Specific absorption rate and tissue temperature in local XXXX .

@entity1 @entity221 @entity5
Specific absorption rate (SAR) and tissue temperature were measured for a total of 83 treatments in 33 @entity1 who received local @entity221 treatment for @entity5 . The @entity1 were grouped into three categories according to @entity5 size. @entity221 was induced by 13.56 MHz electromagnetic energy applied using capacitive coupling. A method is described for evaluating SAR from the tissue temperature traces at any time in the treatment when a step change is made in applied power. The method is possible only if the temperature traces are free from interference and the total power delivered to the @entity1 is monitored. Mean values of SAR ranged from 4.6 to 89 W kg-1 depending on the treatment site. Satisfactory heating was achieved for superficial @entity5 , with temperatures greater than 42 degrees C being recorded in 69% of treatments. For axillary nodes only 4% of treatments exceeded 42 degrees C. For @entity5 an idealized @entity5 model was used to estimate @entity5 temperature from the temperature and SAR measured in the adjacent normal tissue. From the model it appears necessary either to raise the systemic temperature to 40 degrees C or to increase the SAR by at least a factor of 4 to obtain a temperature of 42 degrees C in a typical @entity5 . Measurements of SAR and temperature are essential for feedback control of computer models which, in principle, could provide a complete distribution of temperature during a @entity221 treatment. Furthermore, measured SAR provides a direct comparison of the power deposition from different treatment machines in a clinical environment. The data presented form a basis for comparison with the clinical use of other heating systems.
