Scanning-beam digital x-ray (SBDX) technology for interventional and diagnostic cardiac angiography

Abstract

The scanning-beam digital x-ray (SBDX) system is designed for x-ray dose reduction in cardiac angiographic applications. Scatter reduction, efficient detection of primary x-rays, and an inverse beam geometry are the main components of the entrance dose reduction strategy. This paper reports the construction of an SBDX prototype, image reconstruction techniques, and measurements of spatial resolution and x-ray output. The x-ray source has a focal spot that is electronically scanned across a large-area transmission target. A multihole collimator beyond the target defines a series of x-ray beams directed at a distant small-area detector array. The prototype has a 23 cm X 23 cm target, 100 X 100 focal spot positions, and a 5 cm X 5 cm CdTe detector positioned 150 cm from the target. With this nonmechanical method of beam scanning, patient images with low detected scatter are generated at up to 30 frame/s. SBDX data acquisition is tomosynthetic. The prototype simultaneously reconstructs 16 planes spaced throughout the cardiac volume using shift-and-add backprojection. Image frames analogous to conventional projection images are generated with a multiplane compositing algorithm. Single-plane versus multiplane reconstruction of contrast-filled coronary arteries is demonstrated with images of the porcine heart. Phantom and porcine imaging studies show multiplane reconstruction is practicable under clinically realistic levels of patient attenuation and cardiac motion. The modulation transfer function for an in-plane slit at mechanical isocenter measured 0.41-0.56 at 1 cycle/mm, depending on the detector element to image pixel interpolation technique. Modeling indicates that desired gains in spatial resolution are achievable by halving the detector element width. The x-ray exposure rate 15 cm below isocenter, without table or patient in the beam, measured 11.5 R/min at 120 kVp, 24.3 kWp and 3.42 R/min at 70 kVp, 14.2 kWp.

Calibration‐free device sizing using an inverse geometry x‐ray system

“…19 Briefly, the system uses an electron beam scanned over a large area transmission target with a prepatient multihole collimator. The beams exit the collimator holes and strike the small area, solid state, photon counting detector, creating a series of overlapping narrow field-of-view images from a range of focal spot positions ͑up to 100ϫ 100͒.…”

“…Scanning-beam digital x-ray ͑SBDX͒ is a low dose inverse geometry fluoroscopy system capable of reconstructing multiple tomosynthetic images in real time, 19 which may overcome some of the shortcomings of conventional QCA. Tomosynthetic reconstruction creates an image corresponding to a physical plane, where structures located in the plane are in focus and structures above and below the plane are blurred.…”

X-ray Dose Reduction through Adaptive Exposure in Fluoroscopic Imaging

“…We have shown that radiation dose can be significantly reduced in adult cardiac procedures by using our scanning beam digital x-ray (SBDX) system 4 --a fluoroscopic imaging system that employs an inverse imaging geometry 5,6 ( Figure 1, Movie 1 and Figure 2). Instead of a single focal spot and an extended detector as used in conventional systems, our approach utilizes an extended X-ray source with multiple focal spots focused on a small detector.…”

“…Pediatrics procedures are in general much more complex than those performed on adults and thus are on average four to eight times longer 1 . Furthermore, children can undergo up to 10 fluoroscopic procedures by the age of 10, and have been shown to have a three-fold higher risk of developing fatal cancer throughout their life than the general population 2,3 .We have shown that radiation dose can be significantly reduced in adult cardiac procedures by using our scanning beam digital x-ray (SBDX) system 4 --a fluoroscopic imaging system that employs an inverse imaging geometry 5,6 ( Figure 1, Movie 1 and Figure 2). Instead of a single focal spot and an extended detector as used in conventional systems, our approach utilizes an extended X-ray source with multiple focal spots focused on a small detector.…”

Design and characterization of a spatially distributed multibeam field emission x‐ray source for stationary digital breast tomosynthesis

“…21 The electron-beam CT ͑Ref. 22͒ and the scanning beam digital x-ray ͑SBDX͒ 23,24 utilize an electromagnetic field to steer the electron beam to different spots on the x-ray target to produce a scanning x-ray beam without mechanical motion. Such sources are large and, in the case of SBDX, have limited angular range.…”