Xing Shu, Correa-Alfonso Camilo M, Shin Jungwook, Pursley Jennifer, Depauw Nicolas, Domal Sean, Withrow Julia, Bolch Wesley, Grassberger Clemens, Paganetti Harald
Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York City, New York.
Department of Biomedical Engineering, University of Florida, Gainesville, Florida; Radiation Physics Department, University of Texas MD Anderson Cancer Center, Houston, Texas.
Int J Radiat Oncol Biol Phys. 2025 Apr 1;121(5):1339-1348. doi: 10.1016/j.ijrobp.2024.11.087. Epub 2024 Nov 26.
To assess the impact of liver model complexity on the estimated radiation dose to circulating blood during radiation therapy.
Six patients with hepatocellular carcinoma (HCC) were selected covering a range of clinical treatment volume (CTV) sizes and locations. Photon and proton treatment plans were generated for each patient. Planning computed tomography, CTV contours, and dose distributions were deformably registered to the reference livers provided by the International Commission on Radiological Protection report. Three vasculature models were considered: (1) main vascular tree (MVT), (2) coarse vascular tree (CVT) of 1045 vessels, and (3) detailed vascular tree (DVT) of 2041 vessels. Blood dose-volume histograms (bDVH, bDVH, and bDVH) and the mean circulating blood dose (μ, μ, and μ) were estimated using Monte Carlo simulations for all 3 models. The effect of varying blood velocity (v) in HCC tumors on dose estimation was also evaluated through increasing the tumor v by 1.5, 2, and 4.2 times.
For the 3 lesions located in the left lobe, the estimated μ was lower than μ by an average ± standard deviation of (6 ± 4)% and (17 ± 7)% for photon and proton treatments, respectively. Smaller differences were found for lesions in the right lobe, where μ was on average (2 ± 1)% lower than μ for photon and (3 ± 1)% lower for proton treatments. More pronounced difference between μ and μ was seen in lesions with smaller CTV sizes. We also found that considering the elevated tumor v led to a reduction of estimated dose to circulating blood, with a maximum reduction in the estimated μ of 39% and 8% for CTV of 603 and 249 mL, respectively.
Our study revealed that the impact of liver vasculature model complexity on the estimated dose to blood depended on lesion-specific characteristics. For lesions with larger CTV size on the right liver lobe treated with photons, modeling only major vessels could generate bDVHs that are dosimetrically comparable with bDVHs of more complex vascular models. Increased tumor v resulted in a reduction of the estimated blood dose.
评估肝脏模型复杂性对放射治疗期间循环血液估计辐射剂量的影响。
选择6例肝细胞癌（HCC）患者，涵盖一系列临床治疗体积（CTV）大小和位置。为每位患者生成光子和质子治疗计划。将计划计算机断层扫描、CTV轮廓和剂量分布变形配准到国际放射防护委员会报告提供的参考肝脏。考虑了三种血管模型：（1）主要血管树（MVT），（2）1045条血管的粗血管树（CVT），以及（3）2041条血管的详细血管树（DVT）。使用蒙特卡罗模拟对所有三种模型估计血液剂量体积直方图（bDVH、bDVH和bDVH）以及平均循环血液剂量（μ、μ和μ）。还通过将HCC肿瘤中的血流速度（v）提高1.5、2和4.2倍来评估其对剂量估计的影响。
对于位于左叶的3个病灶，光子和质子治疗的估计μ分别比μ平均低±标准差（6±4）%和（17±7）%。右叶病灶的差异较小，光子治疗时μ平均比μ低（2±1）%，质子治疗时低（3±1）%。在CTV较小的病灶中，μ和μ之间的差异更为明显。我们还发现，考虑到肿瘤v升高会导致循环血液估计剂量降低，CTV为603和249 mL时，估计μ的最大降低分别为39%和8%。
我们的研究表明，肝脏血管模型复杂性对血液估计剂量的影响取决于病灶的特定特征。对于右肝叶CTV较大且采用光子治疗的病灶，仅对主要血管进行建模所生成的bDVH在剂量学上可与更复杂血管模型的bDVH相媲美。肿瘤v增加导致估计血液剂量降低。
