Pickford Scienti Oliver L P, Darambara Dimitra G
Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London SM2 5NG, UK.
Sensors (Basel). 2024 Jul 30;24(15):4946. doi: 10.3390/s24154946.
Effective X-ray photon-counting spectral imaging (x-CSI) detector design involves the optimisation of a wide range of parameters both regarding the sensor (e.g., material, thickness and pixel pitch) and electronics (e.g., signal-processing chain and count-triggering scheme). Our previous publications have looked at the role of pixel pitch, sensor thickness and a range of additive charge sharing correction algorithms (CSCAs), and in this work, we compare additive and subtractive CSCAs to identify the advantages and disadvantages. These CSCAs differ in their approach to dealing with charge sharing: additive approaches attempt to reconstruct the original event, whilst subtractive approaches discard the shared events. Each approach was simulated on data from a wide range of x-CSI detector designs (pixel pitches 100-600 µm, sensor thickness 1.5 mm) and X-ray fluxes (10-10 photons mm s), and their performance was characterised in terms of absolute detection efficiency (ADE), absolute photopeak efficiency (APE), relative coincidence counts (RCC) and binned spectral efficiency (BSE). Differences between the two approaches were explained mechanistically in terms of the CSCA's effect on both charge sharing and pule pileup. At low X-ray fluxes, the two approaches perform similarly, but at higher fluxes, they differ in complex ways. Generally, additive CSCAs perform better on absolute metrics (ADE and APE), and subtractive CSCAs perform better on relative metrics (RCC and BSE). Which approach to use will, thus, depend on the expected operating flux and whether dose efficiency or spectral efficiency is more important for the application in mind.
有效的X射线光子计数光谱成像（x-CSI）探测器设计涉及到对一系列参数进行优化，这些参数既涉及传感器（例如材料、厚度和像素间距），也涉及电子设备（例如信号处理链和计数触发方案）。我们之前的出版物研究了像素间距、传感器厚度以及一系列加法电荷共享校正算法（CSCA）的作用，在这项工作中，我们比较加法和减法CSCA，以确定其优缺点。这些CSCA在处理电荷共享的方法上有所不同：加法方法试图重建原始事件，而减法方法则舍弃共享事件。每种方法都在来自广泛的x-CSI探测器设计（像素间距100 - 600 µm，传感器厚度1.5 mm）和X射线通量（10 - 10光子·mm⁻²·s⁻¹）的数据上进行了模拟，并根据绝对探测效率（ADE）、绝对光峰效率（APE）、相对符合计数（RCC）和分箱光谱效率（BSE）对其性能进行了表征。从CSCA对电荷共享和脉冲堆积的影响方面，对这两种方法之间的差异进行了机理解释。在低X射线通量下，两种方法表现相似，但在较高通量下，它们以复杂的方式存在差异。一般来说，加法CSCA在绝对指标（ADE和APE）上表现更好，减法CSCA在相对指标（RCC和BSE）上表现更好。因此，使用哪种方法将取决于预期的工作通量以及剂量效率或光谱效率对于所考虑的应用来说哪个更重要。
