Comparison of vessel contrast measured with a scanning-beam digital x-ray system and an image intensifier/television system.

Vessel contrast was measured in the fluoroscopic images produced by a scanning-beam digital x-ray (SBDX) system and an image intensifier/television (II/TV) based system. The SBDX system electronically scans a series of pencil x-ray beams across the patient, each of which is directed at a distant small-area detector array. The reduction in detected scatter achieved with this geometry was expected to provide an increase in image contrast. Vessel contrast was evaluated from images of a phantom containing iodinated tubes. The vessels were inserted into an acrylic stack to provide a patient-mimicking scattering medium. Vessel diameter ranged from 0.3 to 3.1 mm. Images were acquired at 100 kVp with the SBDX and II/TV systems and averaged to reduce x-ray noise. The II/TV system was operated in the 6-in. image intensifier mode with an anti-scatter grid. The increase in contrast in the SBDX images, expressed as a ratio of the measured SBDX and II/TV contrasts, ranged from 1.63 to 1.79 for individual vessels. This agreed well with a prediction of the contrast improvement ratio for this experiment, based on measurements of the scatter fraction, object-plane line spread functions, and consideration of the source spectrum and detector absorption properties. The predicted contrast improvement ratio for SBDX relative to II/TV images was 1.62 to 1.77.

[1]  K Rossmann,et al.  Truncation errors in calculating the MTF of radiographic screen-film systems from the line spread function. , 1972, Physics in medicine and biology.

[2]  R. K. Swank.  Absorption and noise in x‐ray phosphors , 1973 .

[3]  R. F. Wagner,et al.  Toward a unified view of radiological imaging systems. Part II: Noisy images , 1974 .

[4]  J A Rowlands,et al.  Absorption and noise in cesium iodide x-ray image intensifiers. , 1983, Medical physics.

[5]  D. Weber.  Absolute diameter measurements of coronary arteries based on the first zero crossing of the Fourier spectrum. , 1989, Medical physics.

[6]  Kunio Doi,et al.  A simple method for determining the modulation transfer function in digital radiography , 1992, IEEE Trans. Medical Imaging.

[7]  K P Maher,et al.  Comparison of scatter measurement techniques in digital fluoroscopy , 1993 .

[8]  H. Blume,et al.  DQE(f) of four generations of computed radiography acquisition devices. , 1995, Medical physics.

[9]  J T Dobbins,et al.  Effects of undersampling on the proper interpretation of modulation transfer function, noise power spectra, and noise equivalent quanta of digital imaging systems. , 1995, Medical physics.

[10]  Edward G. Solomon,et al.  Low-exposure scanning-beam x-ray fluoroscopy system , 1996, Medical Imaging.

[11]  Michael A. Speidel,et al.  Performance assessment of the scanning beam digital x-ray (SBDX) system , 1997, Medical Imaging.

[12]  J. Boone,et al.  An accurate method for computer-generating tungsten anode x-ray spectra from 30 to 140 kV. , 1997, Medical physics.

[13]  Edward G. Solomon,et al.  Scanning-beam digital x-ray (SBDX) system for cardiac angiography , 1999, Medical Imaging.

[14]  Robert E. Melen,et al.  CdZnTe detector array for a scanning-beam digital x-ray system , 1999, Medical Imaging.