Workman A, Cowen A R
Leeds General Infirmary, UK.
Br J Radiol. 1995 Feb;68(806):182-8. doi: 10.1259/0007-1285-68-806-182.
A method of improving image quality in computed radiography (CR) using dual plate exposure has been developed. Two CR image plates are used to increase the fraction of X-ray quanta absorbed from the beam. Spatial registration and combination of images from the two plates leads to an image with improved signal-to-noise ratio characteristics. A cross correlation technique is used to register spatially the images from the front and rear plates. The modulation transfer function and noise power spectrum were measured for the single plate and combined dual plate images. Results indicate a potential increase of approximately 60% in the detective quantum efficiency (DQE) of the dual plate combined image compared with the single plate image. The improvement of DQE at high spatial frequencies is dependent on the accuracy of the registration of the two images. The actual improvement in imaging performance was measured using a contrast detail test piece. A computerized method was used to measure the imaged detail signal-to-noise ratio of the details of different dimension. Results indicate an improvement of 21% in the signal-to-noise ratio of the details imaged with the dual plate arrangement compared with the single plate. This indicates that this technique can result in a significant increase in image quality for the same exposure level. Alternatively this technique could allow reduction in exposure while maintaining the same image quality achievable with the single plate system.
已经开发出一种使用双板曝光来提高计算机放射成像（CR）图像质量的方法。使用两块CR成像板来增加从光束中吸收的X射线量子的比例。对来自两块板的图像进行空间配准和组合，得到具有改善的信噪比特性的图像。采用互相关技术对前后板的图像进行空间配准。测量了单板图像和组合双板图像的调制传递函数和噪声功率谱。结果表明，与单板图像相比，双板组合图像的探测量子效率（DQE）可能提高约60%。高空间频率下DQE的提高取决于两幅图像配准的精度。使用对比细节测试件测量成像性能的实际改善情况。采用计算机化方法测量不同尺寸细节的成像细节信噪比。结果表明，与单板相比，双板布置成像的细节信噪比提高了21%。这表明该技术在相同曝光水平下可显著提高图像质量。或者，该技术可以在保持单板系统可实现的相同图像质量的同时减少曝光量。
