Decreasing beam energy has what effect on photon absorption and DQE?

Decreasing beam energy has what effect on photon absorption and DQE?

• A. It reduces absorption and decreases DQE
• B. It has no effect on DQE
• C. It increases absorption and increases DQE
• D. It increases absorption but decreases DQE

Answer: (C)

Lowering the x‑ray beam energy increases the likelihood that photons are absorbed by the detector material. When photons are more readily absorbed, more of the incident quanta contribute to producing the image signal, which reduces information lost to transmission and scatter. This boost in detected signal relative to noise raises the detector’s ability to preserve image quality, which is what DQE measures. So, as beam energy decreases in the diagnostic range, photon absorption in the detector increases and the DQE improves. (Keep in mind that lowering kVp also changes subject contrast and patient dose, but the detector performance aspect described here moves in the same direction.)

Lowering the x‑ray beam energy increases the likelihood that photons are absorbed by the detector material. When photons are more readily absorbed, more of the incident quanta contribute to producing the image signal, which reduces information lost to transmission and scatter. This boost in detected signal relative to noise raises the detector’s ability to preserve image quality, which is what DQE measures. So, as beam energy decreases in the diagnostic range, photon absorption in the detector increases and the DQE improves. (Keep in mind that lowering kVp also changes subject contrast and patient dose, but the detector performance aspect described here moves in the same direction.)