%0 Journal Article
%A Lustermans, Didier
%A Fonseca, Gabriel Paiva
%A Jeukens, Cécile
%A Taasti, Vicki Trier
%A Parodi, Katia
%A Landry, Guillaume
%A Verhaegen, Frank
%T Evaluating photon-counting computed tomography for quantitative material characteristics and material differentiation in radiotherapy.
%J Physics in medicine and biology
%V 70
%N 10
%@ 0031-9155
%C Bristol
%I IOP Publ.
%M DKFZ-2025-00983
%P 105013
%D 2025
%X Objective.Photon-counting computed tomography (PCCT) counts the individual photons and measures their energy, which allows for energy binning and thereby multi-energy CT imaging. It is expected that quantitative data can be accurately extracted from the images and enable accurate material separation, yet its potential in radiotherapy is mostly unexplored. In this study, PCCT was assessed by evaluating estimation accuracies for relative electron density (RED), effective atomic number (Zeff), and proton stopping-power ratio (SPR), as well as the potential for material differentiation.Approach.PCCT images of a Gammex Advanced Electron Density phantom (Sun Nuclear) with tissue-equivalent materials were acquired in a small and large phantom setup on a NAEOTOM Alpha PCCT scanner (Siemens Healthineers). The scans were performed at 120 and 140 kVp, and virtual monoenergetic images (VMIs) were generated. These VMIs were used to estimate RED,Zeff, and SPR based on two calibration methods for each of the two phantom sizes. These results were compared to findings obtained based on dual-energy CT (DECT) scans acquired on a SOMATOM Confidence scanner (Siemens Healthineers) at 80 and 140 kVp, by using the low and high energy pair and VMIs. Calibration accuracy was quantified by the root-mean-squared error. Additional, material differentiation was assessed for both tissue-equivalent and calcium/iodine inserts by creating [RED/Zeff]-space plots.Main results.There was minimal differences between the two PCCT x-ray spectra, with SPR errors below 0.8
%K Phantoms, Imaging
%K Photons
%K Tomography, X-Ray Computed: methods
%K Tomography, X-Ray Computed: instrumentation
%K Calibration
%K photon-counting CT (Other)
%K quantitative imaging (Other)
%K radiotherapy (Other)
%K spectral CT (Other)
%K virtual monoenergetic imaging (Other)
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:40315900
%R 10.1088/1361-6560/add3ba
%U https://inrepo02.dkfz.de/record/301300