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

平面X光乳房摄影是检测女性早期乳腺癌的金标准筛查方法。然而，新的数字探测器技术已经出现，以取代传统的X射线胶片盒，这激发了人们对使用小型专用CT扫描仪(即计算机断层扫描，有时被称为CAT扫描仪)进行乳房成像的可能性的兴趣。乳房CT的两大优点是：(I)避免了乳房压缩，这可能会导致疼痛并导致程序拒绝；以及(Ii)消除了传统乳房X光检查中总是存在的分散注意力的背景上/下的杂乱。这将产生更容易为放射科医生检测癌症的图像，这可以提高检测率并减少癌症错误检测的可能性，这也是当前筛查技术的主要问题。该项目是关于使用STFC的HEXITEC最先进的成像技术，并将其与X射线源技术的新发展相结合，开发一种新型的乳房CT扫描仪。这一建议中的想法是进行所需的试点工作，以开发第一个可行的固态(即无移动部件)乳腺CT扫描仪，该扫描仪能够进行彩色X射线成像--目前还没有商业医疗扫描仪具有这种类型的彩色成像能力。在这方面，使用彩色X射线成像可以被认为是类似于彩色与单色(光学)摄影：单色照相机生成图像，其中每个像素都有灰度(即灰度或灰度级)，这类似于所有光学图像的平均代表摄像机观察到的场景的特定部分的波长或颜色；然而，彩色相机将这些波长分割成组分(通常是红、绿和蓝)，然后可以重新组合产生彩色图像。传统的CT扫描仪还会产生灰度图像，代表扫描中使用的所有X射线波长的平均值，而HEXITEC技术将允许我们分离或计算单个X射线光子，并将这些光子放入成组的分量波长中，以产生X射线“彩色”图像。开发这种方法带来了令人兴奋的新机会来产生横断面图像，即乳房的虚拟切片，它将以更高的对比度显示恶性疾病，并允许更好地区分良恶性疾病。为了使这种方法成为现实，我们建议解决在传统CT扫描中发生的两个主要问题：在传统的X射线CT中，X射线源和探测器阵列围绕患者(或在这种情况下，乳房)旋转需要时间。然而，使用如上所述的X射线光子计数来将X射线光子脉冲分割成分量波长，需要比传统方法更长的扫描时间。在这个新的项目中，我们建议使用模拟方法来研究一种“不动部件”的几何结构：在扫描过程中，HEXITEC探测器的圆形环位于碳纳米管X射线源的圆形阵列的正下方，从环周围的每个源发射的短X射线爆发允许HEXITEC探测器并行工作，而不是顺序地绕环扫描。这将大大加快扫描时间，从而解决扫描过程中的瓶颈问题。该项目的目的是探索下一代探测器所需的性能，以及如何最大限度地利用这些扫描中使用的X射线剂量，以使‘彩色’X射线乳腺CT成为一种可行的乳腺癌筛查新的成像方法。

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.