The X-ray technique described in this post is a two-dimensional image. The most useful three-dimensional X-ray imaging technique is the CAT scan (Computerized Axial Tomography). To form a three-dimensional image of an organ; say for example the brain, a number of slices of the organ are considered and an X-ray image of the slice is obtained by moving the patient longitudinally or by rotating the X-ray beam. With the help of a computer, these images are then assembled to give a three-dimensional picture of the organ.
The conventional X-ray image of the head will show the dense bone structure of the skull. An angiography will depict the blood vessels of the head and neck but not the soft brain tissue. Magnetic resonance imaging shows the soft tissue and blood vessels but does not give much detail of the bony structure. With CT, digital images on the computer monitor are obtained and a physician can look into soft tissue, and then into blood vessels selectively.
Uses of CT scan
- For measuring bone material density for the detection osteoporosis
- For studying the brain, soft tissues and blood vessels selectively
- For study of the lungs and abdomen
- CT angiography for diagnosing heart disease, stroke and vascular diseases, gangrene and kidney failure
- For diagnosing problems of the inner ear and sinuses for imaging tumours or polyps
- For the study of the entire skeletal system; thoracic and lumbar spine, hands, feet ankles, legs, jaws etc.
X-ray Therapy
Certain cancerous cells can be destroyed by hard X-rays; soft X-rays are used for treating certain skin disorders.
Hazards and Safety Precautions to consider when using X-rays
When X-ray ionizes atoms in cells, sometimes an unnatural chemical reaction in a cell can break DNA chains. The broken strand may die or create mutation. If the DNA mutates, a cell may become cancerous. Nowadays, to avoid the harm caused due to mutation, a minimum dose of X-rays is used. During the first trimester of pregnancy, exposure to X-rays should be avoided.
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