Intra-Fractional Dose Evaluation for Patients with Breast Cancer Using Synthetic Computed Tomography

Sohyun Ahn; So Eun Choi; Jeong-Heon Kim; Kwangwoo Park; Hai-Jeon Yoon

doi:10.14316/pmp.2024.35.4.145

Article

Original Article

Progress in Medical Physics 2024; 35(4): 145-154

Published online December 31, 2024

https://doi.org/10.14316/pmp.2024.35.4.145

Intra-Fractional Dose Evaluation for Patients with Breast Cancer Using Synthetic Computed Tomography

Sohyun Ahn^1,2 , So Eun Choi³ , Jeong-Heon Kim^4,5,6 , Kwangwoo Park⁷ , Hai-Jeon Yoon⁸

Author Info ⁺

¹Ewha Medical Research Institute, Ewha Womans University College of Medicine, Seoul, ²Ewha Medical Artificial Intelligence Research Institute, Ewha Womans University College of Medicine, Seoul, ³Department of Computational Medicine, Ewha Womans University College of Medicine, Seoul, ⁴Department of Medicine, Yonsei University College of Medicine, Seoul, ⁵Medical Physics and Biomedical Engineering Lab (MPBEL), Yonsei University College of Medicine, Seoul, ⁶Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, ⁷Department of Radiation Oncology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, ⁸Department of Nuclear Medicine, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea

Correspondence to:Sohyun Ahn
(mpsohyun@gmail.com)
Tel: 82-2-6986-6305
Fax: 82-0504-158-4052

Received: October 31, 2024; Revised: December 11, 2024; Accepted: December 15, 2024

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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Abstract

Purpose: This study investigated the use of synthetic computed tomography (CT) images derived from cone beam CT (CBCT) scans to analyze dose changes in breast cancer patients undergoing treatment and to evaluate the optimal timing for implementing adaptive radiotherapy.
Methods: A retrospective analysis was conducted on five breast cancer patients treated with tomotherapy-based volumetric-modulated arc therapy at Yongin Severance Hospital. Each patient received 15 fractions, with doses of 320 centigray (cGy) to the high-dose planning target volume (PTV) and 267 cGy to the low-dose PTV. Planning CT images were acquired using the Aquilion scanner, and CBCT images were captured with the VersaHD linear accelerator’s on-board imager. These images were registered in RayStation using a hybrid deformable image registration method to generate synthetic CT images. Dose distributions were reanalyzed using the synthetic CT images, and dosevolume histogram parameters, including the dose to 95% of the volume (D₉₅) and mean dose (D_mean) for the PTV, as well as D₉₅, D_mean, the percentage of the volume receiving at least 5 Gy (V₅) and 10 Gy (V₁₀) for organs-at-risk (OARs), were extracted using MATLAB to assess dose changes during treatment.
Results: For the original plans, the mean D₉₅ for PTV high across all patients was 287.13±31.32 cGy, while for PTV low, it was 245.53±6.21 cGy. In contrast, the adaptive plans yielded a mean D₉₅ of 298.17±12.37 cGy for PTV High and 247.25±4.23 cGy for PTV low. The ART Plan may lead to increased dose exposure in certain structures, such as the spinal cord, while providing targeted improvements in reducing radiation exposure in specific OARs (e.g., contralateral breast and esophagus).
Conclusions: Synthetic CT images generated from CBCT scans provide a fast and efficient means of quantifying dose changes, supporting precise patient care through interfractional evaluation. Future studies will aim to apply this method to other organs and larger patient cohorts.

KeywordsSynthetic computed tomography generation, Adaptive radiotherapy, Breast cancer treatment, Dose-volumetric analysis, Cone beam computed tomography imaging