Mapping of discrete range modulated proton radiograph to water-equivalent path length using machine learning

Fuente: arXiv
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Autores principales: Rahman, Atiq Ur, Wang, Chun-Chieh, Wu, Shu-Wei, Chao, Tsi-Chian, Cho, I-Chun
Formato: Preprint
Publicado: 2025
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author Rahman, Atiq Ur
Wang, Chun-Chieh
Wu, Shu-Wei
Chao, Tsi-Chian
Cho, I-Chun
author_facet Rahman, Atiq Ur
Wang, Chun-Chieh
Wu, Shu-Wei
Chao, Tsi-Chian
Cho, I-Chun
contents Objective. Proton beams enable localized dose delivery. Accurate range estimation is essential, but planning still relies on X-ray CT, which introduces uncertainty in stopping power and range. Proton CT measures water equivalent thickness directly but suffers resolution loss from multiple Coulomb scattering. We develop a data driven method that reconstructs water equivalent path length (WEPL) maps from energy resolved proton radiographs, bypassing intermediate reconstructions. Approach. We present a machine learning pipeline for WEPL from high dimensional radiographs. Data were generated with the TOPAS Monte Carlo toolkit, modeling a clinical nozzle and a patient CT. Proton energies spanned 70-230 MeV across 72 projection angles. Principal component analysis reduced input dimensionality while preserving signal. A conditional GAN with gradient penalty was trained for WEPL prediction using a composite loss (adversarial, MSE, SSIM, perceptual) to balance sharpness, accuracy, and stability. Main results. The model reached a mean relative WEPL deviation of 2.5 percent, an SSIM of 0.97, and a proton radiography gamma index passing rate of 97.1 percent (2 percent delta WEPL, 3 mm distance-to-agreement) on a simulated head phantom. Results indicate high spatial fidelity and strong structural agreement. Significance. WEPL can be mapped directly from proton radiographs with deep learning while avoiding intermediate steps. The method mitigates limits of analytic techniques and may improve treatment planning. Future work will tune the number of PCA components, include detector response, explore low dose settings, and extend multi angle data toward full proton CT reconstruction; it is compatible with clinical workflows.
format Preprint
id arxiv_https___arxiv_org_abs_2509_09514
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mapping of discrete range modulated proton radiograph to water-equivalent path length using machine learning
Rahman, Atiq Ur
Wang, Chun-Chieh
Wu, Shu-Wei
Chao, Tsi-Chian
Cho, I-Chun
Medical Physics
High Energy Physics - Experiment
Applied Physics
Instrumentation and Detectors
Objective. Proton beams enable localized dose delivery. Accurate range estimation is essential, but planning still relies on X-ray CT, which introduces uncertainty in stopping power and range. Proton CT measures water equivalent thickness directly but suffers resolution loss from multiple Coulomb scattering. We develop a data driven method that reconstructs water equivalent path length (WEPL) maps from energy resolved proton radiographs, bypassing intermediate reconstructions. Approach. We present a machine learning pipeline for WEPL from high dimensional radiographs. Data were generated with the TOPAS Monte Carlo toolkit, modeling a clinical nozzle and a patient CT. Proton energies spanned 70-230 MeV across 72 projection angles. Principal component analysis reduced input dimensionality while preserving signal. A conditional GAN with gradient penalty was trained for WEPL prediction using a composite loss (adversarial, MSE, SSIM, perceptual) to balance sharpness, accuracy, and stability. Main results. The model reached a mean relative WEPL deviation of 2.5 percent, an SSIM of 0.97, and a proton radiography gamma index passing rate of 97.1 percent (2 percent delta WEPL, 3 mm distance-to-agreement) on a simulated head phantom. Results indicate high spatial fidelity and strong structural agreement. Significance. WEPL can be mapped directly from proton radiographs with deep learning while avoiding intermediate steps. The method mitigates limits of analytic techniques and may improve treatment planning. Future work will tune the number of PCA components, include detector response, explore low dose settings, and extend multi angle data toward full proton CT reconstruction; it is compatible with clinical workflows.
title Mapping of discrete range modulated proton radiograph to water-equivalent path length using machine learning
topic Medical Physics
High Energy Physics - Experiment
Applied Physics
Instrumentation and Detectors
url https://arxiv.org/abs/2509.09514