Developing x-ray imaging systems of the future
In the run-up to the MediSens conference, we will talk to various members of our Advisory Board, exploring their experience and views on technology, applications and the event which will be held in London this December.
Dr Biju Jacob is Detector R&D Lead at GE Global Research, where for the past 5 years, he has been looking at new x-ray techniques and technologies. As a member of the Advisory Board, he will be influential in shaping the event’s agenda, and reinforcing the quality of topics discussed in subjects closely linked to his own specialism.
Can you give a brief summary of your experience in medical imaging?
I got introduced to this exciting field when I joined GE R&D Headquarters in early 2011 where I got the opportunity to lead several advanced technology projects that shape GE Healthcare’s product roadmap. Notable areas include flat panel detectors for surgery, high resolution detectors for mammography and Advanced CT detectors.
My work is focused on building detectors from components we source from in-house and external vendors, evaluating their performance and reliability and on successful completion transfer the technology to the business for NPI.
Leading this effort offers a unique vantage point from I can assess the component technology landscape, detector cost and drive the CTQ flow between the detector (e.g. mammography detector) and system (e.g. Tomo system). The living thread that connects my career to all these efforts is the passion to “collect photons. Those photons have become more energetic as my career got advanced (from infrared to visible and now x-rays)!
You’ve worked on sensors for telecommunications, with visible light and other parts of the radio spectrum. How does the danger of x-ray radiation change your technical approach?
The technical approach essentially remains the same but one has to be cognizant of the hazards. There are processes and designs (e.g. safety interlock) that are built into the labs to control hazards. Compliance is the key word here, when dealing with radiation. We are expected to follow safe operating practices and monitor radiation exposure, and we are continuously learning new ways to improve safety.
What should clinicians care most about?
Clinicians do not care about the technology of the imaging equipment; they care about clinical outcomes and operational efficiencies.
The key aspects of detector performance that drive clinical outcomes are detective quantum efficiency, resolution (spatial, temporal, contrast, spectral), speed and dynamic range.
In an indirect x-ray (or CT) detector, the image sensor is an important functional element, second only to the scintillator (x-ray to visible light converter) in determining the performance. CMOS technology has many attractive features (advanced lithography, good material quality, IP) that makes it an ideal candidate for x-ray imager sensor.
However, the biggest challenge is the cost of making large (20cm, 30cm and even 40cm) arrays that are needed for medical applications. Clearly we need a different approach to make the sensors – an approach that is driven by the clinical needs and not simply a scaled up version of currently available scientific/consumer image sensor designs.
Some of the greatest medical imaging challenges come from specific patient groups. Can you give some examples of how your work helps clinicians serve these patients?
This is true. I can think of two examples: (1) thick patients in a surgical room and (2) breast cancer screening for micro-calcifications.
Let me elaborate on the first one.
Mobile C-arm systems are inevitable in modern OR. They are flexible and compact but have limited x-ray tube power. This makes the imaging of thick-bodied patients particularly challenging because very few x-ray photons penetrate the patient to reach the detector. A work around is to shoot higher energy x-rays that have higher penetrating power (although poor contrast).
Unfortunately, today’s detector performance is sub-optimal for these high energy x-rays. Developing novel scintillators that are more sensitive to higher x-rays will help to solve this problem.
You’ve studied and worked all over the world. Where have you enjoyed living most, and why?
Indeed, I have experienced different cultures, places, people. These experiences span different phases of my career, hence difficult to compare. Nevertheless, I had the good fortune to be around some great people who have influenced me a lot.
I recollect the afternoons I spent in Sheffield with Professor Peter Robson (already retired by then) discussing models of high field transport in APDs. I enjoyed the company of few good friends and long train rides in Switzerland. And finally, bringing up my kids in a quiet, but beautiful village of NY.
Tell us why MediSens is important to you, and what you’re looking forward to?
I believe there is a great value in bringing the imager sensor community closer to the medial experts. This could help bridge the gap of technology capabilities on one end to the clinical system requirements on the other. Specifically, on CMOS imagers, I believe it has a bright future in the field of medical imaging.
The traditional x-ray flat panels based on amorphous silicon technology has reached its limits in terms of spatial resolution, speed and low signal performance. Detector technology is seeking significant improvements in all these aspects and these are the areas in which CMOS has an upper hand.
To make this a reality one need to rethink the way we build large area (wafer scale) imagers so that the technology is cost effective. Exciting developments are happening in this field, the larger community need to be aware and take advantage of.
I am looking forward to serious dialogues between the communities on ways to improve clinical outcomes and efficiencies utilizing the sensor technologies.
Find out more
Built by medical practitioners and the world’s foremost digital imaging experts, this conference addresses the need for a more integrated approach to developing medical imaging systems for clinical use. Topics discussed will cover a range of sensor technologies including CCD, CMOS and fibre-based systems from macro to micro, connected by photonics technologies and the requirement for high quality, reliable imaging.
By bringing together medical professionals and the imaging technology supply chain, the audience can gain a better understanding of the challenges and capabilities of today’s advanced medical imagers.