Dawson Robert J, Huesa-Berral Carlos, Carter Lukas M, Beekman Chris, Choi Chansoo, Shin Bangho, Bobić Mislav, Cogno Nicolò, Withrow Julia D, Jokisch Derek W, Bertolet Alejandro, Paganetti Harald, Bolch Wesley E
University of Florida, Gainesville, FL, United States of America.
Harvard Medical School, Boston, MA, United States of America.
Phys Med Biol. 2025 Jun 19;70(12). doi: 10.1088/1361-6560/addfa6.
To develop a computational framework coupling multiscale vascular models of the human liver for improved radiation dosimetry calculations that clearly distinguish the absorbed dose to tissue parenchyma and that to its blood content at all spatial scales. This framework thus addresses limitations of homogeneous blood/tissue organ models in present use in radiopharmaceutical therapy.High-fidelity tetrahedral mesh models of liver vasculature were constructed at two spatial scales. At the macroscale, detailed hepatic arterial, venous, and portal venous networks were generated within reference adult male and female computational phantoms. At the microscale, a classical hexagonal liver lobule model incorporating sinusoids, bile compartments, and cellular components was developed. A mathematical framework was further developed to couple Monte Carlo radiation transport results across these spatial scales, enabling comprehensive dosimetric calculations for radiation dose to both blood and parenchymal tissues.The coupled model system successfully accounted for the entire blood content of the liver, with approximately 31% represented in macroscale vessels (⩾100m diameter) and 69% within microscale structures. Specific absorbed fractions were computed for monoenergetic photons, electrons, and alpha particles, demonstrating reciprocity between blood-to-parenchyma and parenchyma-to-blood crossfire. Reference-values were computed for 22 therapeutic and 11 diagnostic radionuclides, providing the first comprehensive dataset for blood-specific and parenchyma-specific internal dosimetry calculations in the liver.This work establishes a novel framework for multi-scale radiation transport calculations in vascularized organs, enabling separate tracking of blood and parenchymal tissue doses. The methodology has immediate applications in improving dose calculations for radiopharmaceutical therapies, Y-90 microsphere radioembolization treatment, and analysis of blood dose during external beam radiotherapy. The approach can be readily adapted for other vascularized organs, representing a significant advancement in radiation dosimetry accuracy for both therapeutic and diagnostic applications by fully and independently accounting for organ activity localized within two tissue compartments-organ blood and organ parenchyma.
开发一个计算框架，将人类肝脏的多尺度血管模型耦合起来，以改进辐射剂量计算，从而在所有空间尺度上清晰区分组织实质和血液成分所吸收的剂量。该框架因此解决了目前放射性药物治疗中使用的均匀血液/组织器官模型的局限性。在两个空间尺度上构建了肝脏血管系统的高保真四面体网格模型。在宏观尺度上，在参考成年男性和女性计算体模内生成了详细的肝动脉、静脉和门静脉网络。在微观尺度上，开发了一个包含窦状隙、胆汁腔和细胞成分的经典六边形肝小叶模型。进一步开发了一个数学框架，以耦合这些空间尺度上的蒙特卡罗辐射传输结果，从而能够对血液和实质组织的辐射剂量进行全面的剂量计算。耦合模型系统成功地考虑了肝脏的全部血液含量，其中约31%存在于宏观血管（直径⩾100μm）中，69%存在于微观结构中。计算了单能光子、电子和α粒子的比吸收分数，证明了血液到实质和实质到血液交叉照射之间的互易性。计算了22种治疗性和11种诊断性放射性核素的参考值，提供了首个用于肝脏血液特异性和实质特异性内照射剂量计算的综合数据集。这项工作建立了一个用于血管化器官多尺度辐射传输计算的新框架，能够分别跟踪血液和实质组织的剂量。该方法在改进放射性药物治疗、Y-90微球放射性栓塞治疗的剂量计算以及外照射放疗期间的血液剂量分析方面有直接应用。该方法可以很容易地应用于其他血管化器官，通过充分且独立地考虑器官活性在器官血液和器官实质这两个组织隔室内的分布，代表了治疗和诊断应用中辐射剂量测定准确性的重大进步。
