{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T11:07:27Z","timestamp":1771931247080,"version":"3.50.1"},"reference-count":31,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T00:00:00Z","timestamp":1745366400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:sec><jats:title>Purpose<\/jats:title><jats:p>To investigate the feasibility of proton therapy planning using stopping power ratio (SPR) maps directly generated from spectral CT raw data, and to perform a comparative evaluation of dose calculation uncertainties between SPR maps derived from conventional CT Hounsfield Unit (HU) conversion and direct spectral CT SPR generation.<\/jats:p><\/jats:sec><jats:sec><jats:title>Materials and methods<\/jats:title><jats:p>A retrospective analysis was conducted on 30 patients with mid-thoracic esophageal squamous cell carcinoma (ESCC) who underwent pre-treatment spectral CT imaging. Target volumes and organs at risk (OARs) were delineated on contrast-enhanced CT images and subsequently registered to both non-contrast CT and SPR maps. Three treatment plans were generated: Intensity-modulated radiotherapy (IMRT) plan based on conventional CT, Intensity-modulated proton therapy (IMPT) plan using HU-SPR conversion, IMPT plan utilizing direct SPR maps (IMPT-SPR) from spectral CT. Dose-volume parameters for target volumes and OARs (lungs, heart, spinal cord) were systematically analyzed. Comparative dosimetric analyses were performed among the three plans and between paired groups.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>All plans met clinical radiotherapy requirements. For OARs (lungs, heart), IMPT plans demonstrated significantly lower dose-volume parameters compared to IMRT, except for maximum dose (Dmax). Between the two IMPT approaches, no statistically significant differences were observed in dose-volume parameters (<jats:italic>p<\/jats:italic>&amp;gt;0.05), except for the gradient index which was significantly higher in the HU-converted IMPT plan (<jats:italic>p<\/jats:italic>&amp;lt;0.05). No significant differences were detected in heart, lung and spinal cord dosimetric parameters between IMPT approaches.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>IMPT demonstrated superior OAR sparing compared to IMRT. For mid thoracic ESCC patients under proton therapy, dose calculations based on CT-HU conversion was showed comparable dosimetric impact to DECT-derived SPR in terms of target coverage and OAR protection. These findings support the clinical feasibility of conventional CT-based proton therapy planning and dose calculation.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fonc.2025.1591139","type":"journal-article","created":{"date-parts":[[2025,4,24]],"date-time":"2025-04-24T06:12:09Z","timestamp":1745475129000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Feasibility study for proton dose calculation of esophageal squamous cell carcinoma based on stopping power ratio directly derived from dual energy 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