Which change increases the detective quantum efficiency (DQE) of an imaging system?

Which change increases the detective quantum efficiency (DQE) of an imaging system?

• A. increasing spatial frequency
• B. decreasing capture efficiency
• C. increasing kVp
• D. decreasing kVp

Answer: (D)

DQE measures how efficiently an imaging system converts incoming x-ray energy into a useful image signal while preserving the signal-to-noise ratio across spatial frequencies. Lowering the peak kilovoltage tends to increase this efficiency because more of the photons that reach the detector contribute as meaningful signal and less of the beam’s energy is wasted as scatter. The result is a higher signal relative to noise at the detector, which raises the DQE. In contrast, increasing spatial frequency generally challenges the system’s ability to preserve contrast at finer details, so DQE tends to drop at higher frequencies. Decreasing capture efficiency means fewer photons are detected, which lowers the signal-to-noise ratio and reduces DQE. Increasing kVp, on the other hand, increases beam penetration and scatter, which can worsen image quality and typically reduces DQE.

DQE measures how efficiently an imaging system converts incoming x-ray energy into a useful image signal while preserving the signal-to-noise ratio across spatial frequencies. Lowering the peak kilovoltage tends to increase this efficiency because more of the photons that reach the detector contribute as meaningful signal and less of the beam’s energy is wasted as scatter. The result is a higher signal relative to noise at the detector, which raises the DQE.

In contrast, increasing spatial frequency generally challenges the system’s ability to preserve contrast at finer details, so DQE tends to drop at higher frequencies. Decreasing capture efficiency means fewer photons are detected, which lowers the signal-to-noise ratio and reduces DQE. Increasing kVp, on the other hand, increases beam penetration and scatter, which can worsen image quality and typically reduces DQE.