PET Scan vs. CT Scan: Know The Difference

PET Scan vs. CT Scan: Know The Difference

3 mins read

A lot of people still get confused with CT scans and PET scans. Although they may use similar-looking machines, they exhibit various differences in how they work, the results they produce and other things. CT scan stands for Computerized Tomography, while PET stands for Positron Emission Tomography. If you are one of many who gets the two scans confused, here are some of the key differences that will help you distinguish them correctly in the future.

Information gathered

A PET scan provides metabolic information regarding a target body part while a CT scan provides anatomic information. PET scan results are also interpreted alongside MRI and CT scan results. Visit a provider of private PET scans in London if you need any of these services.


A PET scan costs almost double that of a CT scan. This is because of some factors such as the time it takes to complete a scan, and most importantly, the information it provides the patient and the healthcare practitioner.


A CT scan usually only takes 5 minutes, with the actual scanning of the patient taking just half a minute, while a PET scan can last as long as 4 hours. This being said, a CT scan is not too sensitive to movement, while a PET scan requires the patient to be steady so that the gathering of metabolic information is more precise and accurate.

Exposure to radiation

Patients who undergo CT scans receive radiation, the amount of which is the same as 3 to 5 years of exposure to background radiation. This type of scan is not recommended for children and pregnant women unless the benefits far outweigh the risks and the imaging is absolutely necessary for the treatment plan. A PET scan, on the other hand, emits moderate to high amounts of radiation. Being on the machine for up to 4 hours, the patient will absorb a relatively high amount of radiation.

Imaging techniques

A CT scan machine uses X-ray images to produce a more detailed image of a target body part. A PET scan uses radioactive tracers, which emit positrons. The emitted positrons are then traced by the machine’s system to create a detailed and thorough 3D image over the duration of the scan.

Scope of imaging

A CT scan can outline the skeletal system fairly accurately, while a PET scan can gather information about biological processes.


A brain CT scan was first done on a patient in 1971, while PET scanning was first introduced for humans in 1976. Ever since then, technological breakthroughs have made both scans more efficient and produce more detailed images and information.

CT scans and PET scans are two entirely different medical procedures that are done by licensed and qualified technicians to patients and are ordered by their doctors to help them in diagnosing illnesses and help them map out a course of action for their patients.

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