Xenon Ionization Detectors for Fan Beam Computed Tomography Scanners

Some of the physical characteristics of pressurized xenon ionization chambers as X-ray detectors for fan beam computed tomography scanners are presented. These include energy absorption efficiency, linearity of response, and sensitivity to scattered and off-focus radiation. A chamber 20 cm in length, pressurized with 5 atm xenon, will usefully absorb about 60% of the incident radiation. Its output can be madess linear over a range of X-ray intensity of 103 or more. We have also found that, with proper detector collimation. scattered radiation is insignificant. A design for a large (239 chamber) detector for use in an experimental fan beam scanner is described.