Historical Evolution of Radiation Quantities and Units

Chapter 4 Radiation Protection Fall 2014
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1895
X-rays are discovered, and the discovery is announced.
1900
Skin erythema dose becomes the unit for measuring radiation exposure.
1904
Clarence Madison Dally becomes the first American radiation fatality.
1910
First cancer deaths among physicians that are attributed to x-ray exposure are reported.
1921
The British X-Ray and Radium Protection Committee is formed to investigate methods for reducing radiation exposure.
1925
The First International Congress of Radiology is held in London, England; radiologists from all over the world collaborate, but no definite system for measuring ionizing radiation exposure is identified. The International Commission on Radiation Units and Measurements (ICRU) is formed.
1928
The ICRU is charged by the Second International Congress of Radiology (Stockholm, Sweden) to define a unit of exposure. The International X-Ray and Radium Protection Commission (predecessor of the ICRP) is established by the Second International Congress of Radiology.
1930s
Tolerance dose is used for radiation protection purposes.
1931
The U.S. Advisory Committee on X-Ray and Radium Protection is formed to formulate recommendations for radiation control.
1934
A tolerance dose of 0.2 R per day is recommended.
1936
The tolerance dose is reduced to 0.1 R per day.
1937
The roentgen (R) becomes internationally accepted as the unit of measurement for exposure to x-radiation and gamma radiation.
1948
The International System of Units (SI) is developed.
Early 1950s
Maximum permissible dose (MPD) replaces the tolerance dose for radiation protection purposes.
1962
The roentgen (R) is redefined to increase accuracy and acceptability.
1963
The National Committee on Radiation Protection and Measurements becomes the National Council on Radiation Protection (NCRP).
1977
The International Commission on Radiological Protection (ICRP) recommends that the dose equivalent limit or effective dose equivalent replace the MPD.
1980
The ICRU adopts SI units for use with ionizing radiation.
1985
The National Council of Radiation Protection (NCRP) adopts SI units for use.
1991
The ICRP replaces effective equivalent dose with the term effective dose (EfD).
1900-1930
Skin erythema dose (SED)
1930-1950
Tolerance dose (TD)
1950-1977
Maximum permissible dose (MPD)
1977-1991
Effective dose equivalent
1991-present
Effective dose (EfD)
November 8, 1895
Wilhelm Conrad Roentgen
Crookes tube with glowing barium platino-cyanide
Discovery of X-Rays
somatic damage
biologic damage to the body of the exposed individual caused by exposure to ionizing radiation
occupational exposure
radiation exposure received by radiation workers in the course of exercising their professional responsibilities
Blood disorders and leukemia
common among early radiologists
radiodermatitis
reddening of the skin
skin erythema dose
the received quanity of radiation that causes diffuse redness over an area of skin after irradiation
early deterministic somatic effects
biologic effects that appear within minutes, hours, days, or weeks of the time of exposure.
threshold dose
a dose of radiation lower than which an individual has a negligible chance of sustaining specific biologic damage
Nausea
Fatigue
Diffuse redness of the skin
Loss of hair
Intestinal disorders
Fever
Blood disorders
Shedding of the outer layer of skin
Early Deterministic Somatic Effects
Cataract formation
Fibrosis
Organ atrophy
Loss of parenchymal cells
Reduced fertility
Sterility
Late Deterministic Somatic Effects
Cancer
Genetic (hereditary) effects
Late Stochastic Effects
EfD is base on
1. The energy deposited in biologic tissue by ionizing radiation
2. The type of radiation (e.g., x-radiation, gamma, neutron)
3.The variable sensitivity of the tissues exposed to radiation
What is EfD?
a measure of the overall risk arising from the irradiation of biologic tissue and organs. It takes into consideration the exposure to the entire body.
EfD unit
expressed in Sv or mSv
the sievert (Sv)
Replaced the rem for the equivalent dose
One sievert
equal to 100 rem
milligray per minute (mGy/min) or roentgens per minute (R/min)
Fluoroscopic entrance dose rates are measured in
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