(i) Computed Scanning (also called computed tomography – (CT): The technique was invented by Sir Godfrey Hounsfield who was awarded a Nobel prize in 1979 for this major achievement. During the last few years, advances in CT technology have led to fast scan times and improved image quality. As a result the scope of CT has widened enormously so that it is now applied to almost any anatomical site.

In CT scanning a computer is used for reconstructing the image made by X-rays instead being recorded directly on the photographic film. The CT scanning technique is used for the diagnosis of the diseases of brain, spinal cord, chest, abdomen and also for the detection of benign and malignant tumours. Thus, it helps to determine the feasibility of operation treatment and also to assess the results of the treatment.

(ii) Prosthesis : Prosthesis is the implantation of an artificial substitute for any body part within the body. It enables the physical handicapped person to live a comfortable and productive life.

Internal prosthesis devices include intraocular lens, dentures. Prosthesis devices also include nose implant for cosmetic reshaping, electronic hearing aids in the ear, artificial arm or leg.

(iii) Pacemaker : It is electronic cardiac-support device that produces rhythmic electrical impulses that take over the regulation of the heartbeat in patients with certain types of -heart disease.

When electrical conduction system is interrupted, as is the case in a number of diseases including congestive heart failure and as an after effect of heart surgery, the condition is called heart block. An artificial pacemaker may be employed temporarily until normal conduction returns or permanently to overcome the block.

The first pacemaker were of a type called asynchronous, or fixed, and they generated regular discharges that overrode the natural pacemaker. The rate of asynchronous pacemakers may be set at the factory or may be altered by the physician, but once set they will continue to generate an electric pulse at regular intervals. Most are set at 70 to 75 beats per minute.

More recent devices are synchronous, or demand pacemakers that trigger heart contractions only when the normal beat is interrupted. Most pacemakers of this type are designed to generate a pulse when the natural heart rate falls below 68 to 72 beats per minute. These instruments have a sensing electrode that detects the atrial impulse.