Advantages and Disadvantages of Computed Tomography
This page covers advantages and disadvantages of Computed Tomography for CT scanning. It mentions benefits or advantages of Computed Tomography and drawbacks or disadvantages of Computed Tomography.
Introduction: Conventional radiography is 2-dimensional image formed by superimposition of images from successive layers of body in the path of X-rays. The image of one layer is obscured by superimposition of images of above and below layers. Tomography is invented to overcome this issue. In tomography technique, images of selected layers are recorded sharply while images of other layers are recorded unsharply. The technique involves some form of movement of patient or equipment during the exposure. Tomography involves synchronized movement of any two of three subjects, viz. X-ray tube, film and patient while third subject remains stationary.
What is Computed Tomography?
Computerized axial tomography combines tomography imaging with computer techniques. The computed tomography (CT) scanner was invented by Godfrey Newbold Hounsfield in England. CT scan makes use of computer processed combinations of many X-ray images taken from different angles to generate cross sectional images.
CT scanner consists of x-ray tube which emits finely collimated fan shaped x-ray beam directed through patient to the series of scintillation detectors. These detectors measure number of photons that exit the patient. The detectors form a contiuous ring around the patient. X-ray tube moves in this circle within the fixed detector ring. The information is used to construct cross sectional image of the patient. The radiation transmitted from body of the patient is sensed by array of detectors. The patient is made to move inside chamber which contains X-ray tube and detectors on a trolley. The detectors can move in one axial direction and machine is called computerized axial tomography (CAT). The purpose of the computer is to reconstruct the images of the body layers from output of the detectors.
The above latest arrangement eliminates any need for linear motion required to be given to X-ray source and detectors which reduces scanning time drastically.
Benefits or advantages of Computed Tomography
Following are the benefits or advantages of Computed Tomography:
➨The CT technique eliminates superimposition of images of undesired structures completely.
➨It offers higher contrast resolution. Hence it can distinguish tissues having differences of less than 1% in their physical densities.
➨Multiplanar reformatted imaging is possible due to multiple contiguous or single helical scan.
➨It provides more detail compare to ultra sonography.
➨It is quicker, cheaper and superior to MRI scanning.
➨Motion artifacts are of less concern in CT scan than MRI.
Drawbacks or disadvantages of Computed Tomography
Following are the drawbacks or disadvantages of Computed Tomography:
➨It is time consuming.
➨It is expensive for routine clinical use.
➨The patient is exposed to higher radiation.
➨It requires expensive equipment and hence it is not always accessible at all levels of people.
➨There is risk of ionizing radiation amd iodinated contrast agents.
The latest variation of computed tomography is Cone Beam Computed Tomography >>. CBCT uses cone shaped beam from X-ray source which produces complete volume image in single rotation i.e. volumetric dataset. Hence CBCT scanner is quicker in providing result compare to CT scanner. Also refer difference between CT scanner and CBCT scanner >>.