WE-G-211-01: Cross-Sectional Imaging - Computed Tomography

The introduction of new cross-sectional imaging techniques in the 1970's and 1980's led to great improvements in the diagnosis and treatment of medical conditions. In this symposium, we will chronicle the development of three of these Methods: computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonic imaging (US). Computed Tomography Early attempts to obtain trans-axial radiographs employed unconventional mechanical motions of the x-ray tube and screen-film image receptor that produced images of limited utility. The introduction of the EMI Mk I computerized axial tomography (CAT) unit revolutionized imaging by providing electronic trans-axial images of the brain that allowed clear separation of various tissues with very similar attenuation coefficients. The great success of this imaging process led to the Nobel Prize for Hounsfield and Cormack in 1979. Examples from the evolution of the x-ray computed tomography technique, introduced initially by a large number of manufacturers over several "generations" of CT scanners will be presented. The changes include improvements in x-ray detectors and detector arrays, image reconstruction algorithms, and body bolus/filters, as well as the introduction of slip ring technology. These upgrades led to shorter scanning and reconstruction times, greater body coverage per rotation, and reduced artifacts, along with increased spatial resolution and improved low contrast performance. A very brief overview of additional cross sectional x-ray imaging devices and techniques that have been developed in recent years will conclude this section of the symposium.