut, Lebanon.
Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, School of Medicine, Saint Joseph University, Beirut, Lebanon.
Cancer Radiother. 2020 Jul;24(4):316-322. doi: 10.1016/j.canrad.2020.01.003. Epub 2020 May 25.
Gantry collision is a concern in linac-based stereotactic radiosurgery (SRS). Without collision screening, the planner may compromise optimal planning, unnecessary re-planning delays can occur, and incomplete treatments may be delivered. To address these concerns, we developed a software for collision prediction based on simple machine measurements.
Three types of collision were identified; gantry-couch mount, gantry-couch and gantry-patient. Trigonometric formulas to calculate the distance from each potential point of collision to the gantry rotation axis were generated. For each point, collision occurs when that distance is greater than the gantry head to gantry rotational axis distance. The colliding arc for each point is calculated. A computer code incorporating these formulas was generated. The inputs required are the couch coordinates relative to the isocenter, the patient dimensions, and the presence or absence of a circular SRS collimator. The software outputs the collision-free gantry angles, and for each point, the shortest distance to the gantry or the colliding sector when collision is identified. The software was tested for accuracy on a TrueBEAM® machine equipped with BrainLab® accessories for 80 virtual isocenter-couch angle configurations with and without a circular collimator and a parallelepiped phantom.
The software predicted the absence of collision for 19 configurations. The mean absolute error between the measured and predicted gantry angle of collision for the remaining 61 cases was 0.86 (0.01-2.49).
This tool accurately predicted collisions for linac-based intracranial SRS and is easy to implement in any radiotherapy facility.
在基于直线加速器的立体定向放射外科治疗（SRS）中，机架碰撞是一个需要关注的问题。如果没有碰撞筛查，计划者可能无法进行最佳规划，可能会出现不必要的重新规划延迟，并且可能会进行不完整的治疗。为了解决这些问题，我们基于简单的机器测量开发了一种用于碰撞预测的软件。
识别出三种类型的碰撞；机架-治疗床支架碰撞、机架-治疗床碰撞和机架-患者碰撞。生成了用于计算从每个潜在碰撞点到机架旋转轴距离的三角公式。对于每个点，当该距离大于机架头部到机架旋转轴的距离时，就会发生碰撞。计算每个点的碰撞弧。生成了一个包含这些公式的计算机代码。所需的输入是治疗床相对于等中心的坐标、患者尺寸以及是否存在圆形SRS准直器。该软件输出无碰撞的机架角度，并且对于每个点，当识别出碰撞时，输出到机架的最短距离或碰撞扇区。该软件在配备了BrainLab®附件的TrueBEAM®机器上针对80种虚拟等中心-治疗床角度配置进行了准确性测试，这些配置有无圆形准直器和平行六面体模体。
该软件预测19种配置无碰撞。其余61例中测量的和预测的机架碰撞角度之间的平均绝对误差为0.86（0.01 - 2.49）。
该工具能够准确预测基于直线加速器的颅内SRS中的碰撞，并且易于在任何放疗设施中实施。
