AbstractID: 9414 Title: Scanning Equalization Digital Radiography (SEDR)- a study of
Noise and Scatter Properties based on spot collimated images and noise simulation.
Background and objectives: Chest radiography is a challenge due to the large attenuation differences across the chest. These
differences result in large variations of the signal-to-noise ratio (SNR) and the scatter-to-primary ratios (SPR) across the image. In
Scanned Equalized Digital Radiography System (SEDR), the x-ray fluence incident on the patient is spatially modulated, leading to a
largely uniform exposure and SNR at the detector. The scanning nature of SEDR also facilitates dose-efficient scatter rejection
achieving SPRs equal to or superior to those achieved with an anti-scatter grid. The development of an SEDR system represents a
challenge, due to the complicated interplay between scatter rejection, exposure equalization, and practical considerations; we have
developed a simulation system to study these relations prior to building a prototype system.
Scope/Methods: We have developed techniques to create simulated SEDR images with various scanning geometries using a series of
spot-collimated, full-field images of an anthropomorphic chest phantom. The absolute SNRs and SPRs were computed for
traditionally acquired images and for simulated SEDR images with the same average entrance exposure allowing us to compute
relative contrast-to-noise ratios (RCNR) to compare these techniques.
Results: We have discovered that the SNR histogram is compressed and lowered in SEDR compared to traditional images but when
the contrast improvements due to scatter rejection are included to compute the RCNRs we can demonstrate that SEDR implemented
with spot or horizontal or vertical slot scanning geometries has RCNRs superior to traditionally acquired digital radiographs.
This work was supported by grant EB00117 from NIBIB