Karim's thesis earns medal

Jul 10, 2003, vol. 27, no. 6
By Diane Luckow



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In hospitals and medical labs, photographic x-ray film is quickly being replaced by digital x-ray imaging systems that can display real-time images of a patient's body on sophisticated flat-panel screens.

For some large-scale digital procedures, however, such as digital fluoroscopy, where patients receive continual low-dose radiation to provide a real-time glimpse of their arterial system on a large screen, the x-ray signal reception is too poor to enable a clear digital image for accurate diagnosis.

New SFU assistant professor of engineering science Karim S. Karim, (left) however, recently proposed a novel solution to this problem in his PhD thesis at Waterloo University in Ontario. For his efforts, this summer he received the prestigious Douglas Colton medal for his substantive contributions to microelectronics, solid state physics and medicine.

In a nutshell, Karim found a way to overcome the fuzzy images of large-format, low-exposure, real-time digital x-ray fluoroscopy by amplifying the x-ray signal at the pixel (the imaging unit which senses the x-ray signal) level using amorphous silicon technology.

Explains Karim, “The pixel amplifier enables the low-dose fluoroscopy x-ray signal to ovecome the noise of the external imaging electronics and create a clearer image.” The difficulty in focusing x-rays makes amorphous silicon semiconductor technology a popular choice for large-format diagnostic medical digital imagers. Amorphous silicon can be easily deposited over a large area, removing the need to focus x-rays in order to form an image.

He points out that large format digital x-ray imaging can provide instantaneous results, making it ideal for remote diagnosis - for instance in medical consultations over the telephone or internet.

An added bonus of his pixel amplifier is that patients may require lower radiation dosages when undergoing diagnostic x-ray imaging.

Karim, whose parents and brother are doctors, is now researching new applications in biomedical imaging using thin film electronics.

“Thin film electronics is a technology that has a lot of potential,” he notes. “It's already used commercially in thin laptop screens and in solar cells on calculators.” One day, he predicts, it will become a mainstream technology for x-ray imaging in hospitals and medical clinics worldwide.

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