This book provides complete descriptions of the techniques involved in medical image processing, using sufficient descriptions and practical references. Chapters cover topics of deformable registration, segmentation, image reconstruction, and integration of these practices into the radiation therapy environment. The four sections provide an overview of the image segmentation and reconstruction techniques using image processing across all modalities, and applications of these approaches in radiation therapy. The book also addresses the applications of registration, segmentation, and image reconstruction for radiation therapy, including adaptive radiotherapy, monitoring and tracking of treatment delivery, quantifying accuracy, and visualizing results.