Historical Evolution of Radiation Quantities and Units
Chapter 4 Radiation Protection Fall 2014
Terms in this set (42)
X-rays are discovered, and the discovery is announced.
Skin erythema dose becomes the unit for measuring radiation exposure.
Clarence Madison Dally becomes the first American radiation fatality.
First cancer deaths among physicians that are attributed to x-ray exposure are reported.
The British X-Ray and Radium Protection Committee is formed to investigate methods for reducing radiation exposure.
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.
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.
Tolerance dose is used for radiation protection purposes.
The U.S. Advisory Committee on X-Ray and Radium Protection is formed to formulate recommendations for radiation control.
A tolerance dose of 0.2 R per day is recommended.
The tolerance dose is reduced to 0.1 R per day.
The roentgen (R) becomes internationally accepted as the unit of measurement for exposure to x-radiation and gamma radiation.
The International System of Units (SI) is developed.
Maximum permissible dose (MPD) replaces the tolerance dose for radiation protection purposes.
The roentgen (R) is redefined to increase accuracy and acceptability.
The National Committee on Radiation Protection and Measurements becomes the National Council on Radiation Protection (NCRP).
The International Commission on Radiological Protection (ICRP) recommends that the dose equivalent limit or effective dose equivalent replace the MPD.
The ICRU adopts SI units for use with ionizing radiation.
The National Council of Radiation Protection (NCRP) adopts SI units for use.
The ICRP replaces effective equivalent dose with the term effective dose (EfD).
Skin erythema dose (SED)
Tolerance dose (TD)
Maximum permissible dose (MPD)
Effective dose equivalent
Effective dose (EfD)
November 8, 1895
Wilhelm Conrad Roentgen
Crookes tube with glowing barium platino-cyanide
Discovery of X-Rays
biologic damage to the body of the exposed individual caused by exposure to ionizing radiation
radiation exposure received by radiation workers in the course of exercising their professional responsibilities
Blood disorders and leukemia
common among early radiologists
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.
a dose of radiation lower than which an individual has a negligible chance of sustaining specific biologic damage
Diffuse redness of the skin
Loss of hair
Shedding of the outer layer of skin
Early Deterministic Somatic Effects
Loss of parenchymal cells
Late Deterministic Somatic Effects
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.
expressed in Sv or mSv
the sievert (Sv)
Replaced the rem for the equivalent dose
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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