Department of Physics, University of Liverpool, Liverpool, United Kingdom.
The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom.
Biomed Phys Eng Express. 2021 Nov 18;8(1). doi: 10.1088/2057-1976/ac3880.
3D imaging modalities such as computed tomography and digital tomosynthesis typically scan the patient from different angles with a lengthy mechanical movement of a single x-ray tube. Therefore, millions of 3D scans per year require expensive mechanisms to support a heavy x-ray source and have to compensate for machine vibrations and patient movements. However, recent developments in cold-cathode field emission technology allow the creation of compact, stationary arrays of emitters. Adaptix Ltd has developed a novel, low-cost, square array of such emitters and demonstrated 3D digital tomosynthesis of human extremities and small animals. The use of cold-cathode field emitters also makes the system compact and lightweight. This paper presents Monte Carlo simulations of a concept upgrade of the Adaptix system from the current 60 kVp to 90 kVp and 120 kVp which are better suited for chest imaging. Between 90 kVp and 120 kVp, 3D image quality appears insensitive to voltage and at 90 kVp the photon yield is reduced by 40%-50% while effective dose declines by 14%. A square array of emitters can adequately illuminate a subject for tomosynthesis from a shorter source-to-image distance, thereby reducing the required input power, and offsetting the 28%-50% more input power that is required for operation at 90 kVp. This modelling suggests that lightweight, stationary cold-cathode x-ray source arrays could be used for chest tomosynthesis at a lower voltage, with less dose and without sacrificing image quality. This will reduce weight, size and cost, enabling 3D imaging to be brought to the bedside.
3D 成像方式，如计算机断层扫描和数字断层合成，通常需要通过单个 X 射线管的长机械运动从不同角度扫描患者。因此，每年需要进行数百万次 3D 扫描，这需要昂贵的机制来支撑重的 X 射线源，并补偿机器振动和患者运动。然而，最近的冷阴极场发射技术的发展允许创建紧凑的、固定的发射器阵列。Adaptix Ltd 已经开发出了一种新颖的、低成本的、正方形的此类发射器阵列，并演示了人体四肢和小动物的 3D 数字断层合成。冷阴极场发射器的使用也使系统变得紧凑和轻巧。本文提出了 Adaptix 系统从当前的 60 kVp 升级到 90 kVp 和 120 kVp 的概念的蒙特卡罗模拟，这更适合胸部成像。在 90 kVp 和 120 kVp 之间，3D 图像质量对电压不敏感，在 90 kVp 时，光子产额降低 40%-50%，而有效剂量降低 14%。发射器的正方形阵列可以从较短的源到图像距离充分照亮被检者，从而减少所需的输入功率，并抵消在 90 kVp 下运行所需的 28%-50%的更多输入功率。这种建模表明，轻型、固定的冷阴极 X 射线源阵列可以在较低的电压下用于胸部断层合成，剂量更小，而不会牺牲图像质量。这将降低重量、尺寸和成本，使 3D 成像能够带到床边。
