离子束治疗中的靶区运动补偿方法
Compensation for Target Motion in Ion Beam Therapy
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摘要: 相对于被动式束流配送系统，由患者呼吸因素而引起的肿瘤靶区运动会对主动式束流配送系统下的离子束放射治疗带来非常严重的影响，造成离子束辐射场剂量分布的严重畸变，甚至对肿瘤靶区周围的健康组织造成严重损伤，很大程度上影响离子束治疗的疗效。因此，在主动式束流配送系统下，建立针对由呼吸因素引起的运动肿瘤靶区的适形调强照射方法就显得必要，且具有重要意义。系统介绍了呼吸运动探测、4D-CT 以及目前主要的3 种运动补偿方法(多次扫描、呼吸门控和主动跟踪技术)，并对这3 种方法在靶区适形度、稳健性以及技术复杂度等方面进行了比较。在靶区适形度方面主动跟踪技术优于门控技术，而门控技术又优于多次扫描技术；在稳健性方面多次扫描技术优于门控技术，而门控技术优于主动跟踪技术；在技术复杂度方面，多次扫描技术最简单，其次是门控技术，而主动跟踪技术最复杂。Active beam scanning results in serious distortion of ion-beam irradiation field in the presence of target motion and causes damage to healthy tissues round tumor target compared to passive beam shaping techniques. Therefore,it is necessary to establish suitable conformal irradiation methods for moving targets caused by the factor such as respiration in active ion beam scanning system. In this paper, motion detection, 4D-CT and three main ion beam specific mitigation techniques, namely rescanning, gating and beam tracking, are introduced. In addition, three motion mitigation techniques are compared comprehensively in terms of target conformation, robustness and mplementation complexity,respectively. For target conformation, the beam tracking is superior to gating, and gating is better than beam rescanning;the robustness decreases in the order rescanning-gating-beam tracking; for implementation complexity, beam rescanning is the most simple technology, followed by gating, while beam tracking is the most complex technique.Abstract: Active beam scanning results in serious distortion of ion-beam irradiation field in the presence of target motion and causes damage to healthy tissues round tumor target compared to passive beam shaping techniques. Therefore,it is necessary to establish suitable conformal irradiation methods for moving targets caused by the factor such as respiration in active ion beam scanning system. In this paper, motion detection, 4D-CT and three main ion beam specific mitigation techniques, namely rescanning, gating and beam tracking, are introduced. In addition, three motion mitigation techniques are compared comprehensively in terms of target conformation, robustness and mplementation complexity,respectively. For target conformation, the beam tracking is superior to gating, and gating is better than beam rescanning;the robustness decreases in the order rescanning-gating-beam tracking; for implementation complexity, beam rescanning is the most simple technology, followed by gating, while beam tracking is the most complex technique.
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