14/12/2022
Source: https://www.auntminnie.com/index.aspx?sec=ser&sub=def&pag=dis&ItemID=52189
NCBI and Google
Evaluation criteria for a good lateral chest projection
All of the lung fields, from apices to the costophrenic angles, should be fully visualized.
The arms should not be superimposed over portions of the lung fields.
Sharp radiographic outline -- the outline of the diaphragm and lung markings --should be sharp. This can be accomplished by ensuring no motion or breathing is taking place at the time of exposure.
No rotation (true lateral projection). The ribs should be superimposed posterior to the vertebral column without any separation of the right and left posterior ribs and both costophrenic angles. However, in broad-shouldered patients, separation of the posterior ribs by 1 cm, because of the divergence of the x-ray beam, is unavoidable. Moreover, the lateral aspect of the sternum forms the anterior border, and no ribs should be projecting in front of the sternum.
No tilt -- thoracic intervertebral spaces and intervertebral foramina should be open, except in patients with thoracic deformities. Tilt, if present, may be evident of closed disk spaces of the thoracic vertebra.
Hilum should be approximately in the center of the radiograph.
NORMAL LANDMARKS
The fissures are important landmarks on a lateral CXR, becoming visible when the X-ray beam passes parallel to them. The oblique fissure begins posteriorly at T4/5 level, passing through the hilum. The left is steeper and finishes 5 cm behind the costophrenic angle whereas the right ends just behind the angle. The horizontal fissure runs anteriorly from the hilum separating the right upper lobe from the middle lobe. On the left there is no horizontal fissure.
Both hemidiaphragms should be visible, silhouetted by the lung air against the fluid-density of the abdominal contents. The anterior end of the left hemidiaphragm may be lost against the heart. The diaphragms can be distinguished from each other if there is clearly gastric air under one, or if one can be seen to be inserted into the magnified ribs further from the X-ray plate.
Vertebral bodies become darker as they proceed caudally (Figure 1) until they reach the diaphragm—because there is more soft tissue and less lung tissue at the apex but more lung tissue and less soft tissue at the bases.
The retrocardiac and retrosternal spaces are normally seen as dark areas about equal in size and lucency.
