Effects of water-filled bolus on the precision of microwave radiometric measurements of temperatures in biological structures

An assessment is made of the degradation that is caused by a water-filled bolus in the precision of tissue temperature measured noninvasively by a five-band microwave radiometry scheme. The precision is expressed in terms of the confidence interval of tissue temperature estimated from a set of five brightness temperatures measured with an experimental instrument operating at center frequencies of 1.2, 1.8, 2.5, 2.9, and 3.6 GHz, with a 0.4-GHz bandwidth. Results show that degradation due to a bolus having a thickness of about 1 cm is small when it is filled with deionized or distilled water. It is concluded that the use of water-filled bolus is permissible for microwave radiometric measurement. This is of a practical importance when the technique is used in combination with electromagnetic heating for hyperthermic treatment of cancer.<>