Exposure adjustments for a patient with emphysema?

Exposure adjustments for a patient with emphysema?

• A. Keep kVp the same, double mAs
• B. Keep kVp the same, halve the mAs
• C. Increase kVp, keep same mAs
• D. No change is necessary

Answer: (B)

Emphysema creates hyperinflated lungs with lots of air, so the lungs attenuate fewer X-rays and look very lucent on radiographs. If you keep the exposure the same, the image can become overexposed (too dark) because more photons reach the film. Reducing the exposure lowers the image density while keeping the same kVp preserves the existing penetration and contrast between air-filled lungs and surrounding tissues. Halving the mAs achieves this dose reduction without sacrificing the overall contrast, whereas increasing kVp would reduce subject contrast and altering mAs differently could lead to under- or overexposure.

Emphysema creates hyperinflated lungs with lots of air, so the lungs attenuate fewer X-rays and look very lucent on radiographs. If you keep the exposure the same, the image can become overexposed (too dark) because more photons reach the film. Reducing the exposure lowers the image density while keeping the same kVp preserves the existing penetration and contrast between air-filled lungs and surrounding tissues. Halving the mAs achieves this dose reduction without sacrificing the overall contrast, whereas increasing kVp would reduce subject contrast and altering mAs differently could lead to under- or overexposure.