Unit 1 Flashcards
Radiation
Transfer of energy from one point to another
Ionizing radiation
Energy to knock out inner shell electron from an atom
Radiobiology
How radiation affect biological tissue
Desquamation
Shedding of skin beyond skin reddening can be dry or moist
Epilation
Hair loss
Law of bergonie and tribondeau
Experimented on rodent testicles
1 stem cells are more radio sensitive
2 younger tissues are more radio sensitive
3 more metabolic activity in cell the more radio sensitive
4 greater rate of division of cell the more radiosensitive
Direct effects
Radiation interacts with target cell directly
Indirect effects
Radiation comes in and interacts with water which creates free radicals which interact with our cells
Fractionation theory
Giving multiple doses over a period of time rather than one large dose is better
Repopulation and protraction
When doses are lowered over time the normal non targeted tissues can heal themselves
Mutagenesis
Radiated fruit flies to see changes in genes but changes identical to what we see in nature just sped up
1927
Oxygen effect
Increased presence of oxygen increased radio sensitivity of cells
NRC
Nuclear regulatory commission
FDA
Good and drug administration
NCRP
National council on radiation protection and measurement
ICRP
International committee on radiological protection
Roentgen
Ionizations in the air and gamma rays only
1928
2.58x10^-4 coloumbs/ kilogram
Replaced by coulomb/kilogram
RAD
Radiation absorbed dose
1953
100 erg/g
Replaced by gray
REM
Radiation equivalent to man-measures biological response
Replaced by sievert
Cosmic radiation
Gets worse as higher in atmosphere
Sun, stars, outer space
Terrestrial radiation
Inside earth, uranium, granite
Internal radiation
Food: bananas, beer
Artificial radiation
Nuclear power, X-rays
What percent of a persons overall radiation exposure is from medical procedures?
50%
Average annual dose in the US
6.2 mSv
Per day person gets .017 mSv
Occupation limit
50 mSv
Student limit
1 mSv
What is the lowest frequency EM waves
Radio waves
What is the highest frequency EM waves
X-rays and gamma rays
Alpha particles
Emitted from atoms as a process of radioactive decay Made of two protons and two neutrons Positive charge Low ability to penetrate matter Lose energy quickly Easily absorbed by skin, paper
Bets particles
Essentially electrons in motion
Emitted from atoms as a process of radioactive beta decay
Medium ability to penetrate matter
Less likely to interact with matter than alpha particles
Can be shielded with wood or lead shielding
Gamma rays
Radiation oncology Similar to X-rays-come from nucleus Emitted from nucleus of cell Highest frequency and shortest wavelength High energy
Skin erythema
Unit used from 1900-1939 to measure radiation exposure
Coulomb
Basic unit of electrical charge
Air kerma
Acronym for: Kinetic energy released in matter Kinetic energy released in material Kinetic energy released per unit mass Expresses radiation concentration transferred to a point
DAP
Sum of total air kerma over exposed area of patients surface
MGy-cm^2
Absorbed dose
Amount of energy per unit mass absorbed by an irradiated object
Biological damage
Absorbed dose is dependent on:
Atomic number of the tissue
Mass density of the tissue
Energy of the incident photon
Equivalent dose
EqD=D xWr
Sv=Gy xWr
Radiation weighting factor
Dimensionless factor used for radiation protection to account for differences in biological impact among various types of ionizing radiation
Linear energy transfer
Amount of energy transferred in average by incident radiation to an object per unit length of track through the object
How much energy it gives off as traveling
High LET=more damaging
Low LET=more picky
KeV/um
Effective dose
EfD=D x Wr x Wt
Sv=Gy x Wr x Wt
Tissue weighting factor
Takes into account the relative detriment job to each specific organ and tissue
