Premium
Dose distribution from x‐ray microbeam arrays applied to radiation therapy: An EGS4 Monte Carlo study
Author(s) -
De Felici M.,
Felici R.,
del Rio M. Sanchez,
Ferrero C.,
Bacarian T.,
Dilmanian F. A.
Publication year - 2005
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 - 10.1118/1.1951043
Subject(s) - microbeam , monte carlo method , imaging phantom , dosimetry , materials science , optics , absorbed dose , photon , planar , dose profile , beam (structure) , bremsstrahlung , polarization (electrochemistry) , photon energy , physics , radiation , nuclear medicine , chemistry , medicine , statistics , computer graphics (images) , mathematics , computer science
We present EGS4 Monte Carlo calculations of the spatial distribution of the dose deposited by a single x‐ray pencil beam, a planar microbeam, and an array of parallel planar microbeams as used in radiation therapy research. The profiles of the absorbed dose distribution in a phantom, including the peak‐to‐valley ratio of the dose distribution from microbeam arrays, were calculated at micrometer resolution. We determined the dependence of the findings on the main parameters of photon and electron transport. The results illustrate the dependence of the electron range and the deposited in‐beam dose on the cut‐off energy, of the electron transport, as well as the effects on the dose profiles of the beam energy, the array size, and the beam spacing. The effect of beam polarization also was studied for a single pencil beam and for an array of parallel planar microbeams. The results show that although the polarization effect on the dose distribution from a 3 cm × 3 cm microbeam array inside a water phantom is large enough to be measured at the outer side of the array (16% difference of the deposited dose for x‐ray beams of 200 keV), it is not detectable at the array's center, thus being irrelevant for the radiation therapy purposes. Finally we show that to properly compare the dose profiles determined with a metal oxide semiconductor field emission transistor detector with the computational method predictions, it is important to simulate adequately the size and the material of the device's Si active element.