An alternate line erasure and readout (ALER) method for implementing slot-scan imaging technique with a flat-panel detector - Initial experiences
An alternate line erasure and readout (ALER) method for implementing slot-scan imaging technique with a flat-panel detector - Initial experiences
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DOI：
10.1109/tmi.2006.870896
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发表时间：
2006-04-01
影响因子：
10.6
通讯作者：
Wang, TP
中科院分区：
文献类型：
--
作者：
Liu, XM;Shaw, CC;Wang, TP
本文描述并演示了一种电子准直方法，称为交替行擦除和读出（ALER）技术，用于使用基于非晶硅（a-Si）薄膜晶体管（TFT）阵列的平板探测器实现槽扫描数字射线照相技术。对无定形硒 (a-Se) 平板探测器进行了改造，以实施用于狭缝扫描成像的 ALER 技术。步进电机驱动的前准直器安装在 X 射线管前面，以产生扫描 X 射线扇形束。调整扫描速度和放大倍数以使扇形光束运动与图像行读出速率同步。扇形光束前缘和后缘上的图像线分别被跟踪并交替重置和读出。前一操作导致在扇形光束到达之前擦除在前缘图像线中累积的散射信号。后一操作导致在扇形光束通过后立即采集集成在后缘图像线中的扇形光束曝光数据。为了证明该技术的散射抑制能力，将拟人化胸部模型放置在 PA 位置，并在 117 kVp 和 32 mA 下以 576 线 (8.0 cm)/s 的速度进行扫描。将钨棒放置在胸部模型的入口侧，以测量散射与主要比率 (SPR)、散射减少因子 (SRF) 和对比度噪声比退化。槽扫描图像中的因子（CNRDF）来评估散射抑制的有效性以及由此产生的图像质量的改进。还测量了开场图像中的SPR和CNRDF并用作比较的参考。通过狭缝扫描成像观察到，下肺和心脏区域的散射减少了 86.4% 至 95.4%。研究发现纵隔区域的 CNR 也比开放视野图像提高了 2 倍。
This paper describes and demonstrates an electronic collimation method, referred to as the alternate line erasure and readout (ALER) technique, for implementing slot-scan digital radiography technique with an amorphous silicon (a-Si) thin-film transistor (TFT) array based flat-panel detector. An amorphus selenium (a-Se) flat-panel detector was modified to implement the ALER technique for slot-scan imaging. A stepping-motor driven fore-collimator was mounted in front of an X-ray tube to generate a scanning X-ray fan beam. The scanning speed and magnification were adjusted to synchronize the fan beam motion with the image line readout rate. The image lines on the leading and trailing edges of the fan beam were tracked and alternately reset and read out, respectively. The former operation resulted in the erasure of the scatter signals accumulated in the leading edge image line prior to the arrival of the fan beam. The latter operation resulted in the acquisition of fan beam exposure data integrated in the trailing edge image line right after the fan beam passed. To demonstrate the scatter rejection capability of this technique, an anthropomorphic chest phantom was placed in PA position and scanned at a speed of 576 lines (8.0 cm)/s at 117 kVp and 32 mA. A tungsten bar is placed at the entrance side of the chest phantom to measure the scatter-to-primary ratio (SPR), scatter reduction factor (SRF), and contrast-to-noise ratio degradation. factor (CNRDF) in the slot-scan images to evaluate the effectiveness of scatter rejection and the resultant improvement of image quality. SPR and CNRDF in the open-field images were also measured and used as the reference for comparison. A scatter reduction by 86.4 to 95.4% across lower lung and heart regions has been observed with slot-scan imaging. The CNRs have been found to be improved by a factor of 2 in the mediastinum areas over the open-field image as well.