Radiography Flashcards

Which Bucky factor is typically used when the grid ratio is 12:1?

Answer: 5-6

A 12:1 grid ratio has a Bucky factor of approximately 5-6, meaning exposure must be increased by that factor to compensate for absorbed scatter.

What is the primary purpose of the anode heel effect in radiography?

Answer: Allow positioning of thicker anatomy under the cathode end

The anode heel effect causes lower intensity at the anode end, so thicker anatomy should be placed under the cathode end where intensity is higher.

A patient receives 200 mR at 100 cm SID. What is the approximate dose at 200 cm SID?

Answer: 50 mR

Using the inverse square law, doubling the distance quarters the intensity: 200 × (100/200)² = 50 mR.

Which type of ionizing radiation has the greatest penetrating power?

Answer: Gamma rays

Gamma rays have the greatest penetrating power among the common forms of ionizing radiation used in medical imaging contexts.

What does the term 'penumbra' refer to in radiographic imaging?

Answer: Geometric unsharpness at the edge of a shadow

Penumbra refers to the zone of geometric unsharpness or partial shadow at the edge of a radiographic image caused by the finite size of the focal spot.

In computed radiography (CR), the latent image is stored in which material?

Answer: Photostimulable phosphor

CR imaging plates contain photostimulable phosphor (barium fluorohalide) that stores the latent image as trapped electrons until laser-stimulated.

Which technical factor has the GREATEST effect on radiographic contrast?

Answer: kVp

kVp primarily controls the energy of the x-ray beam and therefore has the greatest influence on radiographic contrast.