Radiography uses x-rays to generate images of the internal structures of objects. X-rays are generated using an x-ray tube, which accelerates electrons toward a metal target. When the electrons collide with the target, x-rays are produced. These x-rays are used to expose radiographic film, creating a latent image. The film is then developed using chemical processes similar to photographic film development, making the latent image visible. The visible image reveals the internal structures and densities of the object in a manner similar to shadows.

1. Radiography –introduction for ndt

2. •Electromagnetic radiation (photon), of shorter
wavelength than ultraviolet radiation. Produced by
bombardment of atoms by high-quntum-energy
particles. Radiation wavelength is from 10-11 m
•A device for generating X-rays by accelerating
electrons from a filament to strike a metal target
(anode).
An image storage medium consisting of a
transparent base, usually coated on both sides
with a radiation sensitive emulsion.

3. History of Radiography
• X-rays were discovered in 1895 by Wilhelm
Conrad Roentgen (1845-1923)

4. Nature of Penetrating Radiation

5. Properties of X-Rays and Gamma Rays
• They are not detected by human senses (cannot be seen,
heard, felt, etc.).
• They travel in straight lines at the speed of light.
• Their paths cannot be changed by electrical or magnetic
fields.
• They can be diffracted to a small degree at interfaces between
two different materials.
• They pass through matter until they have a chance encounter
with an atomic particle.
• Their degree of penetration depends on their energy and the
matter they are traveling through.
• They have enough energy to ionize matter and can damage or
destroy living cells.
•

6. Bremsstrahlung Radiation

7. Bremsstrahlung Radiation
•from German "bremsen" to brake, and "Strahlung" radiation"). Electromagnetic
radiation produced by the deceleration of a charged particle. In an X-ray tube this
is the radiation that is emitted when electrons are suddenly "braked" when they
collide with the target after being emitted from the cathode. Bremsstrahlung is
characterised as a continuous spectrum with a peak that shifts to higher
intensities and towards higher frequency energies with increasing voltage
potential.
Increasing voltage past the threshold value required for characteristic radiation
does not shift the spike to a shorter wavelength but does increase their intensity.
For a given applied voltage X-ray intensity is zero up to a certain wavelength
termed the short-wavelength limit (SWL). There is no abrupt limit on the long
wavelength side of the curve.
As the voltage is increased the SWL and the position of the peak bremsstrahlung
moves to the left and the intensity at all wavelengths increase.
At some critical voltage that is dependent on the target material, characteristic
radiation (c.v.) is emitted. These are characterised by "spikes" is energy that rise
up out of the continuous background.

8. K-shell Emission Radiation

9. Bremsstrahlung Radiation
1.The abrupt acceleration of the charged particles
(electrons) produces Bremsstrahlung photons.
2The K-shell is the lowest energy state of an atom
3. A tungsten electron of higher energy (from an
outer shell) can fall into the K-shell.
4. The energy lost by the falling electron shows up
in an emitted x-ray photon. Meanwhile, higher
energy electrons fall into the vacated energy state
in the outer shell, and so on

10. • Gamma-rays
A nucleus which is in an excited state may emit
one or more photons (packets of electromagnetic
radiation) of discrete energies. The emission of
gamma rays does not alter the number of protons
or neutrons in the nucleus but instead has the
effect of moving the nucleus from a higher to a
lower energy state (unstable to stable). Gamma
ray emission frequently follows beta decay, alpha
decay, and other nuclear decay processes.

11. . Half-life
• . Half-life is defined as the time required for
the activity of any particular radionuclide to
decrease to one-half of its initial value.

12. excitation and ionization
• 1.The various types of penetrating radiation
impart their energy to matter primarily
through excitation and ionization of orbital
electrons
• The term "excitation" is used to describe an
interaction where electrons acquire energy
from a passing charged particle but are not
removed completely from their atom.

13. ionization"
• Excited electrons may subsequently emit energy
in the form of x-rays during the process of
returning to a lower energy state. The term
"ionization" refers to the complete removal of an
electron from an atom following the transfer of
energy from a passing charged particle. In
describing the intensity of ionization, the term
"specific ionization" is often used. This is defined
as the number of ion pairs formed per unit path
length for a given type of radiation.

