TY  - JOUR
AU  - Lustermans, Didier
AU  - Fonseca, Gabriel Paiva
AU  - Jeukens, Cécile
AU  - Taasti, Vicki Trier
AU  - Parodi, Katia
AU  - Landry, Guillaume
AU  - Verhaegen, Frank
TI  - Evaluating photon-counting computed tomography for quantitative material characteristics and material differentiation in radiotherapy.
JO  - Physics in medicine and biology
VL  - 70
IS  - 10
SN  - 0031-9155
CY  - Bristol
PB  - IOP Publ.
M1  - DKFZ-2025-00983
SP  - 105013
PY  - 2025
AB  - 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
KW  - Phantoms, Imaging
KW  - Photons
KW  - Tomography, X-Ray Computed: methods
KW  - Tomography, X-Ray Computed: instrumentation
KW  - Calibration
KW  - photon-counting CT (Other)
KW  - quantitative imaging (Other)
KW  - radiotherapy (Other)
KW  - spectral CT (Other)
KW  - virtual monoenergetic imaging (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:40315900
DO  - DOI:10.1088/1361-6560/add3ba
UR  - https://inrepo02.dkfz.de/record/301300
ER  -