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

在本研究项目中，提出了一种用于深层肿瘤热疗的新型加热系统，该系统采用折返式谐振式腔体施加器。研制的加热系统由铝合金折返式谐振腔、射频放大器、电源单元、匹配单元和微型计算机组成。为了验证这种加热系统对深层肿瘤的可行性，用柱状体模和狗进行了以下三个实验：(1)实验中使用的琼脂体模直径27.0 cm，高25.0 cm。用热像仪观察了加热模式。实验中采用了三层猪油琼脂体模，体模垂直截面切片的热像清晰地显示了体模的中心区域被集中加热，符合预期。厚度为20.0 cm的琼脂模型夹在厚度分别为2.0 cm和1.5 cm的两层猪油盘层之间。尽管由于边缘效应，猪油层出现了小的热点，但最高温度仍然出现在体模的中心区域。(3)最后的实验是对一只比格犬的肝脏和大脑进行加热。光纤温度传感器被放置在狗组织的四个点上。相对于这些组织的大量血液灌流，测量到的最深处的温度比其他区域高出0.50.7ﾟC，从这些实验加热结果来看，该系统既适用于局部肿瘤降温，也适用于深部肿瘤的降温。

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.