Increasing kVp in an X-ray unit while keeping mAs constant will PRIMARILY result in:
- A Increased patient dose, increased image contrast
- B No change in beam quality but increased quantum mottle
- C Decreased patient dose, decreased image contrast, increased beam penetration ✓
- D Increased penumbra and geometric unsharpness
Correct answer: C. Decreased patient dose, decreased image contrast, increased beam penetration
Explanation
Increasing kVp raises the mean photon energy (harder beam), improving tissue penetration and increasing the proportion of photons reaching the detector (lower patient absorbed dose for the same mAs). However, higher-energy photons show less photoelectric effect and more Compton scatter, reducing subject contrast. Quantum mottle is a noise phenomenon related to mAs (photon quantity), not kVp. Geometric unsharpness depends on focal spot size and geometry, not kVp.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.