[in Japanese]

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For relief of surface pain, we developed a new radiofrequency (RF) capacitive hyperthermic method with a subtrap circuit that has two copper sheets between electrodes to Thermotron RF-8. As a fundamental experiment, we measured the temperature distribution in an agar phantom using RF capacitive hyperthermia combined with the subtrap method. We also evaluated clinical usefullness on relief of surface pain.
In the phantom experiment, temperature distributions vertical to the electrode with the subtrap method were more uniform than with a non-subtrap method. In the clinical trials of deep-seated tumor, Tmax, Tave and Tmin with the subtrap method were higher than with the non-subtrap method. pTmax with subtrap method were significantly higher than with non-subtrap method (p < 0.05). With the subtrap method, surface pain was relieved in half of patients and maximum output power was significantly higher than with the non- subtrap method (p < 0.005).
We considered that the subtrap method was effective for impedance matching and decreasing the leakage of RF wave. As a result, surface pain was relieved and maximum output power was more elevated with the subtrap method. And, with the subtrap method, tumor temperature and lumen temperature adjacent to the tumor were more elevated than with the non-subtrap method.
These results indicated that the RF capacitive hyperthermia combined with the subtrap method was clinically useful for the treatment of deep-seated tumors.

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Interstitial hyperthermia by using a needle electrode has problem that heating range is too narrow to apply for massive tissues. In this study, we tried to extend the heating range by using high-conductivity saline pouring into the heating object. In experiments of RF power heating using pig livers, the higher salt concentration or the thicker the diameter of the needle electrode, the wider the heating range.

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Microwave heating has been used for the target which is located shallow in human body because of its small skin depth. In this study, mono-cycle pulsed microwaves is considered for microwave heating instead of usually used continuous microwaves to attain deeper heating.
In this paper, mono-cycle pulsed microwaves and continuous microwaves of 50MHz are compared by simulation and experiments using human model.
The results indicate that the pulse modulated microwaves propagate to the target effectively. Because lower harmonics, that the mono-cycle pulsed microwaves includes, can propagate into human model without quite losses. Furthermore, the results of simulation by 430MHz indicate that the mono-cycle pulsed microwaves are free from generating standing waves which causes hot spots inside human body.
From these results, it is found that the better treatments on microwave hyperthermia may be realized by using mono-cycle pulsed microwaves.

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Non-thermal effects of magnetic field and electromagnetic field on the living body have been studied using alternating magnetic field (AMF) generation device of 50Hz, 0.08T (800gauss). This device has hardly heating ability used for hyperthermia. In this study, we developed a special use chair for the whole-body AMF exposure. This chair was provided 11 AMF generation devices. The actual intensity of the AMF exposure chair to which the human body was exposed was 0.3 to 7 mT (3 to 70 gauss). Using the AMF exposure chair, a whole-body AMF stimulation was applied to 8 male subjects for 30 minutes, and the urinary levels of adrenaline (Ad), noradrenaline (NA) and VMA (Ad and NA's final metabolite) were measured. Furthermore, the blood flow of the right shoulder and the right third finger tip, and the armpit temperature were also measured. In the control group of non AMF exposure (n=7), there was not significant difference between pre-experiment and post-one in any clinical test item. Contrary to this, in comparison to the pre-experimental levels as 100%, the AMF exposure group (n=8) decreased Ad down to 51.1% (p < 0.01), NA 57.0% (p < 0.05), VMA 60.9% (p < 0.05), and increased the right shoulder blood flow up to 226.3% (p < 0.01) and the blood flow of the right third finger tip 174.9% (p < 0.001). However, the armpit temperature was no change in even AMF exposed group. From above, it is concluded that these phenomena are thought to be a non-thermal effect of the AMF, and are suggested that the whole-body AMF exposure reduce the synthesis or the release of Ad and NA. In the future, this non-thermal effect of AMF would be beneficial to hyperthermic therapy.

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