Radiological Units, Quantities, and Terminology Flashcards
Exposure
Energy deposited by ionizing radiation
Roentgen
Amount of X-ray or gamma radiation less than or equal to 3 MeV that will produce in air 2.58 c 10^-4 coulombs of charge per Kilo of air.
Absorbed Dose (D)
Energy imparted by ionizing radiation per unit mass of irradiated material.
1. Unit of absorbed dose is the Gray(Gy) or rad
2. rad- equal to the absorption of 100 ergs per gram
3. Ergs- amount of energy required to lift a mass of 1/980
4. Gray = 1J/kg = 100 rad
Quality Factor (Q)
Factor which is multiplied by absorbed dose to obtain a quantity which equates to a common scale of any ionizing radiation that an individual is exposed.
Quality Factor (Q) types
Photons:1
Beta + beta - : 1
Thermal Neutrons: 2
Fast Neutron : 10
Protons: 10
Alpha Particle: 20
Dose Equivalent (Ht)
Product of absorbed dose and quality factor. Purpose to have a single unit regardless of type radiation
Rem
Unit of dose equivalent
Rem ( Naval Nuclear Propulsion Program)
The amount of any type of radiation that will cause biological damage equivalent to 1 rad of gamma radiation
Sievert (Sv)
One Sv = 100 rem
Man-rem (person rem)
Total radiation dose received by all of the individuals in a specific group over a specified period of time or during a specific work event
Effective Dose equivalent (He)
Sum of the products of the weighting factors applicable to each of the body organs or tissues that are irradiated and the dose equivalent to these organs or tissues
Organ/ Tissue weighting Factor
Gonads 0.25
Breast 0.15
RB marrow 0.12
Lung. 0.12
Thyroid. 0.03
Bone Surface. 0.03
Remainder. 0.30
Whole Body. 1.00
Remainder is GI system
Deep Dose Equivalent
External Exposure to the whole body at a tissue depth of 1cm
Shallow Dose Equivalent
External exposure to the skin or extremity at a tissue depth 0.007 cm
Eye dose equivalent
External exposure to the lens of the eye at a depth of 0.3 cm
Committed Dose Equivalent
Dose Equivalent to an organ or tissue that will be received from an intake of radioactive material by an individual during a 50 year period following intake
Committed effective dose equivalent
Sum of products of the weighting factors applicable to each of the body organs or tissues that are irradiated and the committed dose equivalent to these organs or tissues
Total Effective dose equivalent (TEDE)
Sum of deep dose equivalent and the committed effective dose equivalent
TEDE= DDE + CEDE
Annual limit on intake (ALI)
Smaller amount of radioactive material taken into the body by an adult worker by inhalation or ingestion in a year that would result in a committed effective dose equivalent of 5 rem committed or committed dose equivalent of 50 rem
Derived Air Concentration (DAC)
Concentration of a given radionuclide in air which, if breathed for a working year under conditions of light work results in an intake of Annual limit on intake (ALI)
ALARA
As low as reasonably Achievable
radiological protection philosophy making every reasonable effort to maintain exposure to ionizing radiation below dose limits.