The acceptability of a multileaf collimator as a replacement for conventional blocks.

A multileaf collimator (MLC) can be used as a replacement for conventional blocks as well as for conformal radiotherapy. This study has assessed the possibility of using a Philips MLC for 218 patients treated with conventionally blocked fields. It was found that MLC field shaping would have been appropriate for over 94% of such patients. The facility to treat large blocked fields has been found to be particularly useful. Use of the predefined shapes stored in the Regular Shape Library provided by Philips was evaluated and it was found that an appropriate shape was available in 52% of cases. The application of MLC fields to the treatment of different anatomical sites is discussed.