Scanning-slit photon counting x-ray imaging system using a microchannel plate detector.
Scanning-slit photon counting x-ray imaging system using a microchannel plate detector.
复制标题
使用微通道板探测器的扫描狭缝光子计数 X 射线成像系统。
DOI：
10.1118/1.1695651
复制
发表时间：
2004
期刊：
影响因子：
3.8
通讯作者：
Molloi,Sabee
中科院分区：
文献类型：
--
作者：
Shikhaliev,PoladM;Xu,Tong;Le,Huy;Molloi,Sabee
评价了一种新型光子计数x射线成像系统的实验样机。该系统基于“边缘上”微通道板（MCP）探测器，并利用扫描狭缝成像配置。该探测器具有光子计数、直接转换、高空间分辨率、可控物理电荷放大、量子限制和无散射等功能。探测器提供60毫米宽视场（FOV），其计数率为整个FOV 200 kHz。当前系统的计数率受到位置编码电子器件的限制，该系统对来自整个检测器的所有事件具有单一输入，并包含一个转换时间为1 μs的单通道ADC。研究表明，使用多通道专用集成电路（ASIC）电子技术和多缝图像采集几何结构，计数率可以潜在地提高到临床可接受的水平。对于本研究中使用的典型采集时间，测量的图像噪声小于医学x射线成像的典型可接受噪声水平。预计在ASIC电子器件实施后，噪声水平也将很低。在50-90 kVp的能量范围内，探测器的量子效率为40%-56%，使用优化参数的mcp可以提高探测器的量子效率。在50 kVp的x射线管电压下获得了分辨率和拟人化的图像。在5 lp/mm的空间频率下，探测器的对比度传递函数值为0.5。该系统的固有空间分辨率为28 μm FWHM，受位置编码电子器件时-数转换精度的限制。考虑到边缘上MCP检测器的优点，如直接转换和物理电荷放大，它可以潜在地应用于乳房x线摄影和胸部x线摄影。
An experimental prototype of a novel photon counting x‐ray imaging system was evaluated. This system is based on an “edge‐on” microchannel plate (MCP) detector and utilizes scanning slit imaging configuration. The detector is capable of photon counting, direct conversion, high spatial resolution, controllable physical charge amplification, quantum limited and scatter free operation. The detector provides a 60 mm wide field of view (FOV) and its count rate is 200 kHz for the entire FOV. The count rate of the current system is limited by the position encoding electronics, which has a single input for all events from the entire detector, and incorporates a single channel ADC with 1 μs conversion time. It is shown that the count rate can potentially be improved to clinically acceptable levels using multichannel application specific integrated circuit (ASIC) electronics and multi‐slit image acquisition geometry. For a typical acquisition time used in this study, the image noise was measured to be less than the typically acceptable noise level for medical x‐ray imaging. It is anticipated that the noise level will be also low after the implementation of the ASIC electronics. The quantum efficiency of the detector was measured to be 40%–56% for an energy range of 50–90 kVp for MCPs used in this study and can be improved to using MCPs with the optimized parameters. Images of resolution and anthropomorphic phantoms were acquired at an x‐ray tube voltage of 50 kVp. The value of contrast transfer function for the detector was measured to be 0.5 at a spatial frequency of 5 lp/mm. The intrinsic spatial resolution of the system is 28 μm FWHM and was limited by the accuracy of the time‐to‐digital conversion of the position encoding electronics. Given the advantages of the edge‐on MCP detector such as direct conversion and physical charge amplification, it can potentially be applied to mammography and chest radiography.