Infographics / Nuclear Medicine

Collimator geometry types (parallel/diverging/converging/pinhole)

Four panels compare collimator hole geometry and the size of the image projected onto the crystal. Parallel-hole collimators have vertical holes and project a 1:1 image with no magnification, and field of view and sensitivity stay constant with distance. Converging collimators have holes angled toward a focal point in front of the crystal and magnify the image (M greater than 1), keeping it upright. Diverging collimators have holes flaring outward and minify the image (M less than 1), fitting a larger field of view onto a smaller crystal. Pinhole collimators use a single aperture where rays cross, producing a magnified and inverted image (M equals b over a). In each panel the lower ink bar is the object on the patient side and the upper teal bar is the projected image on the crystal; a dot marks orientation.