1. X-ray physics
By
Dr. Tarek Mansour

2. Content
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Introduction, history and basic physics.
How radiograph produce.
Interaction of x-ray with patient.
Formation of the image.
Processing the film.

3. Introduction, history
and basic physics.

4. Discovery of x-rays
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Discovered in 1895 by German physicist named
Wilhelm Roentgen.
He found shadow of his bone on fluorescent
screen.

6. 
X-rays are a form of electromagnetic radiation
similar to visible light but with short wave
length.

7. Radiation physics

8. Electromagnetic spectrum
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Electromagnetic radiation consists of energy in
small packets called photons.
They are grouped according to there wave
length and frequency.

10. Properties of x-rays
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Are electromagnetic
radiations composed of
small packets of energy
called photons.
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Travel at speed of light.
Travel in straight lines.
Highly penetrating.
Invisible.
Blacken radiographic
films.
Produce scatter.

11. Atoms structures
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Positively charged
protons in nucleus.
Neutrons of no charge
also in the nucleus.
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Negatively charged
electrons in various
orbits around the
nucleus.

12. Atomic number
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Lighter elements have fewer number of protons
such as oxygen.
Heavier elements have more such as lead.
The number of protons is called the atomic
number.

13. Density of matter.
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Low density matter is loosely packed with large
spaces between each atom like air.
High density matter is tightly packed with atoms
sitting close to each other like lead.

14. How radiographs are
produced

15. Production of radiograph
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X-ray are produced in the machine.
X-ray interact with the patient.
Image is recorded in the x-ray plate.

16. Production of the x-ray
radiations on the
machine.

17. The x-ray tube.
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The tube head consists of a pair of electrodes.
- A negatively charged cathode with
include a heater filaments.
- A positively charged a node with a
tungsten target.

18. Steps in x-ray production.
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Filament is heated and gives off cloud of
electrons.
A large electrical charge is placed in the
cathode/anode space causing the electrons to
race toward the anode.
When they crush into the anode it causes x-ray
to be given off.

19. X-ray machine components.
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The tube head where the x-rays are generated.
The control panel which regulate the strength
and amount of the x-rays produced and trigger
the exposure.
The power supply which provide the energy to
creates the x-rays.

26. X-ray tube head
Stationary anode.
 Found in smaller
machines.
 The target is fixed in
block of copper.
 Only capable of low
output.
 mA to 30
Rotating anode.
 Found in large machines.
 The target is rotate in
tungsten disc.
 Higher output
producing.
 mA up to 300

27. The control panel.
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The three factors that can be varied during
producing radiograph are
The kilovoltage (KV) difference applied between
the anode and cathode during exposure.
The milliamperage (mA) applied to the filament.
The duration of exposure.

28. Control panel
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Higher kv attract the electrons toward the anode by
greater force.
They smash the anode harder and produce x-ray with
higher energy and greater tissue penetrating power.
Increasing mA increase the number of electrons cloud
around the filament. Result in higher number of x-ray
produced per second.

31. How x-ray interact
with patients.

32. Three things occured
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Some x-rays absorbed.
Some pass straight through the patient.
Some scattered.

33. Depend on three things
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X-ray energy. In high kv most of x-rays pass to
the film through the patient.
Atomic number of the absorber.
Thickness and density of the object.

34. How image is formed

35. 
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As an x-ray beam leave the tube head, it fans out
and become weaker.
As the distance double, the strength is reduced.

36. Formation of the image
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The distance from the anode target to the film is
called the film focal distance.
Changing the distance affect the quantity of the
x-ray reaching the film.
Increasing the distance means that less x-rays
reaches the film.

37. Formation of image
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Low density or low
atomic number tissues
allow more x-rays
through causing more
blackening of film.
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High density or high
atomic number tissues
allow less x-ray through
causing less blackening
of the film.

38. Effect of kilovoltage.
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Increasing kV, increases the penetrating ability
of the x-rays photons.
More x-ray photons get through to darken film.
High kv produces darker images but poor
contrast.

39. Effect of milliamperage and time.
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Increasing the mA and mAs, increases the
number of x-rays production.
It does not affect the penetrating power of the
photons.
Increase mA will increase overall blackness of
the film.

40. X-ray film composition.
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Polyester base that provide support has bluish
tint.
Film emulsion is a thin layer of chemicals
coating the base composed of.
- Light sensitive silver halide (mainly Bromide
AgBr) crystals.
- gelatins that keep the silver bromide grains
evenly dispersed.

55. Recording image
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When x-ray hits the atoms in the film emulsion
it causes it to change leaving a latent (hidden),
image.

56. The cassette film
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Light proof container for film.
Lead backed to absorb transmitted radiations
and prevent scatter.
Intensifiers to use lower exposure.
Calcium tungstate.

58. Grids
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Composed of hundreds of alternating thin lead
strips with aluminum or fiber interspaces.
X-ray can pass through the interspaces without
interaction.
Lead strips absorb weak energy scatter x-ray that
hit them.
Strips is encased in protective cover.

61. Processing films

62. Processing the film
There are five steps
 Developing.
 Rinsing,
 Fixing.
 Washing.
 Drying.

63. Development
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Chemical convert the exposed AgBr in to
metallic silver.
The bromine goes into solution.
Unexposed AgBr is less affected.

64. Rinsing
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Essential to rinse of the developer solution so
that the fixer solution is not contaminated.
Contamination leads to faster exhaustion of the
fixer.

65. Fixing
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Stops development.
Washes away unexposed and undeveloped silver
halide crystals.
Hardens the emulsion.

66. Washing
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To wash all traces of fixer from emulsion.

67. Draying
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Hang up in dust free area to dry.
Automatic processors by it by using hot air.