A New Algorithm for a Field Splitting Problem in Intensity-Modulated Radiation Therapy

Intensity-modulated radiation therapy (IMRT) is a modern cancer treatment technique with which optimized radiation fluence distributions, called intensity maps (IMs), are delivered to the target tumors via the help of a device called multileaf collimator (MLC), in order to produce homogeneous dose distributions of a prescribed amount at the target while sparing the surrounding organs and tissue. Due to the maximum leaf spread constraint of the MLCs, IMs whose widths exceed a given threshold cannot be delivered as a whole, and thus must be split into multiple subfields. The field splitting problems in IMRT normally aim to minimize the total beam-on time (i.e. the total time when a patient is exposed to actual irradiation during the delivery) of the resulting subfields. In this paper, we present a new efficient polynomial time algorithm for a general field splitting problem with guaranteed output optimality.