Which practice best reduces patient skin dose while maintaining receptor exposure?

• A. Beam collimation and filtration.
• B. Increase mA.
• C. Increase exposure time.
• D. Increase the beam field.

Answer: (A)

Shaping the beam and removing unneeded photons are the main ideas here. Collimation confines the X-ray beam to the exact area of interest, so skin and other tissues outside that area aren’t exposed. Less irradiated skin means lower skin dose, and reducing scatter also helps image quality.

Filtration takes out the lowest-energy photons from the beam. Those soft photons would be absorbed by the patient, contributing to skin and superficial dose without improving the image. By hardening the beam—removing those photons—the average photon energy increases, so skin dose drops while the photons that reach the detector still provide the necessary receptor exposure. In practice, you combine proper collimation with appropriate filtration to lower dose without losing image quality; if filtration changes the dose, technique adjustments are used to keep the receptor exposure at the desired level.

The other options would raise skin dose: increasing current or exposure time adds more photons to the beam, and enlarging the beam field irradiates more skin.