Biomedical Technology

Clinical doctors employ a number of simple instruments, such as clinical thermometer to monitor your body temperature, stethoscope to hear the natural sounds inside your body and so on. Technological developments have revolutionized the instruments used for disease diagnosis. Any modern hospital or clinic features a wide range of such devices.

DIAGNOSTIC IMAGES

A great deal can be learnt about our body by using X-rays scanners. The images so obtained reveal defects and abnormalities, which aid in disease diagnosis.

X-ray Radiography

X-rays (discovered by German physicist Wilhelm Roentgen, in 1895) have a remarkable ability to penetrate matter. They are a vital diagnostic tool, providing detail images of dense parts of the body, e.g., bones. A burst of X-radiation is aimed at the patient's undressed body part to be examined.

Angiography

X-ray, when coupled with image intensifier, provide real-time images. These images can be viewed continuously by CRT (cathode ray tube) video monitor during surgery. Digital subtraction (DSA) is an imaging technique that produces clear views of flowing blood in vessels and indicates the presence of blockages, if any. An angiography (angeion : vessel; graphein : to record) is taken of the organ, for example, heart and its major blood vessels, and stored in a computer. A second angiography is taken after a contrast agent containing iodine, which is opaque to X-rays, has been injected into the blood stream. The first image is digitally subtracted from the second, leaving behind a clear outline of the second blood flow to heart, brain.

Computed Tomography

Simple radiography images are often difficult to interpret because. In them, a number of internal structures are superimposed, one on top of the other. A technique known as Computed tomography (CT) or computerised axial tomography (CAT) was developed in 1972. This sensitive technique makes it possible to image the internal structures distinct from each other in a manner they would be seen in a thin section of the body.

Magnetic response imaging

The magnetic resonance imaging (MRI) yields the best pictorial form and it does not expose the patient to potentially harmful ionizing radiations. For MRI, the patient lies in a supine position on a couch about 2 meters wide surrounded by the coils of a giant cylindrical electromagnet. This magnet field orients the magnetic moment of the hydrogen nuclei in such a way that they can absorb electromagnetic radiation at a definite frequency. MRI detects water because it focuses on the behavior of hydrogen atoms in water molecules.

Positron emission topography (PET)

Scanners monitor the consumption of a substance like glucose by neurons. The glucose is tagged with a radioisotope that has radioactive nuclei deficient in neutrons and with the excess in protons. This versatile technique is used to study epilepsy, schizophrenia, Parkinson's disease and drug addiction.

Sonography

Sonography is based on ultra sound (frequency above 20 kHz). Ultrasound of frequency between 1 and 15 MHz is beamed into the human body, and the returning echoes are detected. The ultra sound waves pass through homogenous tissues unimpeded. But when they meet another tissue or organ, a partial reflection takes place, the coefficient of reflection depending upon the difference in densities of the two tissues / organs.