14. The intensity of the influence at any
given radius (r) is the source strength
divided by the area of the sphere.

15. atteunation

16. • attenuation

17. the intensity of photons
• Where: I = the intensity of photons
transmitted across some distance x I0 = the
initial intensity of photons s = a
proportionality constant that reflects the total
probability of a photon being scattered or
absorbed µ = the linear attenuation
coefficient x = distance traveled

18. Discuss why X-rays
are important and
how we use them.
• Dentists, doctors, NDE inspectors, and airport
personal are just some examples of people
who use X-rays in their jobs. X-rays can be
used to "look inside" an object and to locate
defects in materials.

19. RADIOGRAPHS AND PHOTOGRAPHS
• In photography, reflected light rays from the
object expose the film to produce an image.
• In radiography, X-rays that pass through the
object expose the film to produce an image.
• Differences in the types and amounts of the
materials that the X-rays must travel through are
responsible for the details of the radiographic
image.

20. THE DISCOVERY OF RADIOACTIVITY
• When the nucleus of an element decays or
disintegrates radiation is emitted, and this
kind of element is called a radioactive
element.
• Minerals that glow when sunlight is exposed
on them are called fluorescent minerals.

21. THE DISCOVERY OF X-RAYS
• X-rays were discovered by William Roentgen
while experimenting with a cathode radiation
• . Henri Becquerel discovered the radioactive
properties of uranium when he stored a piece
with some film and notched an image on the
film. Uranium was named a radioactive
element because if gives off something that is
invisible to the human eye called radiation

22. ATOMS AND ELEMENTS
• Marie and Pierre Curie advanced the study of
radiation and discovered the radioactivematerials
radium and polonium.
• An atom is the smallest particle of an element
that remain identical to all other particles.
• The atoms of one element are different from
those of all other element.
• Compounds are made when atoms of different
elements are chemically combined together.

23. CHEMICAL FORMULA
• Chemical formulas are used to describe the types
of atoms and their numbers in an element or
compound.
• The atoms of each element are represented by
one or two different letters.
• When more than one atom of a specific element
is found in a molecule, a subscript is used to
indicate this in the chemical formula.
• Carbon Dioxide > CO2
Sugar > C6H12O6

24. SUBATOMIC PARTICLES
• Subatomic particles are particles that are smaller
than the atom. Protons, neutrons, and electrons
are the three main subatomic particles found in
an atom. Protons have a positive (+) charge. An
easy way to remember this is to remember that
both proton and positive start with the letter "P."
Neutrons have no electrical charge. An easy way
to remember this is to remember that both
neutron and no electrical charge start with the
letter "N

25. • Neutrons are all identical to each other, just as
protons are.
• Atoms of a particular element must have the
same number of protons but can have different
numbers of neutrons.
• When an element has different variants that,
while all having the same number of protons,
have differing numbers of neutrons, these
variants are called isotopes.

26. ATOMIC NUMBER AND MASS
NUMBERS
• a

27. • An element's or isotope's atomic number tells
how many protons are in its atoms.
• An element's or isotope's mass number tells
how many protons and neutrons in its atoms.

28. • Electrons spin and rotate around the outside
of the nucleus.
• As the electrons circle the nucleus they travel
at certain energy levels but can "jump"
between different energy levels if they gain or
lose energy.
•

29. STABLE AND UNSTABLE ATOMS

30. STABLE AND UNSTABLE ATOMS
• Electromagnetic fields cause like charges to repel each
other and unlike charges to attract each other.
• The protons stay together in the nucleus because the
strong force opposes and overcomes the forces of
repulsion from the electromagnetic field.
• Binding energy is the energy that is associated with the
strong force, and this energy holds the nucleus together.
• A stable atom is an atom that has enough binding energy
to hold the nucleus together permanently.
• An unstable atom does not have enough binding energy to
hold the nucleus together permanently and is called a
radioactive atom

31. RADIOACTIVITY AND RADIOISOTOPES
• Radioactivity is the release of energy and
matter due to a change in the nucleus of an
atom.
• Radioisotopes are isotopes that are unstable
and release radiation. All isotopes are not
radioisotopes.
• Transmutation occurs when a radioactive
element attempts to become stabilized and
transforms into a new element.

