Image Production 2 Flashcards
What is the focusing cup made of
Molybdenum or nickle
Focusing cup
- negatively charged
- controls the path of electrons from cathode to anode
Line focus principle
- The effective focal spot is smaller than the actual focal spot
- angled design of the anode
What gets projected down to the pt
Effective focal spot
Smaller Effective focal spot ______ spatial resolution
Greater
Which will have the greatest heat capacity
Large focal spot with smallest target angle
Ex) 1.0 with 10 degree
Which target degree angle will provide greatest spatial resolution
- pick out smallest angle #*
1) 7 degrees (CORRECT)
2) 11 degrees
3) 15 degrees
4) 20 degrees
Anode target material
-tungsten (high melting point, high atomic number, ability to dissipate heat)
Selecting mA determines the number of electrons free around what
Filament
Induction motor (stator windings and rotor)
- operates rotor that spins anode during an exposure
- engaging rotor switch fires the stator in a circular motion around the outside of the tube resulting in a circular movement of the rotor within the tube
Xray beams are produced how
Isotropically (equal intensity in all directions)
Radiation emitted through the metal protective housing should not exceed what
1 mGy/hr at 1 meter
Or 100 mR/hr at 1 meter
Insulating oil
- Located outside glass envelope but inside metal protective housing
- assists in cooling xray tube
- contributes to inherent filtration
Filtration
Added + inherent = total
Back up timer
- Determines max length of exposure time for AEC exposure
- set at 150% of the anticipated manual exposure time
What is the purpose of using back up timer when using a AEC device
To protect pt if AEC beam fails to terminate exposure
Minimum response time (MRT)
time it takes for a system to respond and send the signal to terminate the exposure
Ohm’s law
V (voltage or electric potential) = I (current measured in Amps) x R (resistance measured in ohms)
Heat unit for single phase (1/2 and full wave)
1.0
Heat unit for three phase 6 pulse
1.35
Heat unit for three phase 12 pulse
1.41
Heat unit for high frequency
1.61
Parallel circuit
Find lowest value and divide by 2
Ex) 5,10,15,20
5/2= 2.5
Transformers operate on the principle of electromagnetic induction and require what to operate
Alternating current
As The number of turns of a conductor material increases ____ electromotive force is produced
Greater
Turns ratio
Ts/Tp
Located on primary low volatility side
1) AC supply
2) master wall switch
3) fuses
4) line voltage meter
5) autotransformer
6) line voltage compensator
7) pre reading kVp meter
8) exposure switch
9) exposure timer
Source for kV
Autotransformer (self induction)
When/where does voltage become kilovoltage
At step up transformer (operates on principle of electromagnetic mutual induction)
Filament transformer
- aka low voltage or step-down transformer
- located within low voltage filament circuit
- electromagnetic mutual induction
What is an example of a precision (variable) resistor
mA station
Types of exposure timers
1) mechanical
2) synchronous (capable of exposure times in multiples of 60
3) electronic (accurate)
4) mAs
5) impulse
6) AEC
Located within filament low voltage circuit
1) mA selector
2) focal spot selector
Located in secondary or high voltage circuit
1) mA meter
2) rectifiers
High frequency
- results in higher xray quality and quantity
- voltage ripple is 1% since voltage waveform is nearly constant
ADC
Performs the sampling and quantization of data
Rescaling
Processing technique used to correct for over or under exposure
Histogram
Present a graphical representation of optimal densities during an exposure and recognition of exposure data requires processing only optimal receptor exposure exposures
Values of interest
The digital data set of information that is arranged into a histogram distribution
LUT is used to as a reference to evaluate what
The raw information and to correct the luminance values
Edge enhancement
Results when the signal average includes fewer pixels in the neighborhood. Used when fine details in an image or shown with some blur
The ability of a system to provide contrast enhancement
Equalization
Another name for smoothing
Low pass filter
Occurs by averaging all pixels frequency with surrounding pixel values to remove image noise
Smoothing
Describes the contribution of all system components towards total resolution
Modulation transfer function
-resolution is best as MTF value approaches 1
Magnification factor=
Image size/object size
Equalization
Makes light areas darker and dark areas lighter
