Minoru Matsuda

A method of solution for a class of inverse problems involving measurement errors and its application to medical microwave radiometry

Retrieval of temperature-vs.-depth profiles in a biological tissue structure from multifrequency microwave radiometric measurement data constitutes a typical inverse problem in which the data involve relatively large measurement errors. The authors have developed a method of solution for a class of problems of this type. The method gives solutions in terms of the confidence interval and level. It also has a built-in capability of assessing the degree of fit of solutions to unknown actual source distributions. An agar phantom experiment and computer simulation based on a five-band (1-4-GHz) radiometry were performed to test the method, and the results are presented.<<ETX>>

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.<<ETX>>