PROFESSOR
Departments of Radiology, Neurosurgery,
and Biophysical Sciences

EDUCATION
B.S., University ofChicago (1964)
M.S., University ofChicago (1965)
Ph.D.,City University of New York (1975)

FOCUS 

Studies in medical physics involve both research into new methods for imaging with X-rays, gamma rays, ultrasound, radioisotopes, and magnetic resonance, as well as practical training in quality assurance of hospital-based imaging systems and administration of radiation safety programs. As part of a new multidisciplinary center based on the donation of imaging equipment worth $3.6 million, we are investigating new imaging detectors, exposure optimization methods, and means to evaluate three-dimensional neurovascular flow. The new imaging methods will be used to aid in the development and application oftherapies our group is developing to replace surgical procedures, primarily in the brain, with new image-guided, minimally invasive, catheter-based treatments. Also, we have quality assurance and radiation safety responsibilities and access to university teaching hospitals, which provide a practical training ground for graduate students while they pursue postgraduate research.

SELECTED PROJECTS

• Imaging detectors: development of new high-resolution solid-state X-ray detectors, including amorphous Se flat panels and a CCD-phosphor system for high-speed, high-resolution vascular imaging
• Exposure optimization: region-of-interest radiography where the beam is physically modulated in accordance with importance of the imaged feature while real-time image processing equalizes the brightness of the displayed information
• Flow quantification: using biplane rapid-sequence digital subtraction radiography, small droplets of contrast media are tracked to provide three-dimensional flow velocities within vessels
• Three-dimensional computed tomography: after X-ray image intensifier images are corrected for distortion, cone beam data are used for multiple plane three-dimensional reconstruction
• Hospital and health physics: quality assurance for radiation sources and medical image-forming systems (radiography, ultrasound, nuclear medicine/radioisotopes, and magnetic resonance imaging), and radiation safety topics

PUBLICATIONS

• P. Massoumzadeh, S. Rudin, and D. R. Bednarek. Filter-material selection for region-of-interest radiologic imaging. Medical Physics 25(2):161­71 (1998).
• M. Kezerashvili, D. R. Bednarek, and S. Rudin. Automatic system for measuring dose-area product (DAP) in ROI fluoroscopy. Physics in Medicine and Biology 42(4):613­23 (1997).
• W. E. Granger, S. Rudin, and D. R. Bednarek. Survey of primary beam exposure outside the displayed fluoroscopic FOV. Medical Physics 24(5):703­7 (1997).
• S. Rudin, B. B. Lieber, A. K. Wakhloo, D. R. Bednarek, L. R. Guterman, and L. N. Hopkins. Quantitative flow velocity measurements in vessels, aneurysms, and arteriovenous malformations (AVMs) using droplet path tracking with a biplane-pulsed fluoroscopy system. In Proceedings from Medical Imaging, Physiology and Function from Multidimensional Images, SPIE vol. 3033 (Newport Beach, CA, 1997) pp. 268­79.
• L. M. Fletcher, S. Rudin, and D. R. Bednarek. Method for image equalization of ROI fluoroscopic images using mask localization, selection, and subtraction. Computerized Med. Imag. and Graphics 20(2):89­103 (1996).

Fig. 1 Design of new solid-state digital X-ray image receptor.

Fig. 2 X-ray-absorbing droplets are tracked to determine blood-flow velocity distribution with a new dual-contrast media digital-subtraction angiographic method for an arteriovenous malformation in the brain.