HEXITEC: Translation grant. The application of colour X-ray imaging

x射线彩色成像有可能在三维密度对比图像中可视化空间分辨率的标本的物理和化学性质。例如，x射线彩色成像可以识别航空航天工业中使用的复杂制造部件是否可能因裂纹或疲劳应力而失效；或行李箱是否装有塞姆汀或可卡因等非法物品；或者活检样本中是否含有正常或异常的组织。一个完整的x射线彩色成像系统需要能量敏感的探测器，它被分割成小的离散像素，并能阻挡高能x射线。此外，由于我们寻找的是非常微弱的信号，来自样本的散射辐射通常必须非常精确地校准。五年前，既没有合适的探测器材料，也没有散射控制系统。后一个问题得到了解决（由EPSRC的另一笔拨款），但世界上任何地方都没有可靠的探测器材料来源。英国缺乏生产合适探测器系统的技术专长，这导致了HEXITEC联盟（高能x射线成像技术；www.hexitec.co.uk）的形成。HEXITEC开发了探测器系统制造的每个阶段，最近展示了其第一个20 × 20像素的原型，作为将于2010年初交付的完整80 × 80设备的先驱。我们现在正在请求资金，以便在三个工作方案中将HEXITEC开发的技术带入下一个发展阶段，这些工作方案涵盖在不同发展阶段的四种广泛应用。工作包1：材料成像的荧光层析成像我们将使用由HEXITEC开发的80 × 80像素探测器系统。荧光断层扫描是基于一种标准的吸收方法，其中样品在光束中旋转，许多部分在数学上重新组合以给出三维图像。关键的区别在于，我们可以在谨慎的能量范围内做到这一点。我们将获得可以在800eV或更好的范围内选择能量的切片。我们将提供一个基于实验室的系统来产生特定元素的图像。工作包2:TEDDI在材料识别和安全扫描中的应用TEDDI方法使用散射（不是直接传输的）x射线，其中包含样品中每个点的晶体结构信息。TEDDI使用多个平行准直器来获得其空间分辨率，并且样品不需要像标准层析成像那样旋转。我们将制作一个基于实验室的TEDDI系统，在1x10- 3mm3的空间尺度上识别复杂样品的每个部分的特定材料。我们还将与我们的合作伙伴Kromek有限公司合作，该公司最初是从杜伦大学物理系分离出来的。他们正在开发用于机场威胁识别的扫描仪。我们将与HEXITEC探测器共同开发TEDDI技术，根据材料的相干散射信号识别材料。这是一个比单纯依靠吸收性信息可靠得多的测试。结合现有的方法，可以显著降低误报率。工作包3：组织活检许多软组织类型有非常相似的衍射模式，特别是那些高含水量的软组织，然而，某些类型的乳腺癌已经被证明很容易通过能量色散衍射方法与正常组织区分开来。我们打算与皇家萨里医院和马斯登医院联合开发一种x射线组织活检方法。通过使用HEXITEC检测系统，我们将获得关于特定组织类型的独特信息，这将大大减少假阳性的数量。这是一个至关重要的目标，因为错误的诊断会给病人带来大量不必要的不适和痛苦。

X-ray colour imaging has the potential to visualise the physical and chemical nature of a specimen spatially resolved within a three dimensional density contrast image. X-ray colour imaging makes it possible to recognise, for example, whether complex manufactured components used in the aerospace industry are likely to fail through cracks or fatigue stress; or whether a suitcase contains illicit substances such as semtex or cocaine; or whether a biopsy sample contains normal or abnormal tissue. A full X-ray colour imaging system requires energy sensitive detectors that are divided into small discrete pixels and can stop high energy X-rays. In addition the scattered radiation from the sample often has to be very finely collimated because we are looking for very weak signals. Five years ago neither suitable detector material nor scatter control systems were available. The latter problem was addressed (by another EPSRC grant) but there was no reliable source of detector material anywhere in the world. The lack of technological expertise within the UK to produce suitable detector systems led to the formation of the HEXITEC consortium (High Energy X-ray Imaging Technology; www.hexitec.co.uk). HEXITEC has developed every stage of detector system manufacture and has very recently demonstrated its first 20 by 20 pixel prototype as a forerunner of a full 80 by 80 device that will be delivered early in 2010. We are now requesting funds to take the HEXITEC developed technology to the next stage of development in three work programmes covering four broad applications at different stages of development. Work package 1: Fluorescence tomography for materials imaging We will use the 80 by 80 pixel detector systems developed by HEXITEC for both purposes. Fluorescence tomography is based on a standard absorptive method where the sample is rotated in the beam and many sections are mathematically recombined to give a 3D image. The crucial difference here is that we will be able to do this in discreet energy ranges. We will obtain slices that can be energy selected in 800eV ranges or better. We will deliver a lab based system to produce element specific images. Work package 2: The appliaction of TEDDI to materails identificatication and security scanningThe TEDDI method uses scattered (not directly transmitted) X-rays which contain information on the crystal structure at each point within the sample. TEDDI uses multiple parallel collimators to obtain its spatial resolution and the sample does not need to be rotated in the same way as standard tomography. We will make a lab based TEDDI system to identify specific materials at each part of a complex sample on a 1x10-3 mm3 spatial scale. We will also work with our partners Kromek ltd who originally spun out of the Durham University Physics Department. They are developing scanners for threat identification at airports. We will jointly develop the TEDDI technology with HEXITEC detectors to recognise materials based on their coherent scattered signals. This is a much more reliable test than relying on purely absorptive information. In conjunction with existing methods the false alarm rate can be significantly reduced. Work package 3: Tissue BiopsyMany soft tissue types have very similar diffraction patterns especially those with a high water content, however certain types of breast cancers have been shown to be quite easily distinguishable from normal tissue by energy dispersive diffraction methods. We intend to develop, jointly with the Royal Surry and Marsden hospitals, an X-ray tissue biopsy modality. By using HEXITEC detector systems we will obtain unique information about specific tissue types that will significantly reduce the number of false positives. This is a vital aim because a false diagnosis leads to great deal of unnecessary discomfort and distress to the patient.