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Media type:
E-Article
Title:
Monte Carlo calculated CT numbers for improved heavy ion treatment planning
Contributor:
Qamhiyeh, Sima;
Wysocka-Rabin, Anna;
Jäkel, Oliver
Published:
Walter de Gruyter GmbH, 2014
Published in:
Nukleonika, 59 (2014) 1, Seite 15-23
Language:
Not determined
DOI:
10.2478/nuka-2014-0002
ISSN:
0029-5922
Origination:
Footnote:
Description:
Abstract Better knowledge of CT number values and their uncertainties can be applied to improve heavy ion treatment planning. We developed a novel method to calculate CT numbers for a computed tomography (CT) scanner using the Monte Carlo (MC) code, BEAMnrc/EGSnrc. To generate the initial beam shape and spectra we conducted full simulations of an X-ray tube, filters and beam shapers for a Siemens Emotion CT. The simulation output files were analyzed to calculate projections of a phantom with inserts. A simple reconstruction algorithm (FBP using a Ram-Lak filter) was applied to calculate the pixel values, which represent an attenuation coefficient, normalized in such a way to give zero for water (Hounsfield unit (HU)). Measured and Monte Carlo calculated CT numbers were compared. The average deviation between measured and simulated CT numbers was 4 ± 4 HU and the standard deviation σ was 49 ± 4 HU. The simulation also correctly predicted the behaviour of H-materials compared to a Gammex tissue substitutes. We believe the developed approach represents a useful new tool for evaluating the effect of CT scanner and phantom parameters on CT number values.