关于肝动脉栓塞热疗的温度场模拟

由于有创测温带来疼痛和提供组织内温度信息有限，肿瘤组织热场模拟技术是热疗临床计划的重要内容，而热模拟的精确程度直接关系到临床疗效。热疗临床计划包括两个步骤：第一步是确定特征吸收率的分布，第二步是模拟出整个温度场的分布。我们研究发现，在肝动脉栓塞热疗中，精确的热模拟必须要考虑磁场的衰减和纳米颗粒的分布。

The invasive thermometry, which at present clinical hyperthermia has to rely on, produces the problems in the patients’ acceptance of pain, as well as the problems with the extremely limited information about highly inhomogeneous thermal dose distributions. The thermal simulation technique is essential for hyperthermia plan and accuracy of it directly affects the clinical effects. Hyperthermia treatment planning is a two-step process; after the calculation of the specific absorption rate distribution the temperature distribution has to be computed. We found that the inhomogeneous heating is caused by two factors; the inhomogeneous physical parameters of magnetic field and heterogeneous particles distribution. By the knowledge of these two factors, the thermal model in future will give significantly different results to those for a model of homogeneous heating and thus will be preferable when accurate results are required.

Fig.1. Scheme of the ferrite-core-applicator operating system and maghemite particles with 20nm diameters, which were homogeneously distributed in the cylindrical composite, induced by the AC magnetic field and acting as thousands of little heat sources.

Fig.2. Temperature Elevation Experiment: The cylindrical maghemite-gelled composite was located in the device aperture. Six optic fibers were inserted into the composite to measure the temperature. When the device power was switched on, the AC magnetic field was produced and the cylindrical composite was heated up.

Fig.3. Scheme of arterial embolization hyperthermia applied to a hepatocellular carcinoma. The small tumor region contains injected magnetic nanoparticles.

Fig.4. The 3-D graph with simulated results after 2400s. The temperature ascends to the peak of 8.3℃and the lowest point of 5.5℃in the composite model.

Ruizhi Xu, Yu Zhang, Ming Ma, Jingguang Xia, Jiwei Liu, Quanzhong Guo, Ning Gu.IEEE TRANS.ON.MAG. 43(3), March 2007.