Computed Tomography
The advent of the CT scanner has revolutionized the way medicine is practiced today. This technology enables us to diagnose disease rapidly, using a non invasive technique with few contraindications. In the Emergency Department, CT studies are ordered commonly in patients presenting with acute symptoms where information is needed rapidly. Like X-Rays, CT scans are performed with radiation. Although the diagnostic information that CT affords is often essential in diagnosing disease and monitoring response to therapy, it is important to take potential side effects into account before ordering this test on your patients.
In this section you will find information regarding how CT came to be, a summary of how CT works, important details about CT safety, terminology used to describe images, and indications for ordering CT exams.
History of CT
In the early 1970's computed tomography (CT) was invented independently by both Godfrey Hounsfield, a British engineer and by physicist Allan Cormack from Tufts University. Hounsfield spent the majority of his career working at the Electrical Musical Industries (EMI), which at the time also started to invest in the music industry. In 1971, the first CT scan was used in medical practice.1 By 1975 the first "whole body" CT scanner was constructed. In 1979 both Godfrey Hounsfield and Allan Cormack received the Nobel Prize for Medicine/Physiology for their groundbreaking work.2
What is the connection between the CT scanner and the Beatles? Hounsfield's parent company, EMI, was able to fund Hounsfield's research because it had amassed a small fortune by investing in the music company Capitol Records.1 The success of groups including the Beatles markedly increased EMI's revenue, allowing the company to finance research by Hounsfield.1 The first CT scanner was actually first known as the EMI scanner.
The "Hounsfield scale" remains the standard measurement of radiodensity on CT images. Initial CT scanners took minutes to acquire each "slice" of data and hours to reconstruct the data set. Modern scanners can perform scans in seconds.
Sir Godfrey Hounsfield2