Radiographic Exposure Techniques Flashcards

Which exposure factor primarily controls the quality (penetrating power) of the x-ray beam?

Answer: kVp

kVp (kilovoltage peak) determines the energy of x-ray photons, directly controlling the beam's ability to penetrate tissue.

Doubling the mAs while keeping all other factors constant will:

Answer: Double radiographic density

mAs controls x-ray quantity; doubling mAs doubles the number of photons reaching the image receptor, doubling radiographic density.

The '15% rule' states that increasing kVp by 15% requires what mAs adjustment to maintain the same density?

Answer: Halve the mAs

Increasing kVp by 15% doubles the effect on density, so mAs must be halved to maintain the original exposure level.

What is the standard source-to-image distance (SID) used for PA chest radiographs?

Answer: 72 inches

72 inches (180 cm) is the standard SID for PA chest radiographs to minimize magnification and accurately represent cardiac size.

According to the inverse square law, if SID is doubled, x-ray beam intensity at the image receptor:

Answer: Decreases to one-quarter

The inverse square law states intensity is inversely proportional to the square of distance; doubling SID reduces intensity to 1/4.

Which exposure factor has the GREATEST effect on radiographic contrast?

Answer: kVp

kVp controls the differential absorption of x-rays between tissues, making it the primary determinant of radiographic contrast.

Using a small focal spot instead of a large focal spot will primarily result in:

Answer: Improved recorded detail/sharpness

A smaller focal spot reduces geometric unsharpness (penumbra effect), improving spatial resolution and recorded detail.