Rad Biology and Safety Flashcards
What is thermionic emission?
The boiling off, or liberation of electrons
Where does the current come from to produce thermionic emission?
Step-down transformer
What is the unit of electric potential?
Volt/Voltage
What charge is the anode?
positive
What material makes up the target surface?
tungsten with rhenium
What two components make up the cathode?
filament wires and focusing cup
What charge does the cathode carry?
negative
What material is the focusing cup?
molybdenum or nickel
What material makes up filament wires?
thoriated tungsten
Where do electrons turn into X-rays?
the tungsten target
What is the Z-value of tungsten?
74
First shell of electrons?
K-Shell
Electrons have what charge?
Negative
What is the maximum number of electrons in any shell?
Orbital shell # used in 2(n)^2
What is the maximum number of electrons in the valence shell?
8 electrons
What is the blinding energy of the K-shell of tungsten?
69.53 keV (other shells L=12, M=3, N=1)
What does “A” stand for?
atomic mass
What does ionization mean?
removal of an orbit shell electron
After ionization takes place, what is the charge of the atom?
positive
What interactions are formed in the tube? (production)
Brems and Characteristic
In X-Ray production, what is the interaction with the electrostatic field of the nucleus?
Brems
In X-Ray production, describe the interaction where a high speed electron interacts with a tungsten target atom by ejecting an INNER shell electron, causing a cascade effect and ionizing the atom?
Characteristic
Which is more common, Brems or Characteristic?
Brems
Which is more common, Brems or Characteristic?
Brems
How do you calculate the energy of the new electron in characteristic radiation?
Take the energy of the K-Shell and subtract whichever shell replaces it. Ex. K=70 L=12 M=3 N=1 70-12= 58 keV is the new energy.
Difference in the binding energies of each shell.
What are types of particulate radiation?
Alpha and Beta
What is frequency?
rate of rise and fall of electromagnetic photon and is measured in unit Hertz (hz)
Every X-Ray, regardless of kV, travels at what speed?
3 x 10^8 meters/second (186,000 miles per second)
Difference between X-rays and Gamma Rays?
Source of origin
- X-ray from ionization
- Gamma from nucleus decay
Wavelength, Frequency, Energy relationships
Direct or Inversely proprotional
Wavelength and Frequency- Inversely proportional
^(most important and likely to show up)
Wavelength and Energy- Inversely proportional
Frequency and Energy- Directly proportional
mAs
- Controls patient dose
- Quantity
kVp
- Controls quality
- Energy of X-Ray
The intensity shows up only under inverse square law questions, not direct
The intensity shows up only under inverse square law questions, not direct
What is the formula for inverse square law?
Intensity 1 (SID 2)^2 -------------- = ---------- Intensity 2 (SID 1)^2
What is the formula for direct square law?
Intensity 1 (SID 1)^2 -------------- = ---------- Intensity 2 (SID 2)^2
What effects the half-value-layer (HVL)?
kVp and filtration
What is the half-value-layer (HVL)?
amount of material necessary to reduce the intensity to 1/2 of its original value
What are the photon interactions with matter?
Compton Effect Photoelectric Absorption Coherent (Unmodified scatter, Classical, Thompson) Pair Production Photodisintegration
What is another name of remnant radiation?
Exit Radiation
What interaction with matter is called, partial absorption, contains an incident X-ray photon that interacts with an outer shell, resulting in image contrast and occupational exposure? One incoming electron and two leaving?
Compton Scatter (OUTER SHELL)
What interaction with matter involves an incident X-ray photon that interacts with a K-Shell electron, involves absorption of energy, and is the primary source of patient radiation exposure?
Photoelectric Absorption
What interaction with matter causes no ionization?
Classical/Unmodified scatter
What energy level needs to be known for Pair Production?
1.022 MeV
What energy level needs to be known for Photodisintegration?
> 10 MeV
What is the technologist largest source of occupational exposure?
Compton Scatter
At what angle from the patient will the technologist receive the least exposure? (during fluoro)
At a 90 degree angle, or as close to it as possible
What is better for the patient, fractionation or protraction?
Fractionation
What is linear energy transfer? (LET)
Defines the rate of energy deposited per unit track length through an absorber
What is relative biologic effectiveness? (RBE)
Defines the ability of aerobic conditions to enhance the effectiveness of radiation.
All of the following are diagnostic imaging exposure energies, except?
Pair Production and Photodisintegration
