GXMO Radiographic Exposure Techniques 2

Question 1

A technique of 200 mA and 0.1 sec produces an acceptable image. Which combination produces the SAME density?

Accepted Answer

400 mA and 0.05 sec

Answer

Original mAs = 200 × 0.1 = 20 mAs; 400 mA × 0.05 sec = 20 mAs, maintaining identical density.

Question 2

If SID is decreased from 40 inches to 20 inches with all other factors constant, radiographic density will:

Accepted Answer

Increase fourfold

Answer

Halving the SID increases beam intensity by a factor of 4 per the inverse square law, quadrupling radiographic density.

Question 3

To maintain the same density when SID is decreased from 40 inches to 20 inches, mAs should be:

Accepted Answer

Reduced to one-quarter

Answer

Since halving SID quadruples intensity, mAs must be reduced to 1/4 to compensate using the exposure maintenance formula (mAs₂/mAs₁ = SID₂²/SID₁²).

Question 4

High-kVp techniques (above 100 kVp) produce images characterized by:

Accepted Answer

Low contrast with long gray scale

Answer

High kVp causes more Compton scatter and less differential photoelectric absorption, producing a long gray scale (low contrast) image.

Question 5

Which body part typically requires the LOWEST kVp setting?

Accepted Answer

Hand or wrist

Answer

Extremities like the hand and wrist require low kVp (50–65 kVp) to produce adequate contrast between fine bony detail and soft tissue.

(GXMO) General X-Ray Machine Operator Practice Test