在给胸内有疾患的病人复查时,欲确定病变的好转或进展,常用胸部透视与胸片进行初步比较。当病灶变化显著时容易判断;病灶变化较小时就不那么容易了。判断时一般主要是根据病灶范围的增大或缩小来决定。同时病灶密度的高低,形态的改变,如溶解或边缘的变化等也是参考依据,但通常更多的还是以范围的增大或缩小来确定。由于摄片时X线球管与身体距离较透视时为远,所以,成像较透视像为小,显然用 In the intrathoracic patients with disease review, to determine the improvement or progression of the lesion, chest radiography and chest radiographs were used for a preliminary comparison. It is easy to judge when the lesion changes significantly; when the lesion is small, it is not so easy. Judgment is generally based mainly on the scope of the lesion to increase or decrease to decide. At the same time the level of lesion density, morphological changes, such as dissolution or changes in the edge is also a reference, but usually more or to determine the scope of the increase or decrease. Since the X-ray tube when the film is far from the perspective of body distance, so the imaging is relatively small perspective, apparently with