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Sensitivities in the production of spread‐out Bragg peak dose distributions by passive scattering with beam current modulation
Author(s) -
Lu HsiaoMing,
Brett Robert,
Engelsman Martijn,
Slopsema Roelf,
Kooy Hanne,
Flanz Jay
Publication year - 2007
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 - 10.1118/1.2776255
Subject(s) - sobp , beam (structure) , optics , bragg peak , scattering , modulation (music) , intensity modulation , physics , range (aeronautics) , bragg's law , materials science , acoustics , phase modulation , diffraction , phase noise , composite material
A spread‐out Bragg peak (SOBP) is used in proton beam therapy to create a longitudinal conformality of the required dose to the target. In order to create this effect in a passive beam scattering system, a variety of components must operate in conjunction to produce the desired beam parameters. We will describe how the SOBP is generated and will explore the tolerances of the various components and their subsequent effect on the dose distribution. A specific aspect of this investigation includes a case study involving the use of a beam current modulated system. In such a system, the intensity of the beam current can be varied in synchronization with the revolution of the range‐modulator wheel. As a result, the weights of the pulled‐back Bragg peaks can be individually controlled to produce uniform dose plateaus for a large range of treatment depths using only a small number of modulator wheels.