Infographics / Nuclear Medicine

Gamma camera QC: flood-field uniformity & artefacts

Two circular flood-field images from a gamma camera. The left field shows an even, uniform density of counts and is marked acceptable. The right field shows the same density interrupted by a focal cold spot caused by a cracked crystal or photomultiplier drift. Below is a list of gamma-camera quality-control tests: uniformity uses a flood-field acquisition with a uniform planar source and should be a few percent, not twenty percent; spatial resolution uses a bar phantom or point or line source measured as full width at half maximum; linearity uses a line source; and intrinsic tests are done without a collimator while extrinsic tests include the collimator, so intrinsic resolution is better than system resolution.