The Present study investigated the changes in blood flow and oxygen kinetics of the hindlimb skin and muscles in eighteen mongrel dogs during induced hyperthermia (38°C to 43°C). Cardiac output increased and systemic vascular resistance decreased during hyperthermia. Muscle, subdermal and dermal blood flow did not change significantly during hyperthermia. The femoral oxygen extraction rate increased significantly as the temperature was increased. The difference in lactic acid concentration between the femoral arterial and venous blood did not increase with hyperthermia. Plasma cAMP levels increased as the temperature rose, whereas cGMP levels did not increase significantly.
Results of the present study suggest that the cause of hyperdynamics during hyperthermia is due to increased cAMP concentration induced by heating. Although blood flow in the muscle and skin did not increase, the oxygen supply was sufficient to maintain normal muscle metabolism during induced hyperthermia.

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The thermosensitivity of two rat glioma cell lines (C6 and 9L) was evaluated with colorimetric microtiter (MTT) assay and colony formation assay (CFA).
The results of 2 assays were compared to assess the reliability of MTT assay for in vitro experiment of hyperthemia.
Cultured glioma Cells (C6 and 9L) were exposed to 42, 43 and 44°C for 30, 60, 90 and 120 minutes, and the rate of survival was examined by MTT assay and CFA. Their survivals were reduced in a temperature-dependent and heating time-dependent fashion. The results of MTT assay were mostly consistent with those of CFA, although some part of the survival curves did not correlate especially in C6 glioma cells. These results suggest that both C6 and 9L rat glioma cell lines are thermosensitive and MTT assay is a useful method for the evaluation of thermosensitivity in cultured glioma cells.

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Electrical resistivity of living tissues shows the strong temperature dependence. The temperature coefficient is about -2% /°C which is almost the same as that of saline solution. If one can measure the resistivity change of tissues due to the body temperature change by impedance CT (IMPCT), one could estimate the body temperature change non-invasively.
The current applied to the body through a electrode spreads in the body and reaches to the opposite electrode. Therefore, it is impossible to measure the resistivity change of tissues by 2 dimensional impedance CT (2DCT). We should apply 3 dimensional impedance CT (3DCT) for the aim. But we must calculate 3 dimensional Poisson equation for 3DCT. It takes a very long time to do it. And also 3DCT requires very accurate voltage measurement and many electrodes arranged on the body surface. It is very hard for us to solve these three important problems now. On the other hand, 2DCT can be implemented without very high accurate measurement, many electrodes nor very long calculation time. So, we modified the 2DCT algorithm in order to measure the resistivity distribution of the 3 dimensional interest by 2DCT instead of 3DCT. And we put the modified 2DCT algorithm to the proof by the computer simulation and the phantom experiment. From the results of the computer simulation and the phantom experiment, we can find that the modified 2DCT algorithm provides the good resistivity change distribution image for 3 dimensional interest without three big problems mentioned above and is very useful to apply IMPCT to the clinical use, especially, to the measurement of the temperature change inside the body during hyperthermia therapy.

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Basic heating characteristics of a flexible and variable shape electrode were measured for a new internal hyperthermic therapy under laparoscopy. A metal chain was used as an internal electrode in 13. 56 MHz RF heating. Heating characteristics were measured with various shapes of chain electrodes, i. e. zigzag, spiral, radiation and layers. From the results of experiments using muscle-equivalent phantoms, we conclude that concentrated heating characteristics were produced between the internal electrode and the reference electrode when spreading the chain electrode arranged in layers, parallel to the reference electrode.

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A “reentrant resonant-cavity applicator” is a hyperthermic system having a resonant cavity, inside of which are two reentrants. In simulated heating test, the applicator produced a cylinder-shaped area of high temperature in the center of a heated object. This paper describes the heating characteristics of the applicator, in order to appraise its ability to produce concentrated heating for cylindrical-shaped phantoms of 24 cm diameter and 12 cm height. In experiments using these phantoms, concentrated heating characteristics were produced, which are superior to RF capacitive heating. In order to perform concentrated heating, 1) the height of the phantoms must be maintained at less than about 40% of the distance between the two reentrants, 2) the diameter of the plates concentrating the electric field must be about 1.5 times larger than the height of the phantom, 3) the impedance between the applicator and a power supply must be matched.

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[in Japanese]

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Surgery is the first choice of treatment for rectal cancer. But local recurrence is most common problem after sugery. To reduce local recurrence of rectal cancer, we conducted the clinical trial of preoperative radiation therapy and regional hyperthermia using the heating device of rediofrequency capacitive type (THERMOX 1000, OMRON). Fifteen patients with rectal cancer treated with combined therapy were evaluated. Radiotherapy was administered every day at a dose of 1.8Gy to a total of 30.6Gy with anterior posterior field. Regional hyperthermia was given once a week for 5060 minutes in sequence with radiation therapy. After sugery was performed, microscopic examination of the resected specimens were done.
All patients tolerated this combined preoperative therapy. Microscopic examination revealed a marked necrosis of tumors treated with combined therapy. But two patients developed anastomotic leakage after sugery, and one patient received reoperation because of ileus. Follow up periods of this preliminary study were very short, longterm follow up is needed to evaluate this combined preoperative therapy for rectel cancer.

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Heating of deep seated tumors is not always easy and can not be considered to be effective in all cases. Considering that interstitial hyperthermia by use of the needle left in the lesion after brachytherapy can heat only the lesion efficiently, a basic study was conducted with agar phantom.
When the phantom or pig with a Tefron-coated needle inserted is heated with Thermotoron RF8, the needle acts as an cathode which enhances convergence of RF waves to the cathode needle, thus quickening the heating up to a terget temparature.
In this study, enough temparature rise was observed. If substantial tecnical improvemnts in the temparature distribution, this needle is considered to have a favorable property as cathode needle for interstitial hyperthermia with Thermotoron RF8.

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The development of better heating and temperature measuring equipment allows for better clinical results in the study of hyperthermia. In this report, large amounts of data using capacitive-type heating systems has been compiled. The data was taken from the development and implementation of clinical hyperthermia systems. The data has then been categorized with a possible solution presented for each problem.

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