ABSTRACT

This chapter presents a logical sequence of presenting the most recent developments in the use of a multileaf collimator (MLC) for intensity modulated radiation therapy (IMRT). It deals with the description of interpreters or sequencers which convert planned modulated beams into leaf patterns. The chapter considers leakage which leads naturally to a discussion of how the delivery features of the machine affect the interpretation. It is concerned with verifying individual treatment and also deals with quality assurance of the MLC equipment. The history of the MLC goes back at least to the patent by Gscheidlen in 1959 and the first commercial MLCs appeared in the mid to late 1980s. The work describes a method for converting an idealized beam-intensity distribution to a deliverable sequence of static MLC segments. The use of an MLC to perform IMRT by changing the leaf pattern with the radiation continually switched on is known as the dynamic MLC technique.