This paper describes a system for sub-pixel registration of mask and opacified digital X-ray images so that the mask image can be accurately subtracted out from the opacified image. Our technique results in digital subtraction angiograms (DSAs) with fewer artifacts and better contrast.

An x-ray imaging system, using digital subtraction techniques, has been developed. The system requires: (1) high output generation equipment; (2) an image intensifier capable of receiving high output exposures, 1 mR (2.58 X 10(-7) C/kg) at the face of the intensifier, without loss of either contrast or resolution; (3) a precision digital video camera; (4) processing computer with sufficient sto...

We present Chandra observations of nine high-redshift quasars (z = 2.7−5.9) discovered by the Sloan Digital Sky Survey with weak or undetectable high-ionization emission lines in their UV spectra (WLQs). Adding archival X-ray observations of six additional sources of this class has enabled us to place the strongest constraints yet on the X-ray properties of this remarkable class of AGNs. Althou...

Spot density is commonly used as an indication of shower energy in emulsion chambers. In a system originally developed for JACEE analysis, the optical density of a spot on x-ray film is estimated from macroscopic digital images. The spot’s size is used to compensate for the lack of dynamic range obtainable with digital imaging hardware. These densities are compared to manually measured densities.

Digital x-ray radiographic systems are desirable as they offer high quality images which can be processed, transferred, and stored without secondary steps. However, current clinical systems are extraordinarily expensive in comparison to film-based systems. Thus, there is a need for an economical digital imaging system for general radiology. The x-ray light valve (XLV) is a novel digital x-ray d...

Existing x-ray detecting technologies can be classified as either photon-counting (digital) or integrating (analog). Multi-wire proportional counters (MVVPC) are digital detectors that have advantages such as high quantum sensitivity, high dynamic range, and high intrinsic energy resolution, and have a wide range of applications. However, most photon-counting detectors rely on gas conversion of...

X-ray scatter is a major cause of nonlinearity in densitometry measurements using digital mammography. Previous scatter correction techniques have primarily used a single scatter point spread function to estimate x-ray scatter. In this study, a new algorithm to correct x-ray scatter based on image convolution was implemented using a spatially variant scatter point spread function which is energ...