Endterm Flashcards
Electromagnetic induction and voltage transformation, its function is to provide current at high voltage to the x-ray tube
X-ray generator
electrical power available in the hopsital or clinic provided up to?
480V
Much __ than 20,000 to 150,000 needed for x-ray production
Lower
__ are principle components of x-ray generators they convert low voltage to high voltage through a process called __
Transformers, electromagnetic induction
Effect that occurs with changing magnetic field and alternating electrical current, a reciprocal between electric and magnetic field
Electromagnetic induction
Performs task of transforming alternating input voltage to alternating output voltage using principle of electromagnetic induction
Transformers
Input ac power (voltage and current) produced?
Oscillating electrical and magnetic field
One insulated wire wrapping (primary winding) carries the__ other insulated wire wrapping (secondary winding) carries
Input load (primary voltage and current), induced output load (secondary voltage and current)
Primary and secondary windings are electrically but not __ isolated by insulated wires
Magnetically
Secondary windings are bathed in the?
Oscillating magnetic field
Ns is?
Seconday coil
Np is?
Primary coil
Vs is
Alternating input
Vp is?
Alternating output
Ns > np
Step up transformer
Ns<np
Step down transformer
Ns=np
Isolation
Is the ratio of energy production of expenditure per unit of time
Power
__ unit of power is __
51, watt (W)
The high-voltage section of an x-ray generator
contains a step-up transformer, typically with a
primary-to-secondary turns ratio of ?
1:500 to 1: 1,000.
Within this range, a tube voltage of __ requires
an input peak voltage of __ to __, respectively.
100 kVp, 200V, 100V
Is the electrical potential of earth. center tapping to ground does not affect the maximum voltage at any point in the circuit relative to the ground to 1/2 of peak voltage applied to the tube.
Ground potential
Maximum voltage st any point in the circuit for a center-tapped transformer of?
150 kVp is -75 kVp or + 75 kVp
Low kVp (__) used in mammography does not present a big electrical insulation problem
Less than 50 kVp
Consist of a single coil wire wrapped around an iron core. It has fixed number of turns, two lines on the input side and two lines on the output side
Autotransformers
Autotransformers operates on the principal of?
Self induction
Standard transformer operates on the principle of?
Mutual induction
Permits much larger increase/decrease in voltage and it electrically isolates primary from secondary circuits
Standard transformer
Has a number of taps on input and output sided to permit small incremental increase/decrease in output voltage
Switching autotransformers
X-ray tube provides an environment for x-ray production via?
Bremsstrahlung and characteristic radiation mechanism
Major components of x-ray tube
Cathode, anode, rotor,stator, glass(metal envelope), and tube housing
__ is the rate of electron flow from cathode to anode measured in __ where 1 mA = __
Tube current, milliamperes, 6.24X1015 electrons/sec
__ is used to adjust kVp produced by xray generator
Switched autotransformers
__ is provided to the input side of autotransformers and __ of the autotransformers is provided to the primary side of __
Standard alternating current, output voltage, high voltage transformer
For continuous fluoroscopy the tube current is typically _ to _
1-5 mA
For projection radiography tube currents from __ to __ mA are used with short exposure time (less than __msec)
100,1000, 100
Three major selectable parameters on x-ray generator control panel that determine the x-ray beam characteristic (quality and quantity)
kVp, mA and exposure
The sources of electron in the x-ray tube is the __ which is a helical filament of tungsten wire surrounded by a __
Cathode, focusing cup
This structure is electrically connected to the __
Filament circuit
The filament circuit provides a voltage up to __ to the filament, producing a current up to about __ through the filament.
10 V, 7 A
Electrical resistance heats the filament and releases electrons via a process called?
Thermionic emission
For diagnostic imaging, electrons from cathode filament are accelerated towards anode by a peak voltage ranging from __ to __ V (__ to__ kVp)
20,000 to 150,000 V (20 to 150 kVp)
