Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
Eur J Nucl Med Mol Imaging. 2024 May;51(6):1506-1515. doi: 10.1007/s00259-023-06567-9. Epub 2023 Dec 29.
Transarterial radioembolization (TARE) procedures treat liver tumors by injecting radioactive microspheres into the hepatic artery. Currently, there is a critical need to optimize TARE towards a personalized dosimetry approach. To this aim, we present a novel microsphere dosimetry (MIDOS) stochastic model to estimate the activity delivered to the tumor(s), normal liver, and lung.
MIDOS incorporates adult male/female liver computational phantoms with the hepatic arterial, hepatic portal venous, and hepatic venous vascular trees. Tumors can be placed in both models at user discretion. The perfusion of microspheres follows cluster patterns, and a Markov chain approach was applied to microsphere navigation, with the terminal location of microspheres determined to be in either normal hepatic parenchyma, hepatic tumor, or lung. A tumor uptake model was implemented to determine if microspheres get lodged in the tumor, and a probability was included in determining the shunt of microspheres to the lung. A sensitivity analysis of the model parameters was performed, and radiation segmentectomy/lobectomy procedures were simulated over a wide range of activity perfused. Then, the impact of using different microspheres, i.e., SIR-Sphere®, TheraSphere®, and QuiremSphere®, on the tumor-to-normal ratio (TNR), lung shunt fraction (LSF), and mean absorbed dose was analyzed.
Highly vascularized tumors translated into increased TNR. Treatment results (TNR and LSF) were significantly more variable for microspheres with high particle load. In our scenarios with 1.5 GBq perfusion, TNR was maximum for TheraSphere® at calibration time in segmentectomy/lobar technique, for SIR-Sphere® at 1-3 days post-calibration, and regarding QuiremSphere® at 3 days post-calibration.
This novel approach is a decisive step towards developing a personalized dosimetry framework for TARE. MIDOS assists in making clinical decisions in TARE treatment planning by assessing various delivery parameters and simulating different tumor uptakes. MIDOS offers evaluation of treatment outcomes, such as TNR and LSF, and quantitative scenario-specific decisions.
经动脉放射性栓塞（TARE）通过将放射性微球注入肝动脉来治疗肝脏肿瘤。目前，迫切需要通过个性化剂量学方法来优化 TARE。为此，我们提出了一种新的微球剂量学（MIDOS）随机模型，以估计肿瘤、正常肝脏和肺部的放射性药物输送量。
MIDOS 结合了成人男性/女性肝脏计算体模以及肝动脉、肝门静脉和肝静脉血管树。可以根据用户的判断在两个模型中放置肿瘤。微球的灌注遵循簇状模式，采用马尔可夫链方法进行微球导航，微球的最终位置确定为正常肝实质、肝肿瘤或肺部。实施了肿瘤摄取模型以确定微球是否被截留，并且在确定微球向肺部分流的概率时包括了该模型。对模型参数进行了敏感性分析，并在广泛的活性灌注范围内模拟了肿瘤放射性肝段切除术/叶切除术。然后，分析了使用不同的微球，即 SIR-Sphere®、TheraSphere®和 QuiremSphere®，对肿瘤-正常比（TNR）、肺分流分数（LSF）和平均吸收剂量的影响。
高度血管化的肿瘤导致 TNR 增加。对于高颗粒负荷的微球，治疗结果（TNR 和 LSF）的变异性明显更大。在我们以 1.5GBq 灌注的情况下，在节段性/叶状技术的校准时间，TheraSphere®的 TNR 最高；在校准后 1-3 天，SIR-Sphere®的 TNR 最高；在 3 天校准后，QuiremSphere®的 TNR 最高。
这种新方法是朝着开发 TARE 个性化剂量学框架迈出的决定性一步。MIDOS 通过评估各种输送参数并模拟不同的肿瘤摄取来协助进行 TARE 治疗计划的临床决策。MIDOS 提供了治疗结果（如 TNR 和 LSF）的评估，并提供了定量的特定于场景的决策。
