"Preface External-beam radiotherapy has long been vexed by the simple fact that patients can (and do) move during the delivery of radiation. The most elegant and forward-looking solution to this reality is to actively adapt the radiation delivery process to the patient's natural movements. Recent advances in imaging and beam delivery technologies have now made this solution a practical reality. The purpose of this book is to present to researchers and clinical practitioners in radiation therapy an overview of the current and prospective state of the art in motion-adaptive radiation therapy. It presents technical reviews of each of the contributing elements of a motion-adaptive system (including target detection and tracking, beam adaptation, and patient realignment), discusses treatment planning issues that arise when the patient and internal target are mobile, describes several integrated motion-adaptive systems that are in clinical use or at advanced stages of development, and concludes with a review of the system control functions that must be an essential part of any therapy device that operates in a near-autonomous manner with limited human interaction. From these chapters, the reader will hopefully gain not only an understanding of the technical aspects and capabilities of motion adaptation but also practical clinical insights into planning and carrying out various types of motion-adaptive radiotherapy treatment"--Provided by publisher.