Computed tomography (CT) and Positron Emission Tomography (PET) are frequently used to investigate numerous human diseases such as disorder of bones, central nervous system. cardiac system, cancer and etc. There are some comprehensible differences between CT scan and PET as discussed in the following table.
|Parameters||CT Scan||PET Scan|
|Acronym||Abbreviated as computed tomography||Abbreviated as positron emission tomgraphy|
|Discovery||Sir Godfrey Hounsfield invented first CT scanner that was available commercially and the first scan was done on 1st October, 1971.||Abbas Alvi was the person, who first administered the compound into two normal participants in August, 1976 in order to get a PET scan.|
|Duration of Test||Time taken for complete scan is 5 min||Usually takes 2 to 4 hours|
|Application||It is possible to outline the bone accurately by using CT scan. It provides anatomic information||It is useful to determine biological processes of the body. A PET Scan provides imaging to produce a three-dimensional picture of functional processes in the body.|
|Radiation exposure||Radiation exposure from CT ranges from 2 to 10 mSv, which is about the same as the average person receives from background radiation in 3 to 5 years. Usually, CT is not recommended for pregnant women or children unless absolutely necessary||Moderate to high radiation risk|
|Principle||The principle behind CT scan relies on a series of X-rays||The principle behind PET relies radioactive substance like fluorine-18(F-18)|
|Procedure||During a CT scan, the patient is moved along the scanning system, during which multiple X-ray images of the organ being examined are acquired from different angles. Sophisticated computer algorithms combine all these images to create a view of the organ.||During PET The tracer is injected into the body on a biologically active molecule and emits of gamma rays. The PET Scan system detects these gamma rays and determines the movement of the tracer in the body over time.|
|Merits||CT Scanning is useful for screening detecting injuries and abnormalities in the head, chest, heart, abdomen and extremities||PET Scan is helpful in neurology, cardiology, oncology, psychiatry, muscle skeletal imaging|
|Cost||Its cost varies depending upon the type of hospitals. Such as in Pakistan its price in Govt. hospitals is 2500 rupees, in semi-Govt. hospitals 5000 and in private sector its price is more than 12000 rupees. In certain other hospitals located in different countries, its price could be in a range of $1200 to $3200.||Its cost is more in comparison to CT scan (3000 to 6000 dollars).|
|Discovery||Sir Godfrey Hounsfield invented first CT scanner that was available commercially and the first scan was done on 1st October, 1971.||Abbas Alvi was the person, who first administered the compound to two normal participants in August, 1976.|
|Demerits||CT scans are associated with the risk colon cancer and leukemia. This is mainly due to the use of X-rays. However, these disadvantages can be reduced with the use of lower doses.||Some allergic reactions and low sugar level of causing cancers, such as lung cancer, may observed as risks.|
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