X-RAY TUBE AND PRODUCTION OF X-RAYS IS DESCRIBED IN DETAIL IN THIS PPT. CONTENT TAKEN FROM MULTIPLE BOOKS AND JOURNALS.

1. X-RAY TUBE
Mr. Rohit Bansal
Assistant Professor (Radio-physics)

2. CONTENT
• Introduction
• History
• Principle of x-Ray tube
• Types of x-ray tube
• Components of xray tube
• Production of xrays

3. Xray tube is a device meant for Xray production.
INTRODUCTION
An x ray tube is a vacuum tube
Contains a pair of electrode i.e cathode and anode
Cathode contains filament that releases electrons when
High voltage is applied
 Anode is made up of tungsten which attract the electrons
When the electrons released from the cathode come in
contact with the tungsten they release energy in the form of
photons
 These high energized photons are channelled through a
lead cylinder and series of filters grating of X rays

6. HISTORY
• XRAYS were discovered by Sir WC Roentgen on Friday
8th November 1895 in Germany
• At the time of discovery he was experimenting
about cathode rays when he passed current
through crooks type tube covered with card
board shield to stop any light arising from the
fluorescence of glass walls in a dark room. He
was surprised to note small glow coming from
near placed sheet of paper painted with barium
platinocyanide .He confirmed these emanation of
rays coming from the tube and named them
XRAYS.

9. PRINCIPLE
• Xrays tube is a device based on the
principle of energy conversion
• When the fast moving electron
comes in the vicinity of the heavy
nucleus it gets attracted towards the
positive charged nucleus due to
Columbic force and gets deviated
from its original path . In this process
kinetic energy of fast moving electron
is lost and converted into heat(99%)
and X-Ray energy (1%).

10. HISTORY AND
DEVELOPMENT OF XRAY
TUBE
• 1895: X-rays were discovered from experimental discharge tube called
as Crooks tube or Cold cathode tube.
• In 1913: Crooks tube was improved by William Coolidge c/as Coolidge
tube or Hot cathode tube.
• In 1915: Hooded anode tube.
• In 1920: Oil cooled tube.
• In 1929: Rotating anode tube.
• In 1932: Grid controlled stationary anode tube
• In 1937: Grid controlled rotating anode tube.
• In 1959: High speed tube.

11. CONT....
• In 1962: Rhenium alloyed tungsten composite anode tube.
• In 1967: Mammography unit with Mb anode.
• In 1971: Glass metal tube with Mb anode.
• In 1973: Three layer anode tube.
• In 1979: Metal ceramic tube.
• In 1981 : Three focus tube.
• In 1989: Direct anode cooling with noiseless rotor.
• In 1989: Introduction of helical CT ube ( by Sienmens).
• In 1990: MRC tubes ( Maximus rotalix ceramic) by Philips.

12. CONT.....
• In 1998: Development of grid control
rotatingAngiography X-tay tube cooporaled with
PuliseFuoroscopy applicable cathodeanode for
angiography by Toshiba.
• In 1999: Double focus stationary anode x-raytube for
mobile c-arm.
• In 2000: Food inspection x-ray tube.
• In 2002:High speed rotation bearing rotatinganode
tube for angiography.
• In 2003: Micro-focus X-ray tubewith power supply
used forinspection technology.
• In 2006: there is introduction of STATRONx-ray tube
by Siemens.

13. TYPES
1.On the basis of cathode
• Cold Cathode Tube ( Crooke’s tube)/(Gas Discharge
tube)
• Invented by British physicist William Crookes in early
1870.
• Crookes tube also called cold cathode to because they
do not have a heated filament in them that release
electron
• Early X-Ray tube called as gas tube because :-
• Its action depends on the presence of small residual
amount of gas present in it and the radiographer kept a
selection of tubes of various mAs values on a reck.
• When the change in mAs was required the radiographer

14. COMPONENTS
• Cathode is on the right anode is
in the centre with attach heat
sink at left.
• The device at the top is a
softener used to regulate the gas
pressure.
• An aluminium cathode plate
having curved shape to created
the beam of electrons.
• A platinum anode target to
generate Xrays.

