Difference Between Radiographs & CT Scans

Radiographs versus CT scans

Radiographs (x-rays) and CT scans (computed tomography, or computed axial tomography, also called CAT scans) are two types of diagnostic radiology procedures that differ in radiation amounts, cost and availability. Radiographs are often used to examine broken bones, tumors and obstructions. A CT scan is a more advanced x-ray that produces a three-dimensional, cross-sectional image of organs, bones and tissues. It provides 1,000 times the clarity of an x-ray and is used to diagnose problems of the brain, abdomen and pelvis.

Radiographs (X-rays)

X-rays can show bones or organs.

According to the Medical Tests Sourcebook, radiographs use a small dose of radiation to produce an image of bones or organs. The patient stands next to (or lays on) a box containing the x-ray film, with an x-ray tube about 6 feet away. Different part of the anatomy absorb different amounts of radiation, appearing lighter or darker on the image. Radiologists and physicians then interpret the images for medical diagnoses.

CT scans

CT scans can produce 3D images.

CT scans involve the patient laying on a movable table which is passed through a large, doughnut-like x-ray machine, according to the "Patient's Guide to Medical Tests." The technician controls the machine from another room. As the "doughnut" rotates, narrow x-ray beams are shot from numerous angles. A computer reconstructs the individual cross-sectional images to produce one so detailed it can show legions less than 1/8-inch long.

Radiation amounts

A major difference between x-rays and CT scans is the amount of radiation exposure. A spinal x-ray can expose a patient to the equivalent of six months of natural background radiation at once, while a spinal CT scan can expose a patient to two years worth of background radiation, according to the Radiological Society of North America,

Cost

CT scans are more expensive than x-rays, and their widespread use is coming under greater scrutiny. According to "The Patient's Guide to Medical Tests," CT scans can cost between $900 and $2,500, depending upon the extent of the examination (versus a few hundred dollars for a regular x-ray). CT-scan machines themselves can cost $1 million to $2 million each, versus a few thousand dollars for an x-ray machine.

Availability

CT scans are less available than x-rays, especially in rural areas. X-ray machines are commonplace in hospitals and clinics. However, only an estimated 8,500 CT scanners are in use in the United States, according to a 2006 study of CT scanning in the Finger Lakes Region of upstate New York State. Limitations on the use of CT scans, MRIs and other radiology imaging in 12 major metropolitan areas began in 2007, according to a study by the Center for Studying Health System Change.

References

• National Cancer Institute: Computed Tomography (CT): Questions and Answers
• "The Patient's Guide to Medical Tests" Second Edition; Facts on File; 2002
• "Medical Tests Sourcebook"; Omnigraphics Inc.; 2008
• RadiologyInfo.org: Radiation Exposure in X-ray Examinations
• Global Health Insurance Marketing: Fewer Employees, Higher Health Insurance Costs

Resources

• RadiologyInfo.org: Procedures A to Z
• Finger Lakes Health Systems Agency: CT Scanning in the Finger Lakes Region 2006