X-ray imaging exams are recognized as a valuable medical tool for a wide variety of examinations and procedures. The discovery of X-rays and the invention of CT represented major advances in medicine. A CT exam involves a higher radiation dose than conventional radiography because the CT image is reconstructed from many individual X-ray projections. A computer reconstructs all the individual images into cross-sectional images or “slices” of internal organs and tissues. CT - many X-ray images are recorded as the detector moves around the patient's body.Fluoroscopy can result in relatively high radiation doses, especially for complex interventional procedures (such as placing stents or other devices inside the body) which require fluoroscopy be administered for a long period of time. Fluoroscopy - a continuous X-ray image is displayed on a monitor, allowing for real-time monitoring of a procedure or passage of a contrast agent (“dye”) through the body.Mammography is a special type of radiography to image the internal structures of breasts. Radiography - a single image is recorded for later evaluation.Ionizing radiation is a form of radiation that has enough energy to potentially cause damage to DNA and may elevate a person’s lifetime risk of developing cancer.ĬT, radiography, and fluoroscopy all work on the same basic principle: an X-ray beam is passed through the body where a portion of the X-rays are either absorbed or scattered by the internal structures, and the remaining X-ray pattern is transmitted to a detector (e.g., film or a computer screen) for recording or further processing by a computer. Computed tomography (CT), fluoroscopy, and radiography ("conventional X-ray" including mammography) all use ionizing radiation to generate images of the body. There are many types - or modalities - of medical imaging procedures, each of which uses different technologies and techniques. Medical imaging has led to improvements in the diagnosis and treatment of numerous medical conditions in children and adults. Medical device requirements for manufacturers of x-ray imaging devices.Electronic Product Radiation Control (EPRC) requirements for manufacturers and assemblers.Regulations and guidelines pertaining to imaging facilities and personnel.Information for the referring physician.Principles of radiation protection: justification and optimization.Questions to ask your health care provider.
Like the MRI scanners, various CTs have patient weight limits (which may vary from about 300 – 500 pounds) and/or limits on the size of the patient to fit through the scanner. In general, if you are pregnant you should not get a CT scan unless necessary however, you and your doctor have to decide whether the risks are worth the benefits of a CT scan. Pregnancy - MRI scans are not recommended during pregnancy, particularly in the first three months.Some MRI machines have weight limits and may vary from 300 to 500 pounds, and such patients need to fit into the scanner opening.
Implantable cardioverter-defibrillators.Artificial (prosthetic) metal heart valves.Talk to your doctor about your circumstance before the test.) (NOTE: not all of these things are definite contraindications for getting an MRI. The following list is examples of things that are not compatible with MRI scans, particularly metal implants, or fragments containing iron. If you are unsure about having any metal fragments in your body (war shrapnel or metalworking injuries), you may need an X-ray before your MRI. Some types of metal implants or orthopedic hardware are magnetic and are not compatible with an MRI, especially older types. Certain types of CT scans may not be appropriate during pregnancy. Moreover, other canisters that are metal (like some oxygen tanks) need to be kept away from MRI machines because they can be attracted to the magnet and injure or kill the patient.ĬT scans do not have these problems however, they do expose the patient to radiation, though it’s a relatively low dose. Any metal devices that can interact with a magnetic field, for example, the presence of metal shavings in an organ, the eye, or extremity may be pulled out by the magnetic field. MRI scans should not be done on patients that have aneurysm clips (clips of the vessels within the brain) unless these clips are known to be MRI safe, as these clips can be pulled off and the patient could die from bleeding into the brain.Īnother problem with the MRI is the presence of some cardiac pacemakers or defibrillators because the magnets can cause malfunctions in these battery-operated devices. In general, both CT and MRI scans are relatively safe.
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