16. LIMITATIONS
1.Low output
2.Unstable X-Ray production.
3.This tube cannot produce x- rays
continually.
4.We cannot operate the kVp and the mAs
independently as there is presence of
gases.

17. 2. Hot cathode tube ( Coolidge
tube)
• The coolidge tube was improved by William
Coolidge in 1913.
• In the coolidge tube electrons are produced by
thermionic effect (on heating metal element emit
electrons).
• It permitted:-
• Greater flexibility in the quality and quantity of X-
Ray produced.
• Greater tube stability during the production of X
rays.
• Smaller tube size.
• Longer tube life.
• Coolidge tube is the prototype of modern X rays
tubes being used today.
• An early problem with this mode cathode to the

18. 2. ON THE BASIS OF ANODE
• Stationary Anode Tube
• Anode is stationary.
• Small focal spot area.
• Low heat loading.
• Mostly used in dental unit and
portable machine.
• Rotating AnodeTube
• Anode rotate at very high
speed.
• Large focal spot area.
• High heat loading
capacity.
• Mostly used in diagnostic
machine.

19. COMPONENTS OF
MODERN XRAY
TUBE
1.Tube support
2.Glass envelope
3Cathode
4.Anode
5.Protective housing

20. 1. GLASS ENEVLOPE
• The glass envelope is made up of pyrex
glass.
• The envelope maintains a vacuum inside
to to allow more efficient Xray production
and longer tube life.
• The primary function of envelope is to
provide support and electrical insulation for
anode and cathode assemblies.
• At point where primary Xray beam exit
glass is thinner.

21. 2. TUBE SUPPORT
• Xray tube and housing assembly are quite heavy and
therefore require a support mechanism so that the
radiologic technologist can position it.
• There are 3 methods of X-Ray tube support :-
1. Ceiling support system
2. Floor to ceiling support system
3. C-arm support system

22. CEILING
SUPPORT
SYSTEM
The ceiling support
systemis probably the
mostfrequently used.
• It consistofof 2
perpendicular sets
ofceiling-mounted
rails. This allow for
both longitudinal and
transverse travel of
the x-ray tube.

23. FLOOR TO
CEILING
SUPPORT
SYSTEM
The floor to ceiling
support system has a
single column with
rollers at each end and
one attached to a ceiling
mounted rail and other
attached to a floor
mounted rail. The tube
slides up and down as a
coulmn rotates

24. C-ARM
SUPPORT
SYSTEM
Interventional radiology
suites of an hour are
equipped with c-arm
support system so called
because the system is
shaped like a letter c
.These system are
ceiling mounted and
provide for very flexible
x-ray tube positioning .

25. 3. CATHODE
.It is the negative electrode of
the X-ray tube
.It consist of a metal structure to
support the filament.
:It consists of
1. Filament source of electrons
2. Connecting wires which
supply the voltage about (10
volt )and current (3 to 5 A).
3. Metallic focusing cup.

26. FILAMENT
• Cathode filament made of
thin tungsten wire which is a
source of electrons.
• It works on the phenomena of
thermionic emission.
• Tungsten spiral wire of
diameter 0.2 mm.
• Length 1.0 cm.
• Diameter of spiral 0.2 cm.

29. TUNGSTEN
• Tungsten is used as filament material because of
following reasons:-
1. It has a high melting point of 3370 degree Celsius
2. Less tendency to vaporize.
3. High tensile strength means it can be drawn into wires.
4. High thermal conductivity and specific heat.
5. Appropriate threshold or work function.

30. FOCUSING CUP
• It is a device surrounding the cathode filament in the Xray tube.
• This is actually a third electrode in the tube called a wehnelt electrode.
• Because of the forces of mutually reversion of a large number of
electrons this electron stream would tend to spread itself out and result
in a bomb bardment of large area on the anode of Xray tube.
• This is prevented by focusing Cup which surround the filament.
• If this electrode is not present the electrons wood heat the anode over a
large very large area.
• It is usually made up of nickel because of:-
1. Light weight
2. Poor thermal conductivity
3. High melting point.

32. 4.ANODE
• It is a positive electrode of X-Ray tube.
• It consists of a target (focus spot) and cylindrical copper block or tungsten.
• Made up of a small plate of tungsten 2 or 3mm thick that is embedded in a large
mass of copper.
• Square or rectangular in shape with each dimension usually greater than 1 cm.
• We use tungsten as a target material because of the following reasons:-
1. High atomic number( 74).
2. High melting point( 3370`c )
3. High thermal conductivity.
4. It does not vaporize easily.

