TESTING OF DYNAMIC MULTILEAF COLLIMATION

It has been shown that intensity-modulated fields have the potential t o deliver optimum dose distributions, i.e., high dose uniformity in th e target and lower doses in the surrounding critical organs. One way t o deliver such fields is by using dynamic multileaf collimation (DMLC) . This capability is already available in research mode on some treatm ent machines. While much effort has been devoted to developing algorit hms for DMLC, the mechanical reliability of this new treatment deliver y mode has not been fully studied. In this work, we report a series of tests designed to investigate the mechanical aspects of DMLC and thei r implications on dosimetry. Specifically, these tests were designed t o examine (1) the stability of leaf speed, (2) the effect of lateral d isequilibrium on dose profiles between adjacent leaves, (3) the signif icance of acceleration and deceleration of leaf motion, (4) the effect of positional accuracy and rounded-end of the leaves, and (5) create a simple test pattern that may serve as a basis for routine quality as surance checks. Results of these tests are presented. The implications on dosimetry and consideration for the design of leaf motion are disc ussed. (C) 1996 American Association of Physicists in Medicine.