Preceptors and Mentors
Faculty from six departments (Radiology, Electrical Engineering, Bioengineering, Radiation Oncology, Pediatrics, and Medicine) have come together to jointly train students from seven degree granting programs, in five departments (Applied Physics, Bioengineering, Computer Science, Electrical Engineering, and Physics) and in two interdepartmental programs (Biomedical Informatics and Biophysics). See the RESEARCH Page for information on faculty reasearch.
Norbert Pelc, ScD, Director
Professor, Department of Radiology
Professor and Chair, Department of Bioengineering
Dr. Pelc has been active in diagnostic imaging research for more than 40 plus years.Although he is best known for his work in Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), he has also worked in nuclear medicine, x-ray, and ultrasound imaging. During his graduate training, he was one of the first to work in "fully 3D" PET. His early contributions in CT include theoretical research on quantum noise and practical work including the first demonstration of "bone detail" reconstructions and illumination of the source of several image artifacts. In the early 1980's Dr. Pelc's research included high impact work on digital and dual energy x-ray imaging. In MRI, he contributed to the development of hardware systems, including quadrature excitation and advanced transceivers, to imaging methods including cardiac cine, MR angiography, respiratory compensation, single and half-NEX imaging, and motion studies based on velocity mapping. He worked on hybrid imaging in collaboration with Drs. Butts Pauly, Fahrig, and Daniel, especially x-ray/MR systems for guiding minimally invasive procedures.
Recently, his interests have returned to CT imaging. Computed tomography has made phenomenal technical advances since its introduction in the early 1970s. As an example, Fig 4 shows the progress in clinical CT scanning speed since the earliest systems. Figure 4. Evolution of CT speed This, combined with improvements in spatial and contrast resolution, have made CT a powerful tool in diagnosis and management of patients. The growth in the utilization of CT is evidence of its success. However, even though the dose per slice is decreasing, the dose to the population is significant, which is roughly half of that due to natural sources, has raised concerns. While the benefits from clinically indicated CT exams far outweigh any risk from radiation, it is prudent to reduce CT radiation dose as much as physically possible, and NIBIB has encouraged the scientific and medical community to develop further reductions in CT radiation dose. Dr. Pelc has contributed to this effort in several ways. He developed the concept of “inverse geometry” CT, a system design that can lead to improved volumetric imaging and significant dose reduction through precise control of the x-ray field illuminating the patient, but is very difficult to implement.
More recently, his group proposed a more feasible way to achieve the dose reduction, through control of the illuminating field using a dynamic piece-wise linear pre-patient attenuator comprising triangular wedges (“dynamic bowtie”, Fig 5). Figure 5. Dynamic bowtie Computer simulations predict that a dynamic bowtie can reduce dose by 30-40% in conventional studies and even more in exams where only a fraction of the in-plane field of view is of clinical interest. With funding from NIBIB, an initial feasibility model is being built and tested (Fig 5). Of importance to the current proposal, these projects led to the dissertations of 4 PhD students.
Along with his excellent research track record, Dr. Pelc is a highly regarded teacher of both pre-doctoral and post-doctoral trainees (including physicians). Dr. Pelc was the principal advisor of 14 PhD students, 11 of whom have completed their studies. He has been the primary or co-advisor of 17 postdoctoral fellows. His students have gone on to successful careers in academia and industry in roughly equal numbers. They have won recognition for their research with awards that include two ISMRM Young Investigator winners, five RSNA research fellow prizes, and one AAMI Young Investigator award. Dr. Pelc has served on the admissions committees of two degree-granting programs at Stanford (Bioengineering and Biophysics) and has been a secondary advisor or on the thesis committees of many doctoral students. He has advised graduate students in six degree granting programs (EE, ME, BioE, Physics, Applied Physics, and Biophysics) at Stanford, an indication of his experience and ability to work closely with the programs and departments that are linked to the training program.