Medical Imaging is a process used to create images of the human body for medical purposes. Different methods provide pictures of the interior of the body by using electromagnetic radiation or sound waves that pass through body tissues.

Tomography is the most advance imaging technique use, itcreate detailed images of cross sections of the body. An imaging procedure that is repeated many times to obtain a complete image or set of images of a region of the body is commonly referred to as a scan. The person being scanned typically lies on a table called gantry, which has detecting devices positioned around it.

Imaging Methods

Among the most important medical imaging methods are the following:

• Computed Tomography (CT) or Computerized Axial Tomography (CAT). This method uses narrow beams of X-rays that are recorded by an array of detectors around the body. CT is used to produce images of muscle and connective tissue, and organs (liver, kidney, spleen, pancreas, bladder, adrenal glands, prostate glands and lymph nodes). CT is extremely useful in examining the brain to detect damage or deterioration or the size and location of a tumor. Three-dimensional images of bones can be generated by CT and used in planning reconstructive orthopedic surgery.
• Fluoroscopy. A method that uses X-rays projected onto a TV-like monitor so that the body part and its motion are seen in details. Example is the beating of the heart. Most fluoroscopic examination requires contrast dye to highlight a particular area of the body.

• Magnetic Resonance Imaging (MRI). A method that uses a magnetic field and pulses of radio wave energy to make an image of organs and structures inside the body. In most cases MRI gives different information about structures in the body than can be seen with an X-ray, ultrasound or computed tomography scan. MRI may also show problems that cannot be seen with other imaging methods. MRI is very useful in evaluating diseases of the brain and spine, the extent of damage caused by stroke and the condition of the spine following surgery. It is also useful for examining joints and abnormalities in muscle and connective tissue, tumors and blood vessel diseases or infection. During the MRI test the area of the body being studied is placed inside a special machine that contains a strong magnet.

• Radioisotope Imaging or Nuclear Medicine Imaging. In this method very small amounts of radioactive substances or tracers are injected into a vein. These substances emit gamma rays or some other form of radiation, and they tend to concentrate in specific tissues or tumor cells. One of the simplest techniques for using the tracers to produce an image is with a device called a gamma camera, which records gamma rays to produce an image similar to a conventional X-ray image. Radioisotope imaging is used to study the heart, brain and liver. It is especially useful in determining the extent of damaged brain tissue following a stroke, and the metabolic activity accompanying mental deterioration, such as that caused by Alzheimer's disease. Before and during the test a patient may be given an iodine solution to prevent the thyroid from absorbing too much of the radioisotope.
• Ultrasonography or Ultrasound Imaging. This method uses a high-frequency sound wave to produce images. Ultrasonography is typically used for images of the heart and various organs in the abdomen and to evaluate the development of a fetus.
• X-ray Radiography. This method is used to create film X-rays. It is the most commonly used method of medical imaging. Images obtained by this method are typically used for examining the lungs, bone fractures, and teeth, and to detect ulcers, kidney stones, and cancer.

Uses of Medical Imaging: Diagnosing and treating diseases, injury, screening a patient for cancer, medical research and in planning reconstructive surgery.