External Beam Treatment Planning and Delivery

This chapter discusses the major steps in the treatment planning process and describes the role of virtual simulation in radiation therapy treatment planning. It also describes serial tomotherapy and helical tomotherapy. For conventional treatment planning, the alteration of treatment parameters is conducted by trial and error and is influenced by the combined experience of the planner and the physician. Forward planning techniques are utilized to achieve a uniform dose to the target volume. The advantage of intensity modulation is that it allows the delivery of uniform dose distributions to concave target volumes which is not possible with unmodulated beams. Beam direction can be important in the optimization process. There are three general classifications of anatomical structures in intensity-modulated radiation therapy (IMRT) planning which include target volumes, critical structures or organs at risk (OARs), and dose shaping structures. A robot-controlled linear accelerator has been developed for stereotactic radiosurgery (SRS) and IMRT.