DEVELOPMENT OF RE-ENTRANT TYPE RESONANT CAVITY APPLICATOR FOR DEEP TUMOR HYPERTHERMIA

在本研究项目中，我们提出了一种用于深部肿瘤热疗治疗的新型加热系统。所开发的加热系统由铝合金制成的可重入式谐振腔、射频放大器、电源单元、匹配单元和微型计算机组成。为了验证该加热系统用于深部肿瘤的可能性，我们使用圆柱形幻影和狗进行了以下三个实验：(1)本实验使用的琼脂幻影直径27.0cm，高25.0cm。用热成像仪观察加热模式。琼脂幻影垂直切面的热像清晰地显示，幻影中心区域被同心加热，与预期一致。(2)实验采用三层猪脂琼脂模型。将厚度为20.0cm的琼脂体膜夹在厚度分别为2.0cm和1.5cm的两层猪油盘之间。虽然由于边缘效应，在猪油层中出现了小的热点，但最高温度仍然出现在幻像的中心区域。最后的实验是加热比格犬的肝脏和大脑。光纤温度传感器被放置在狗组织的四个点上。在大量血流灌注的情况下，测量到的最深区域的温度比组织其他区域高0.5 ~ 0.7ºC。从这些实验加热结果，证实了该系统可以适用于局部和深部肿瘤热疗。

In this research project, a new heating system using a re-entrant resonant type cavity applicator for deep-seated tumor hyperthermia treatment is proposed. The developed heating system consists of a re-entrant type resonant cavity made of an aluminum alloy, an RF (radio frequency) amplifier, a power supply unit, a matching unit, and a microcomputer. To verify the possibility of this heating system for deep-seated tumor, the following three experiments using cylindrical phantoms and dogs were perfomed :(1) The agar phantom used in this experiment was 27.0cm in diameter and 25.0cm high. Heating pattems were observed with a thermographic camera. The thermal image of the vertical sectional slice of the agar phantom clearly showed that the center region of the phantom was heated concentrically, as expected.(2) The three layred lard agar phantom was used in the experiment. The agar phantom, wich 20.0cm in thickness, was sandwiched between the two lard-disk layrs, which were 2.0cm and 1.5cm in thickness respectively. Although small hot spots, due to the edge effect, appeared in the lard layrs, maximum temperature still appeared at the center region of the phantom.(3) The final experiment was to heat the liver and brain of a beagle dog. Fiber optic temperature sensors were placed at four points in the dog's tissue. Against much blood perfusion in these tissues, the measured temperatures at the deepest region was 0.5-0.7ﾟC higher than the other regions of the tissue.From these experimental heating results, it is confirmed that the system can be applicable to both local and deep tumor hypethermia.