GXMO Radiographic Exposure Techniques

Question 1

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

Accepted Answer

kVp

Answer

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

Question 2

Doubling the mAs while keeping all other factors constant will:

Accepted Answer

Double radiographic density

Answer

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

Question 3

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

Accepted Answer

Halve the mAs

Answer

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

Question 4

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

Accepted Answer

72 inches

Answer

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

Question 5

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

Accepted Answer

Decreases to one-quarter

Answer

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

(GXMO) General X-Ray Machine Operator Practice Test