Midterm Study Guide Flashcards
Physics involves what two things?
Matter, energy
This part of physics occupies space
Matter
Energy has the ability to do _____
Work
List the three atomic parts:
- Protons (+)
- Neutrons (neutral)
- Electrons (-)
The # of protons = what?
The atomic number
1 proton (#1 on table of elements)
Hydrogen
The ___ number = protons + neutrons
Mass
When an element is the same (same number of protons), but the mass number is different (different # of neutrons) it is called an ______
Isotope
When you change the number of ELECTRONS this is called ____
Ionization
More electrons = (__) ion, less electrons = (__) ion
-, +
What do the letters stand for? E=MC^2
Energy = Mass(Constant^2)
Constant is what?
Speed of light
There are many forms of energy. This type is created by movement (windmill)
Mechanical
This type of energy is “stored energy”, as is pressure loading a spring
Potential
Energy in motion (such as a roller coaster) is known as _____
Kinetic
A battery can be categorized as ___ energy
Chemical
___ energy is movement of electrons (such as power wires)
Electrical
____ energy is “in the tight bonds of atoms”. Ex: bomb
Nuclear
Energy that holds electrons in their orbits around the nucleus
Binding energy
Energy that moving electrons possess in their orbit
Centripetal energy
The closer the nucleus, the ___ the binding energy and the ___ the centripetal energy
Greater, lower
The three components of the electromagnetic spectrum:
- Wavelength
- Frequency
- Energy
____ is measured as the distance from crest to crest on a “wavy” line
Wavelength
____ = frequency x wavelength
Velocity
Frequency and wavelength are ____ proportional. One gets larger the other gets smaller
Inversely
Frequency and Energy are ____ proportional. They both get larger or smaller together
Directly
Frequency is measured in ___
Hertz (Hz)
The discoverer or developer of X-Rays
Wilhelm Roentgen (1895)
These are electrically neutral, travel straight and at the speed of light, can cause ionization in matter, cause fluorescence (light from crystals), cannot be focused by a lens, produce changes in matter, and produce secondary/scatter radiation
X-rays (these are their properties)
In general, the # of something per area is called ____
Density
When radiation can go THROUGH the object, that object is considered radioLUCENT. This results in an area of ____ radiographic density (black area on film)
High
An object that can stop the radiation from going through it is considered radioopaque. This results in an area of ___ radiographic density (clear/white on film)
Low
The negative end of the X-ray tube is called _____, the positive end is called ____
Cathode, anode
The ____ on the cathode end of the tube heats up to 2,200 degrees to release electrons
Filament
The release of electrons from the filament is called ___ emission
Thermionic
This is a rotating part of the X-Ray Tube, made of tungsten due to it’s high melting point. This is where the “X-rays” are made
Anode
____ are created by getting the electrons up to 1/2 the speed of light and smashing them into the anode
X-rays
The ___ motor rotates the anode at 3,600 RPM
Stator
Why do they have the anode rotate?
Dissipates heat
Current is measured in ____
Amperes (amps)
mA stands for?
Milliamperes (milliamps)
This is a measure of the current through the filament. It controls the NUMBER of electrons that are boiled off
Milliamps (mA)
Force is measured in ___
Voltage (V)
This controls the SPEED of electrons and energy of the x-ray
Force (kV)
Peak force, AKA ____
kVp
When we set the voltage on an x-ray machine we call it ____
Kilovolts peak (kVp)
What are the 3 settings to get an image via x-ray?
- mA (current)
- kVp (peak force)
- Time
The Big Formula?
mA x Time(S) =mAS
If you increase the mAS you ____ the density
Increase
So, doubling the mAS would ___ the radiographic density
Double
The ____ interaction is when electrons interact with the nucleus, the path is changed and energy is given off in the form of an x-ray
Bremsstrahlung
Tungsten is #___ on the table of elements
74
When vibration of the electrons without removing the electron from it’s shell occurs, ____ is the result
Heat
Heat is __% of the electron interactions at the anode
99%
Bremsstrahlung is __-__% of the remaining 1% of electron interactions at the anode (heat is 99%)
80-90%
This is equal to mA x kVp x S(time)
Heat units
The higher the kVp, the ____ the radiographic density (if mA and time stay the same)
Higher
If you increase the kVp by __% you will have the same effect as doubling the density.
15%
Rule of thumb for 15% kVp increase: an increase in kVp by __ in the 60-90 range will double the radiographic density
10
A variation of the intensity of the x-ray beam due to the configuration of the anode is called the ____ effect
Anode heel
An x-ray photon with energy > or = to 10 MeV (10,000 kV) strikes the nucleus of an atom. The energy of the photon is absorbed and a nuclear particle is ejected. Not seen in diagnostic radiology because of remarkably high levels of energy that are necessary for it. This is called ____
Photodisintegration
____ is an interaction of x-rays with matter at 1,000 kV. The photon hits the nucleus and 2 particles are produced, one negative electron and one positive electron (positron).
Pair production
Coherent/classical scattering of x-rays is below __ kV w/no change in energy, just direction.
5
____ scattering removes and electron (e-) and changes direction w/most of it’s energy
Compton’s
The ___ effect occurs when there is absorption of the energy and an electron (e-) is ejected. The X-ray has been stopped.
Photoelectric
3 factors of?
- X-ray photon must have more energy than the electron to knock it out of it’s shell.
- The closer the energies of the photon and electron the more likely the effect is to happen
- Electrons that are more tightly bound will increase the chances that this effect occurs (more electrons = more likely to occur)
Photoelectric effect
Increased kVp = _____ scatter
Increased (less likely that photoelectric effect will occur)
If you go up 15% kVp (to double the density), you would have to do what to your mAS to keep the radiographic density the same as it was on the first image?
Cut it in half
