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What Is the Difference Between a Bone Scan and a CT Scan?

Reviewed on 1/21/2021

What is the difference between a bone scan and a CT scan?

A bone scan and a CT scan are used to diagnose various bone conditions.
A bone scan and a CT scan are used to diagnose various bone conditions.

A bone scan and a computed tomography (CT) scan are both used to diagnose various bone conditions. The specific use of a bone scan is to diagnose active bone diseases, such as osteoporosis, Paget’s disease or the spread of cancer into the bone. A CT scan is a high-resolution X-ray that gives detailed information about organ anatomy.

Table. The difference between a bone scan and a CT scan

DifferencesBone scanCT scan
DescriptionA bone scan is a nuclear imaging test that aids in the diagnosis and tracking of several bone diseases.A CT scan uses a combination of X-rays and a computer to create images of the bones.
TypeNuclear imagingNoninvasive diagnostic
ToolsUses radioactive materialsCombination of X-ray and computer technology
Radiation exposureThere is minimal yet definite risk of radiation exposureHigher risk of radiation exposure
Procedure
  • In a bone scan, the physician injects a radioactive material or tracer into the vein to highlight the problematic areas.
  • Next, a large camera scans and clicks images of the highlighted areas.
  • You might also need to have a follow-up CT scan to know the exact location of this abnormal area.
  • In a CT scan, you are secured to a scan table that slides into a large, round opening of the scanning machine.
  • Once you are inside the machine, the scanner rotates around you. You will be exposed to X-rays for short intervals.
  • The X-rays absorbed by body tissues are  identified by the scanner and transmitted to the computer.
OutcomesIt diagnoses active diseases of the bone.Provides detailed information on bone tissue and bone structure. It also gives information about the injuries and diseases of the bone.
Safety

Generally, it is a safe procedure with occasional risks, including:

  1. Reaction to the dye
  2. Kidney failure
  3. Radiation exposure risk
  1. Higher radiation exposure risk
  2. CT scan with contrast may result in anaphylaxis and reactions.
CostLess expensiveMore expensive
Duration30 minutes to one hourA few minutes to half an hour

What to expect during a bone scan

You can expect the following procedure during a bone scan

  • The procedure will be explained to you and your consent will be recorded.
  • The physician will inject a radioactive substance into your vein.
  • This substance collects in the bone over time.
  • The radioactive substance then emits gamma rays that are picked up by a special camera.
  • The signals are processed by a computer and turned into 2D (two-dimensional) or 3D (three-dimensional) pictures.
  • A radiologist interprets the images and sends a report to your doctor.

What to expect during a CT scan

You can expect the following procedure during a CT scan

  • You are secured to a scan table that slides into a large, round opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
  • Once you are inside the machine, the scanner rotates around you. You will be exposed to X-rays for short intervals.
  • The X-rays absorbed by body tissues are identified by the scanner and transmitted to the computer. The computer then converts the data into an image to be interpreted by a specialist.
  • A CT scan may also be done after injecting a contrast dye to obtain better information.

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References
Medscape Medical Reference

John Hopkins Medicine


American Cancer Society


Cancer Research UK


Mayo Clinic


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