Chapter 9 Flashcards
What is Radiation?
Energy transmitted by waves through space or through matter.
What is Energy?
Ability to do work
What is Ionization?
Any process by which a neutral atom gains or loses an electron thus acquiring a net charge.
Radiography
making of records of internal structures by passing x-rays through the body to act on specialized film or digital image receptor
ALARA
As Low As Reasonably Achievable
Always wear a………
Radiation monitoring badge
Two basic sources of ionizing radiation
Natural background and Human made
Examples of Natural radiation
Radium, radon, cosmic rays from the sun, uranium
Examples of Man Made radiation
nuclear, radionucleides, x-rays, dental x-rays
What is an x-ray?
form of electromagnetic radiation
travel at the speed of light
bundles of energy moving as waves through space….deposits energy randomly
For an x-ray to be produced you must have?
- Source of electrons
- Force to move them rapidly
- Something to stop this movement rapidly
Thermionic emission
when the filament heats up so hot that it is burning off electrons
What is the filament in the cathode assembly made of?
thoriated tungsten
what does mA stand for?
milliamperage
what does KV stand for?
kilovoltage
Once s-rays strike matter 1 of 3 things can happen
- they can be absorbed
- they can transfer some energy then scatter
- pass through unaffected (exit or remnant radiation)
Classic Coherent Scatter (Thomson)
- Energy less than 10 KeV
- incoming x-ray photon strikes an atom and is absorbed exciting the atom which release another x-ray photon of the same energy but goes in a different direction.
- travel until srike anything in its path
- results in NO energy transfer to the patient
Scattering
change in direction
Photoelectric effect
- Incoming x-ray photon strikes an inner shell electron and ejects it from its orbit around the nucleus. Creating an ION PAIR.
- Atom that lost electron is now positively charged and released electron termed photoelectron continues to travel until combines with matter.
- all energy is completely consumed which presents the greatest hazard to the patient.
What is an ion pair?
two opposite charged ions (+,-)
Compton Scattering
- incoming x-ray photon strikes target atom and uses portion of its energy to eject an outer shell electron
- remainder of photon’s energy proceeds in different direction
- Results in Compton or “recoil” electron which travel until it strikes matter
- most occupational exposure comes from Compton scatter
heterogeneous
high and low energies
What is a rad?
radiation absorbed dose
What does a rad do?
measures the amount of radiation a person or body part absorbs as xrays pass through the body
What is the SI unit for rad?
Gray
How many rads in 1 gray (Gy)
100
What is a rem?
Radiation equivalent man
What is the SI unit for rem?
Sievert
How many rems in 1 Sievert (Sv)
100
What is the SI for curie?
Becquerel
How many Becquerel (Bq) in 1 Curie (Ci)?
3.7x10 ^10
CDRH
Center for Devices and Radiological Health
NCRP
National Council on Radiation Protection and measurements
MPD
Maximum Permissable Dose
