Gamma Cameras
Extrinsic uniformity
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The extrinsic uniformity measures the uniformity of the entire detector system, including the collimators. A flood source has to be used to produce the uniform flux of gamma rays across the detector face. This can either be a fillable water tank with Tc99m in it or a CO57 sheet source, the later being particularly common for daily checks.
Image: A fillable flood source suitable for extrinsic uniformity.
Image B: Extrinsic uniformity measurement using a cobalt flood source
