Dr. Safa Kasap

Canada Research Chair in Electronic and Optoelectronic Materials and Devices

Despite remarkable advances such as MRIs and CT scans, the most basic of all medical imaging tools has seen little change in the past 40 years: X-rays are still taken using silver halide film. Dr. Safa Kasap of the University of Saskatchewan hopes the work he is involved in will change that.

“We’re working on technology that will bring x-rays into the digital age,” Dr. Kasap, a Professor in the Department of Electrical Engineering, says. He is currently collaborating with colleagues at Sunnybrook and Women’s College Health Sciences Centre at the University of Toronto on a direct conversion, flat panel x-ray image detector.

“X-ray imaging with these detectors is more efficient because there’s less radiation dose and images can be quickly transferred electronically,” Dr. Kasap says. “It’s more convenient and less expensive in the long run because the solid state detector doesn’t need film or developing chemicals.”

The benefits are significant. The quality of the digital images is excellent, offering a clear advantage in diagnosis. Just as important is that images can be quickly sent electronically to specialists in referral centres, enabling remote or low population regions to be served through “teleradiology”.

Kasap is one of the world’s leading researchers on photoconductors, the part of the system that captures the x-ray image and converts it to a digital signal. He is collaborating on three types of digital imaging: mammography, chest x-rays and fluoroscopy, or real time imaging.

The work was greeted with enthusiasm when Kasap and collaborator John Rowlands, of Sunnybrook Health Sciences Centre, published an article in Physics Today in 1997. But it is not without competition.

“There is a competing system called indirect conversion that uses a phosphor-based two-step approach, compared to our solid state system’s one-step direct conversion approach,” Dr. Kasap says. “We’re realistic about the competition, but we’re also hopeful. Direct conversion offers a better quality image and doesn’t need a humidity controlled environment. It’s more efficient and less expensive.”

Work has progressed to the point that a direct conversion flat-panel x-ray image detector is now in clinical testing for mammography.

“Ideally, we’d like to develop a panel that can be used in all three areas, that’s one of our challenges,” Dr. Kasap says. Right now, his team is tweaking the performance of existing photoconductors to get the best conversion possible, as well as searching for new materials and models to design better detectors.

In addition to his photoconductor work, Kasap is collaborating with scientists at TRLabs and the University of Alberta in Edmonton on photonic devices for use in optical communications. With two strong research directions underway, he feels the Canada Research Chair has come at the right time.

“We’re at the peak of our research. My work is very experimental, very hands on; the Canada Research Chair allows us to expand and equip ourselves,” Dr. Kasap says. “It is tremendously exciting. We’re catching up with the rest of the digital world. In 10 years, I hope people have forgotten what x-ray film was for.”