AbstractID: 9296 Title: Synchronized Moving Aperture Radiation Therapy (SMART):
Dynamic MLC Leaf Sequencing with Tumor Motion
We have recently proposed the Synchronized Moving Aperture Radiation Therapy1 (SMART) technique for treating mobile tumors.
SMART combines respiratory gating with MLC tracking of tumor motion induced by respiration. In this work, we investigate a
dynamic MLC leaf sequencing algorithm for delivering the desired intensity maps to moving tumors in thorax and abdomen. The
MLC leaf sequences are derived based on the knowledge of measured average tumor trajectory (ATT) and are optimized such that the
total beam-on time is minimized. We study the dependence of the total cumulative monitor units required to deliver an arbitrary
intensity map to the moving tumor on initial tumor phase, dose rate and maximum allowed leaf speed. The algorithm is validated by
comparing the intensity maps delivered to the moving tumor using the optimized leaf sequences with the static intensity maps. We
find that the dynamic MLC sequencing algorithm provides accurate and efficient delivery of IMRT treatment plans to tumors with
one-dimensional motion. The collimator angle has to be optimized such that the MLC leaf motion is parallel with tumor motion. For
tumors with large hysteresis, the tumor motion perpendicular to the MLC leaf motion has to be further compensated and this will be
investigated in our future work.
1
Neicu, et al. Phys. Med. Biol. 48(5), 587-598 (2003).
Supported by the Whitaker Foundation.