Plain film
From Medical-Wiki
Neuroradiology has many applications in modern medicine’s diagnostic purposes and in directing medical treatment. The plain film has been of key significance since its invention in 1895 by Wilhelm Conrad Röntgen, playing a role in the evaluation of the central nervous system. Its uses include, but are not limited to, imaging of the brain, neck, and spine.
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Plain Film Physics
Plain films, or X-rays, are electromagnetic waves that are passed through the body and give the physician an image of the internal structures. As these waves traverse through the body, the density of the structures is detected. A denser structure, such as bone, will appear as white on the x-ray film. Less dense structures, including skin, muscles, blood vessels, and intestines appear darker. Oftentimes, a contrast medium is given internally, either through drinking or by injection, to better visualize the organs. [1]
Examples of contrast mediums include barium, which is used mainly for the Gastrointestinal system, or iodine.
Plain Film General Uses
Plain films have established their uses in many disease processes, but is most useful in detection of skeletal or bony abnormalities. It can also be used in identifying pulmonary pathologies including pneumonia, pulmonary edema, and lung cancer. In addition, kidney stones and, sometimes, gallbladder stones show up on x-ray. CNS indications are illustrated below.
Understanding Plain Film in Trauma
Plain films were very important in the diagnoses of head trauma before the advancements in CT and MRI. Negative findings on radiographs do not absolutely exclude injury- plain film radiographs are generally done if an emergency CT scan or MRI is not indicated.
Skull/Facial Trauma
Skull films should be interpreted by a radiologist because up to 10% of abnormalities are not detected by untrained eyes. Having no apparent fracture on x-ray does not rule out an incracranial hematoma. Fractures of the facial bones, such as the mandible or maxilla, are often less serious and are routinely checked by x-ray.[2]
Spinal Trauma
Radiological clearance of cervical spines can be done by plain films of CT-scan. Approximately 5-10% of patients who present to the Emergency Room with loss of consciousness as a result of a motor vehicle accident have a major injury to the cervical spine.
The most fatal cervical spine injuries occur at C1(atlas) or C2(axis). The axis contains the odontoid process which is further stablized by the transverse ligament.In addition to obtaining a lateral film of the entire C-spine, the “open mouth” view is sometimes indicated to assure that the odontoid process is intact. Odontoid fractures can be divided into three types:
Type 1- on the tip of the dens
Type 2- at the base
Type 3- with involvement of the body
Type 2 is the most common.
Paralysis may also occur from spinal trauma or other processes if the spinal cord is affected.Quadriplegia may occur if the injury is in the cervical region while paraplegia is common if the injury is in the lumbar or sacral area.
Other Skull and Spinal Plain Film Uses
The radiograph is sometimes used to detect the following abnormalities, with varying success rates:
•Tumors, including lytic bone lesions
•Erosion
•Decalcification of the bone
•Hydrocephalus
•Malocclusion of teeth
•Mastoiditis
•Meningitis
•Chronic Otitis media
•Otosclerosis
•Pituitary tumor
•Acute sinusitis
Plain Film Risks
Many patients fear the risks of radiation from radiographs and other imaging techniques. Due to the fact that x-rays are a form of radiation, the risk of overexposure can be harmful. Typically, however, patient exposure is minimal. Most physicians agree that the benefits often outweigh the risks.
References
[1]RadiologyInfo.Http://www.radiologyinfo.org/en/info.cfm?pg=bonerad&bhcp=1
[2]Mark Graber, MD. and Mary Kathol, MD. AAFP. Cervical Spine Radiographs in the Trauma Patient.Http://www.aafp.org/afp/990115ap/331.html
