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Determination of dosimetrical quantities used in microbeam radiation therapy (MRT) with Monte Carlo simulations
Author(s) -
Siegbahn E. A.,
Stepanek J.,
BräuerKrisch E.,
Bravin A.
Publication year - 2006
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 - 10.1118/1.2229422
Subject(s) - microbeam , monte carlo method , imaging phantom , dosimetry , materials science , superposition principle , beam (structure) , optics , photon , radiation , physics , computational physics , nuclear medicine , mathematics , medicine , statistics , quantum mechanics
Microbeam radiation therapy (MRT) is being performed by using an array of narrow rectangular x‐ray beams (typical beam sizes 25 μ m × 1 cm ), positioned close to each other (typically 200 μ m separation), to irradiate a target tissue. The ratio of peak‐to‐valley doses (PVDR's) in the composite dose distribution has been found to be strongly correlated with the normal tissue tolerance and the therapeutic effect of MRT. In this work a Monte Carlo (MC) study of the depth‐ and lateral‐dose profiles in water for single x‐ray microbeams of different shapes and energies has been performed with the MC code PENELOPE. The contributions to the dose deposition from different interaction types have been determined at different distances from the center of the microbeam. The dependence of the peak dose, in a water phantom, on the microbeam field size used in the preclinical trials, has been demonstrated. Composite dose distributions for an array of microbeams were obtained using superposition algorithms and PVDR's were determined and compared with literature results obtained with other Monte Carlo codes. The dependence of the PVDR's on microbeam width, x‐ray energy used, and on the separation between adjacent microbeams has been studied in detail.