Investigating improvements in Breast CT using photon counting detectors

Breast Computed Tomography (BCT) is an emerging diagnostic imaging technique that can represent the breast in 3D and improve visualization of important anatomical features. Early clinical studies have suggested that BCT reduces tissue structural overlap, which is often a limiting factor in reading mammographic images, and provides sufficient spatial and tissue contrast resolution for accurate detection of masses and microcalcifications in the breast. For a number of reasons, image quality of the current generation BCT may be improved by use of an energy resolving photon counting detecter (PCD).;Advantages of an energy resolving PCD include an energy resolved readout, reduced electronic noise; improved spatial resolution and signal to noise ratio (SNR) with energy weighting, the potential to minimize radiation dose and the feasibility of single exposure spectral imaging. The potential improved image quality provides radiologists with valuable information that could assist in accurately detecting and diagnosing breast cancer at all stages. Early diagnosis of breast cancer helps in prognosis, better treatment planning and allows less invasive lumpectomy with reduced positive tumor margins.;To achieve images of the highest radiological quality at minimal radiation dose, imaging parameters such as energy bin size, energy weighting methods, x-ray spectra and estimation algorithms must be optimized. The focus of this dissertation is to investigate by computer simulation experiments; a) the optimal energy window combinations for diagnostic imaging with a three energy window PCD based BCT (PCD-BCT), b) improvements in image quality (i.e. SNR of microcalcifications, carcinoma and iodinated carcinoma inserted in breast phantoms) with 1) energy weighting with PCD, 2) using quasi mono-chromatic x-ray spectra, c) the improvements in image quality by evaluating human observer performance in detection of anatomical features in PCD-BCT reconstructed images and d) the performance basis material decomposition (tissue estimation) of the breast using iodinated contrast agent at a single exposure. The methods herein demonstrate how a PCD-BCT may be a) employed to achieve improved radiological performance at a reduced radiation dose, and b) reconfigured to address the wide range of clinical diagnostic imaging needs. The results provide an upper limit of the image quality that can be achieved with a PCD-BCT.