Units of radiation are used to define what 3 quantities of radiation?
exposure
dose
dose equivalent
What are the 2 systems usedto define radiation measurements? (in order from oldest to youngest)
traditional or standard system
Systeme internatioale (SI)
What are the 3 traditional units of measurement?
roentgen (R)
radiation absorbed dose (rad)
roentgen equivalent in man (rem)
What are the 3 SI units of measurement?
coulombs/kilogram (C/kg)
gray (Gy)
sievert (Sv)
the measurement of ionization in air produced by x -rays
exposure
What is the traditional unit of exposure for x-rays
roentgen (R)
a way of measuring the radiation exposure by determining the amount of ionization that occurs in air
roentgen (R)
the quantity of x radiation or gamma radiation that produces an electrical charge of 2.58 z 10-4 coulombs in a kilogram or air at standard temperature and pressure conditions
Roentgen
true or false. In the roentgen (R) a known volume of air is irradiated.
true
the interaction of x-ray photons with air molecules results in______ or the formation of_______-
ionization
ions
One roentgen is equal to the amount of radiation that produces how much ion pairs in 1 cubic centimeter of air?
about 2 billion, or 2.08 x 109 ion pairs in 1 cc of air
the roentgen measures the amount of energy that____________of an organism, but does not describe the________________
reaches the surface
amount of radiation absorbed
the roentgen is essentially limited to measurements in____
air
by definition the roentgen is only used for_______ and ________ and does not include any other type of radiation
x-rays
gamma rays
What is the SI unit for exposure equialent to the roentgen (R)?
there is none
How is exposure stated in the SI system?
coulombs per kilograms (C/kg)
a unit of electrical charge in the SI system
coulomb (C)
What measures the number of electrical charges, or the number of ion pairs in 1 kg of air?
coulombs per kilogram (C/kg)
How is the conversion for roentgen and coulombs per kilogram expressed?
1 R = 2.58 x 10-4 C/kg
1 C/kg = 3.88 x 103 R
the amount of energy absorbed by a tissue
dose
what is the traditional unit for dose?
radiation absorbed dose (rad)
true or false. the rad is not restricted to air, and can be applied to all kinds of radiation
true
a special unit of absorbed dose that is equal to the deposition of 100 ergs of energy per gram of tissue (100 erg/g)
rad
In using the SI unit, one rad is equivlent to how many joules per kilogram?
0.01 J/kg
What is the SI unit equivalent to the rad?
the gray (Gy), or 1 J/kg
How is the conversion for rad and Gy expressed?
1 rad = 0.01 Gy
1 Gy = 100 rads
measurement used to compare the biologic effects of different types of radiation
dose equivalent
What is the traditional unit of the dose equivalent?
roentgen equivalent in man (rem)
the product of absorbed dose (rads)and a quality factor specific for the type of radition
rem
What is used to place the exposure effects of different types of radiatin on a common scale?
Quality Factor (QF) or dimensionless multiplier
Why is does each type of radiation have a specific quality factor?
because different types of radiation produce different types of biologic damage
what is the QF for x-rays equal to?
1
What is the SI unit equivalent of the rem?
sievert (Sv)
how is the conversion for the rem and seivert expressed?
1 rem = 0.01 Sv
1 Sv = 100 rems
what prefix is used in dental radiography to express small quantities of exposure, dose and dose equivalent?
