Dr. Segars’ research involves the development and application of innovative computer-generated phantoms and simulation techniques to investigate and optimize medical imaging systems. As new imaging devices and techniques emerge in response to disease, a major challenge is how to evaluate which is best in terms of patient diagnosis and treatment. It is essential for the advancement of emerging imaging systems to have a tool that can be used for technique development, evaluation, and comparison. Each technique involves several selectable parameters for image acquisition, reconstruction, processing and analysis. It would be ethically and practically impossible to test every combination of parameters and every clinical task on patients under clinical conditions to assess both quality and safety. This is especially true for x-ray systems given the exposure to radiation. The only practical approach to optimization and evaluation is, therefore, through the use of realistic computer simulation.
In simulation, computational phantoms provide a virtual model of the patient’s anatomy and physiology. Imaging data of a phantom can be generated as if it were a live patient using an accurate computerized model of the imaging device or scanner including all the physics of the imaging procedure. The figure above shows an example of a computed tomography (CT) simulation. With simulation, it is therefore possible to perform clinical experiments entirely on the computer. The advantage in using such studies is that the exact anatomy of the phantom is known, thus providing a “gold standard” or “truth” from which to quantitatively evaluate and improve imaging devices and techniques. In order for simulation results to have merit, however, it is vital to have digital phantoms that are realistic; otherwise, the results will not be indicative of what would occur in actual subjects. Using state-of-the-art computational modeling techniques, as used in current movies and computer games, we develop ultra-realistic and flexible computerized phantoms of anatomy and physiology capable of producing simulated medical images close to those of live subjects.