Advanced detector technology for Digital Breast Tomosynthesis

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X-ray imaging detectors rely on indirect or direct conversion of x-ray quanta to an electron signal, with the indirect method most commonly on commercial systems. In this case the multi-stage conversion process begins with a scintillator converting x-ray quanta into optical photons. The optical photons in turn diffuse through a phosphor and then are converted to electrons by an array of photodiodes. In the direct method, the x-ray quanta are absorbed in a photoconductor that directly creates electron hole pairs. The electron hole pair is separated by a bias field to generate an electron signal in the imaging array. The advantages inherent in direct conversion are: (a) high spatial resolution, (b) improved dose efficiency down to the lowest required radiation exposure, and (c) the direct conversion detector system is simpler, and hence potentially more economical to manufacture since the need for separately integrated photodiodes is avoided. Applications in digital x-ray imaging that are ideal for this technology include high resolution low-dose high-resolution x-ray imaging, such Digital Breast Tomosynthesis (DBT), which is an advanced breast cancer imaging technique that has emerged to address the inconclusive nature of standard 2D mammography for a large group of patients. The goals of this NSERC Alliance Grant is to undertake material science research into a new x-ray photoconductive structure based on two different polymorphs of lead oxide (PbO) photoconductor for direct conversion x-ray detectors, and to demonstrate the technical feasibility PbO technology for DBT applications. The new technology of PbO photoconductors will achieve higher sensitivity and improved spatial resolution compared to existing commercial methods. Our innovative approach to radiation medical detector improves the diagnostic capabilities and efficiencies of cancer detection, while reducing the dose associated with radiation medical imaging. As a result, the citizens of Canada and other individuals world-wide, will benefit from high quality and radiation-safe diagnostic imaging.