Basic characteristics of the radio imaging method for biomedical applications.

The radio imaging method (RIM), a technology used practically for geophysical surveys, was applied to biomedical measurements. The characteristics of a subject between a pair of simple loop antennas were measured by using a feeble electromagnetic wave of low frequency. Water distribution inside the human body was expected to be measured, as well as the original method imaged mineral distributions. In geophysical surveys, finer resolution is provided than a wavelength of the electromagnetic wave. This was also expected for biomedical measurements. An acrylic water tank was used as a phantom of the abdominal portion of the human body, and basic measurements were performed with the phantom. The inner tank of the phantom, whose cross section was 6 x 8 cm, was detected by the method when the frequency was 54 MHz or the wavelength was nearly 6 m in free space. The resolution provided by the experiment suggested that the proposed method was effective even if the wavelength was longer than the dimensions of the targeted area. The advantage of the method is simplicity, economy and safety. The authors are looking for specific applications for example, a urination sensor or a vital monitor for in-home care, where the strong points of the method are suitable.