A practical exposure-equivalent metric for instrumentation noise in x-ray imaging systems.
The performance of high-sensitivity x-ray imagers may be limited by additive instrumentation noise rather than by quantum noise when operated at the low exposure rates used in fluoroscopic procedures. The equipment-invasive instrumentation noise measures (in terms of electrons) are generally difficult to make and are potentially not as helpful in clinical practice as would be a direct radiological representation of such noise that may be determined in the field. In this work, we define a clinically relevant representation for instrumentation noise in terms of noise-equivalent detector entrance exposure, termed the instrumentation noise-equivalent exposure (INEE), which can be determined through experimental measurements of noise-variance or signal-to-noise ratio (SNR). The INEE was measured for various detectors, thus demonstrating its usefulness in terms of providing information about the effective operating range of the various detectors. A simulation study is presented to demonstrate the robustness of this metric against post-processing, and its dependence on inherent detector blur. These studies suggest that the INEE may be a practical gauge to determine and compare the range of quantum-limited performance for clinical x-ray detectors of different design, with the implication that detector performance at exposures below the INEE will be instrumentation-noise limited rather than quantum-noise limited.
Yadava
G K
GK
Toshiba Stroke Research Center, State University of New York at Buffalo, Buffalo, NY 14214, USA.
Kuhls-Gilcrist
A T
AT
Rudin
S
S
Patel
V K
VK
Hoffmann
K R
KR
Bednarek
D R
DR
D000465:Algorithms; D016477:Artifacts; D019544:Equipment Failure Analysis / Q000379:methods* / Q000592:standards; D011859:Radiography / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States