Gröndahl K, Gröndahl H G, Webber R L
J Clin Periodontol. 1984 Jul;11(6):411-20. doi: 10.1111/j.1600-051x.1984.tb01339.x.
The influence of differences in imaging geometry on the detection of small periodontal bone lesions was studied when using a digital subtraction technique. The results were compared with those from conventional radiographs. Reference radiographs were obtained on human mandibular jaws before small lesions were made in the marginal alveolar bone. Subsequent radiographs were taken with the same imaging projection as well as with changes of the angulation in either vertical, or horizontal direction, or both. 10 dentists served as observers, who compared the conventional radiographs taken before and after the lesions were made, and registered the presence or absence of lesions using a diagnostic rating scale. The conventional radiographs were digitized, and subtraction images made. These images were interpreted by the same observers. For each observer, image modality and projection, the resulting rates of true positive and false positive diagnoses were plotted on a graph. The area under the curve, obtained by connecting the paired values of true positive and false positive results associated with the different diagnostic ratings, was used as a measure of diagnostic accuracy. Statistically significant differences could be demonstrated between the results obtained from the subtraction images, whether produced from identical or non-identical pairs of conventional radiographs, and the results from the conventional radiographs obtained under ideal conditions.
在使用数字减影技术时，研究了成像几何差异对小牙周骨病变检测的影响。将结果与传统X线片的结果进行比较。在边缘牙槽骨制造小病变之前，先获取人类下颌骨的参考X线片。随后，采用相同的成像投影以及在垂直或水平方向或两者方向上改变角度拍摄X线片。10名牙医作为观察者，比较病变制造前后拍摄的传统X线片，并使用诊断评分量表记录病变的有无。将传统X线片数字化并制作减影图像。这些图像由相同的观察者进行解读。对于每个观察者、图像模态和投影，将得到的真阳性和假阳性诊断率绘制在图表上。通过连接与不同诊断评分相关的真阳性和假阳性结果的配对值获得的曲线下面积，用作诊断准确性的度量。无论是从相同还是不同的传统X线片对产生的减影图像结果，与在理想条件下获得的传统X线片结果之间，都能证明存在统计学上的显著差异。
