Tomography Introduced
Tomography is a form of imaging where three dimensional objects can be viewed slice by slice. It produces a cross sectional view of the three dimensional object, be it a human, animal or inanimate object, that allows the object to be studied at particular depths. It can reveal the presence of abnormalities not visible through other types of imaging. The process uses x-ray or sound to produce the images which appear in sharp contrast to the other parts of the object being studied. The process is commonly referred to as a CT (computed tomography) scan or a PET (positron emission tomography) scan. The technique is used in a variety of sciences including astrophysics, radiology, oceanography, geophysics, biology, archeology and materials science.
The process was first used in the 1930s by Alessandro Vallebona, a radiologist. While it was helpful when used with the x-ray machines at that time, the improvements in computer technology and the linking of the two technologies has made tomography very effective for a wide variety of applications. Medically the use of the tomographic technology requires taking a series of pictures from different angles and feeding them into a computer. The series of pictures are combined to create a three dimensional image. This makes it easier to see, understand, diagnose and treat a variety of ailments.
There are a number of different types of tomography that are popular today. One of the most popular types is magnetic resonance imaging, or MRI. This is used regularly by medical professionals of varying stripes. There is also seismic tomography, Zeeman-Doppler imaging, ultrasound transmission tomography, photo-acoustic imaging in biomedicine, ocean acoustic tomography, optical projection tomography and a host of others. The ability to look at cross-sections of a variety of objects and take photos that can be studied closely has been embraced by scientists from a wide variety of disciplines.
Tomography combines and utilizes x-rays, gamma rays, radio frequency waves, ions, electrons and electron-positron annihilation to gather different types of images. These images are fed into a computer and depending on the algorithm used provide various types of images. The use of a tomographic reconstruction algorithm to process the information fed into a computer has led to the explosion of uses for tomography.
Initially the process of tomography was used solely with X-ray. The medical staff created an image by moving the x-ray and the film in opposite directions while the film was being exposed. This allowed the object being focused on to become clear and sharp while the surrounding tissue appeared blurred. This technique so excited the scientific community they began adapting its use to all manner of scientific applications.
The word tomography comes from the Greek word 'tomos' which means part and 'graphen' meaning to write. This is exactly what tomography entails. It is the writing or photographing of a part or slice of a structure to allow scientist to more closely examine the structure. Tomography has now made peering deep into the body, the ocean or the earth simple.