34. TARGET MATERIAL
• Target material is based on the three
characteristics:-
1. Atomic number:- must be high so that it
results in a high efficiency in X Ray
production
2. Thermal conductivity:- must be able to
conduct heat away from the target.
3. High melting point:- must be able to

35. FOCAL SPOT
• It is the area actually bombarded by electron stream
on the target.
• It can be larger or smaller in size.
• Small focal spot is required for producing good
radiographic detail but it may also lead to
overheating of target.
• Where as large focus port allows greater heat
loading but does not produce sharp image.
• This problem was solved in 1918 by the development
of line focus principle.

36. LINE FOCUS PRINCIPLE
• Explain the relationship between actual focal spot on the anode surface
and the effective focal spot size.
• It states that the effective focal spot is smaller than the actual focal spot.
• By angling the face of anode target a large actual focal spot size can be
maintained and a small effective focal spot can be created.
• Typical anode angle 6- 20° .
• Advantages:-
1. Provide small effective focal spot for good radiographic details.
2. Provide large actual focal spot for greater heat loading.

38. TYPES OF ANODE
1.Stationary Anode
• lt is a solid bar of copper with an insert of tungsten on the face of bar
opposite the cathode filament.
• Advantages:-
• compact unit
• Low cost
• Limitations:- since area covered by electrons beam on the target for example
x-ray source and the area over which heat is supplied are the same so we
cannot use higher electrical loads or high mAs.
• Application:- dental x-ray sets small portable and mobile X units with limited
output.

41. ROTATING ANODE
• An Xray tube in which the anode rotates when Xray
are being produced.
• This means that there is a larger effective target
surface of anode which can be able to generate the
X-rays.
• Constructed of tungsten target , molybdenum and
graphite.

43. 5. PROTECTIVE
HOUSING
• The Tube housing function is to containing and supporting
the Xrays tube and oil and protecting them from external
damage.
• The metal tube has two other important function to
perform:-
1. Firstly it it provides a completely and encircling metallic
shield because it is firmly connected electrically to earth
potential protects the user from any possibility of
electrical shock.
2. The second purpose of tube shield is to afford protection
to radio grapher and patient against unwanted radiation.

45. PRODUCTION OF XRAYS
• Xrays are produced by energy conversion when a fast moving stream of
electron is suddenly be accelerated in the target anode of xray tube.
• Electrons produced at cathode can be accelerated by a high potential
difference towards anode.
• Electron produced by heated tungsten filament and accelerated across tube
to hit the tungsten target where Xrays are produced.
• Fast moving electrons are suddenly stopped by impact on the metal target.
• High speed electron lose energy by two processes :-
1. Reaction of electrons with nucleus of tungsten atoms.
2. Collision between high speed electron and electrons in the shell of target
tungsten atom.

47. TYPES OF XRAYS
• When a high speed electron lose energy
in the target of Xray tube two processes
of xray generation occcur :-
1. General radation/ Bremsstrahlung
radiation.
2. Characteristic radation.

48. BREMSSTRAHLUNG
RADIATION
• When an electron pass near the nucleus of tungsten atom the positive charge of nucleus acts on negative
charge of electron.
• The electron is thus deflected form its original position.
• Electron may lose energy and slows down when its direction changes.
• The kinetic energy lost by electron is directly emitted in the form of photon radiation.
• The electron only gives up part of its energy in the form of radiation - braking radiation.
• Wavelength of radiation produced depends on energy of electron and the potential difference .

50. CHARACTERISTIC
RADATION
• The electron bombarding the target eject electron from the inner orbit of target atom.
• Removal of an electron from the tungsten atom causes the atom to have an excess
positive charge :- a positive ion.
• In the process of returning to its normal state the ionized atom of tungsten may get rid
of excess energy in two ways :-
1. An additional electron may be expelled by the atom and carry excess energy (there is
no x ray production in this way)
2. The atom emits radiation that has a wavelength in the range of diagnostic X-rays
called characteristic Xrays.