his is part of a department where the “Chest X-ray”, a common term most people are familiar with, is done. The more appropriate term is a chest radiograph. Radiology evolved to its present state from this point. Plain radiographs are still the most common examination done in a radiology department and is usually the starting point for most subsequent radiological investigations. Although it may be considered as a relatively “old” technique, nevertheless it is an essential component in radiology. 

Images can either be captured on an X-ray film as “still” images or on special detectors to make “movies”. Images are produced when X-rays passing through the body falls on to the film or detector. The amount of radiation passing through the body depends on the type of tissue as well as thickness of the tissue. Bone, being denser than air, will absorb more X-rays and therefore will appear white on the film compared to air which will appear black since it absorbs little, if any, X-rays. However, the rest of the body e.g. muscles, liver, kidneys, heart as well as brain will all absorb about the same amount of X-rays due to the fact that they are of the same density. Therefore, they will appear to be having the same shade of grey and will be difficult to differentiate on radiographs. This limitation has been overcome by the use of “dye” (contrast medium) either by swallowing, injection or via the rectum (enema). 

Some of the common examinations that are done using contrast are: