| Popis: |
We have conducted experiments quantitating the effects of microwave heating on the regrowth time of mammary tumors implanted on the flank of C3H mice. To minimize the size and shape dependence of the microwave heating, we immersed the tumors in tissue equivalent bolus and treated them with parallel opposed transverse electromagnetic applicators. The animals were not anesthetized during microwave irradiation. Two types of bolus were used: a semisolid gel and a temperature-controlled solution of isotonic saline and alcohol. During tumor irradiation in the gel, temperatures were monitored adjacent to, but not inside of, the tumors. During irradiation in the liquid bolus, tumor temperatures were monitored for one out of each six animals per data point. Data from tumors treated in the semisolid bolus yielded lower regrowth slopes and higher intercepts than those heated by water baths. Both findings can be interpreted as indicating thermal nonuniformity of the microwave-heated tumors. Plots of thermal sensitivity versus temperature are parallel to, but displaced from, those determined with water bath heating, suggesting that at least some small part of the tumor treated with microwaves was about 1°C lower than the target temperature. Tumors which were heated in the liquid bolus yielded regrowth curves consistent with homogeneous heating. A plot of thermal sensitivity versus temperature suggests that all parts of the tumors were at or slightly above target temperature. Regrowth time of the probed tumors was significantly greater than that of tumors in which no probe was present during microwave irradiation. |
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