Linac-Based Image Guided Intensity Modulated Radiation Therapy

Abstract

Intensity modulated radiation therapy (IMRT) has become the mainstay of modern radiation therapy and it is now possible to produce highly conformal radiation dose distribution. The ubiquitous organ motion either between fractions or within a fraction has been one of the major uncertainties in radiation therapy. This fact coupled with the improved dose conformity and steep dose gradients in IMRT has made accurate target localization and beam targeting all the more important for radiotherapy treatments. Image-guided radiation therapy (IGRT) utilizes advanced imaging technology to better define and localize the tumor target and is the key to reducing and ultimately eliminating the uncertainties in radiation therapy. This chapter reviews the basics and some of the recent advancements in LINAC-based IGRT. Various image guidance techniques will be discussed, covering the full range of the radiation therapy process, including patient simulation, treatment planning, patient setup, and treatment delivery. In addition to the techniques currently used in clinical practice, some important research topics will also be discussed. We hope to provide the reader with a comprehensive understanding of the concepts and components of the new developments in IGRT, and offer useful hints on how to apply the new modalities in clinical practice.