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Optimal field splitting for large intensity‐modulated fields
Author(s) -
Kamath Srijit,
Sahni Sartaj,
Ranka Sanjay,
Li Jonathan,
Palta Jatinder
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1823572
Subject(s) - workaround , intensity (physics) , intensity modulation , field (mathematics) , linear particle accelerator , field intensity , dosimetry , multileaf collimator , mathematics , field size , computer science , algorithm , optics , physics , nuclear medicine , imaging phantom , beam (structure) , nuclear magnetic resonance , medicine , phase modulation , phase noise , pure mathematics , programming language
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.