Computarized Transaxial Tomography (CT scan)

This technique was developed by Nobel Prize winner Sir Geoffrey Hounsfield. This non-invasive technique generates computerized images with the help of X-rays to provide a three dimensional measured density of the brain. Compared to ordinary X-rays where a single X-ray is sent out through the body, in CT scan several beams are simultaneously sent from different angles. This generates a series of two-dimensional images. Though this technique is used to scan any part of the human body, in terms of brain it provides clear images of bony structures. CT scans have been useful in evaluating strokes, tumors, vascular accidents, head injuries, and intracranial lesions or atrophy.

In the recent years the technology behind CT scans has advanced and now it is possible to obtain the scans in seconds. Newer scanners known as spiral or helical scanners take fraction of seconds to produce three-dimensional scans. Scientists at ANURAG ( Advanced Numerical Research and Analysis Group ), a Defense Research and Development Laboratory at Hyderabad , India , have come forward with software named ANAMICA (ANURAG's Medical Imaging and Characterization Aid) that generates three-dimensional images (grid). The two images given below show CT scans of a right temporal lobe damaged patient and a left parietal lobe damaged patient, respectively.

 

Courtesy: Bhushan, B. (1999). The right hemispheric locus of visuospatial processing in focal brain-damaged patients and normal subjects. Ph.D. thesis submitted to BRAB University, India.

The visualisation has been largely used to study different types of cranial injuries and their effect of human behaviour. You may find CT scan technique used for studying elderly psychiatric patients (Rozenbilds & Gilchrist, 1989) and other behavioural studies too.