Solid-State Breast CT with X-ray Colour Imaging: A new approach to breast screening using STFC's HEXITEC imaging detector technology

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Planar X-ray mammography is the gold standard screening method used for detecting early-stage breast cancer in women. However, new digital detector technologies have emerged to replace the conventional X-ray film cassette, which has stimulated interest in the possibility of using small dedicated CT scanners (i.e. Computed Tomography, sometimes referred to as CAT scanners), which produce cross-sectional slices, for breast imaging.The two major advantages of breast CT are :(i) avoidance of breast compression, which can be painful and lead to procedure refusals; and(ii) removal of the distracting over/underlying background clutter which is always present in a conventional mammogram. This produces images that makes the detection of cancer easier for a radiologist, which can improve detection rates and reduce the probability of false cancer detection, which is also a major problem with current screening technology.This project is about using STFC's HEXITEC state-of-the-art imaging technology and combining it with new developments in X-ray source technology to develop a new type of breast CT scanner. The idea in this proposal is to undertake the pilot work needed for developing the first viable solid state (i.e no moving parts) breast CT scanner capable of 'colour ' X-ray imaging - currently there are no commercial medical scanners that have this type of 'colour' imaging capability.Using 'colour' X-ray imaging in this respect can be thought of as analogous to colour vs monochrome (optical) photography: a monochrome camera generates an image where each pixel has a shade of grey (i.e. grayscale or grey level) that is akin to an 'average' of all the optical wavelengths or colours representing a particular part of the scene viewed by the camera; however, a colour camera splits these wavelengths into component groups (usually red, green and blue) which can then be recombined to produce colour images. Conventional CT scanners also produce grayscale images that represent an average across all the X-ray wavelengths used in the scan, whereas the HEXITEC technology will allow us to separate or COUNT the individual X-ray photons and put these into groups of component wavelengths, to produce X-ray 'colour' images. Developing this approach opens up exciting new opportunities to produce cross-sectional images, or virtual slices of the breast which will show malignant disease with higher contrast, and allow better differentiation between malignant and benign conditions.To make this approach a practical reality, we propose to address two major issues that occur during a conventional CT scan: in conventional X-ray CT it takes time for the X-ray source and detector array to rotate round the patient (or in this case, the breast). However, using X-ray PHOTON COUNTING as described above, to split the X-ray photon pulse into component wavelengths, requires an even longer scanning time than the conventional approach. These bottle-necks slow up the scanning process and currently make it impractical for clinical work as patient throughput, comfort, and image quality (due to inevitable patient motion during the scan time) would be compromised.In this new project we propose to use simulation methods to investigate a 'no moving parts' geometry: a circular ring of HEXITEC detectors which sits immediately below a circular array of carbon nanotube X-ray sources During a scan, a short X-ray burst fired from each source around the ring allows the HEXITEC detectors to work in parallel rather than sequentially scanning round the ring. This will dramatically speed up the scanning time and so addresses the bottlenecks in the scanning process. The aim of this project is to explore the performance needed for the next generation of detectors and how to make best use of the X-ray dose used in these scans so as to make 'Colour' X-ray Breast CT into a viable new imaging approach for breast cancer screening.