Bachman D M, Ellis K, Austin J H
Radiol Clin North Am. 1978 Dec;16(3):465-85.
Minor degrees of obliquity affect the appearance of the lateral chest radiograph. For 100 normal subjects we compared findings on three left lateral projections: the "straight lateral", rotation of the subject's right side 10 degrees anterior ("right anterior"), and rotation of the patient's right side 10 degrees posterior ("right posterior"). A number of structures appeared generally best seen in the "right anterior" lateral projection, less well seen in the "straight posterior" lateral projection and least well seen in "right posterior" lateral projection. These structures were the epicardial fat stripe and pericardial line, the anterior margin of the ascending aorta, the hilar vessels, the origins of the upper lobe bronchi, and the posterior wall of the bronchus intermedius. The heart appeared largest in the "right anterior" lateral view, while in the "right posterior" lateral view it appeared smallest (whether assessed subjectively or by measurement of posterior left ventricular overlap of the inferior vena cava). Similarly, the hilar vascular shadows and major bronchi were most prominent when rotated apart in the "right anterior" projection and least prominent when more nearly superimposed in the "right posterior" projection. Slight rotation showed no significant effect on the anteroposterior diameter of the trachea, the width of the left pulmonary artery, or the diameters of the upper lobe bronchi. The azygos vein and a well visualized posterior tracheal band were seen in a few patients. They tended to be best and most frequently seen in the "right posterior" lateral view. Either obliquity tended to improve delimeation of the anterior pleural margins and the costophrenic angles. This was also true for the interlobar fissures, but confusing superimposition shadows were less likely in the "right anterior" than the "right posterior" lateral radiograph.
轻度倾斜会影响胸部侧位X线片的影像。我们对100名正常受试者的三种左侧位投照结果进行了比较：“正侧位”、受试者右侧向前旋转10度（“右前位”）以及患者右侧向后旋转10度（“右后位”）。一些结构通常在“右前位”侧位投照中显示最佳，在“正后位”侧位投照中显示较差，而在“右后位”侧位投照中显示最差。这些结构包括心外膜脂肪条纹和心包线、升主动脉前缘、肺门血管、上叶支气管起始部以及中间支气管后壁。心脏在“右前位”侧位视图中看起来最大，而在“右后位”侧位视图中看起来最小（无论是主观评估还是通过测量下腔静脉左心室后壁重叠情况）。同样，肺门血管阴影和主要支气管在“右前位”投照中旋转分开时最突出，而在“右后位”投照中更接近重叠时最不突出。轻微旋转对气管的前后径、左肺动脉宽度或上叶支气管直径没有显著影响。少数患者可见奇静脉和清晰显示的气管后带。它们往往在“右后位”侧位视图中显示最佳且最常见。任何一种倾斜都倾向于改善前胸壁胸膜边缘和肋膈角的显示。叶间裂也是如此，但“右前位”侧位X线片比“右后位”侧位X线片出现混淆性重叠阴影的可能性更小。
