Which of the following would decrease the DQE?

Which of the following would decrease the DQE?

• A. Decreased spatial frequency
• B. Increasing kVp
• C. Increasing capture efficiency
• D. Decreasing kVp

Answer: (B)

DQE measures how efficiently a detector converts incoming x-ray quanta into a usable image signal while preserving detail and keeping noise low. It depends on how many photons the detector actually captures and how faithfully those captured photons are turned into image information, across spatial frequencies. Raising kVp shifts the x-ray spectrum toward higher-energy photons. These photons interact with detector material less readily, so fewer incident quanta are absorbed and converted into signal for the same dose. At the same time, the relative noise can increase because the signal per photon is smaller, leading to a lower DQE. In contrast, decreasing kVp increases absorption and tends to improve DQE. Increasing capture efficiency directly increases DQE since more of the incident photons contribute to the signal. Decreasing spatial frequency usually does not cause a decrease in DQE; in fact, DQE typically declines with increasing spatial frequency, so lower frequencies are less demanding on the detector.

DQE measures how efficiently a detector converts incoming x-ray quanta into a usable image signal while preserving detail and keeping noise low. It depends on how many photons the detector actually captures and how faithfully those captured photons are turned into image information, across spatial frequencies.

Raising kVp shifts the x-ray spectrum toward higher-energy photons. These photons interact with detector material less readily, so fewer incident quanta are absorbed and converted into signal for the same dose. At the same time, the relative noise can increase because the signal per photon is smaller, leading to a lower DQE. In contrast, decreasing kVp increases absorption and tends to improve DQE. Increasing capture efficiency directly increases DQE since more of the incident photons contribute to the signal. Decreasing spatial frequency usually does not cause a decrease in DQE; in fact, DQE typically declines with increasing spatial frequency, so lower frequencies are less demanding on the detector.