The inaugural Glenn F. Knoll Lecture in Nuclear Engineering and Radiological Sciences took place on October 2nd before a full White Auditorium. Longtime friend and colleague of Professor Knoll, Dr. William Moses of Lawrence Berkeley National Laboratory (LBNL), gave the series’ first lecture.
Before starting his talk, “Recent Advances in Time-of-Flight PET,” Moses recounted his first trip to U-M some 25 years ago. He was coming for a conference organized by Professor Knoll, and Moses, at the time admittedly a “wet-behind-the-ears postdoc,” was to give his very first oral conference presentation.
“I knew who Glenn was; he had no idea who I was,” Moses said. After the talk, Knoll approached Moses to chat and invited him to a barbeque he was hosting for conference organizers.
“That was very typical of Glenn. He always treated me like a colleague and like an equal, even though he was far senior to me…and I really appreciated that,” Moses said.
Today Moses is a senior staff scientist at LBNL and his lab’s focus is on advanced instrumentation for nuclear medical imaging, including Time-of-Flight Positron-Emission-Tomography (TOF PET).
About one million PET scans are performed annually in the United States, most commonly in oncology to find tumor metastases and assess patients’ response to treatment. But patient bodies attenuate gamma rays, and scans of larger diameter patients result in lower image quality.
Using time-of-flight information can reduce noise in the resulting image, and that brings a host of benefits, Moses explained: a reduction in scan time, better image quality, lower injected dose of radioactive tracer, or some combination — “all good things,” he said.
Major manufacturers today now offer TOF PET cameras, and Moses and his team are looking at further advances, including how to improve timing resolution. Their work led to the realization that, to do so, design changes to the camera’s photo multiplier tubes and detector ring geometry would be required.
Next, Moses’ group built a camera to demonstrate the changes, although the camera is not necessarily commercially viable at this time, he noted.
A task-specific performance evaluation is underway. To date, the new camera improves the signal-to-noise ratio by a factor of 2.3 and it features the best time resolution of any camera in the world.
That’s not enough for Moses, who, through scintillator modeling and Monte Carlo simulations, has identified changes that can enable further improvements in timing resolution.
His goal is to reduce timing resolution to the point — 50 picoseconds, he believes — where reconstruction algorithms and computed tomography might no longer be necessary.
“You could acquire and reconstruct an image in under one minute, which…” he said, “I’d like to do.”
The Glenn F. Knoll Lecture in Nuclear Engineering and Radiological Sciences was generously endowed by Gladys Knoll, wife of late Professor Emeritus Glenn Knoll.
If you missed the lecture, you can watch the video.