Methodology for simulating x-ray sources of computed tomography systems using GATE 10 without manufacturer data.

Fiche publication

Date publication

mars 2026

Journal

Physics in medicine and biology

Auteurs

Membres identifiés du Cancéropôle Est :
Dr EL BITAR Ziad

Tous les auteurs :
Lê AT, Raymond G, Sidibé R, El Bitar Z, Arbor N, Moussier A, Leygnac S, Cras Y, Maigne L, Deutsch E, Fournier-Bidoz N, Robert C

Lien Pubmed

https://www.ncbi.nlm.nih.gov/pubmed/41843992

Résumé

This study aims to implement and evaluate a source modeling method for Monte Carlo (MC) simulation of computed tomography (CT) systems in the absence of manufacturer data. This work enables simulation of realistic CT x-ray sources by integrating experimental measurements, particularly x-ray spectrometry, and to assess its applicability to single-energy CT (SECT) scanners. Approach: An experimental method was implemented combining x-ray spectra using a CdTe spectrometer and a bowtie filter attenuation profile measured with an ionization chamber, and compared to manufacturer data. Two source models with different levels of complexity were created for GATE 10 simulations. First, a basic model (Single-spectrum) using one energy spectrum measured on the beam axis combined with the attenuation profile was considered. Multi-spectra model incorporated additional spectra off-axis. For comparison, the Single-spectrum model was used with manufacturer's data. These source models were evaluated by comparing simulations and measurements of half-value layers (HVL) of aluminum at three voltages (80 kV, 120 kV and 140 kV), as well as CT dose index (CTDI) values measured on both head and body phantoms. Main results: HVL of Single-spectrum and Multi-spectra models showed a better agreement with measurements, yielding a mean difference of 4%. CTDI values derived from simulations based on Multi-spectra source outperformed the other sources, with differences inferior to 7% with measurements. Single-spectrum results had good agreement with measurements (<10%), but underestimated dose evaluation in some cases by up to 16%. The Manufacturer source showed the largest discrepancies, especially at 140 kV. Significance: This work highlighted that modeling spectral variations across the x-ray beam significantly improves CT source model. The proposed framework offers a replacement for manufacturer data when not available and participates in the foundation for using Monte Carlo methods to support the integration of new CT systems.