The Generation of X-Rays:

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Chapter 3

• The Generation of X-Rays
• The X-Ray Machine

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The X-ray Machine

• The x-ray machine is divided into three separate
  circuits, each having a specific function but
  collectively having one goal - the production of
  a controlled x-ray beam.
• The three circuits are
• Primary or tube filament regulating circuit
• Secondary or tube kilovoltage regulating circuit
• Timing circuit

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Transformers

• A transformer is an electrical device with no
  moving parts operates on the principle of
  mutual induction that transmits current from one
  circuit (primary circuit) to another (secondary
  circuit) that are not electrically or physically
  connected.
• The two are magnetically connected in that they
  are both wound around the same iron core.

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Transformers

• Transformers are made up of four parts
• Primary coil
• Secondary coil
• Core
• Insulation
• In transmitting the current from the primary
  circuit to the secondary circuit, alterations are
  made in the voltage amperage.

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Transformers

• This is due to the conservation of energy. A
  transformer that raises the voltage is a step-up
  transformer one that lowers voltage is a
  step-down transformer.
• The determining factor in whether a transformer
  is step-up or step-down to what extent it
  performs either of these tasks is the relative
  number of windings in the primary secondary
  coils.

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Transformers

• If there are more primary windings than secondary
  it is a step-down transformer, conversely if the
  number of secondary windings is greater than the
  number of primary windings it is a step-up
  transformer.

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Transformers

• Recall that when voltage goes up, the amperage
  goes down. Therefore a step down transformer will
  have increased amperage coming out.
• We can decrease both the amperage the voltage
  by using resisters.

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Transformers

• The amount of voltage increase or decrease when
  using transformers can be calculated using the
  following relationship (which does not account
  for transformer loss)
• Applied voltage of primary windings
  Delivered volts of secondary windings

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Transformers

• For example, if a transformer has 10 times as
  many primary windings as secondary (step-down)
  110 volts are applied to it. What is the
  delivered voltage?
• Applied voltage of primary windings
  Delivered volts of secondary windings
• 110 10 X 1
• 10X 110
• X 11 Volts

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Transformers

• According to the Law of Conservation of Energy,
  energy can neither be created or destroyed but
  can be changed to different forms.
• The unit of electrical energy is the watt, which
  is the product of voltage times amps.
• Volts X Amps Watts

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Transformers

• Or substituting
• Volts X Amps(primary) Volts X Amps(secondary)
• We can therefore see that an increase in voltage
  will mean a corresponding decrease in amperage.
• A transformer delivering 500 times the applied
  voltage will deliver 1/500th of the applied
  amperage

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Autotransformers

• A variable or autotransformer is a transformer
  with a single core. It allows us to fine tune the
  amount of amperage voltage. Current is supplied
  to this coil from an incoming line the voltage
  for each turn of the coil is calculated as
• Applied Voltage Voltage Per Turn
  of Turns

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Autotransformers

• For Example, if an autotransformer has 100 turns
  in the coil and 100 volts were applied. What
  would be the voltage for each turn?
• Applied Voltage Voltage Per Turn
  of Turns
• 100 1 100

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Autotransformers

• This is the fine tuner and on a whole, will be
  increasing voltage for x-ray production.

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PRIMARY or TUBE REGULATING CIRCUIT

• This functions to accomplish the first essential
  for the generation of x-rays
• The source of electrons (thermionic emission or
  the boiling off of electrons).

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The Primary or Tube Filament Regulating Circuit

• The parts of the circuit are
• Incoming voltage supply - 110 or 220 volts.
• Choke coil voltage regulator (variable resister)
  - it decreases both voltage amperage.
• Voltmeter or Ammeter.
• Filament or Step-down transformer - lowers the
  line current to 3-10 volts 3-5 amps.
• Cathode filament of the tube

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The Secondary or Tube Kilovoltage regulating
Circuit

• This functions to accomplish the second third
  essentials for the generation of x-rays
• The means of accelerating the electrons
• Stopping them with great impact

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The Secondary or Tube Kilovoltage regulating
Circuit

• The parts of this circuit are
• Incoming voltage Supply-110 or 220 volts
• Autotransformer - step-up
• Peak kilovoltage meter
• Power or step-up transformer to increase incoming
  voltage to 30 to 120 kV
• Rectification system-converting from AC to DC
  current
• X-ray tube
• Milliammeter - measuring the of e- passing from
  the cathode to anode

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The Timing Circuit

• This functions to control the predetermined time
  that the high voltage is applied to the tube,
  therefore controlling the time that x-rays will
  be produced.
• It is attached to the secondary circuit.
• The timing circuit is completely independent from
  the primary secondary circuits.