Physics for radiography Flashcards
3 Basic form of matter
Solid , liquid ,and gas
The quantity of matter that makes up any physical object
Mass
Located in an orbit around the nucleus of an atom
Electron
What’s a negative (-) electrical charge
Electron
Considered fundamental particles of atoms
Proton and neutron
When a neutral atom gains or loses an electron, the atom is said to be
Ionized
Mechanical energy can be classified as either kinetic energy
Potential energy
X-ray consist of
Electromagnetic energy
X-ray with greater energy have a shorter ___ and are more penetrating
Wavelength
Which electromagnetic energy has the shortest wavelength
Diagnostic rays
Characteristics of X-rays
They are highly penetrating and invisible
They travel in straight lines at the speed of light
Smallest possible unit of electromagnetic energy
Photon
The common unit of measurement for the potential difference across an X-ray tube is
volt
The purpose of a transformer is
Increase or decrease voltage
Which electron shell in the atom is most important for the production of X-ray
K
The name of the innermost shell of an atom that is important in radiology
K-shell
What’s the atomic name of the particles that circle the nucleus of the atom
Electron
Electrons are held in place in their shell by ?
Binding energy
One of the most important elements used in the production of an X-ray is
Tungsten
When an electron is removed from an atom in the human body the process is
Ionization
The official name of the type of X-ray energy that occurs in high frequency sine wave
Electromagnetic
In a sine wave the name given to the distance from one crest of the wave to another crest is
Wavelength
Unit of electromagnetic frequency is
Hertz
In the us and canada public utilities deliver electrical current at what frequency
60 cycles for 60 hertz per sec
Diagnostic X-ray consist of what type of radiation on the electromagnetic spectrum
Ionizing
What type of wavelength do X-rays have
Very short
What type of frequency do X-rays have
Very high
5 characteristics of X-ray
1 have no más
2. Highly penetrating and invisible
3. Electrically neutral
4 travel in straight line
5 can ionize matter
Current is the quantity of electrons flowing in an electrical circuit . Current is measured in
amps or milliamperes
Potential difference is the force behind the current in an electrical circuit. This force is measured in
Volts or kilovolts
Typical X-ray tube operate in what kilo voltage range
50-125 kilovolts
Typical X-ray tube operates in what milliampere range
50-500 milliamperes
What type of current is delivered to homes in the us and Canada
Alternating
The process of changing AC to DC is called
Rectification
When an electrical current uses it’s magnetic field to create a secondary current the process called
Electromagnetic induction
Name of the device that produces the high voltage needed for X-ray production
Transformer
Name the two types of X-ray transformer that can raise or lower the voltage
Step up and step down
Quantum mottle
*under exposure
When imaging system does not record the anatomy
Umbra
Actual anatomic area, body part, shown in the radiographic image
Penumbra
Unsharp edges of the umbra or body part
Compton effect
40-125 vp
As kVP goes up Compton goes up - outer shell interaction
Photoelectron
True absorption
No radiation comes out kVP goes up less photoelectron
Scatter radiation
Creates fog that reduces both contrast & the visibility of spatial resolution
4 fog
- Volume of tissue
- Higher kVP
- Density of absorbing matter - denser the body part less scatter
- Field size Collimation increased - scatter radiation fog increase
2 type of grid
Parallel and focus
Excessive absorption of useful radiation by the grid
Grid cutoff
High frequency grid that does not move during the exposure
Stationary grid
Dose creep
Rescaling without regard to appropriate exposure amount. Danger in relying on the system to fix image
Contrast resolution
Software ability to distinguish similar structure
Characteristics radiation
Created when an incoming electron interacts with the kshell electron and knocks it out of orbit
Bremsstrahlung
Created when incoming electron is suddenly slowed down , changes direction and leaves the tungsten atom ( braking)
Produce a continuous X-ray spectrum
Roentgen discovered X-rays while working with an ___tube
Crooked
An “electron cloud” surrounding the filament of the cathode is referred to as a
Space charge
Free electrons for X-ray production come from the
filament
The creation of the space charge In the X-ray tube produces
Thermionic emission
The majority of photon in the X-ray beam are created by which process
Bremsstrahlung interaction
More then 99% of the energy of the electron stream is converted into
Heat
The high speed rotation (10,000) of the anode enables
Greater dissipation of heat from high technical factor
The degree of angulation of the X-ray tube target will determine the s
Size of the actual and effective focal spot
A dual- focus X-ray tube has
2 filament and 2 focal spots
The anode heel effect is a phenomenon of X-ray production that results in
Uneven distribution of radiation within the X-ray field
Potential difference
The force or speed of the electron flow in the current
Current
Is the quantity of electrons flowing in a circuit
Ampere
Is the unit used to measure the rate, or volume of current flow in the circuit
Step up transformer
Increases voltage from primary to secondary, amperage is decreased
Step down transformer
Decreases voltage from primary to secondary, amperage is increased
