An Liu, PhD
Radiation Oncology Department
City of Hope Medical Center
Duarte, CA 91010
Radiation therapy for cancer treatment has evolved significantly since the advent of the medical linear accelerator. 3D conformal therapy (3DCRT) is a change from traditional practice. It uses CT images to identify targets and normal structures on multiple transverse images. A physicist or dosimetrist can design the fields based on beam’s eye view projections, volumetric dose calculations, and volumetric plan evaluation tools, such as dose volume histograms (DVHs). With 3D conformal planning, physicians can design field shapes using blocks or multi-leaf collimator (MLC) to irradiate only the tumor while shielding the critical organs nearby. Intensity modulated radiation therapy (IMRT) is an extension of 3DCRT that seeks to further shape dose distributions by modulating the intensity of each field. It uses non-uniform radiation beam intensities that have been determined by various computer-based optimization techniques. These new technologies allow the clinical implementation of highly conformal, non-convex dose distributions. These complex, but promising, treatment modalities are rapidly proliferating in both academic and community practice settings. This presentation concentrates on the practical implementation of 3D conformal and IMRT in a typical clinical setting. Topics include hardware and software selection, treatment planning commissioning and clinical setup for different disease sites. Some treatment techniques used in routine clinics to minimize patient toxicity and increase treatment efficacy are also discussed.
TA28－调强放射治疗的临床实施：从三维适形放射治疗到调强放射治疗
Radiation Oncology Department
City of Hope Medical Center
Duarte, CA 91010
自从出现医用直线加速器以后，肿瘤的放射治疗得到了突飞猛进的发展。三维适形放射治疗（3DCRT）是对传统治疗技术的改进。它使用CT图像来在多幅横断面图像上勾画靶区和正常结构。物理师或剂量师可以根据射野方向观（BEV）投影设计射野，同时它还使用三维体积剂量计算和剂量－体积直方图（DVH）等三维体积剂量评估工具。通过三维适形计划，医生可以使用挡块或多叶准直器（MLC）设计射野，保证只照射肿瘤区而保护附近的危及器官。调强放射治疗（IMRT）是三维适形放射治疗（3DCRT）的进一步发展，其目的是通过调整每个射野内的强度来进一步改善剂量分布。调强放射治疗使用基于很多计算机优化技术产生的非均匀射束强度实施照射。这些新技术可以在临床上产生高度适形、非凸形的剂量分布。这些复杂但很具有发展前景的治疗技术在学术研究和临床实践中迅速发展。本报告将主要讲述三维适形放射治疗和调强放射治疗的实际临床实施。其中包括软硬件的选择、治疗计划系统的验收和不同肿瘤的临床治疗计划设计。同时也将讨论用于减小治疗副作用和提高疗效临床常用的一些治疗技术。