What term describes the reduction of the size of the x-ray beam?

• A. Collimation
• B. Filtration
• C. Distance
• D. Density

Answer: (A)

Collimation is shaping and limiting the x-ray beam to the size of the area of interest. In dental radiography, using a collimator (often rectangular) reduces the beam to the dimensions of the receptor, which lowers patient dose and improves image quality by cutting down scatter and geometric unsharpness at the edges of the image. Filtration lowers the energy of photons but doesn’t change beam size; distance changes the intensity reaching the receptor without altering the beam’s dimensions; density refers to how dark the image appears and is controlled by exposure factors, not by the physical size of the beam.