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.