Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Z Med Phys. 2012 Dec;22(4):272-80. doi: 10.1016/j.zemedi.2012.06.011. Epub 2012 Jul 15.
The development of 4D CT imaging technology made possible the creation of patient models that are reflective of respiration-induced anatomical changes by adding a temporal dimension to the conventional 3D, spatial-only, patient description. This had opened a new venue for treatment planning and radiation delivery, aimed at creating a comprehensive 4D radiation therapy process for moving targets. Unlike other breathing motion compensation strategies (e.g. breath-hold and gating techniques), 4D radiotherapy assumes treatment delivery over the entire respiratory cycle - an added bonus for both patient comfort and treatment time efficiency. The time-dependent positional and volumetric information holds the promise for optimal, highly conformal, radiotherapy for targets experiencing movements caused by respiration, with potentially elevated dose prescriptions and therefore higher cure rates, while avoiding the uninvolved nearby structures. In this paper, the current state of the 4D treatment planning is reviewed, from theory to the established practical routine. While the fundamental principles of 4D radiotherapy are well defined, the development of a complete, robust and clinically feasible process still remains a challenge, imposed by limitations in the available treatment planning and radiation delivery systems.
4D CT 成像技术的发展使得创建能够反映呼吸引起的解剖变化的患者模型成为可能，方法是在传统的仅 3D、空间的患者描述中添加时间维度。这为治疗计划和辐射传递开辟了新的途径，旨在为移动目标创建全面的 4D 放射治疗过程。与其他呼吸运动补偿策略（例如屏气和门控技术）不同，4D 放射治疗假设在整个呼吸周期内进行治疗传递——这对患者舒适度和治疗时间效率都有额外的好处。时间相关的位置和体积信息有望为因呼吸而移动的目标提供最佳、高度适形的放射治疗，潜在地提高剂量处方，从而提高治愈率，同时避免涉及附近的结构。本文回顾了 4D 治疗计划的现状，从理论到既定的实践常规。虽然 4D 放射治疗的基本原理已经得到很好的定义，但完整、稳健和临床可行的过程的开发仍然是一个挑战，这是由可用的治疗计划和辐射传递系统的限制造成的。
