Quantitative Analysis of the Impact of Iodine Contrast Agent on Heart Volume and Radiation Dose
Abstract
Purpose
The purpose of this study was to quantitatively analyze the effect of iodine contrast agent injection on heart volume and target volume positioning in patients with thoracic tumors adjacent to the heart, and to further evaluate how these changes influence the dose to both the heart and the target volume.
Methods
A retrospective analysis was conducted on 30 patients with thoracic tumors located close to the heart between June 2024 and November 2025. All patients underwent both contrast-enhanced 3DCT and non-contrast 3DCT imaging. Physicians delineated normal organs and target volumes on both contrast-enhanced and non-contrast images. Changes in heart volume and the displacement of target volume boundaries between contrast-enhanced and non-contrast images were statistically analyzed. Volumetric modulated arc therapy (VMAT) plans were designed on contrast-enhanced images for all 30 patients, and these plans were subsequently transferred to non-contrast CT images for dose recalculation. The differences in dose to the heart and target volume between the two image sets were compared and analyzed.
Results
The mean heart volume on contrast-enhanced CT images was (557 ± 112) cm³, while on non-contrast images it was (538 ± 108) cm³. Compared to non-contrast CT, contrast-enhanced CT showed an average increase in heart volume of (25 ± 7.8) cm³. The mean dose to the heart increased by 2.21 ± 0.75 Gy, The displacement of target volume boundaries on fused images was (1.33 ± 0.16) mm, and the difference in target volume V100% was 1.4 ± 0.4 Gy.
Conclusion
Iodine contrast agent leads to a slight enlargement of the cardiac volume. However, as the contrast agent is metabolized by the time of treatment, the actual radiation dose delivered to the heart increases. It is recommended to delineate the target volume on contrast-enhanced images while using non-contrast images for radiotherapy planning to ensure treatment precision.