Automation of a Crawford-cell exposure system

An automated 50-Ω Crawford cell exposure system for irradiating laboratory animals in the 225–500-MHz frequency range is described. Power measurements are obtained and analyzed in this system via an HP 436A power meter under the control of an LSI-11 minicomputer. Dosimetrie information, in terms of the specific absorption rate (SAR), is collected with the minicomputer automatically measuring absorbed power at preset exposure time intervals for a specified duration. Instantaneous values of SAR are computed, stored on a disk file, and displayed on a video terminal. The average whole-body SAR is computed and displayed at the end of each exposure. An interactive system-operating program facilitates data acquisition and analysis, and provides maximum flexibility and ease of operation.