Optimization of low-dose, low cost mobile 3D X-ray Imaging

数字断层合成（DT）是X射线成像的3D模式。这种成像模式既可以从X射线图像中提取典型的2D信息，也可以提取被成像身体的深度信息。这通常是通过在设定的角度范围内改变X射线管的角度来实现的，其中在每个独特角度处创建的图像对应于成像身体的某个深度层[1]。这些图像可以使用重建算法[2]来重建，以创建与在2D X射线图像中看到的相比具有增强的感兴趣对象和背景之间的对比度的奇异图像。然而，用于医疗目的的传统DT成像机器需要高功率来操作，并且由于体积太大而无法携带，因此无法应用于床边成像。Adaptix Ltd [3]开发的便携式DT系统改变了这一点。该系统采用冷阴极平板X射线源（FPS）阵列。这些阵列由25个单独的发射器组成，它们依次发射，产生传统上由X射线管旋转产生的多个投影[4]。该设备已成功用于小动物和人类骨科成像。因此，已经证明了用于胸部成像目的的这种放大的概念验证[5]，并且目前正在积极研究这种潜在的低成本和便携式胸部DT成像方法的开发。该技术在非破坏性材料评估（NDE）和牙科环境中有额外的应用。该博士项目旨在利用Geant 4 [6]，一种蒙特-卡罗模拟软件，来解决这些设备进一步开发中出现的工程和科学问题。初步工作已经完成，以调查不同的X射线靶结构对X射线光谱产生的影响，从而对病人的剂量和输出的图像质量。正在进行的工作致力于通过实现一个现实的检测器来进一步开发这个模拟框架，以允许从这项工作中创建的图像与从物理设备本身输出的图像进行更密切的比较。这应该另外通知讨论的最佳检测器的建设，这种DT方法，并identifyhow最好参数化检测器的质量在这种情况下。未来的工作计划通过应用这个基准模拟环境来研究现代x射线方法，如双能量成像，以确定如何最好地适应这些新功能的设备。这将创建模拟数据，然后可以用设备本身进行实验验证。因此，该项目的叙述将反映一个准确的模拟环境内的Geant 4 softwarewhich可用于解决实际问题时提出的构建这种技术在一个morecost-和劳动力效率的方法比可以实现实验。与现有数据的比较将确保准确的基准测试，以证明模拟的可靠性，从而使其能够与实验工作相结合，为未来的发展提供信息。苏达卡尔？基奇卡Pipavath，and Gautham P. Reddy.胸部的数字断层合成：当前和新兴的应用。射线照相，34：359-372，3 2014。[2]Vadim Y Soloviev，Kate L Renforth，Conrad J Dirckx，and Stephen G威尔斯.医学生物学中的物理学数字断层合成的无网格重建技术。Phys.Med. Biol，65：85010，2020。[3]Adaptix Ltd，https://adaptix.com/。[4]托马斯普里米迪斯。超紧凑、高分辨率3D X射线成像系统的设计和优化。[5]托马斯G Primidis，Stephen G威尔斯，Vadim Y Soloviev，和Carsten P Welsch.使用固定平板源阵列和固定探测器的3D胸部断层合成：概念的蒙特卡罗证明。2021

Digital Tomosynthesis (DT) is a 3D mode of X-ray imaging. This imaging mode extracts both the typical2D information you would expect from an x-ray image, as well as depth information on the body beingimaged. This is conventionally achieved by altering the angle of an x-ray tube over a set angular range,where the image created at each unique angle corresponds to a certain layer of depth of the imaged body[1]. These images can be reconstructed using reconstruction algorithms [2] to create a singular imagewith enhanced contrast between the object of interest and background than is seen in 2D x-ray images.However, conventional DT imaging machines for medical purposes require high power to be operated, andare too large to be portable and hence have no application in bedside imaging.A portable DT system created by Adaptix Ltd [3] has changed this. This system has been designed andconstructed which uses cold-cathode, flat panel x-ray source (FPS) arrays. These arrays are constructed of25 individual emitters that emit sequentially, creating the multiple projections conventionally created bythe rotation of the x-ray tube [4]. This device has been successful for small animal and human orthopaedicimaging. Hence, proof-of-concept for the scaling up of this for chest imaging purposes has been shown [5]and active research is now underway for the development of this potential low-cost and portable methodof chest DT imaging. This technology sees additional application in non-destructive material evaluation(NDE) and dentistry contexts.This PhD project aims to utilise Geant4 [6], a Monte-Carlo simulation software, to address the engineeringand science questions that arise within the further development of these devices. Initial work has beencompleted to investigate the effect of different x-ray target constructions on the x-ray spectra producedand hence the dosage to the patient and the quality of the image outputted. Ongoing work endeavours todevelop this simulation framework further by implementing a realistic detector to allow closer comparisonof the images created from this work to those outputted from the physical device itself. This shouldadditionally inform a discussion on the optimal detector construction for this DT approach and identifyhow best to parameterise detector quality in this context. Future work is planned to follow on fromthis by applying this benchmarked simulation environment to look at modern x-ray approaches, suchas dual-energy imaging, to identify how best to adapt the device for these novel capabilities. This willcreate simulation data that can then be experimentally verified with the device itself. Hence, the projectnarrative will reflect the development of an accurate simulation environment within the Geant4 softwarewhich can be used to address practical questions raised when constructing this technology in a morecost- and labour-efficient method than can be achieved experimentally. Comparison with existing datawill ensure accurate benchmarking to prove the reliability of the simulation and hence allow it to informfuture developments in combination with experimental work.References[1] Shinn Huey Chou, Greg A. Kicska, Sudhakar N. Pipavath, and Gautham P. Reddy. Digital tomosynthesisof the chest: Current and emerging applications. Radiographics, 34:359-372, 3 2014.[2] Vadim Y Soloviev, Kate L Renforth, Conrad J Dirckx, and Stephen G Wells. Physics in medicinebiology physics in medicine biology meshless reconstruction technique for digital tomosynthesis. Phys.Med. Biol, 65:85010, 2020.[3] Adaptix Ltd, https://adaptix.com/.[4] Thomas Primidis. Design and optimisation of ultra-compact, high-resolution 3d x-ray imaging systems.2022.1[5] Thomas G Primidis, Stephen G Wells, Vadim Y Soloviev, and Carsten P Welsch. 3d chest tomosynthesisusing a stationary flatpanel source array and a stationary detector: a monte carlo proof ofconcept. 2021