title: Optimal field splitting for large intensity-modulated fields.
abstract: The multileaf travel range limitations on some linear accelerators require the splitting of a large intensity-modulated field into two or more adjacent abutting intensity-modulated subfields. The abutting subfields are then delivered as separate treatment fields. This workaround not only increases the treatment delivery time but it also increases the total monitor units (MU) delivered to the patient for a given prescribed dose. It is imperative that the cumulative intensity map of the subfields is exactly the same as the intensity map of the large field generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. In this work, we describe field splitting algorithms that split a large intensity-modulated field into two or more intensity-modulated subfields with and without feathering, with optimal MU efficiency while satisfying the hardware constraints. Compared to a field splitting technique (without feathering) used in a commercial planning system, our field splitting algorithm (without feathering) shows a decrease in total MU of up to 26% on clinical cases and up to 63% on synthetic cases.
authors.affiliation: Department of Computer and Information Science and Engineering, University of Florida, Gainesville, Florida 32611-6120, USA. srkamath@cise.ufl.edu
authors.forename: Srijit
authors.initials: S
authors.lastname: Kamath
authors.forename: Sartaj
authors.initials: S
authors.lastname: Sahni
authors.forename: Sanjay
authors.initials: S
authors.lastname: Ranka
authors.forename: Jonathan
authors.initials: J
authors.lastname: Li
authors.forename: Jatinder
authors.initials: J
authors.lastname: Palta
mesh_terms: D000465:Algorithms; D001822:Body Burden; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000295:instrumentation / Q000379:methods*; D012062:Relative Biological Effectiveness; D012542:Scattering, Radiation