Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy

Purpose: Dual-energy computed tomography (DECT) has been used to derive relative stopping power (RSP) maps by obtaining the energy dependence of photon interactions. The DECT-derived RSP maps could potentially be compromised by image noise levels and the severity of artifacts when using physics-base...

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Main Authors: Tonghe Wang, PhD, Yang Lei, PhD, Joseph Harms, PhD, Beth Ghavidel, MS, Liyong Lin, PhD, Jonathan J. Beitler, MD, Mark McDonald, MD, Walter J. Curran, MD, Tian Liu, PhD, Jun Zhou, PhD, Xiaofeng Yang, PhD
Format: Article
Language:English
Published: Particle Therapy Co-operative Group 2021-02-01
Series:International Journal of Particle Therapy
Subjects:
Online Access:https://theijpt.org/doi/pdf/10.14338/IJPT-D-20-00020.1
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author Tonghe Wang, PhD
Yang Lei, PhD
Joseph Harms, PhD
Beth Ghavidel, MS
Liyong Lin, PhD
Jonathan J. Beitler, MD
Mark McDonald, MD
Walter J. Curran, MD
Tian Liu, PhD
Jun Zhou, PhD
Xiaofeng Yang, PhD
author_facet Tonghe Wang, PhD
Yang Lei, PhD
Joseph Harms, PhD
Beth Ghavidel, MS
Liyong Lin, PhD
Jonathan J. Beitler, MD
Mark McDonald, MD
Walter J. Curran, MD
Tian Liu, PhD
Jun Zhou, PhD
Xiaofeng Yang, PhD
author_sort Tonghe Wang, PhD
collection DOAJ
description Purpose: Dual-energy computed tomography (DECT) has been used to derive relative stopping power (RSP) maps by obtaining the energy dependence of photon interactions. The DECT-derived RSP maps could potentially be compromised by image noise levels and the severity of artifacts when using physics-based mapping techniques. This work presents a noise-robust learning-based method to predict RSP maps from DECT for proton radiation therapy. Materials and Methods: The proposed method uses a residual attention cycle-consistent generative adversarial network to bring DECT-to-RSP mapping close to a 1-to-1 mapping by introducing an inverse RSP-to-DECT mapping. To evaluate the proposed method, we retrospectively investigated 20 head-and-neck cancer patients with DECT scans in proton radiation therapy simulation. Ground truth RSP values were assigned by calculation based on chemical compositions and acted as learning targets in the training process for DECT datasets; they were evaluated against results from the proposed method using a leave-one-out cross-validation strategy. Results: The predicted RSP maps showed an average normalized mean square error of 2.83% across the whole body volume and an average mean error less than 3% in all volumes of interest. With additional simulated noise added in DECT datasets, the proposed method still maintained a comparable performance, while the physics-based stoichiometric method suffered degraded inaccuracy from increased noise level. The average differences from ground truth in dose volume histogram metrics for clinical target volumes were less than 0.2 Gy for D95% and Dmax with no statistical significance. Maximum difference in dose volume histogram metrics of organs at risk was around 1 Gy on average. Conclusion: These results strongly indicate the high accuracy of RSP maps predicted by our machine-learning–based method and show its potential feasibility for proton treatment planning and dose calculation.
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spelling doaj.art-ef918afd2a69455eaad220367c6604f22024-04-17T03:28:17ZengParticle Therapy Co-operative GroupInternational Journal of Particle Therapy2331-51802021-02-0173466010.14338/IJPT-D-20-00020.12331-5180-7-3-46Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation TherapyTonghe Wang, PhD0Yang Lei, PhD1Joseph Harms, PhD2Beth Ghavidel, MS3Liyong Lin, PhD4Jonathan J. Beitler, MD5Mark McDonald, MD6Walter J. Curran, MD7Tian Liu, PhD8Jun Zhou, PhD9Xiaofeng Yang, PhD10Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USADepartment of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, USAPurpose: Dual-energy computed tomography (DECT) has been used to derive relative stopping power (RSP) maps by obtaining the energy dependence of photon interactions. The DECT-derived RSP maps could potentially be compromised by image noise levels and the severity of artifacts when using physics-based mapping techniques. This work presents a noise-robust learning-based method to predict RSP maps from DECT for proton radiation therapy. Materials and Methods: The proposed method uses a residual attention cycle-consistent generative adversarial network to bring DECT-to-RSP mapping close to a 1-to-1 mapping by introducing an inverse RSP-to-DECT mapping. To evaluate the proposed method, we retrospectively investigated 20 head-and-neck cancer patients with DECT scans in proton radiation therapy simulation. Ground truth RSP values were assigned by calculation based on chemical compositions and acted as learning targets in the training process for DECT datasets; they were evaluated against results from the proposed method using a leave-one-out cross-validation strategy. Results: The predicted RSP maps showed an average normalized mean square error of 2.83% across the whole body volume and an average mean error less than 3% in all volumes of interest. With additional simulated noise added in DECT datasets, the proposed method still maintained a comparable performance, while the physics-based stoichiometric method suffered degraded inaccuracy from increased noise level. The average differences from ground truth in dose volume histogram metrics for clinical target volumes were less than 0.2 Gy for D95% and Dmax with no statistical significance. Maximum difference in dose volume histogram metrics of organs at risk was around 1 Gy on average. Conclusion: These results strongly indicate the high accuracy of RSP maps predicted by our machine-learning–based method and show its potential feasibility for proton treatment planning and dose calculation.https://theijpt.org/doi/pdf/10.14338/IJPT-D-20-00020.1stopping powerdual-energy ctproton therapymachine learning
spellingShingle Tonghe Wang, PhD
Yang Lei, PhD
Joseph Harms, PhD
Beth Ghavidel, MS
Liyong Lin, PhD
Jonathan J. Beitler, MD
Mark McDonald, MD
Walter J. Curran, MD
Tian Liu, PhD
Jun Zhou, PhD
Xiaofeng Yang, PhD
Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
International Journal of Particle Therapy
stopping power
dual-energy ct
proton therapy
machine learning
title Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
title_full Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
title_fullStr Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
title_full_unstemmed Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
title_short Learning-Based Stopping Power Mapping on Dual-Energy CT for Proton Radiation Therapy
title_sort learning based stopping power mapping on dual energy ct for proton radiation therapy
topic stopping power
dual-energy ct
proton therapy
machine learning
url https://theijpt.org/doi/pdf/10.14338/IJPT-D-20-00020.1
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