x-ray circuit

1
Operating console

• Set x-ray tube current and voltage
• Controls line compensation, kVp, mA and
  exposure time
• (mAs) via digital meters
• - Make the useful x-ray beam on its proper
  quantity and quality.
• Radiation quantity measured in ( mR / mAs )
• Refers to the number of x-rays or intensity of
  the x-ray beam.
• Radiation quality is measured in ( kVp )
• - Refers to the penetrability of the x-ray beam.

2
Operating console

• -usually provides for control of
• kVp- kilovoltage peak
• mA- milliamperage and the
• Exposure time

3
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4
Operating Console -Line Compensation

• Incoming Line Voltage (Mains)
• Electricity supply in US is 60 Hz AC, with a
  nominal
• rms of 200 240 volts
• Polarity reverses 120 times/sec
• Voltages constantly fluctuate as resistors are
  activated
• in circuit in accordance with Ohms Law
• Can vary 5 affecting x-ray production
• Supplied in the form of a three-phase power
  cycle

5
Autotransformer

• -has a single winding and is designed to supply a
  precise voltage to the filament circuit and to
  the high voltage circuit of the x-ray imaging
  system.
• - Works on the principle of electromagnetic
  induction.

6

• Supplies precise voltage to the high voltage
• (secondary) and filament circuits
• -Good for controlling voltage on low voltage side
  of x-ray circuit
• -Follows the transformer law

7
Autotransformer
8
Autotransformer Law

• Vs

Ns

Vp
Np
Where Vp - the primary voltage Vs- the
secondary voltage Np - the no. of windings
enclosed by primary connection Ns the no. of
windings enclosed by the secondary connection
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Autotransformer
c
Example If the transformer is supplied with 220
volts to the primary connections , which enclose
500 windings, what is the secondary voltage
across bb1 (500 windings), cb1 (700 windings),
de (200 windings)?
b
a
d
e
a1
b1
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Vp 220v BB1 500 windingsNp 500 windings
Cb1 700 windings DE 200 windings

• Answer
• BB1 Vs Vp ( Ns/ Np )
• 220V ( 500/ 500)
• 220V ( 1 )
• 220V
• CB1 Vs 220V ( 700/ 500)
• 220V ( 1.4)
• 308V
• DE Vs 220V ( 200/ 500)
• 220V ( 0.4)
• 88V

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Autotransformer
c
b
a
A, A1 primary connections that conduct input
power to Autotransformer C Increases voltage
due to proximity to end and number of turns
encased by the connections E Decreases voltage
d
e
a1
b1
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To be continue