| The CAT scan (Computerized Axial Tomography), | | | | experienced physician, thereby reducing the cost and |
| also known as a CT scan, was invented by Sir Godfry | | | | complexity of the procedure. The main difference |
| and Robert Ledley in 1975. It was the first diagnostic | | | | between the CT and PET scans is the PET scan |
| tool able to see inside the body and brain. A CT | | | | shows molecular function and activity instead of |
| scanner emits a group of narrow beams of radiation | | | | structure, and therefore can often differentiate |
| through the human body, unlike an X-ray machine that | | | | between normal and abnormal tissue. A PET scan |
| uses just one beam of radiation. The key drawback of | | | | produces three dimensional images and usually |
| a CT scan is the use of radiation. CT scans use | | | | compliments rather than replaces the information |
| radiation that can cause damage to a person's DNA | | | | obtained from a CT scan. By measuring blood flow |
| after continued exposure. However, some radiology | | | | and metabolic rate within the heart, physicians using |
| departments still use CT scans as a preferred | | | | PET scans can discover areas of decreased blood |
| screening test for ailments including chest ailments and | | | | flow, such as those areas with blockages, and |
| broken bones. | | | | differentiate living muscle from damaged muscle that |
| Positron Emission Tomography (PET) scans measure | | | | has inadequate blood flow. This information is |
| emissions from positron-emitting molecules. In the | | | | particularly important for patients who have had |
| 1970s, PET scanning was introduced to the medical | | | | previous myocardial infarction or who are being |
| community. During the 1980s, the technology that | | | | considered for a procedure such as a coronary artery |
| underlies PET advanced greatly. Commercial PET | | | | bypass surgery or angioplasty. |
| scanners have resolution that is more precise and | | | | The information provided here shows the need for |
| images that are more accurate than CT scanners. | | | | discernment in deciding which or how many scans to |
| Many of the steps required for producing a PET scan | | | | consider. Each test has its place depending on exactly |
| are performed by a trained technician or an | | | | what type of condition needs to be diagnosed. |