SOCIETY AWARDS
Christopher J. Thompson
Edward J. Hoffman Medical Imaging Scientist Award

For over 30 years Christopher J. Thompson has been an innovator advancing the design and development of PET imaging systems, making significant contributions that have shaped the way in which PET systems operate to this day. In 1978 he and his team constructed the first BGO-based PET system, the Positome II, which demonstrated that BGO was a viable scintillator for PET applications and had significant sensitivity gains as compared with NaI(Tl) based detectors. For the 20 years following this work BGO remained the premier scintillator for PET imaging applications.
In 1994, Chris published the first paper describing the concept of Positron Emission Mammography (PEM) based on two planar detectors positioned above and below the breast. This work led to the construction of a prototype PEM system integrated with an x-ray mammography unit and formed the basis for the PEM Flex system manufactured by Naviscan PET Systems. This device was the first high-resolution PET system designed specifically for imaging small body parts to obtain FDA clearance.
Chris has continuously worked to improve PET image quality through both hardware and software solutions. By recognizing that spatial under-sampling leads to reduced spatial resolution, he first worked on detector ring wobbling techniques to improve spatial sampling and later developed depth-of-interaction capable detectors to improve spatial sampling with a stationary ring. Patient motion in PET studies is a major source of error and loss of resolution. In response to this, he developed techniques for correcting for subject motion in PET scanning by triggering new acquisition frames when the subject moved. Chris was among the first to demonstrate the utility of now commonly used Monte Carlo simulation techniques in PET. The PETSIM Monte Carlo package he developed was used successfully by his and other groups to optimize PET system designs. Chris realized that out-of-field activity degraded the quality of brain PET studies through increased randoms counts. To counter this problem, he developed the "NeuroShield" to reduce the effects of out-of-field activity and demonstrated a 35% increase in the noise equivalent count rate for brain studies. Most recently, Chris developed a timing alignment probe to aid in the timing calibration of time-of-flight PET systems, which is very relevant given the recent clinical introduction of TOF systems.
Throughout his career, Chris has published nearly 100 peer reviewed papers and holds 10 patents related to PET imaging. In his 30 years as a faculty member at McGill University he has supervised 24 master's and Ph.D. students, most of whom have gone on to work in imaging technology development or as medical physicists.
Chris Thompson retired from McGill last year and is now a post-retirement professor. He continues to work on PET detectors in his basement in Montreal, Canada. Email: christopher.thompson@mcgill.ca

Katsuyuki ‘Ken’ Taguchi
Young Investigator Medical Imaging Award

Katsuyuki "Ken" Taguchi is unique in that he has made significant scientific contributions in the development of algorithms for cardiac, multi-slice, and four-dimensional x-ray CT imaging in both industry and academia. After receiving his Master of Science from Tokyo Institute of Technology in 1991, Ken joined Toshiba where he remained until 2005. His work on the multi-slice CT project began in 1994 and he very quickly began work on algorithms that were incorporated into the 4-, 8-, 16-, and 64-slice x-ray CT scanners developed by Toshiba. In one of his first projects, he developed an algorithm for multi-slice CT in which cone-beam data could be reformulated into reconstructions of a stack of fan beam geometries. He was one of the first to propose the use of multi-slice CT for cardiac imaging developing an algorithm that used projections only during the cardiac phase of interest. These works were published in Medical Physics. In 1998-2000, Ken spent a year and a half at the University of Utah as a visiting scientist. It was during this time that Toshiba introduced their first multi-slice CT scanner (4 slices) implementing both of Ken’s published algorithms in this scanner. While in Utah, he developed a cone beam reconstruction algorithm that reformatted helical cone beam data into Radon planar integrals using a combination of spherical harmonics and Grangeat’s formulation. In 2000, he returned to Japan where he continued working full time for Toshiba. Working long hours at Toshiba and at the same time trying to finish his Ph.D. thesis, he implemented cone beam algorithms of the extended Feldkamp-type in the Toshiba 8-, and 16-slice scanners. Ken finished his Ph.D. thesis in 2002 and moved to Chicago to work for Toshiba America Medical Systems where he developed a direct cone beam reconstruction algorithm that was implemented in the Aquilion64 for cardiac imaging. The algorithm was able to eliminate the characteristic banding artifact seen in the multi-slice CT cardiac images. In 2005, Ken moved on to Johns Hopkins University to join the Medical Physics Group of Benjamin Tsui, Ph.D. where he has continued to work on x-ray CT algorithms. His motion correction algorithm developed with Professor Kudo was published in IEEE Transactions on Medical Imaging in 2008. His present projects include: time-resolved cardiac 4D CT imaging, CT imaging with photon counting x-ray detectors, and quantitative interventional tumor oncology using C-arm CT imaging. He is presently Assistant Professor of Radiology at Johns Hopkins University and is funded by NIH, American Heart Association, and Siemens. In addition to his impressive record of peer viewed publications (15), Ken has 25 US patents and 90 Japanese patents.
Katsuyuki "Ken" Taguchi can be reached at Johns Hopkins University, Department of Radiology, 601 North Caroline Street, JHOC 4253A, Baltimore, MD 21287. 433-287-2974. ktaguchi@jhmi.edu.