Line-Scanning Proportional Counter Camera

A new method was developed for imaging spatial distributions of photons, charged particles, or neutrons over large areas by a line-scanning camera. This camera uses a linear position-sensitive proportional counter (PSPC) based on resistance-capacitance (RC) position encoding. 1-6 Applications of this camera include low-dose, medium-resolution radiography of large objects (>2 by 2 m); and, in nuclear medicine, low-dose, whole-body radionuclide imaging and radiography with low energy photons (<150keV). A prototypic camera was built and tested to scan an area of 60 by 100 cm. The spatial resolution is 1 by 1 mm fwhm for radiography with 60-keV photons and 3 by 3 mm fwhm for radionuclide imaging with 50-keV photons (limited by collimator resolution). Compared to point-by-point scanning, the line-scanning method reduces the mechanical complexity of the camera and eliminates problems encountered in construction of large-area, high pressure PSPCs. This method is superior to the area PSPC for imaging objects >60 by 60cm.