chapter  3
125 Pages

IMRT USING A MULTILEAF COLLIMATOR

In this chapter we turn our attention to the delivery of IMRT using a multileaf collimator (MLC). IMBs may be constructed using a sequence of static MLCshaped fields in which the shape changes between the delivery of quanta of fluence, the so-called multiple-static-field (MSF) technique. Alternatively, the leaves may define changing shapes with the radiation on, the so-called dynamic multileaf collimator (DMLC) technique. However, classification is messy because the latter can operate in a step-and-shoot mode in which essentially the ‘movement’ is between MSF locations. This chapter is organized in order to present the DMLC technique first, including this possibility, and then we shall return at the end (section 3.3) to the pure MLC-MSF technique, which includes specifically the delivery of a few MSF configurations. This chapter is the longest because these two techniques have been subject to the greatest expansion in recent years.