The Effect of the Irradiation Geometry on the Image Quality Obtained by Gamma Transmission Method

Abstract

The effect of the irradiation and counting geometry on the image quality obtained by gamma transmission method has been investigated. As the object for imaging, an absorber was made out using aluminium and lead plates with the dimensions of 40 mm., 20 mm., 4mm. framed with Plexiglas. The absorber has been irradiated with the 662 ke V gamma rays of Cs -137, which were collimated in different apertures. A 4.44 cm.x5.87 cm. Nal(Tl) crystal was used to detect the gamma rays transmitted through absorber. The beam intensity distributions were measured for different collimator and beam width. The measurements have been repeated for the different source-to-detector distances to accommodate the beam intensity.