磁共振引导直线加速器治疗肝转移瘤 SBRT 中对比增强 CT 对剂量学的影响。
Impact of contrast-enhanced CT in the dosimetry of SBRT for liver metastases treated with MR-Linac.
机构信息
College of Computer Science and Cyber Security, Chengdu University of Technology, Chengdu, China.
Department of Radiation Oncology, Sichuan Cancer Hospital & Institute, Affiliated Cancer Hospital of University and Electronic Science and Technology of China, Chengdu, China.
出版信息
Radiat Oncol. 2024 Oct 15;19(1):144. doi: 10.1186/s13014-024-02533-3.
BACKGROUND
To investigate the impact of using contrast-enhanced computed tomography (CHCT) in the dosimetry of stereotactic body radiation therapy (SBRT) for liver metastases treated with MR-Linac.
METHODS
A retrospective study was conducted on 21 liver cancer patients treated with SBRT (50 Gy in 5 fractions) using a 1.5 Tesla Unity MR-Linac. The clinical treatment plans optimised on plain computed tomography (pCT) were used as reference. The electronic density (ED) of regions of interest (ROIs) including the liver, duodenum, esophagus, spinal cord, heart, ribs, and lungs, from pCT and CHCT, was analysed. The average ED of each ROI from CHCT was used to generate synthetic CT (sCT) images by assigning the average ED value from the CHCT to the pCT. Clinical plans were recalculated on sCT images. Dosimetric comparisons between the original treatment plan (TP) and the sCT plan (TP) were performed using dose-volume histogram (DVH) parameters, and gamma analysis.
RESULTS
Significant ED differences (p < 0.05) were observed in the liver, great vessels, heart, lungs, and spinal cord between CHCT and pCT, with the lungs showing the largest differences (average deviation of 11.73% and 12.15% for the left and right lung, respectively). The target volume covered by the prescribed dose (V), and the dose received by 2% and 98% of the volume (D, and D, respectively) showed statistical differences (p < 0.05), while the gradient index (GI) and the conformity index (CI) did not. Average deviations in target volume dosimetric parameters were below 1.02%, with a maximum deviation of 5.57% for. For the organs at risk (OARs), significant differences (p < 0.05) were observed for D and D of the spinal cord, D for the stomach, D for the heart, and D for the liver-GTV, with mean deviations lower than 1.83% for all the above OARs. Gamma analysis using 2%-2 mm criteria yielded a median value of 95.64% (range 82.22-99.65%) for the target volume and 99.40% (range 58-100%) for the OARs.
CONCLUSION
The findings suggest that the use of CHCT in the SBRT workflow for liver metastases may result in minor target volume overdosage, indicating its potential for adoption in clinical settings. However, its use should be further explored in a broader context and tied to personalized treatment approaches.
背景
为了研究使用对比增强 CT（CHCT）在使用 MR-Linac 治疗肝转移的立体定向体放射治疗（SBRT）剂量学中的影响。
方法
对 21 例接受 SBRT（50Gy 分 5 次）治疗的肝癌患者进行回顾性研究，使用 1.5T Unity MR-Linac。以优化的平扫 CT（pCT）临床治疗计划作为参考。分析包括肝脏、十二指肠、食管、脊髓、心脏、肋骨和肺在内的感兴趣区域（ROI）的电子密度（ED），来自 pCT 和 CHCT。通过将 CHCT 的平均 ED 值分配给 pCT，用 CHCT 的平均 ED 值生成合成 CT（sCT）图像。在 sCT 图像上重新计算临床计划。使用剂量-体积直方图（DVH）参数和伽马分析对原始治疗计划（TP）和 sCT 计划（TP）进行剂量学比较。
结果
CHCT 与 pCT 之间的肝脏、大血管、心脏、肺和脊髓的 ED 存在显著差异（p<0.05），其中肺的差异最大（左肺和右肺分别为平均偏差 11.73%和 12.15%）。目标体积覆盖的处方剂量（V）和体积接受的 2%和 98%剂量（D 和 D ）显示出统计学差异（p<0.05），而梯度指数（GI）和适形指数（CI）没有。目标体积剂量学参数的平均偏差低于 1.02%，最大偏差为 5.57%，用于肝脏-GTV。对于危及器官（OARs），脊髓的 D 和 D 、胃的 D 、心脏的 D 和肝脏-GTV 的 D 存在显著差异（p<0.05），所有上述 OARs 的平均偏差均低于 1.83%。使用 2%-2mm 标准的伽马分析，目标体积的中位数为 95.64%（范围 82.22-99.65%），OARs 的中位数为 99.40%（范围 58-100%）。
结论
研究结果表明，在肝转移 SBRT 工作流程中使用 CHCT 可能导致目标体积剂量过度，表明其在临床环境中具有潜在应用价值。然而，应在更广泛的背景下进一步探索其使用，并与个体化治疗方法相结合。
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