exposure
discovered “x-rays” on November 8, 1895, during an experiment investigating the nature of cathode rays and fluorescent materials.
German physics professor Wilhelm Conrad Roentgen
In 1980 who adopted SI units for use with ionizing radiation.
International Commission on Radiation Units and Measurement (ICRU)
is the amount of energy per unit mass absorbed by an irradiated object.
Absorbed dose (D)
specifies how the potential for biologic damage from different types and doses of radiation will be equivalent if correct weighting factors are included. To calculate equivalent dose: EqD = D × WR.
EqD
The whole-body TEDE regulatory limit for exposed personnel is
0.05 Sv
Many individuals who were exposed to substantial doses of x-rays in the early years after their discovery developed what from the exposure exposure.
somatic effects
SI radiation units are preferred for specifying radiation quantities because the traditional system of units does not fit into the metric system that provides .”
“one unified system of units for all physical quantities
is used for measuring absorbed dose in air (Gya) or for measuring absorbed dose in tissue (Gyt).
The gray (Gy)
describes the total biologic damage to a human that is caused by equivalent doses received by specific organs. To calculate effective dose: EfD = D × WR × WT.
EfD
in radiation protection is the total effective dose to an individual resulting from an intake of radioactive material into the body. Such material may remain in the body for some time, resulting in a dose that accumulates over time.
The committed effective dose equivalent (CEDE)
was used from 1900 to 1930 as the unit for measuring radiation exposure. Eventually a tolerance dose was established for occupationally exposed individuals that could be regarded as a threshold dose.
Skin erythema dose
is used for specifying x-ray or gamma-ray exposure in air only. This exposure unit is equal to an electrical charge of 1 C produced in a kilogram of dry air by ionizing radiation.
Coulomb per kilogram (C/kg)
The number of gray times 1000 equals the number of
milligray.
, Sv, or the subunits, millisievert (mSv) and microsievert (μSv), are used to specify EqD and EfD. These units are used for occupational radiation exposure.
In the SI system
principle provides a method for comparing the amount of radiation used in various health care facilities in a particular region for specific imaging procedures.
ALARA
In what year did dose equivalent or effective dose equivalent replaced the MPD.
1977
is an SI quantity that is used to express how energy is transferred from a beam of radiation to air.
Air kerma
is the amount of energy transferred on average by incident radiation to an object per unit length of track, or passage, through the object and is expressed in units of kiloelectron volts per micrometer (keV/μm).
LET
represents an attempt to describe the radiation exposure of a population or group from low doses of different sources of ionizing radiation. Person-sievert is the radiation unit used to calculate this quantity. According to the ICRP it is not a valid method for computing the potential number of deaths from cancer.
Collective effective dose (ColEfD)
is used for the welfare of the patient, the potential benefits of this exposure to radiant energy must far outweigh any slight chance of inducing a radiogenic malignancy or any genetic defects.
When ionizing radiation
is based on the energy deposited in biologic tissue by ionizing radiation. It takes into account both the type of radiation and the variable sensitivity of the tissues exposed to the radiation.
Efd
is the sum total of air kerma multiplied by the exposed area of the patient’s surface.
Dose area product (DAP)
are the quantities of choice for measuring biologic effects when all types of radiation must be considered.
EqD and EfD
, is designed to take into account all possible sources of radiation exposure and is used for the monitoring for occupationally exposed persons who are likely to receive possibly significant radiation exposure during the course of a year.
The radiation dosimetry quantity, total effective dose equivalent (TEDE)
Six consequences of ionization in human cells are
(1) creation of unstable atoms, (2) production of free electrons, (3) production of low-energy x-ray photons, (4) creation of highly reactive free molecules (called radicals) capable of producing substances poisonous to the cell, (5) creation of new biologic molecules detrimental to the living cell, and (6) injury to the cell that may manifest itself as abnormal function or loss of function.