MLC Leaf width and plans

http://www.aapm.org/meetings/amos2/pdf/59-14909-99229-745.pdf

Quick summary of findings

Surprisingly, we noticed no difference in TV coverage and sparing of OARs. Furthermore, the isodose distributions and DVHs for the RPC and TG-119 phantoms show no major dosimetric gains for the smaller MLC widths, the cord for the RPC phantom received lower doses with the 1cm MLC system (our benchmark reference), for the same TV coverage across the systems. For the clinical cases, all systems gave comparable TV coverage and sparing of the OARs, with the Primus MLC system again, to provide slightly better conformity (lower CI). This better dose conformity is the reason that the dose fall-off within the "Ring" structure is higher, for the Primus system.

Conclusions:
This study is the first that comprehensively compares the majority of today’s MLC systems and has shown no significant indication that smaller MLC widths can lead to optimal plans, when multi-field IMRT techniques are used for planning.