Advanced CT Strategies for Image Quality Improvement and Dose Reduction

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X-ray computed tomography (CT) produces detailed images of the body and is a critical tool in health care. These systems are employed in every facet of medicine from cancer screening to assessing injuries to guiding treatments such as radiotherapy and surgery. ******However, there is significant opportunity enhance CT technology by better exploiting the underlying physics to improve image quality and minimize the radiation dose to patients. This program of research builds upon over 20 years of experience in X-ray imaging methods and system development to develop next-generation CT methods that leverage advances in computational methods, mechatronics, and nanotechnology. The research focuses on two major topics:***1. Improving image quality by using physics-based models to correct for unwanted X-ray scatter***2. Lowering the risk associated with CT imaging using a novel approach called fluence-field modulated CT (FFMCT). ******In brief, CT works by sending a beam of X-rays from an emitter through the patient to a detector. The signal changes depending on what's in-between the two, e.g. with bone blocking more X-rays than muscle. However, some X-rays are scattered and didn't follow a straight line through the patient. These scattered X-rays have a significant effect on image quality, which is exacerbated in cone beam CT (CBCT) due to the volume of tissue irradiated and lack of a rejection method. Accurate modeling of the physics underlying scatter with Monte Carlo (MC) simulations allows us to better understand and correct for scatter, leading to improved images and patient dose management. We recently made the simulations more efficient and faster, a first step needed to incorporate them in clinical imaging systems. This project will improve the modelling and accuracy of the simulations, and extend the work to other imaging modalities with similar challenges such as positron emission tomography (PET). ******FFMCT was developed in my laboratory and has the potential to transform CT technology by changing the operation of the CT scanner depending on the objective of the imaging task. It involves dynamically adjusting the X-ray fluence pattern during image acquisition so that the image quality and dose are adjusted for specific regions-of-interest. FFMCT can reduce dose to sensitive tissues not of interest (e.g. breast tissue in lung screening)and as a result lower the exposure risk while assuring or improving upon existing CT image quality. New nanotechnology-based X-ray emitters will let us develop a novel FFMCT prototype with multiple programmable sources; this approach will also leverage the physics-based models being advanced in my lab.