Basic definitions
Electromagnetic spectrum
Wave therapy
Quantum Theory
Types of radiation comprising ES
Properties of ...
Energy is defined as ability to do work.
There are different types of energy:
KINECTIC ENERGY: it is energy produced
by...
The level of heat is indicated by
temperature.
ELECTRICAL ENERGY: it is measured by
multiplying the electric charge bein...
NUCLEAR ENERGY: it is that energy that is
locked up in the heart of the nucleus of an
atom also called, atomic energy.
R...
RADIATION: it is defined as the emission
and propagation of energy through space or
substances in form of waves or partic...
X rays belong to a group of radiation known
as electromagnetic radiation.
Electromagnetic radiation is the transport
of ...
EM radiation is made up of an electric and a
magnetic field that mutually supports each
other.
EM radiation propagates in the form of
waves.
They may be compared to waves travelling
down a stretched rope when one en...
The distance between the two successive
crests or troughs is the wave length and is
denoted by λ (Greek letter lambda, th...
The number of waves passing through a
particular point in a unit time is the
frequency, denoted by “ν” (the Greek letter
...
If each wave has a length λ, and ν waves pass
a given point in unit time, the velocity of the
wave is given by:
V= λ × ν
...
c= λ × ν
Because all types of radiation have the same
velocity, frequency of the radiation must be
inversely proportiona...
The various parts of the spectrum are
named according to the manner in which
the type of radiation is generated or
detect...
There is considerable overlap in the
wavelengths of various members of the
spectrum.
 X-rays are considered useful when their energy
level is matched to the task of interest
 Of the total amount of x-rays ...
Short EM waves, such as X rays, may react
with matter as if they were particle rather
than waves.
These particles are ac...
If the frequency is doubled, the energy of
the photons is doubled.
The actual amount of energy can be
calculated by mult...
The particle concept is used to describe the
interactions between radiation and matter.
The EM spectrum is the ENTIRE range of
EM waves in order of increasing frequency
and decreasing wavelength.
HERTZIAN WAVES: these waves are used by
high altitude transmission satellites, and
have wavelength of 1016 to 1013 Å.
 These waves can pass through most
materials except that of great bulk.
Wavelength varies from 1013 to 108 Å.
MEDICINE: radiowaves are used to transmit
the pattern of the heartbeat through a
monitor.
OTHERS: to convey information ...
Wavelength: 3×10-2m to 3×10-4 , these
overlap the wavelength of communication
waves on one end and infrared on other
end.
Transmit information to satellite.
Mobile phones.
Microwave ovens.
These waves can penetrate tissues and cause
moistur...
In ophthalmology.
In selected cases of cancer therapy.
In oral surgery, to reduce postoperative
swelling and trismus ar...
The name infrared means “below the red”.
These have wavelength ranging from 40,000
to 1,00,000 Å
These occupy the part ...
To study cloud structure.
The temperature of a distant object can be
determined by analysis of infrared radiation
from t...
Medical uses include technique of thermal
imaging of thermography.
In dentistry: it is used for tooth vitality
testing, ...
 Wavelength ranges from 4,000 to 7700Å.
 The range of colour is often called “VIBGYOR”,
with red having the longest wave...
In optical fibers.
In dentistry it is used in dental photography
and operative field illumination.
Wavelength ranges from 1,000 to 2,000Å.
These rays have slight penetrating power
and can penetrate live tissues for a de...
Bactericidal effect.
Aging of skin.
Eyes are sensitive to UV rays which can
cause cataract or keratitis.
Is an agent i...
The UV rays can be divided into 3
categories:
Between 200 and 290 nm, short or
germicidal UV rays or UVC, these can caus...
Between 320 and 380 nm , long or black
light UV rays or UVA, on its own it is not
damaging but when used with sensitizing...
Photography
In dentistry:
Disclose plaque
Photo polymerization of composite used
for:
Fissure sealing
Splinting teet...
Four types:
Grenz or super soft X rays: 1-2 Å, mainly
used to treat superficial lesions
Soft X rays: 1-0.5 Å, used in c...
Its properties of fluorescence is used in
medicine for fluoroscopic examination and
intensifying screens in extra oral
ra...
They are high powered X rays, having wave
length of 0.001 Å.
These are EM radiations, but there source is
from radioacti...
These have the shortest wavelength of
0.0001 Å.
They played a critical role in the scientific
study of atomic nucleus an...
Light amplification by stimulated emission
of radiation is a device which can operate in
infrared, visible or UV region o...
If a body of atoms is raised to excited state
by pumping, then an incident light wave will
simulate photon emission and n...
 LASER light has four characteristics that
distinguish it from light produced by other
sources. These are:
 Laser light ...
Laser concentrates and amplifies the light to
a given concentrated beam of energy which
can melt metals and drill holes i...
It has also reduced blood loss due to its
ability to seal blood vessels, less post
operative infection and the fact that
...
In dentistry two types of lasers are used:
Soft tissue laser (800-900 nm): eg. Argon,
CO2.
Hard tissue laser (2500-3000...
Surgical excision of benign tumors and
small soft tissue growths (eg: epulis)
Frenectomy
Nerve regeneration
Cavity det...
For ulcerative lesions.
Oral biopsies
Tooth sensitivity
Melanin pigmented gingiva
For etching
Cutting and contouring...
