BRH test pattern for the evaluation of gamma-camera performance.

A transmission test pattern has been developed for the simultaneous evaluation of intrinsic resolution, field uniformity, and spatial distortion of gamma cameras of any model and age. Holes 2.5 mm in diameter are drilled with high precision through a 3.2-mm thick lead-alloy plate, forming an orthogonal array of holes. The minimal lead spacing separating adjacent holes is a constant 2.5 mm in th Y direction, but varies along the X axis, in groups of six holes, from 1.5-7 mm in steps of 0.5 mm. The performance of gamma cameras has been investigated with the gamma rays of Tc-99m and the low-energy photons from Xe-133 and Tl-201. Images of the test pattern provide a simple, rapid, and sensitive method for gamma camera quality control, acceptance testing of new instruments, and checking of a camera's operating and maintenance procedures.