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Planned exposure – limits given for occupational, medical and public exposure. The occupational exposure limit of effective dose is 20 mSv per year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. The public exposure limit is 1 mSv in a year. [11] Emergency exposure – limits given for occupational and public ...
Number of chest X-rays resulting in same effective dose Skull radiography (X-ray) 0.015 1 Chest X-ray 0.013 1 Lumbar spine X-ray 0.44 30 Abdomen X-ray 0.46 35 Pelvis X-ray 0.48 35 Screening mammography (4 views) 0.2 15 Dental X-ray (intraoral) 0.013 1 Diagnostic fluoroscopy: barium swallow 1 70 Cardiac angiography 7 500 Head CT 2 150 Chest CT 10
Occupational exposure limits may be one of two types: rate limited or dose limited. Rate limits characterize the exposure based on effective energy (radiance or irradiance, depending on the type of radiation and the health effect of concern) per area per time, and dose limits characterize the exposure as a total acceptable dose.
In the "1951 Recommendations" the commission recommended a maximum permissible dose of 0.5 roentgen (0.0044 grays) in any 1 week in the case of whole-body exposure to X and gamma radiation at the surface, and 1.5 roentgen (0.013 grays) in any 1 week in the case of exposure of hands and forearms. [1]
Background radiation level is widely used in radiological health fields as a standard for setting exposure limits. [1] Presumably, a dose of radiation which is equivalent to what a person would receive in a few days of ordinary life will not increase their rate of disease measurably.
Unprotected experiments in the U.S. in 1896 with an early X-ray tube (Crookes tube), when the dangers of radiation were largely unknown.[1]The history of radiation protection begins at the turn of the 19th and 20th centuries with the realization that ionizing radiation from natural and artificial sources can have harmful effects on living organisms.
Between March and July 1962, a radiation incident in Mexico City occurred when a ten-year-old boy took home an industrial radiography source that was not contained in its proper shielding. Five individuals received significant doses of radiation from the 200- gigabecquerel cobalt-60 capsule, [ 1 ] four of whom died.
Radiation can have harmful effects on solid materials as it can degrade their properties so that they are no longer mechanically sound. This is of special concern as it can greatly affect their ability to perform in nuclear reactors and is the emphasis of radiation material science , which seeks to mitigate this danger.