Units of measurement Flashcards
Define roentgen
is the measure of the ionization of air created by x or gamma rays under 3MeV
Limitations of the roentgen
- Only measures the ionisation of air it doesn’t consider tissue interaction
Radiation exposure
Measure of radiation based on its ability to produce ionization of air under standard temperature and pressure.
S.I unit for radiation exposure
Coulombs/kg in air OR
Roentgen(R)=2.58×10^-4C/Kg(only for air )
Absorbed dose
Is the measure of the energy deposited by ionizing radiation per unit mass of a material.
S.I unit of absorbed dose
Gray(Gy)= J/Kg
1 rad= 0.01Gy
Biological effectiveness
- This refers to the relative amount of biological damage caused by different types of radiation for the same amount of absorbed dose.
Radiation weighting factor
A number assigned to different types of ionizing radiation that reflects their biological effectiveness.
Importance of the radiation weighting factor
Helps account for the varying biological effects when comparing radiation exposure.
Equivalent dose
the measurement of radiation exposure that takes into account the type of radiation and its biological effects on human tissue.
formula for equivalent dose(sievert)
HT=DT×WR
Where:
( H_T ) is the equivalent dose
( D_T ) is the absorbed dose
( W_R ) is the radiation weighting factor
Effective dose
The measure of the amount of radiation a person has received.
Use/ importance of equivalent dose
to compare biological effectiveness of different types of ionizing radiation
Effective dose SI unit
Milliisievert(mSv)
1 curie(Ci)
=3.7x10^10 disintegrations/sec
