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Rad Protection Ch.4
Radiation Quantities & Units
| Question | Answer |
|---|---|
| What is the equivalent of the SI unit seivert? | Rem. |
| What is the unit for Equivalent Dose? | Sv. |
| Total Effective Dose Equivalent | Defined by NRC as the sum of effective dose equivalent from external radiation exposures and a quantity called committed effective dose equivalent (CEDE) from internal radiation exposures. |
| EfD = D x WR x WT | Effective Dose. |
| Collective Effective Dose Equivalent (ColEfD) | - Used for radiation exposure of a population from different sources. -Unit = person-sievert. - The product of the average EfD for an individual belonging to the exposed population or group and the number of persons exposed. |
| Effective Dose (EfD) | - Provides a measure of the overall risk of exposure to ionizing radiation. - Takes into account the type of radiation as well as the Radiosensitivity of the organ or body part irradiated by a process of tissue weighting factors. |
| Tissue Weighting Factor (Wt) | - A value denoting the percentage of the summed stochastic (cancer plus genetic) risk stemming from irradiation of tissue to the all-inclusive risk, in which the entire body is irradiated in a uniform fashion. |
| Tissue Weighting Factor (Wt): | - Assigns risks for potential biologic responses from various types of radiation on a common scale. - Takes into account the Dose, the radiation weighting factor and the tissue weighting factor. |
| X-rays, beta particles, gamma photon and high energy external protons | WR = 1. |
| Alpha Particles | WR = 20. |
| Protons | WR = 2. |
| What measures the amount of radiation an occupationally exposed individual receives? | REM/Eqd. |
| What measures the amount of radiation a non-occupationally exposed individual receives? | RAD/ Gyt. |
| What measures the amount of radiation coming from the x-ray tube prior to reaching the patient? | Roentgen/Air Kerma/ Gya. |
| Rem - Roentgen Equivalent Man | - The unit for measuring exposure to the occupationally exposed. - Also known as equivalent dose. - Measured in Sv. |
| Absorption depends on: | - Atomic number. - Mass density. - Energy of the photon. - Effective atomic numbe. |
| Absorbed Dose (D) | - The amount of energy per unit mass absorbed by the irradiated object. - Responsible for biologic damage. - RAD (radiation absorbed dose) or Gy is the traditional unit of measure. |
| Radiation absorbed dose (RAD) | - The amount of energy per unit mass absorbed by the irradiated object. - The SI unit = gray (Gyt). - Also referred to as Absorbed Dose (D). |
| Dose Area Product (DAP) | Sum total of air kerma over the exposed area of the patient's surface. |
| Air Kerma | - Term that is replacing Exposure or Roentgen. - Can measure "kinetic energy" in air - Gya. - Or "kinetic energy" in tissue - GyT. - Used mainly in fluoro units. |
| Exposure (X) | - When a volume of air is irradiated with x-rays or gamma rays causing the neutral atoms in the air to become ionized. - Measured in coulombs per kilogram (C/kg) or R. - Used to calibrate x-ray equipment and measure output intensity. |
| Fluoro entrance doses are measured in _____________. | R/min. |
| Roentgen (R) | - Measurement of exposure to x-radiation and gamma radiation. - Measurement in air. - Also measured in coulombs per kilogram. - The SI unit most closely related to R is Exposure (X) and is used to describe this unit of measure. |
| 1991 | The term effective dose (EfD) was coined. |
| 1980 | Adoption of SI units. |
| 1970 | Adequate dosimetry and risk analysis. |
| MPD | Is the largest dose of ionizing radiation that an occupationally exposed person was permitted that was not anticipated to result in adverse biological effects.. |
| 1950 | - Modern Era or Radiation Protection. - Maximum permissible doses were established. |
| 1946 | National Commission on Radiation Protection (NCRP) was established. |
| 1934 | Recommended tolerance doses established. |
| Short-term effects (acute or early effects) | Were used as a measure for radiation dose. |
| A ___________________ was accepted to be the level with which exposure did not cause apparent harmful side effects. Is now called the threshold dose | Tolerance level. |
| 1900 to 1930 | Skin Erythema Dose. |
| 1925 | - International Commission on Radiation Units and Measurements . - Roentgen was accepted unit of exposure but did not have a great definition. |
| 1921 | - British X-ray & Radium Protection Committee. - did not have a workable radiation unit. Could not complete task . |
