Purpose

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.

Methods

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.

Results

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.

Conclusion

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.

中文翻译：

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MIDOS：一种用于肝肿瘤微球剂量测定治疗计划系统的新型随机模型

目的

经动脉放射栓塞 (TARE) 手术通过将放射性微球注入肝动脉来治疗肝脏肿瘤。目前，迫切需要优化 TARE 以实现个性化剂量测定方法。为此，我们提出了一种新型微球剂量测定（MIDOS）随机模型来估计传递到肿瘤、正常肝脏和肺的活性。

方法

MIDOS 将成年男性/女性肝脏计算模型与肝动脉、肝门静脉和肝静脉血管树相结合。用户可以自行决定将肿瘤放置在两种模型中。微球的灌注遵循簇模式，并且将马尔可夫链方法应用于微球导航，微球的末端位置被确定为在正常肝实质、肝肿瘤或肺中。采用肿瘤摄取模型来确定微球是否滞留在肿瘤中，并在确定微球分流至肺部时考虑了概率。对模型参数进行了敏感性分析，并在广泛的灌注活动范围内模拟了放射段切除术/肺叶切除术。然后，分析了使用不同微球（即SIR-Sphere®、TheraSphere®和QuiremSphere®）对肿瘤与正常比（TNR）、肺分流分数（LSF）和平均吸收剂量的影响。

结果

高度血管化的肿瘤转化为 TNR 增加。对于高颗粒负载的微球，处理结果（TNR 和 LSF）的变化明显更大。在我们的 1.5 GBq 灌注场景中，TheraSphere® 在肺段切除/肺叶技术校准时 TNR 最大，SIR-Sphere® 在校准后 1-3 天，QuiremSphere® 在校准后 3 天达到最大。

结论

这种新颖的方法是开发个性化 TARE 剂量测定框架的决定性一步。MIDOS 通过评估各种输送参数并模拟不同的肿瘤摄取，协助在 TARE 治疗计划中做出临床决策。MIDOS 提供治疗结果评估，例如 TNR 和 LSF，以及针对特定场景的定量决策。