Dexela Introduces Fast, Low Noise CMOS Flat Panel X-ray Detectors





exela introduces a family of flat panel CMOS X-ray detectors based on an innovative CMOS sensor design that combines unprecedented speed and superior image quality. The Dexela family of detectors includes a wide range of detector sizes including the largest available CMOS radiography detector. Dexela detectors are suitable for a range of medical applications including mammography and tomosynthesis, breast CT, dental CBCT, fluoroscopy, cardiology and angiographic imaging and bone densitometry, and also some applications in scientific instrumentation and non-destructive testing.

This is an exciting time for Dexela,” comments Edward Bullard, CEO of Dexela. “The introduction of our family of CMOS X-ray detectors enables OEMs to apply the superior performance of CMOS technology to a much wider range of applications than was possible previously. This creates opportunities for better, faster and more reliable imaging systems.

The major advantages of the technology are high frame rate, low noise, high reliability, absence of image lag and high spatial resolution. The clinical benefits in medical applications are lower radiation dose to the patient (about 50% lower dose in some applications) combined with superior image quality when compared with flat panel detectors based on amorphous silicon sensor technology. Dexela has used the flexibility, speed and low noise of CMOS technology to create detectors that are more flexible, faster, more sensitive, higher resolution and more stable than TFT-based flat panel detectors.

A new CMOS detector design

The Dexela detector family’s main components are: CMOS image sensor, scintillator(structured CsI or Gadox), control electronics, readout electronics and communications with the workstation.

The Dexela CMOS image sensor consists of a photodiode array with a pixel size of 75µm. The sensor has very low dark current and read noise, with high linearity and consistency of response. The detector is capable of multi-resolution readout with dynamically adjustable binning at 1×2, 2×2, 1×4, 2×4 and 4×4. For the largest model in the range, the frame rate ranges from 26 frames per second at full resolution (75µm) to 86 framesper second binned 4×4 (300µm pixel pitch) over the whole active area of 29cm x 23cm.

The high fill factor, efficiency and low noise of the sensor combine to produce a high DQE of 0.70 at a skin dose of only 280µGy. This results in lower patient dose and superior image quality when compared to TFT-based detectors with significantly lower DQE.

The Dexela CMOS flat panel X-ray detectors all operate from a low-voltage DC supply. The aluminium housing is shock and vibration resistant. The detectors are highly robust with a storage temperature range of -5 to +55 (C) and an operating temperature range  +10 to +40 (C).

Dexela detectors have been designed using a modular technology platform, enabling production of different detector models with different dimensions, all sharing the same components. A range of models is offered with the model number based on the active area: 1207 (115mm x 65mm), 1512 (145mm x 115mm), 2315 (230mm x 145mm), 2321 (230mm x 210mm),2923 (290mm x 230mm), and 2923MAM (290mm x 230mm).

The 2923MAM has an enclosure specifically designed to maximise the amount of tissue imaged close to the patient’s chest wall. It is the largest CMOS X-ray detector ever developed for mammography or breast tomosynthesis.The 3529 detector with an active area of 35cm x 29cm is planned for 2010.

Scintillator options

The Dexela flat panel CMOS X-ray detectors can be used in a range of applications employing different X-ray energy ranges. This is achieved by offering a choice of scintillators: 150µm structured CsI or fine Gadox screen for mammography and 500µm structured CsI for cone beam CT and dynamic imaging. The scintillator can be easily customised for specific OEM applications.

Software

Dexela provides software drivers and companion software with its detectors. The software includes a basic application for image acquisition and viewing on a workstation or laptop running Microsoft Windows XP or Vista (x32 or x64).The development kit includes the Dexela SCAP software application that performs detector calibration, sensor set-up, image acquisition and image corrections. SCAP includes file translators for .smv, .raw and .tif formats.

Dexela also offers DexView image processing software for mammography and other types of radiography. DexView enhances the visibility of structures, removes noise and compensates for variations in exposure within an image. Features include:

• Noise reduction whilst preserving tiny structures
• Image enhancement (contrast, edge)
• Peripheral equalization

DexView image processing software can be customised for specific OEM products.

Interface options

Interface options include high speed Camera Link (full configuration for the 2923, medium configuration for the 2315 and base configuration for the 1512) and USB 2.0. Gigabit Ethernet will be offered in 2010. Images are displayed instantly on a user-supplied workstation fitted with the appropriate interface board or a standard USB port.

Optional accessories
Dexela can supply these optional accessories with its detectors:

• Mains power supply unit (PSU)
• Camera Link interface board

Key features

• High Speed: 26–86 fps
• High spatial resolution: 75µm – 300µm (depending on binning)
• Superior image quality: high DQE and dynamic range
• Ultra low noise electronics
• Absence of image lag
• Fibre-optic faceplate (FOP) for increased lifetime
• Flexible, reliable and robust

Dexela will exhibit its new flat panel CMOS X-ray detectors at RSNA 2009,Hall D, Booth 2218.