I. George Zubal, Ph.D.

Associate Professor of Diagnostic Radiology

Ph.D. Biophysics, 1981, University of Saarland, work conducted at DKFZ in Heidelberg, Germany.

General Nuclear Medicine provides a direct means to image human organ functions (e.g. ventilation, blood flow, etc.) by detecting very low levels of radio pharmaceuticals injected into the body. These radio pharmaceuticals are radioactive analogues of naturally occurring bio-molecules and by studying their transport through the body, we can measure the functions of various organs.

One area of research in General Nuclear Medicine applies computer models to simulate the anatomy of the human and implements Monte Carlo algorithms to calculate the interactions of radiation as it passes through human tissue. These simulations also model the important components of the imaging instrumentation and associated processing electronics. With such a complete mathematical representation of the radio-pharmaceutical, patient, and camera, the image formation process can be studied in detail and leads to image processing techniques to correct for image degradations. Projects within General Nuclear Medicine mathematically model organs as homogeneous compartments in order to establish more accurate ways to determine organ function from external measurement.

An exciting inter-modality field hass recently emerged which requires two independent imaging modalities to be fused into a single representation. Image manipulation and processing techniques are applied to SPECT (Single Photon Emission Tomography) 3-dimensional images in order to register them with other modalities which show better detail of the anatomical structures (MRI or CT). Being able to register two 3-dimensional patient brain image sets is a development with immediate clinical applications. By objectively locating identical points or surfaces in both image sets and then by mathematically re-orienting SPECT scan of the head, brain function can be more correctly localized and quantitated. The combined information of anatomy registered to SPECT functional images leads to new methods of reconstructing the SPECT data from its original projection data. The prior information afforded by anatomy constrains image parameters which iteratively converge to a SPECT image with better characteristics. Such new techniques are proving valuable for studying the brain.

 

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zubal@biomed.med.yale.edu