@inproceedings{d7c45f6b2bee40cbb0ce019616f3a012,
title = "Accurate proton stopping power images reconstructed using joint statistical dual energy CT: Experimental verification and impact of fan-beam CT scatter",
abstract = "Proton radiotherapy has the potential to provide clinically effective treatment and highly conformal dose delivery when the rapid dose falloff at the end of its proton-beam range is correctly aligned to the distal margin of the clinical target volume. However, in current clinical practice an additional 2-3.5% safety margin must be added to the proton range to account for uncertainties in the estimation of proton-beam range when using stopping-power ratios (SPRs) derived from single-energy CT scans. Several approaches have been proposed to estimate stopping power by using dual-energy CT (DECT) and have been shown through theoretical analysis to outperform single-energy CT (SECT) under the presence of tissue composition and density variations. Our lab previously proposed a joint statistical image reconstruction (JSIR) method built on a basis-vector model (BVM) tissue parameterization for SPR estimation, which was shown to perform comparatively better than other DECT image- and sinogram-domain decomposition approaches on simulated as well as experimental data. This comparison, however, assumed theoretical SPR values calculated from the samples{\textquoteright} known compositions and densities as ground truth and used the mean excitation energy and effective electron density from ICRU reports along with a simplified version of the Bethe-Bloch equation to determine SPR reference values. Furthermore, CT scans were acquired with an assumed ideal point source at a narrow beam collimation; thus, the signal formation assumed by our JSIR process neglected scatter and off-focal radiation. In this paper, we verify the accuracy of our method by comparing the SPR values derived from JSIR-BVM to direct measurements of relative SPR, as well as present a preliminary study on the impact of fan-beam scatter radiation on JSIR-BVM SPR prediction accuracy.",
keywords = "Alternating minimization, Collimation, Dual-energy computed tomography, Proton stopping power, Proton therapy, Scatter, Statistical image reconstruction",
author = "Maria Medrano and Ruirui Liu and Tyler Webb and Tianyu Zhao and Jeffrey Williamson and Bruce Whiting and Politte, {David G.} and Mariela Porras-Chaverri and O{\textquoteright}Sullivan, {Joseph A.}",
year = "2020",
doi = "10.1117/12.2549788",
language = "English",
series = "Progress in Biomedical Optics and Imaging - Proceedings of SPIE",
publisher = "SPIE",
editor = "Guang-Hong Chen and Hilde Bosmans",
booktitle = "Medical Imaging 2020",
note = "null ; Conference date: 16-02-2020 Through 19-02-2020",
}