Radiation Units - Week 4 Flashcards
Reddening of the skin after exposure, leading to cancerous lesions
Radio dermatitis
Bone marrow failure
Aplastic anemia
Abnormal overproduction of WBC
Leukemia
What was the initial of measuring radiation in 1900-1930?
Skin erythema dose
The amount of ionizing radiation that may strike an object (human body) when in the area of a radiation exposure
Exposure
Traditional unit = Roentgn (R)
SI unit = C/kg
What are xray tube outputs measured in?
Roentgens or milliroentgens (mR)
Basic unit of electrical charge
Coulomb (C)
The amount of radiation required to create 1 coulomb of charge (or electrons released in ionization) in 1 kilogram of dry air
Coulombs per kilogram (C/kg)
Conversion of Roentgen to C/kg
1R = 2.58x(10)^-4C/kg
Kinetic energy released in matter
KERMA
SI unit that expresses total kinetic energy released in a unit mass (kg) of air
Air kerma
Expressed as J/kg
Air kerma
Expresses total kinetic energy released in a unit mass of tissue
Tissue kerma
Unit of measurement = Gray Gy
Total of air kerma on the exposed area of the patients surface
Dose area product (DAP)
What unit is DAP usually specified in?
mGy-cm2
Indicates the amount of radiation energy a patient absorbs during DI procedures
Absorbed dose (D)
Traditional unit = Rad
SI unit = Gray
What are some factors that can affect absorbed dose?
-atomic number of irradiated tissue
-mass density of tissue
-energy of incident photon
Defined as an energy absorption of 1 joule (J) per kilogram (kg) of matter in the irradiated object
Absorbed dose measured in grays (Gy)
1 Gy = 1 j/kg
T/F
Equal absorbed doses of different types of radiation produce different amounts of biological damage
True
What is the quality factor of xray photons?
1
The product of the average absorbed dose (D) in a tissue or organ in the human body and its associated radiation weighting factor (Wr) for a type and energy specific to that radiation
Equivalent dose (EqD)
Traditional unit = REM
SI unit = Sv
Measures the equivalent dose for biological effects for EqD and EfD. Takes into account the absorbed dose received by a certain type of radiation
REM (EqD)
Sv
1Rem = 1/100 Sv
Measure of overall risk of exposure to humans from ionizing radiation
Effective dose (EfD)
Traditional unit = REM
SI unit = Sv
Tissue weighting factor
Wt
