Development of system of irradiation synchronized with respiration gate

我们研究了如何确定适当的照射范围和对呼吸运动目标的辐射技术。当我们考虑肺尖肿瘤的放射技术时，通常通过停止呼吸时拍摄的CT图像来确定靶体积。但由于肺尖肿瘤在呼吸时由前斜向后斜移动，部分靶部位的辐射剂量会降低。然后在制定治疗计划前分别在吸入和呼气时进行CT成像。总结吸入和呼气时的肿瘤体积，并根据总结的靶体积制定治疗计划。通过这种处理方案，我们可以确定光束的方向，以防止目标偏离辐照场。为了实现这一点，需要具有合成两个目标体的功能。我们可以通过输入两个目标体积来解决这个问题。我们可以通过…将两个目标体积输入到三维治疗计划系统中来解决这个问题。因为这使得目标在三维空间中的运动变得清晰，我们可以通过最优方向照射目标。按照通常的方法，在治疗计划完成后，我们用x射线模拟器验证目标的运动，并扩大辐射场。与常规方法相比，该方法可大大减少处理量。当目标随着器官的生理运动而运动时，通常采用运动目标某一时刻的CT图像作为治疗方案，在确定目标体积时存在不确定性。在此基础上，提出了利用运动目标的两个最大值进行三维治疗规划的方法。利用该方法，可以解决常规治疗计划方法中的不确定性，知道最小治疗体积，使目标体积偏离传统场的危险最小化，对运动目标做出最优治疗计划。少

We examined how we can decide the appropriate irradiation field and radiation technique to the target moved by respiration. When we consider the radiation technique to the tumor of the lung apex, the target volume is usually decided by using CT imagings that are taken when breath is stopped. However, because the tumor of the lung apex moves from anterior oblique to posterior oblique at the respiration, the radiation dose of some part of the target can decrease. Then, we took CT imagings at inhalation and expiration before the treatment planning. The tumor volumes at inhalation and expiration were summed and the treatment planning was performed by using the summed target volume. By this treatment planning, we can decide the direction of the beam to prevent the target deviate from the irradiation field. To realize this, it is required to have the function to synthesize the two target volumes. We could solve that problem by inputting the two target volumes. We could solve that problem by … More inputting the two target volumes to the three-dimensional treatment planning system. Because this makes the movement of the target in the three-dimensional space make clear, we can irradiate the target through the optimal direction. In the usual way, after the treatment planning, we verify the movement of the target with the x-ray simulator and enlarge the radiation field. As compared with the usual way, this new method could decrease the treatment volume more. When the target moves with the physiological movement of the organ, there was the uncertainty at the decision of the target volume in the usual way of the treatment planning in which CT imagings at one moment of the moving target are used. Then, we developed the method of three-dimensional treatment planning by using two mamaximum values of the moving target. By using this method, we can solve the uncertainty in the usual way of the treatment planning, know the minimum treatment volume, minimize the danger that the target volume deviates from the radition field, and make the optimum treatment planning to the moving target. Less