GaAs Biomedical Probes and Their Applications in Nuclear Medicine

A set of GaAs biomedical probes for in vivo measurement of ß- and γray emitting radioactive elements has been fabricated from liquid-phase epitaxial and boat grown GaAs materials. The probes use a GaAs surface barrier diode as a radiation sensing element and utilize three diode structure shapes, such as side window, frontal window and single ended coaxial structures. The noise performance of GaAs biomedical probe was less than 18 keV at room temperature. Some of GaAs probes developed had good counting efficiency for ß- and g=g-ray emitting radioisotopes and also had good energy resolution for low energy γ-ray and X-ray. The preliminary results of GaAs biomedical probes developed to diagnose malignant tumor and measure regional blood flow were good. The feasibility of GaAs detector as a fluorescent X-ray detector operating at room temperature in nuclear medicine is also discussed.