32. RADIOACTIVE DECAY
• As an unstable atom tries to reach a stable
form, energy and matter are released from
the nucleus. This spontaneous change in the
nucleus is called radioactive decay.
• When there is a change in the nucleus and
one element changes into another, it is called
transmutation.

33. NUCLEAR REACTIONS
• The symbol for Uranium-238 =
This shows you that Uranium has a mass number of 238 and an atomic number of
92.
Symbols are also utilized to represent alpha and beta particles.
•The symbol for an alpha particle =
The symbol for a beta particle is
The chemical symbol for a neutron =

34. A nuclear reaction can be described by an equation, which
must be balanced.
The symbol for an atom or atomic particle includes the
symbol of the element, the mass number, and the atomic
number.
The mass number, which describes the number of protons
and neutrons, is attached at the upper left of the symbol.
The atomic number, which describes the number of protons
in the nucleus, is attached at the lower left of the symbol.

35. RADIOACTIVE HALF-LIFE
• The term half-life describes how long it will
take for half of the atoms to decay, and is
constant for a given isotope.
• The curie the unit of measure used to
describe the radioactivity of radioactive
material. (1C = 3.7 X 1010 disintegrations/sec)
• The disintegration of the atoms from different
isotopes can produce different amounts of
radiation.

36. RADIOACTIVE HALF-LIFE (CONTINUED
• The half-life of radioisotopes varies from
seconds to billions of years.
• Carbon-dating uses the half-life of Carbon-14
to find the approximate age of an object that
is 40,000 years old or younger.
• Radiographers use half-life information to
make adjustments in the film exposure time
due to the changes in radiation intensity that
occurs as radioisotopes degrade.

37. half-life affect an isotope
• How does the half-life affect an isotope?
• Let's look closely at how the half-life affects an
isotope. Suppose you have 10 grams of Barium-139. It
has a half-life of 86 minutes. After 86 minutes, half of
the atoms in the sample would have decayed into
another element, Lanthanum-139. Therefore, after
one half-life, you would have 5 grams of Barium-139,
and 5 grams of Lanthanum-139. After another 86
minutes, half of the 5 grams of Barium-139 would
decay into Lanthanum-139; you would now have 2.5
grams of Barium-139 and 7.5 grams of Lanthanum-
139.

38. X-RAY GENERATION
• The three things needed to create x-rays are a
source of electrons, a means of accelerating
the electrons to high speeds, and a target for
the accelerated electron to interact with.
• X-rays are produced when the free electrons
cause energy to be released as they interact
with the atomic particles in the target.

39. CHARACTERISTICS OF RADIATION
• Radiation is an electromagnetic wave that has
no charge and no mass.
• X-rays and gamma-rays can be characterized
by frequency, wavelength, and energy.

41. INTERACTION OF RADIATION AND
MATTER
1.When radiation encounters a material, some of
the energy will be absorbed through interactions
subatomic particles.
2.More radiation will be absorbed by materials
with high atomic numbers (generally more dense
materials) because there are more subatomic
particles to interact with the radiation.
3.Energy can never be created or destroyed;
therefore, the energy does not disappear but is
converted into something other form.

42. IONIZATION
• An ion is an atom, group of atoms, or a
particle with a positive or negative charge.
• With an electron removed, the atom
possesses a plus one charge, therefore it is a
positive ion. Consequently, the liberated
electron is a negative ion, as long as it exists
by itself and does not combine with another
atom.

43. 1.The three principle level of ionization are the
Photoelectric effect, the Compton Effect, and
Pair-Production.
2.This process of radiation absorption is called
ionization.

