This fourth revised edition of “Technical Basis of Radiation Therapy: Practical Clinical Applications”, edited by S. H. Levitt, J. A. Purdy, C. A. Perez, and S. Vijaykumar, continues this publication’s outstanding excellence in the definition of the technical advances for radiation therapy. The previous three editions were milestones in the definition of new technologies and how they would be applied in clinical practice. The present volume presents significant and important concepts of treatment planning, not only with regard to appropriate treatment plans but also how various auxiliary technologies can be used to achieve the best clinical outcome with the minimum complication