Baruffaldi F, Angelini A L, Testi D, Mattioli P, Pierotti L
Istituti Ortopedici Rizzoli, Laboratorio di Tecnologia Medica, Bologna, Italy.
Med Inform Internet Med. 2001 Apr-Jun;26(2):101-14.
Until hospitals convert to 'filmless' radiology departments, computerized display and archival of x-ray images will necessitate devices to transform conventional X-ray films into digital images. Current methods for digitizing x-ray films include laser based and Charged Couple Device (CCD) based scanners. There is now much interest in the use of CCD devices for demanding applications, with the lower cost of ownership contributing towards the diffusion of CCD scanners. We report a study comparing the performance of three CCD based systems (an x-ray film digitizer, and two low cost flatbed scanners), looking at characteristic curve, useful optical range with respect the noise, repeatability, Modulation Transfer Function (MTF), and geometric distortion. In addition, we evaluated the potential and limitations of these devices in the clinical assessment of x-ray films. The most important weakness of CCD devices derived from the stability and the noise of CCD detectors, mostly affecting the useful optical range in the darker regions of x-ray films. Spatial resolution and geometric distortion were confirmed be the real points of strength of CCD technology. Therefore, the most appropriate system for each user depends on what type of clinical decision will be made following inspection of the digitised images.
在医院转变为“无胶片”放射科之前，X射线图像的计算机化显示和存档将需要将传统X射线胶片转换为数字图像的设备。当前数字化X射线胶片的方法包括基于激光和基于电荷耦合器件（CCD）的扫描仪。目前，人们对将CCD设备用于要求苛刻的应用兴趣浓厚，较低的拥有成本有助于推动CCD扫描仪的普及。我们报告了一项研究，比较了三种基于CCD的系统（一种X射线胶片数字化仪和两种低成本平板扫描仪）的性能，研究内容包括特性曲线、相对于噪声的有用光学范围、重复性、调制传递函数（MTF）和几何畸变。此外，我们评估了这些设备在X射线胶片临床评估中的潜力和局限性。CCD设备最重要的弱点源于CCD探测器的稳定性和噪声，这主要影响X射线胶片较暗区域的有用光学范围。空间分辨率和几何畸变被证实是CCD技术的真正优势所在。因此，每个用户最合适的系统取决于在检查数字化图像后将做出何种临床决策。
