Line Scanning and Needle-Based CR Detector Technology

Agfa HealthCare (Ridgefield Park, NJ) has introduced a new digital x-ray technology that the company believes can provide the image quality inherent in DR systems with costs that are closer to current CR systems. Using line scanning and a new needle-based detector technology, the DX-S digitizer offers providers a new choice in digital x-ray imaging.

Conventional CR is practiced with a rapidly moving laser beam (“flying spot”) sampling the CR detector in a raster pattern. This detector is a photostimulable phosphor screen, also called an image plate (IP), consisting of tiny storage-phosphor particles embedded in a binder. The image quality of this combination is comparable to or slightly better than that of screen/film systems.

The latest CR systems change this model dramatically. CR line scanners contain rows of laser sources, beam and collection optics, photodetectors, and electronics that collect image data from an entire line at once, enabling more compact and faster systems. Novel CR detectors consisting of vertically evaporated storage phosphor needles contain no binding material, resulting in higher x-ray absorption in the same volume, with correspondingly better dose efficiency. In addition, the needle structure has a light-piping effect, which keeps spatial resolution high and allows even thicker screens (higher absorption) to be used without the typical sharpness degradation due to light spread found in conventional CR with powder IPs.

Figure. Movable scanhead contains line-scanning components.

The first commercial system combining these new technologies is Agfa’s DX-S digitizer for CR. The combination of new DirectriX structured detectors and a movable scanhead containing all the line-scanning components (see Figure) produces image quality that rivals that of the latest flat-panel DR systems, at a cost that is significantly lower. The first DX-S systems are cassette-based, offering patient- and detector-positioning flexibility that is difficult to achieve in a fixed-detector DR system. However, the same technology can be built into a panel format for use in devices often paired with flat-panel DR systems today, such as wall units and bucky tables.

The characteristics of this technology combination make the DX-S system ideally suited for decentralized and in-room use in imaging environments in which high image quality, high productivity, and a patient-centric workflow are required, such as in the emergency and pediatrics departments.

Fuji received FDA approval in early July to market ClearView for digital mammography products in the United States.

The Spec Sheet

  1. Image quality: DQE (detective quantum efficiency) is ~2x higher than that of conventional CR (~0.5 to 0.6 versus ~0.25 to 0.3)
  2. Dose reduction: ~2x reduction relative to conventional (powder-based) CR
  3. Spatial resolution: scanning is done at 50 ?m sampling pitch; final pixels are binned to 100 ?m
  4. Throughput: 5-second scan time, independent of IP size, resolution; cassette return time < 30 seconds (throughput ~120 IP/hr)
  5. Preview image: available at local display in ~10 s after start of scan, allowing immediate QC and patient release
  6. Footprint: DX-S digitizer is 33 x 79 x 85 cm (W x D x H)
  7. Detector sizes: 18 x 24 cm, 24 x 30 cm, 15 x 30 cm, 35 x 43 cm

The Visible DIfference

Agfa’s DX-S CR solution bridges CR and DR by providing flexibility and a higher level of image quality and speed than traditional CR offerings. Through the unique combination of two technologies, DirectriX needle-based detector technology and ScanHead line scanning, the DX-S CR solution produces image quality that the company says rivals that of the latest flat-panel DR system, at a significantly lower cost.