Infographics / Image Quality

Scatter degradation & reduction by grids/collimation

An anti-scatter grid sits between the patient and the detector. Forward-directed primary photons pass through the interspaces to the detector, while obliquely angled scattered photons are absorbed by the lead strips. Grid ratio equals lead strip height h divided by interspace width D; a higher ratio removes more scatter. The grid improves image contrast but increases patient dose, described by the Bucky factor of about two to six.

Anti-scatter grid: primary transmitted, scatter absorbed An anti-scatter grid sits between the patient and the detector. Forward-directed primary photons pass through the interspaces to the detector, while obliquely angled scattered photons are absorbed by the lead strips. Grid ratio equals lead strip height h divided by interspace width D; a higher ratio removes more scatter. The grid improves image contrast but increases patient dose, described by the Bucky factor of about two to six. Anti-scatter grid: primary transmitted, scatter absorbed X-ray focus patient anti-scatter grid lead strip interspace detector / film grid ratio = h / D h D higher grid ratio = more scatter removed primary beam — transmitted scattered photons — absorbed contrast improves as scatter is removed patient dose increases — Bucky factor ~2–6 grid lies between patient and detector
Practise questionsDownload SVG

More in Image Quality

Practice the Physics paper

FRCRX is a Part 1 Physics question bank: true/false items with explanations, timed mocks and topic analytics.

Start question practiceSee plans