44. DEPTH OF PENETRATION OF
RADIATION ENERGY
1.The more subatomic particles in a material the
more quickly radiation energy will be absorbed
resulting in less depth of penetration.
2.The half-value layer is the depth within a material
where half of the radiation energy has been
absorbed. The HVL is useful in making material
comparisons.
3.Higher energy radiation will penetrate deeper
into a material before it is absorbed.

45. RADIATION SOURCES
• Artificially produced radioisotopes are
primarily used by industry because they can
be produced so as to have much more
radioactive energy that natural types.
• The three ways to produce radioisotopes are
neutron activation, fission product separation,
and charged particle bombardment.
• Elements that are atomically unstable and
radioactive are called radioisotopes.

46. X-RAY GENERATORS
1.The three main parts to an x-ray generator
setup are an x-ray tube, a high voltage power
supply, and a control unit.
2.The X-ray generator provides three things that
are required to produce X-rays, and they are a
source of electrons, a means of acceleration,
and a target for interaction.

47. • Radioisotopes, x-ray generation, and particle
accelerators are different methods that
generate radiation.
1.Devices that measure ionization are the most
commonly used instruments for detecting
radiation.
2.Three important words to help you minimize
your exposure to radiation are time, distance,
and shielding.

48. PRODUCING A RADIOGRAPH
• Describe how an image is produced on a
radiograph.
• The making of a radiograph requires some
type of recording mechanism. The most
common device is film. A radiograph is
actually a photographic recording produced by
the passage of radiation through a subject
onto a film, producing what is called a latent
image of the subject.

49. PRODUCING A RADIOGRAPH
• A latent image is an image that has been
created on the film due to the interaction of
radiation with the material making up the
film. This latent image is not visible to the
naked eye until further processing has taken
place. To make the latent image visible the
film is processed by exposure to chemicals
similar to that of photographic film.

50. DEVELOPING FILM
• An image storage medium consisting of a
transparent base, usually coated on both sides
with a radiation sensitive emulsion.
•

51. base
• a base for which the other materials are
applied. The film base is usually made from a
clear, flexible plastic such as cellulose acetate.
This plastic is similar to what you might find in
a wallet for holding pictures. The principle
function of the base is to provide support for
the emulsion. It is not sensitive to radiation,
nor can it record an image.

52. DEVELOPING FILM
• The emulsion
• The film emulsion and protective coating
comprise the other two components and are
essentially made from the same material. They
are applied to the film during manufacturing and
usually take on a pale yellow color with a glassy
appearance. Although they are made from the
same material, they offer two distinct features to
the film. These features are separated into the
image layer of the emulsion, and the protective
layer.

53. DEVELOPING FILM
• The protective layer
• The protective layer has the important function of protecting the softer
emulsion layers below.
• The softer layers of the gelatin coating are technically known as the
emulsion. An emulsion holds something in suspension. It is this material in
suspension that is sensitive to radiation and forms the latent image on the
film. During manufacturing of the film, silver bromide is added to the
solution of dissolved gelatin. When the gelatin hardens the silver bromide
crystals are held in suspension throughout the emulsion. Upon exposure
of the film to radiation, the silver bromide crystals become ionized in
varying degrees forming the latent image. Each grain or crystal of silver
bromide that has become ionized can be reduced or developed to form a
grain of black metallic silver. This is what forms the visible image on the
radiograph. This visible image is made up of an extremely large number of
silver crystals each is individually exposed to radiation but working
together as a unit to form the image.

54. DEVELOPING FILM
• 1. To begin the process of converting the latent
image on the radiograph to a useful image we
first expose the film to the developer solution.
• 2.The function of the stop bath is to quickly
neutralize any excessive development of the
silver crystals.
• 3. The third step in development is the fixer. Its
function is to permanently fix the image on the
film.

55. DEVELOPING FILM
• 4. Once the film has been properly developed,
it is then rinsed in water and dried so that it
may be visually examined.

56. summary
1.The three main part to radiographic film are
the base, the emulsion, and the protective
coating.
2.Steps in developing film include developing,
stopping the developer, fixing, rinsing and
drying.