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SU‐GG‐T‐148: Planning Study for Cone Beam Therapy
Author(s) -
Chen G,
Hu X,
Corbit C,
Shukla H,
Li X
Publication year - 2010
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 - 10.1118/1.3468538
Subject(s) - tomotherapy , arc (geometry) , nuclear medicine , beam (structure) , radiation therapy , linear particle accelerator , quality assurance , radiation treatment planning , medical physics , computer science , mathematics , medicine , optics , physics , radiology , geometry , external quality assessment , pathology
Purpose : Cone beam therapy (CBT) has been proposed as a form of rotational IMRT that can potentially offer fast delivery with equal or superior plan quality. This work aims to investigate CBT planning methods to generate high‐quality plans. Methods and Materials : The idea of CBT is to spread apertures for a beam to neighboring beam angles enabling non‐overlapping apertures to be delivered with gantry rotation. A prototype (Prowess Inc) with this algorithm implemented was used for this study. A full arc consisting of 72 equally‐spaced initial coplanar beams, optionally combined with a partial arc and non‐zero couch angle selected to avoid direct irradiation of organs‐at‐risk (OAR), was used to generate single‐ or two‐arc CBT plans. Plans for TomoTherapy, and conventional IMRT were also generated using the same CT and contours. For CBT and IMRT plans, a linac equipped with 160 MLC (Artiste, Siemens) with a possible dose rate of 1000 MU/min was considered. Plans for 10 representative brain and head and neck cancer patients were generated. Results : Two‐arc CBT offers equal or better plan quality than single‐arc. On average, the uniformity index for PTV was improved by 1.4% and the EUD for organs at risk (OAR) reduced by 25% when comparing two‐ and single‐arc CBT plans. Compared with TomoTherapy, the two‐arc CBT can lead to reduced EUD for OAR (12.9% on average) but with reduced dose uniformity in target (5.6% on average). The average delivery times for single‐ and two‐arc CBT are estimated to be 2 and 5 minutes, respectively, shorter than TomoTherapy (8 minutes). Conclusion : Two‐arc CBT can generate equal or better plans than single‐arc CBT and conventional IMRT. Compared with TomoTherapy plans, the two‐arc CBT plans offer improved OAR sparing but with decreased dose uniformity in targets. The delivery times of CBT were estimated to be 2–5 minutes.