| First occupational notes was reddening of the skin _____________________. | Radiodermatitis. |
| What made early radiography pioneers investigate radiation protection measures? | Early radiation injuries such as radiodermatitis. |
| Aplastic Anemia | Result from bone marrow failure. |
| Leukemia | Abnormal overproduction of whit blood cells. |
| 1904 | The first death related to radiation induced injuries was with Clarence Dailey. |
| 1896 | First cases of radiation induced damages were noted. |
| Total Effective Dose Equivalent (TEDE) | Is a radiation dosimetry quantity that was defined by the Nuclear Regulatory Commission (NRC) to monitor and control human exposure to ionizing radiation. |
| Tissue Weighting Factor (Wt) | A value that denotes the percentage of the summed stochastic risk stemming from irradiation of tissue to the all-inclusive risk when the entire body is irradiated in a uniform fashion. |
| Stochastic Effects | Mutational or randomly occurring biologic changes, independent of dose, in which the chance of occurrence of the effect rather than the severity of the effect is proportional to the dose of ionizing radiation. |
| Somatic Damage | Biologic damage experienced by living organisms as a result of exposure to ionizing radiation. |
| Sievert (Sv) | The SI unit of measure for equivalent dose (EqD), and effective dose (EfD). It is the product of the absorbed dose and the radiation weighting factor |
| Radiation Weighting Factor | A dimensionless factor (a multiplier) that was closed for radiation protection purposes to account for differences in biologic radiations. This factor places risks associated with biologic effects on a common scale. |
| Occupational Exposure | Radiation exposure received by radiation workers in the course of exercising their professional responsibilities. |
| Linear Energy Transfer (LET) | The average of energy deposited by ionizing radiation in an object per unit length of track as it passes through the object. It is expressed in units of keV/um. |
| Late Tissue Reactions | Nongenetic consequences of radiation exposure that appear months or years afterward. These effects may be either stochastic or tissue reactions. |
| International System of Units (SI) | System of units that makes possible an interchange of units among all branches of science throughout the world. |
| Gray (Gy) | SI units of absorbed dose and air terms. |
| Genetic, or Heritable Effects | Biologic effects of ionizing radiation on future generations due to irradiation of germ cells in previous generations. Also known as hereditary effects. |
| Exposure (X) | The total electric charge of one sign, either all pluses or all minuses, per unit mass that x-ray and gamma ray photons with energies up to 3 million electron volts generate in dry air that standard temperature and pressure. |
| Exposure (X): | The amount of ionizing radiation that may strike an object, such as the human body, when in the vicinity of a radiation source. In the SI system it can be measured in coulombs per kilogram. |
| Equivalent Dose (EqD) | A radiation quantity used for radiation protection purposes when a person receives exposure from various types of ionizing radiation. |
| Equivalent Dose (EqD): | This quantity attempts to numerically specify the differences in transferred energy and therefore potential biologic harm that are produced by different types of radiation. |
| Effective Dose (efD) | Quantity that is used for radiation protection purposes to provide a measure of the overall risk of exposure to humans from ionizing radiation. |
| Early Tissue Reactions | Reactions in biologic tissues that are dependent on the duration of time after the exposure to ionizing radiation. |
| Dose Area Product (DAP) | The sum total of air karma over the exposed area of the patient's surface. |
| Coulombs Per Kilogram (C/kg) | Si unit of radiation exposure: 1 column per kilogram of air equals 1 SI unit of exposure. C/kg is used for x-ray equipment calibration because x-ray output intensity is measured directly with an ionization chamber |
| Coulomb (C) | Basic Si unit of electrical charge. It represents the quantity of electrical charge flowing past a point in a circuit in 1 second when an electrical current of 1 ampere is used. |
| Committed Effective Dose Equivalent (CEDE) | A measure of the probabilistic health effect on an individual as a result of intake of radioactive material into the body. It takes into account the length of time that the radioactive material may stay within the body. |
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