Premium
Contrast resolution of a kinestatic charge detector
Author(s) -
Tenney Charles R.
Publication year - 1998
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598400
Subject(s) - detective quantum efficiency , detector , optics , physics , contrast (vision) , photon , contrast to noise ratio , monte carlo method , x ray detector , nuclear medicine , image quality , mathematics , medicine , computer science , statistics , artificial intelligence , image (mathematics)
The low‐contrast imaging capabilities of the kinestatic charge detector (KCD), a gas‐filled detector for slot‐beam digital radiography, are examined and compared with those of conventional x‐ray detectors. Monte Carlo modeling is used to investigate detector efficiency, detected contrast, and scatter rejection. Three indices for detector performance are developed. The high‐frequency limit to DQE shows the effects of secondary photon reabsorption in the detector. It corresponds to zero‐frequency DQE, and is equally simple to model computationally. The contrast factor links DQE with the task‐dependent DQE of Tapiovaara and Wagner by relating signal‐to‐noise ratio (SNR) to contrast‐to‐noise ratio (CNR). Detected scatter reduces the square of SNR by a factor equal to the detected primary fraction for noise variance. Highly loaded KCDs are seen to absorb photons more efficiently than conventional detectors. Krypton suffers less than xenon from DQE losses at high frequency. Contrast effects moderate the DQE advantages of KCDs, and detected CNR may even decline with increasing detector loading. KCDs regain their advantage when scatter effects are included. X‐ray beam utilization is sufficient for KCDs to match or exceed the CNR of conventional systems, at lower patient dose, for all cases studied except for the thickest patients with the lowest energy beams. Further improvements are expected from changes in KCD system design.