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XRay Imaging
Radiography, known to most people as x-ray, is the oldest and most frequently used form of medical imaging. For nearly a century, diagnostic images have been created by passing small, highly controlled amounts of radiation through the human body, capturing the resulting shadows and reflections on a photographic plate. X-ray imaging is the fastest and easiest way for a physician to view and assess broken bones, cracked skulls and injured backbones. At least two films are taken of a bone, and often three films if the problem is around a joint (knee, elbow, or wrist). X-rays also play a key role in orthopedic surgery and the treatment of sports injuries. X-ray is useful in detecting more advanced forms of cancer in bones. Very early cancer findings require other methods. Radiologists have developed alternative imaging methods that do not rely on radiation, such as ultrasound and magnetic resonance imaging (MRI). However, because x-ray was the first imaging modality, many people (and medical imaging professionals) continue to use the term "radiology" to include all types of imaging. Strictly speaking, though, radiology refers to the use of x-rays. What are some common uses of the procedure?Probably the most common use of bone radiographs is to assist the physician in identifying and treating fractures. X-ray images of the skull, spine, joints, and extremities are performed every minute of every day in hospital emergency rooms, sports medicine centers, orthopedic clinics, and physician offices. Images of the injury can show even very fine hairline fractures or chips, while images produced after treatment ensure that a fracture has been properly aligned and stabilized for healing. Bone x-rays are an essential tool in orthopedic surgery, such as spinal repair, joint replacements, or fracture reductions. X-ray images can be used to diagnose and monitor the progression of degenerative diseases such as arthritis. They also play an important role in the detection and diagnosis of cancer, although usually computed tomography (CT) or MRI is better at defining the extent and the nature of a suspected cancer. On regular x-rays severe osteoporosis is visible, but bone density determination detects early loss of bone density. Bone density determination is usually done on special equipment. How should I prepare for the procedure?There is no special preparation required for most bone radiographs. Once you arrive, you may be asked to change into a gown before your examination. You will also be asked to remove jewelry, eyeglasses, and any metal objects that could obscure the images, since those show up on x-rays and may block the bones. Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant. What does the equipment look like?Radiography equipment consists of a large, flat table with a drawer that holds an x-ray film cassette into which a film is placed. Suspended above the table is an apparatus that holds the x-ray tube which can be moved over the body to direct the x-ray. How does the procedure work?Radiography involves exposing a part of the body to a small dose of radiation to produce an image of the internal organs. When x-rays penetrate the body, they are absorbed in varying amounts by different part of the anatomy. Ribs, for example, will absorb much of the radiation and, therefore, appear white or light gray on the image. Soft tissue such as the liver or lungs will appear darker because it absorbs less radiation. Broken bones or malignancies in the bone can usually be detected with radiography. The images may be placed on film or may be stored electronically on PACS (picture archiving and communication systems). Films are usually stored in a film jacket in the radiology department or in the doctor's office for approximately seven years (unless the patient is a child, then until age 21). Images may be digitally acquired or may be digitized from analog images and can be stored on PACS. How is the procedure performed?The technologist positions the patient on the examination table, places a flat holder (cassette) under the table in the area of the body to be imaged. Sandbags or pillows may help the patient hold the proper position. Then the technologist goes to a small adjacent room and asks the patient to hold very still without breathing for a few seconds. The radiographic equipment is activated, sending a beam of x-rays through the body to expose the film. The technologist then repositions the patient for another view, and the process is repeated. When the x-rays are completed you will be asked to wait until the technologist checks the images for adequate exposure and motion. What will I experience during the procedure?In most cases, x-ray imaging is painless and the only discomfort results from the coldness of the plate. Sometimes, to get a clear image of an injury such as a possible fracture, you may be asked to hold an uncomfortable position for a short time. Any movement could blur the image and make it necessary to repeat the procedure to get a useful, clear picture. Who interprets the results and how do I get them?A radiologist, who is a physician experienced in bone x-ray and other radiology examinations, will analyze the images and send a signed report with his or her interpretation to your primary care or referring physician, who will inform you on your test results. New technology also allows for distribution of diagnostic reports and referral images over the Internet at many facilities. What are the benefits vs. risks?Benefits
Risks
Radiation risks are further minimized by:
What are the limitations of Bone Radiography?While x-ray images are among the clearest, most detailed views of bone, they may not provide equally revealing information about involved soft tissues. In the case of a knee or shoulder injury, for example, an MRI may be more useful in identifying ligament tears, joint effusions or other problems. Even in the evaluation of traumatic injury to the bone not severe enough to cause a visible crack, MRI may detect a so-called bone bruise. Other imaging modalities, such as positron emission tomography (PET), bone scans or CT, may be more effective in diagnosing bony metastases or primary bone tumors. MR in any spine injury or suspected metastases is especially useful because the bones and the spinal cord can be evaluated. Ultrasound using sound waves instead of ionizing radiation has also been useful in injuries around joints and in evaluating hips for congenital hip dysplasia. |
