This document summarizes the key concepts in x-ray physics. It begins with a brief history of x-rays and their properties as electromagnetic radiation. It then describes how x-rays are produced in an x-ray machine using a cathode and anode to generate photons. Next, it explains how x-rays interact with the body, being absorbed or scattered differently depending on tissue density and thickness. Finally, it outlines the process by which x-rays expose film to form an image, and the subsequent chemical processing required to develop the latent image.

1. X-ray physics
By
PROF.Dr. Osama El Abd

2. Content
 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
 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
 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
 Are electromagnetic
radiations composed of
small packets of energy
called photons.
 Travel at speed of light.
 Travel in straight lines.
 Highly penetrating.
 Invisible.
 Blacken radiographic
films.
 Produce scatter.

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

12. Atomic number
 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.
 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
 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.
 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.
 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.
 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.
 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
 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
 Some x-rays absorbed.
 Some pass straight through the patient.
 Some scattered.

33. Depend on three things
 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.  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
 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
 Low density or low
atomic number tissues
allow more x-rays
through causing more
blackening of film.
 High density or high
atomic number tissues
allow less x-ray through
causing less blackening
of the film.

38. Effect of kilovoltage.
 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.
 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.
 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
 When x-ray hits the atoms in the film emulsion
it causes it to change leaving a latent (hidden),
image.

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

58. Grids
 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
 Chemical convert the exposed AgBr in to
metallic silver.
 The bromine goes into solution.
 Unexposed AgBr is less affected.

64. Rinsing
 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
 Stops development.
 Washes away unexposed and undeveloped silver
halide crystals.
 Hardens the emulsion.

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

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