Main Session
Oct 01
QP 27 - Radiation and Cancer Physics 13: Imaging for Treatment Monitoring

1158 - Quantitative Analysis of the Impact of Iodinated Contrast Agent Volume on Target Displacement in Cardiac-Peripheral Tumors

12:15pm - 12:20pm PT
Room 159

Presenter(s)

Wei Yao, RT - radiotherapy department, xi'an, Shaanxi

W. X. Yao1, B. Fei2, Q. X. Hu3, F. T. Yang1, L. L. Xu3, L. Zhang4, J. Zang5, and L. Zhao6; 1Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University., xi'an, shaanxi, China, 2Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University. Xi’an, China, Xi'an, Shanxi, China, 3Department of Radiation Oncology,Xijing Hospital,Air Force Medical University CN, xi'an, ShaanXi, China, 4Department of Radiation Oncology,Xijing Hospital,Air Force Medical University CN, Xi'an, ShaanXi, China, 5Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, China, 6StateKey Laboratory of Holisticntegrative Managementof Gastrointestinal Cancersand Department of RadiationOncology,Xijing Hospital,Fourth Military MedicalUniversity, Xi'an, China

Purpose/Objective(s):

While iodinated contrast-enhanced CT is widely adopted for radiotherapy planning, the dose-dependent influence of contrast volume on cardiac-adjacent tumor target motion remains underexplored. This study aims to quantify the correlation between iodinated contrast volume and target displacement in heart-proximal tumors, thereby optimizing margin strategies for improved clinical precision.

Materials/Methods: A retrospective analysis was conducted on patients with thoracic tumors adjacent to the heart who underwent radiotherapy at our center from June 2024 to January 2025. All patients underwent non-contrast four-dimensional CT (4D-CT) and contrast-enhanced arterial-phase 3D-CT imaging. The Medmind auto-contouring software was utilized to delineate cardiac volumes and tumor targets on both non-contrast 4D-CT and contrast-enhanced 3D-CT images. Parameters including iodinated contrast agent volume, hydration saline volume, injection rate, and delay time were recorded. The relationship between cardiac volume changes (observed on 4D-CT versus contrast-enhanced images) and contrast agent volume was statistically analyzed. Additionally, discrepancies in cardiac and target boundaries were measured after co-registration of the 4D-CT average intensity projection (AIP) and contrast-enhanced 3D-CT images.

Results: A total of 30 patients with cardiac-proximal thoracic tumors were included in the analysis (16 males, 14 females), with a median age of 52 years (range: 38–70).The non-contrast CT cardiac volume was(568 ±106 )cc;whereas the contrast-enhanced CT cardiac volume significantly increased to( 648 ± 115 )cc,p=0.048 ;The increase in cardiac volume exhibited a strong positive correlation with both iodinated contrast agent and hydration saline volumes (r=0.984,p<0.001);There is displacement deviation at the heart boundary in the fusion image (1.85± 0.76)mm,The left ventricle was offset to the extranulmonary zone about 2.7mm.Fusion target boundary displacement deviation (2.13± 0.56)mm.

Conclusion: While iodinated contrast agents enhance target visibility, they induce cardiac volume expansion, leading to outward displacement of cardiac-peripheral targets toward the pulmonary periphery compared to non-contrast images. It is recommended that clinicians integrate non-contrast and contrast-enhanced images for target delineation in radiotherapy but finalize treatment planning using non-contrast images to ensure geometric accuracy. This study provides evidence-based guidance for optimizing iodinated contrast agent use in radiotherapy for tumors near the heart.