What are X-ray tests for cancer?

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The use of a machine to produce radiation that is passed through a particular body part to show its size and density.
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Cancers diagnosed: Medical imaging using X rays is designed to help diagnose cancers, metastases, diseases, fractures, or abnormalities. These diagnostic tests are not to be confused with radiation therapy, which is used to destroy cancers. Most cancers can be seen with the use of radiographic imaging; however, all cancers vary widely in their visibility. Some cancers hide until late in the disease process and then metastasize (grow and spread) quickly.

X-ray tests help diagnose bone cancers, bone marrow cancers, soft-tissue cancers, cancers of vital organs, blood-related cancers, lung cancers, lymph node and lymphoma cancers, spinal cord cancers, abdominal and pelvic cancers, head and neck cancers, liver and gallbladder cancers, reproductive organ cancers, breast cancers, leukemia, esophageal and colon cancers, Hodgkin and non-Hodgkin diseases, advanced skin cancers, brain cancers, and metastases.

Why performed: Diagnostic X rays are used to identify fractures, pneumonias, cancers, sinus infections, bowel obstructions, foreign objects, and anatomical abnormalities, or to confirm that there are no abnormalities. CT, MRI, nuclear medicine scans, and angiography are extremely helpful in locating diseases and cancers that are hard to find. Clinical observation and laboratory tests, combined with X-ray imaging, give the physician a more complete view of the extent of a particular disease. The combination of all tests and exams helps the doctor form a treatment plan for the patient. Any of these imaging devices may also be used to assist with guiding a biopsy, in needle placement, or to verify the location of wires and instruments during surgical procedures.

Patient preparation: Because there is such a wide variety of exams and a vast range of reasons for a radiology exam, it is best for the patient to consult with the medical doctor or discuss the preparation with the technologist three days prior to the exam. Some of the tests are routine, involving no preparation. Others may require eating or drinking restrictions, an increase in the amount of fluids in the bladder, or ingestion of contrast preparations for enhanced viewing in certain areas.

Steps of the procedure: The patient should tell the X-ray technician if there is any chance of pregnancy. If pregnancy is not a factor, then the patient is positioned between the X-ray tube and the radiographic film. Depending on the procedure and part being radiographed, the patient may be sitting, standing, or lying on a table for the exam. A lead shield (radiation protection device) is placed on the area surrounding, but not on, the region to be radiographed. Technique is set according to the size and density of the part. The length of time for procedures varies from five minutes to two hours depending on the test. Often, several images using different angles are needed. Some X-ray exams require the use of a contrast medium (dye). It may be taken orally or injected into the patient prior to or during the imaging process. Contrast materials are used when specific parts need to be enhanced or defined on film.

Contrast materials include barium sulfate (for upper GI and colon studies), iodine-based media (for IVP, CT, and angiography), gadolinium (for MRI), radioactive pharmaceutical materials and radioactive isotopes (for nuclear medicine scans), and xenon gas (for lung scans).

After the procedure: A radiologist will view the X-ray images and document the findings. The report will be given to the patient’s doctor. At a follow-up appointment, the results will be discussed. If the imaging used a contrast material, then it is often suggested that the patient drink plenty of fluids to flush the contrast from the body. Over the next several days, the contrast will be eliminated through the body’s waste products. Depending on the type of contrast and amount used, an unpleasant taste can linger in the mouth for a few weeks.

Risks: The physician will evaluate the patient’s medical situation and determine if the diagnosis and treatment from the radiographic knowledge outweigh the potential risk from the X rays. If the patient is pregnant, then the procedure may be canceled or rescheduled or the patient may be double-shielded to protect the fetus. With the use of high-speed film, fast and accurate imaging equipment, collimation, and lead shielding, radiation is kept to a minimum for the patient. Diagnostic X-ray procedures carry no obvious short-term effects; however, any amount of radiation has the potential to harm cell structure. High doses of radiation that produce ill effects are seen in radiotherapy for cancer treatments. Long-term or high-dose effects of radiation can cause fetal or genetic defects, mutations or cancers, nausea, diarrhea, vomiting, or death.

In addition to medical and dental X rays, the general population is exposed to background radiation that increases their total body exposure when they live in a brick house, walk by a brick building, fly in an airplane, smoke or breathe secondhand smoke, live at higher elevation levels, heat their home with natural gas, breathe air pollution, work with natural elements or radiation in their profession, watch television, and work or play on a computer. One can calculate the radiation dose from many potential sources at http://www.epa.gov/radiation/understand/calculate.html.

Other risks of X rays include claustrophobia in CT or MRI scanners and allergic reactions to contrast materials. Allergic reactions can include rash, itching, hives, nausea, vomiting, coma, or death.

Results: The radiographic image is developed and viewed by the radiology technician, who gives the film to the physician or radiologist. Depending on the procedure, the patient may receive a preliminary diagnosis or may have to wait until the final report from the radiologist, which may be several days later. The patient’s current health status and extent of disease help determine a treatment plan.

Bibliography

Frank, Eugene D., Bruce W. Long, and Barbara J. Smith. Merrill’s Atlas of Radiographic Positioning and Procedures. 11th ed. St. Louis: Mosby-Elsevier, 2007. Print.

Goldmann, David R., and David A. Horowitz, eds. American College of Physicians Complete Home Medical Guide. Rev. ed. New York: DK, 2003. Print.

Haidekker, Mark A. Medical Imaging Technology. New York: Springer, 2013. Print.

Linet, Martha S., et al. "Cancer Risks Associated with External Radiation from Diagnostic Imaging Procedures." CA: Cancer Journal for Clinicians 62.2 (2012): 75–100. Print.

Nambiar, Shruti, Ernest K. Osei, and John T. W. Yeow. "Polymer Nanocomposite-Based Shielding against Diagnostic X-rays." Journal of Applied Polymer Science 127.6 (2013): 4939–46. Print.

Putman, Charles E., and Carl E. Ravin. Textbook of Diagnostic Imaging. 2nd ed. Philadelphia: Saunders, 1994. Print.