This document provides information about x-ray generators. It discusses the key components of x-ray generators including transformers, rectifiers, and exposure timers. The transformers are used to increase or decrease voltage in the circuit. Rectifiers convert alternating current to direct current. Exposure timers control the length of x-ray exposures. The document also describes different types of x-ray generators such as three-phase generators, power storage generators, and automatic exposure control systems.

1. X-RAY GENERATORS
Presented By- PRINCE PRAJAPATI
B.Sc in Medical technology in Radiography
(Second year)

2. CONSOLE
TRANSFORMER
ASSEMBLY
X-RAY
GENERATORS
• Low voltage Transformer
• High voltage Transformer
High voltage rectifiers

3. CONSOLE

4. Transformer assembly
• The transformer assembly is a grounded
metal box fill with oil.
• It contains the low voltage Transformer for
the filament circuit and high voltage
Transformer and group of rectifiers for the
high voltage circuit.

5. TRANSFORMERS
• A transformer is a device that either
increases or decreases the voltage in a
circuit.
• Current only flows in the secondary circuit
when the magnetic field is increasing or
decreasing
• When current flow through the primary
coil it creates magnetic field in the core and
this magnetic field induces a current in the
secondary coil.

6. • The voltage in the two circuits is proportional to the number of
turns in the coils.
• A transformer can’t create energy, the power of primary circuit is
equal to the secondary circuit.
• Step up Transformer
• Step down Transformer

8. The Autotransformer
An Autotransformer consist of single
winding wound on a laminated closed core.
It works on the principle of self induction
Function:-
Provides voltage for the x-ray tube filament
circuit and convenient location for kVp
meter that measures voltage across the x-
ray tube

9. Low voltage circuit
• The filament circuit regulates current flow through the
filament of x-ray tube.
• The power to heat the filament provided by small step
down transformer called filament transformer.
• Precise control of filament heating is critical because a
small change in filament current results in large
variation in x-ray tube current.

10. High voltage circuit
• The high voltage circuit has two transformers
Autotransformer andstep up Transformer.
• Autotransformer is actuallythe kVp selector.
• Step up Transformer increases the voltage
approximately150kVp in secondary coil.
• Two meters are incorporatedinto high voltage circuit
kVp meter and mAs meter.

11. Rectification
• Rectification is the process of changing
alternating current into direct current by a
device called Rectifier.
• Rectifier allows an electrical current to flow in
one direction but does not allow current to
flow in other direction.
• The heart of solid staterectifier is a
semiconductor which is usually a piece of
crystalline silicon.

12. Full-wave
rectification
Half-wave
rectification

13. Three-Phase generators
Three phase generators produce an almost constantpotential
difference across x-ray tube.
3 basic types:-
• Six pulse, six-rectifiers
• Six pulse, twelve-rectifiers
• Twelve-pulse
• ADVANTAGE:-
1. Produce x-ray efficiently throughoutthe exposure
2. Provide much higher tube rating for extremely short
exposure.

14. Three-Phase Transformer
• A three phase transformer has three sets of
primary and secondary windings.
• The three sections of copper windings in the
primary or secondary are connected in one of
two configuration, termed Delta and Wye(star).

15. Six-Pulse, Six Rectifier
The output of secondary windingsis rectified with six
solid state rectifier.
Here three maximum and three minimum voltage in on
complete cycle, after rectification,there will be six
maximum voltages per cycle.
Ripple factor is the variationin the voltage across the
x-ray tube expressed as a percentage of maximum
value.

16. Six-Pulse, Twelve-Rectifier
This circuit also a six-pulse circuit with 13.5% theoretical
ripple factor.
This circuit has a fixed potentialto ground, advantageover
six-rectifiers circuit.

17. Twelve -Pulse
• Twelve pulse transformer looks similar to the six
pulse, twelve rectifier transformer but secondary is
not a double Wye connection; it is wye and delta
connection
• When delta and Wye connected together in the
secondary, the output of delta will lag the wye by
30° resulting twelve pulse output.
• Ripple factor reduced to 3.5%theoretically.

18. Power storage generators
• Power storage generators provide supplying powerfor the x-ray tube independent of an
external supply.
• Capacitor-Discharge Generators
• Capacitor is an electrical device for storing charge or electrons.
• In a capacitor discharge generator, standard 110 or 220V power is fed into a step up
transformer.
• Capacitor discharge unit provide very high milliampearge for very short exposure time.
• The capacitor mustbe charged immediately prior to use.

19. • Battery-Powered Generators
• In a battery power generators, a standard power
supply is used to charge large capacity nickel-
cadmium batteries.
• Direct current from the batteries does not supply
the x-ray tube directly.
• Output Of battery => DC chopper => high voltage
Transformer => rectification.

20. Medium-Frequency
Generators

21. Transformer ratings
• The rating of of a transformer statesthe maximum safe output of its
secondary winding.
• The rating expressed as the maximum safe output of its secondary
winding in kilowatts.
• If rating is exceeded, the transformer may overheat and burnout its
windings.

22. Falling load generator
• The purpose of falling load generator is to
produce an x-ray exposure in the shortest
possible exposure time by the operating x-ray
tube at it maximum kilowatt rating during the
entire exposure.
• It automatically starts the exposure at highest
mAs for selected kVp, drops the mA during the
exposure based tube heat loading.

23. Exposure Timers
• Control length of exposure
• Types
• Electronic Timers
• AEC(Phototimer)

24. Electronic Timers
• The length of exposure is determined by the time required to
charge a capacitor through a selected resistance.
• The exposure is terminated when the capacitor is charged to a
value necessary to turn on associated electronic circuits.
• Operator select the exposure time by measuring patient
thickness and estimate density of tissue.

25. Automatic exposure control
(Phototimer)
• AEC measure the amount of radiation required to produce the correct exposure
for a radiographic examinationto produce a satisfactory radiograph.
• The essential element in phototimers is a device that can detect radiation and,
response to this radiation, produce a small electric current. LOCATION;.
ENTRANCE & EXIT TYPE.
• Three such devices
1. PHOTOMULTIPLIER DETECTORS
2. IONIZATION CHAMBERS
3. SOLID-STATE DETECTOR

26. • Photomultiplier detector:-
• The detector made of Lucite, which is a material that can transmit light, The
Lucite is coated with one or more areas of a phosphor that will emit light when
irradiated with x rays.

27. • IONIZATION CHAMBER
• Always used as entrance type autotimers.
• It consist of two thin sheets of aluminium or lead foil,
air is present between two sheets.
• Before exposure charge is placed on plate

29. References:-
• Christensen's physics of diagnostic radiology.-4th ed. /Thomas S. Curry III, James E.
Dowdey,Robert C. Murry, Jr.
• Radiologicscience for technologists : physics, biology,and protection.-11th ed./ Stewart
Carlyle Bushong.

30. THANK YOU