- 15 - 16 February, 2012
Southern Electronics - 08 March, 2012
UK Technology Day - 23 May, 2012
ElectroTestExpo
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MRI (magnetic resonance imaging) scans provide extraordinarily clear images of the human body and are commonly used to diagnose a wide range of illnesses and injuries, such as Alzheimer’s disease, cancerous tumors, and torn ligaments. Analog Devices has introduced what it is describing as a breakthrough in data conversion that will be capable of giving clinicians and radiologists the much improved image clarity that they need to see smaller anatomical structures and abnormalities, such as breast cancer cells.
ADI’s AD5791 high-accuracy 20-bit digital-to-analogue converter (DAC) is the industry’s first to feature true 1-ppm (parts per million) resolution and accuracy, provides four times greater accuracy and four times more resolution than competing converters. 1-ppm analogue system design typically entails the complex engineering challenges involved with combining multiple lower-resolution DACs with a significant number of discrete components and support ICs—along with considerable development risk and costly amounts of engineering time—to optimize circuit parameters, minimise errors, and design complex auto-calibration circuitry. The AD5791, with its 1-ppm resolution and accuracy, low noise (sub 1 ppm), fast refresh rates (1 us), and extremely low output drift (sub 1 ppm), significantly simplifies the design task, lowers development cost and reduces risk
In MRI systems, this technology improves image quality, enables precise control of the magnetic gradient in high-field-strength applications, and results in superior image resolution and contrast. The low noise, drift, and linearity performance of the AD5791 maximises operational up-time by eliminating the need to take the MRI system offline for system calibration cycles. The new converter also reduces the necessity for complex calibration algorithms, resulting in lower engineering and system maintenance costs. In addition to MRI systems, other applications for the AD5791 include test and measurement systems, high-end scientific and aerospace instrumentation, communications equipment, and industrial control systems.
Enhancements in data conversion allow imaging system designers to improve image clarity and speed clinicians’ ability to diagnose illnesses at an early stage and make timely treatment possible. The AD5791 DAC delivers extremely low-noise performance, lessening unwanted image artifacts and thereby reducing the need for multiple MRI scans. Additionally, lower image-error rates and higher availability ensure that healthcare facilities can effectively treat more patients within a shorter time period.
More than 60 million diagnostic MRI procedures are performed worldwide each year. A non-invasive technique, MRI takes images of the human body without using ionising radiation, making it a method of choice to diagnose many different injuries and conditions because of its ability to tailor the exam to meet specific imaging parameters such as the field of view.
According to Patrick O’Doherty, vice president for the Healthcare Group, Analog Devices, “For system architects, the 1ppm performance level makes a single DAC architecture possible, reducing design footprint and cost. This means that for the first time designers are able to free up a large portion of the system error budget, the savings of which can be applied to critical components in other subsystems or to improve the overall MRI performance.”
The 20-bit AD5791 offers a relative accuracy specification of ±1 LSB max, and operation is guaranteed monotonic with a ±1 LSB DNL max specification. The product delivers 0.025ppm low frequency noise and features 0.05ppm/C output drift. The output can be configured for standard unipolar (+5 V, +10 V) or bipolar (±5 V, ±10 V) output ranges. The AD5791 uses a versatile three-wire serial interface that operates at clock rates up to 50 MHz.
