Before interpreting a chest X-ray it is important to assess the quality of the image. Without this step you may diagnose disease that is not genuine or you may be wrongly reassured.
This tutorial covers the principles of chest X-ray quality and discusses the limitations of sub-optimal images. Anatomical inclusion, projection, rotation, inspiration/lung volume, penetration and artifact all contribute to image quality. Each are discussed in turn.
If the image is not of best quality but the clinical question can still be answered, a chest X-ray need not be repeated. If you are not sure if a repeat image will be of use then discuss the case with a radiographer or radiologist.
Do not discard a chest X-ray because it is not perfect. Even sub-optimal images demonstrate life-threatening abnormalities, which may require your immediate attention.