Integrated Treatment Planning System of Proton Therapy for Deeply Seated Tumors

研制了一套实用的250 MeV参数质子束放射治疗计划系统。该系统可根据靶区的输入和照射方式的选择，在CT图像上快速显示等剂量分布和距离补偿器(BOLUS)设计。该治疗计划系统可通过设计数据在钻床或铣床上进行加工，并借助三维子程序扩展了治疗计划系统的记录和显示功能。三维显示了多个CT层面上的人体体积、靶区体积、相关器官和团状物的二维输入数据。这些3D图像使确认和优化治疗计划的结果成为可能。呼吸门控被引入到受呼吸运动影响的肿瘤的照射中。在呼吸曲线上任意设置的门控信号触发直线加速器的微波振荡器，从而产生间歇照射。使用专门设计的模拟肺癌患者的体模和低感光度胶片进行验证。临床应用中，采用面罩和胸腹压气囊检测肿瘤在体模中的移位，单独使用气囊。这项技术的效果得到了令人满意的证明。门控照射可以消除肿瘤的漂移，从而有助于对隔膜附近的肿瘤进行精确的放射治疗。

A practical system of radiotherapy treatment planning has been developed for 250 MeV proton beam at PARMS. The system allows rapid display of isodose distribution and range compensator (bolus) design on CT image, according to the input of target volume and irradiation mode selection. The bolus fabrication can be done by either drill or milling machine numerically controlled by the design data.The recording and displaying functions of this treatment planning system were extended with the aid of 3D subprogram. The 2D input data of body contor, target volume, related organs and bolus shapes in several CT slices have been three-dimensionally displayed. These 3D images have made it possible to confirm and optimize the results of treatment planning.Respiratory gating was introduced to the irradiation of tumors affected by respiratory movement. A gate signal arbitrarily set on the respiratory curve triggers a microwave oscillator of a linear accelerator, which gives rise to intermittent irradiation. A phantom specially designed to simulate a lung cancer patient and low sensitivity film were used for verification. A mask for ventilation and an airbag for thoracoabdominal pressure were employed to detect excursion of the tumor both in the phantom stury and the airbag alone was used in the clinical application. The efficacy of this technique was satisfactorily proven. Gated irradiation can contribute to precise radiotherapy for tumors close to the diaphragm by eliminating the excursion of the tumors.