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Impact of thoracic tumor motion on spinal cord radiation dose parameters in interstitial brachytherapy
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G. Zhang   , J. Zhang , Z. Huang , Y. Han , B. Yang |
| Department of Oncology, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China , 530018842@qq.com |
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Abstract: (21 Views) |
Background: In thoracic tumor radiotherapy, tumor movement with respiration can affect dose distribution, potentially complicating the assessment of dose delivery to organs at risk (OAR). However, no standardized evaluation methods have been reported. We aimed to evaluate the dose–response effects caused by target movement and propose a more accurate method for assessing spinal cord dose in interstitial brachytherapy. Materials and Methods: Computed tomography (CT) data from 14 patients with lung cancer undergoing interstitial brachytherapy were used to design a distance-change model: f(d)=a×ebd. In this model, the distance (d) between the spinal cord and the clinical target volume (CTV) was defined, and f(d) represented spinal cord radiation dose parameters, including the maximum spinal cord dose (Dmax), dose to 1 cm³ (D1cc), dose to 0.1 cm³ (D0.1cc), and dose to 1% of the volume (D1%). Each parameter was fitted separately, assuming that the CTV exhibited simple harmonic oscillation. An experiment was designed to measure the effect of radiation source movement on point dose. Results: The coefficient of determination (R²) for the exponential fitting curves of all dose variables exceeded 0.90. Specifically, the R² value was 0.94 for Dmax and 0.95 for D1cc, D0.1cc, and D1%. The significance of f(d) was evaluated using the F-test, with p<0.05 considered statistically significant. The F-values for Dmax, D1cc, D0.1cc, and D1% were 2,362.63, 3,158.41, 2,705.33, and 2,604.93, respectively, all with p<0.01. Conclusion: Reliance on static CT images in radiotherapy planning systems may result in inaccurate spinal cord dose estimates. |
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| Keywords: Interstitial Radiotherapy, Lung, Neoplasms, Spinal Cords, Target, Movement. |
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Full-Text [PDF 1113 kb]
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Type of Study: Original Research |
Subject:
Radiation Biology
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