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Journal of Medical Imaging

Implementing the complete beam hardening effect of the bowtie filter versus scaling beam intensities: effects on dosimetric applications in computed tomography
Author(s): Xochitl Lopez-Rendon; Guozhi Zhang; Hilde Bosmans; Raymond Oyen; Federica Zanca
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Paper Abstract

The bowtie filter is an essential element of computed tomography scanners. Implementation of this filter in a Monte Carlo dosimetry platform can be based on Turner’s method, which describes how to measure the filter thickness and relate the x-ray beam as a function of bowtie angle to the central beam. In that application, the beam hardening is accounted for by means of weighting factors that are associated to the photons according to their position (fan angle) and energy. We assessed an alternative approximation in which the photon spectrum is given a fan angle-dependent scaling factor. The aim of our investigation was to evaluate the effects on dose accuracy estimation when using the gold standard bowtie filter method versus a beam scaling approximation method. In particular, we wanted to assess the percentage dose differences between the two methods for several water thicknesses representative for different patients of different body mass index. The largest percentage differences were found for the thickest part of the bowtie filter and increased with patient size.

Paper Details

Date Published: 30 December 2014
PDF: 7 pages
J. Med. Imag. 1(3) 033507 doi: 10.1117/1.JMI.1.3.033507
Published in: Journal of Medical Imaging Volume 1, Issue 3
Show Author Affiliations
Xochitl Lopez-Rendon, Katholieke Univ. Leuven (Belgium)
Guozhi Zhang, UZ Leuven (Belgium)
Hilde Bosmans, Katholieke Univ. Leuven (Belgium)
UZ Leuven (Belgium)
Raymond Oyen, Katholieke Univ. Leuven (Belgium)
UZ Leuven (Belgium)
Federica Zanca, Katholieke Univ. Leuven (Belgium)

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