Intro Flashcards
What is stochastic effect
occur BY CHANCE, regardless of TLV
Signif of radioactive materials
- MIXES with air, food, water
- SIGNIF EXTERNAL sources that may radiate INTO our BODIES
- DIFFICULT to remove if enter ENVIRONMENT
Radiation?
process in which energetic particles travel through medium or space
Types of Radiation
- Ionizing
- Non-ionizing
Ionizing or Non ionizing Radiation:
UV-C
Ionizing
T/F Ionizing has more energy than non-ionizing
True; kaya non kasi not enough energy to produce IONS
T/F Cosmic waves are examples of non-ionizing radiation
F; Ionizing pa rin, natural radioactive material eh;
What is the lower energy limit for ionizing radiation (in keV)
> 10 keV
T/F GAMMA rays are ionizing radiation
True!
Extremely low-frequency waves are examples of _____
Non-ionizing radiation
T/F UV-B and UV-C are ionizing
F, UV-B is NON-IONIZING
Radioactive elements contain nucleus that is _________ compared to most elements
UNSTABLE; can’t be sustained
RADIATION (Release energy)
happens in order for radioactive atom to ATTAIN STABLE STATE
Differentiate PHYSICAL from BIOLOGICAL half-life
Physical is the reduction of radioactivity level due SOLELY TO RADIOACT /DECAY/;
Biological- gradual reduction of radioact isotopes by KIDNEY, RESPIR, PERSPI
2 bone seekers with half-life rather long
Radium and Strontium!
This is the radioactive half-life for animals and plants in the area; less precise than physical and biological hal-life;
Radio-ecological half-life
They have been known to hyper-accumulate radiocesium fro soil
Fungi
T/F High or low pressure or temp has no effect on dcay rate of radiisotope
True
For radioactive compounds, we have to CALCULATE the biological half-life because the mass of theisotope is usually on the nanogram scale much too small to measure directly
TRUE
EFFECTIVE Half-Life is defined as the period of time required to reduce the radioactivity
level of an internal organ or of the whole body to exactly one half its original value due to
___________
BOTH ELIMINATION AND DECAY
Formula for Effective half-life
1/E=1/P + 1/B
Sources of Radiation types
Naturally-occuring Man-made Medical Industrial Secondary
Frequent fliers ad people living in higher altitudes are more exposed to this (as a result of interaction bw CERTAIN GASES in earth’s atm and COSMIC RAYS)
Cosmogenic NORM
Uranium and Thorium are original terrestrial norm
TRUE; along with K-40
Majority of Natural dose from NORM is this type; 1000 microSv per year
Terrestrial
T/F Terrestrial NORM does not cause adverse health outcomes
True;
Does not exceed biological exposure index for radiation
_________ is ionizing radiation constantly present in nat’l environment
Background radiation
Activities that increase exposure of people to Ionizing rad (examples of NORM)
burning coal, fertilizers, oil & gas production
T/F Radium and Radon come from what source of radiation
NORM
Technically enhanced norm (TeNORM)
radionuclides which have been produced through natural processes BUT CONCENTRATED BY HUMAN ACTIVITY (Build-up)
Man-made radioactive materials
in nuclear medicine, biochem, manufacturing and agriculture; BY BOMABARDING ELEMENT w PARTICLE
___ most efficient particle
Neutron; no charge, passes thru nucleus
Medical sources
Xray machines;
Kinetc energy->radiant energy when particle is stopped(by dense materials)
Radioisotopes
Formation of ions in cells it passes through
Industrial sources
extermination of insects;
electricity generation
nuclear weapons and nuclear reactors (manily relying on splitting/fissionig uranum and plutonium nuclei)
Secondary sources
Scatter radiation
Ionizing radiation 2 TYPES
Particulate
Electromagnetic
Particulate radiation
Alpha, Beta, Neutron radiation
MAY MASS
Electromagnetic radiation
No mass and no charge!
Alpha particle is identical to nucleus of what element
He!
Why is alpha radiation substances only internal hazard
Limited penetration externally (CAN BE SHIELDED BY SKIN,CLOTHES, PAPER) but is completely absorbed into bodily tssues when taken into body
Beta radiation
charged particles from atom’s nucleus identical to electrons; (N transformed INTO PROTON AND ELECTRON)
Beta radiation is only internal hazard;
False! External din, can penetrate dead outer layer of skin and deposit energy in active skin cells
Energy of beta rad is ___
while energy of Alpha rad is
several KeV to 5 MeV;
1.5-11 MeV
Example of beta decay
H-3 To He-3
Only natural source of neutrons; nuclear reactor
one fission event can cause chain reaction
SPONTANEOUS FISSION
What is best used for shilding vs Netron radiation
Materials containing hydrogen atoms! (PARAFFIN WAX and PLASTIC)
PHOTON RADIATION can penetrate deeply and only be reduced in intensity by materials such as ______ or _______
Lead/Steel
Example of photon emission
Co-60 to Ni-60
What type of electromag rad is widely used to treat most cancers
Photon rad bc it penetrates bodily tissues when source is OUTSIDE body
T/F Gamma rad is emitted when nucleus undergoes transition from lower to higher energy state
False;
HIGHER TO LOWER;
Gamma rays-Nucleus still has excess energy to get rid off after a decay reaction so ENERGY IS LOST
BY EMITTING PULSE OF ELECTROMAGNETIC RADIATION (mostly cosmic rays)
Xrays and gamma similar except
ORIGIN;
Gamma in atomic nucleus;
Xrays electron interactions
X-rays ____ energy compared to Gamma
lower
How are xtrays produced
accelerating e- across large potential difference,—–then decelerated quickly in dense, material;; Electrons collide with material-> Some paths deflected-> production of XRAYS
Bremsstrahlung radiation resistant material
TUNGSTEN
Photon interaction
Photoelectric
Explain Photoelectric effect
<100 keV energy
Photon GIVES ALL ENERGY to an electron, which then leaves
the atom or molecule
The photon ALSO disappears
Explain Compton effect (energies
from about 100 keV to approximately 20 MeV)
FOR RADIATION THERAPY;
P&E collide as particles; Photon new direction with reduced energy, electron remainder/extra energy
Explain Pair production
most significant when photon energy ABOVE 20 MeV;
Photon disappears, E-P pair appearsl
Neutron interaction
Inelastic collision
Explain Inelastic collision
NUCLEUS colliding with NEUTRON– nucleus gets higher energy level;
release energy by gamma/beta particle or both
Explain NEUTRON CAPTURE/ Radiative capture
An affected nucleus may ABSORB THE NEUTRON and eject energy as gamma or x-rays or beta particles or both
• SECONDARY PARTICLES CAUSE IONIZATION
Explain Fission
HEAVY nucleus ABSORBS the Neutron and SPLITS into two
lighter nuclei that are almost always radioactive
RXN gives LARGE amount of energy and emits two
or more neutrons, and gamma rays.
Explain Fission
HEAVY nucleus ABSORBS the Neutron and SPLITS into two
lighter nuclei that are almost always radioactive
RXN gives LARGE amount of energy and emits two
or more neutrons, and gamma rays.
