Open AccessQuantitative analysis of brass compensators for commissioning of the Pinnacle planning system for IMRT
Author(s) -
Gates Larry L.,
Gladstone David J.
Publication year - 2015
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v16i6.5531
Subject(s) - pinnacle , brass , beam (structure) , materials science , attenuation , radiation treatment planning , optics , physics , copper , medicine , metallurgy , radiation therapy
Brass compensators for beam modulation present an alternative method for IMRT treatment planning to traditional dynamic leaf modulation. In this work, we present a detailed method to commission the Pinnacle treatment planning system for IMRT using brass compensators. Beam attenuation from various brass thicknesses were measured using an ion chamber, as well as a MapCHECK device, for a representative seven‐field IMRT plan. We show that Pinnacle's parameters for compensators can be optimized to match the measured results while still maintaining the original open‐beam model. Only Pinnacle's modified scatter factor and brass density value were adjusted. Beam attenuation in several brass slabs were optimized by minimizing a χ 2function of measured and modeled data for several depths in solid water. Using MapCHECK, Pinnacle's parameters were optimized by minimizing the number of points that fail during a gamma analysis of seven fields in a typical IMRT plan. Our results show that Pinnacle's 10X beam is best modeled using a brass density of 7.8 g / cm 3and a modified scatter factor of 0.1 cm − 1 . PACS numbers: 87.56.N, 87.56.ng, 87.55.kh, 87.55.de