A radiograph is an X-ray image obtained by placing a part of the patient in front of an X-ray detector and then illuminating it with a short X-ray pulse. Bones contain much calcium, which due to its relatively high atomic number absorbs x-rays efficiently. This reduces the amount of X-rays reaching the detector in the shadow of the bones, making them clearly visible on the radiograph. The lungs and trapped gas also show up clearly because of lower absorption compared to tissue, while differences between tissue types are harder to see.
Radiographs are useful in the detection of pathology of the skeletal system as well as for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer, or pulmonary edema, and the abdominal x-ray, which can detect bowel (or intestinal) obstruction, free air (from visceral perforations) and free fluid (in ascites). X-rays may also be used to detect pathology such as gallstones (which are rarely radiopaque) or kidney stones, which are often (but not always) visible. Traditional plain X-rays are less useful in the imaging of soft tissues such as the brain or muscle.
Your x-ray exam will consist of typically one to five images per body part being examined and usually only takes a few minutes. The area to be examined will be centered in front of or above the detectors used to detect the x-rays to form the image. You may be asked to turn in different directions or to hold your breath, depending on the type of exam being performed. It is very important that you do not reposition yourself during the process; the technologist will instruct you as to when moving is permissible. The x-ray itself is painless, although if obtaining the correct views puts strain on the body part to be imaged, there may be brief moments of discomfort. Your x-ray exam will be performed as quickly and painlessly as possible.
You may be asked to change clothes or remove your electronics and other objects from your pockets, depending on the body part to be examined. Zippers, snaps, cell phones, coins, etc., will “over-shadow” the area of interest if they are present, so removing those items is in your best interest for an accurate exam.