X rays are weightless packages of pure
energy that are without electrical charge
and that travel in waves along a straigh...
Wavelength 10-0.01 Å.
They travel through space in a wave motion.
In free space they travel in a straight line.
They t...
As they travel through space, they can
produce an electric field at right angle to
their path of propagation and a magnet...
 They are invisible to eye and can not be seen,
heard or smelt.
 They can not be focused by a lens.
 They can not be re...
In free space they obey the inverse square
law, which states that for a point source of
radiation the intensity (I) at an...
X rays are produced by collision of electrons
by tungsten atoms.
Collision can be of two types:
Continuous spectra (gen...
 Also called as brems, white, or general radiation.
 Derived from two German words: bremse- ‘brake’ &
strahl- ‘ray’
 Ca...
The incoming electron penetrates
the outer electron shell and passes
close to the nucleus of the
tungsten atom.
The incomi...
The incoming electron collides with an
inner shell tungsten electron, displacing it
to outer shell (excitation), or displa...
Generation of photons with a wide range of
photon energies (continuous spectrum)
This is due to :
a) Continuously varying ...
X rays can penetrate various objects and
degree of penetration depends upon:
Quality (penetration power), is defined as
...
Property of attenuation, absorption, scatter
when passing through matter the intensity
of radiation is reduced (attenuati...
 Components of the body arranged in order of
their power to absorb X rays, starting from
lowest value:
 Air
 Fat
 Soft...
 When x-ray photons arrive at patient:
a. Some x-rays are merely scattered with no loss
of energy
b. Some x-ray photons a...
In the case of diagnostic X ray beam there
are three mechanisms by which these
processes take place:
Coherent scattering...
It is a process by which radiation is
deflected without losing energy.
X rays when passing close to an atom causes
the b...
The incident photon then ceases to exit.
The vibration causes the electron to radiate energy
in the form of another X ray ...
Contributes to 8% of the total no. of
interactions.
Is of little importance in radiography as the
it involves low energy...
At energy levels employed in diagnostic
radiology, the effect of coherent scattering is
negligible in production of fog.
...
It is a process of interaction of the incident photon ant the bound electron
leading to emission of characteristic radiati...
The kinetic energy imparted to the recoil electron is equal to the energy of the
incident photon minus that required to ov...
In diagnostic radiography the characteristic
radiation generated is of no significance as
the X ray photons which are abs...
Or inelastic scattering is an interaction of
photons with free or loosely bound outer
shell electron.
The photon gives some of its energy to the electron and it, itself continues
in a new direction, but with reduced energy a...
If scattered through a small angle, very
small amount of energy is lost to the outer
electron.
The recoil electrons furt...
This creates a serious problem as photons
that are scattered at narrow angles have an
excellent chance of reaching the fi...
Due to their energy, rays can emit
photoelectrons from metals, when allowed
to fall on them.
HEATING EFFECT: the product...
FLUORESCENCE: when X rays fall upon
certain material, visible light is emitted
called fluorescence.
IONIZATION: this is ...
The outer electron of the atoms play an
important role in chemical combinations
and therefore any disturbance in the oute...
X rays induces color changes in several
substances:
Methylene blue gets bleached
Sodium platinocyanide which is apple g...
Water in organic substances undergo
oxidation and reduction reactions when
irradiated.
X rays can cause oxidation of fer...
X rays can cause destruction of the
fermentation power of enzymes, which are
vital substances for metabolism of cells of
...
When X rays are incident on an atom, one of
the reaction it produces is excitation. this
property is used in:
Treatment ...
The effect is cumulative and depends upon
the type of tissues and intensity of the
radiation.
It may range from simple s...
This is due to radiation induced mutation of
genes and chromosomes.
These are usually seen in off springs of
irradiated ...
PHOTOGRAPHIC EFFECT:
Photographic film when exposed to X rays
and developed will turn black.
This blackening is known a...
RADIOLOGY:
Diagnostic use in dentistry and medicine.
Medico legal cases.
RADIOTHERAPY:
Used to destroy malignant cell...
In industries
Photochemistry.
Oral Radiology Principles and
Interpretation, 2nd Edition, Gaoz and White.
Oral Radiology, Principles and
Interpretation...
electromagnectic spectrum and properties of x -rays
electromagnectic spectrum and properties of x -rays
electromagnectic spectrum and properties of x -rays
electromagnectic spectrum and properties of x -rays
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electromagnectic spectrum and properties of x -rays

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  • Light and its nature have caused a lot of ink to flow during these last decades. Its dual behavior is partly explained by (1)Double-slit experiment of Thomas Young - who represents the photon’s motion as a wave - and also by (2)the Photoelectric effect in which the photon is considered as a particle. However, Einstein himself writes: "It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty." A Revolution: SALEH THEORY solves this ambiguity and this difficulty presenting a three-dimensional trajectory for the photon's motion and a new formula to calculate its energy.More information on: https://youtu.be/mLtpARXuMbM
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electromagnectic spectrum and properties of x -rays

  1. 1. Basic definitions Electromagnetic spectrum Wave therapy Quantum Theory Types of radiation comprising ES Properties of X rays References
  2. 2. Energy is defined as ability to do work. There are different types of energy: KINECTIC ENERGY: it is energy produced by virtue of movement. POTENTIAL ENERGY: produced by virtue of its position ex: coiled spring. HEAT ENERGY: it is movement of molecules and atoms of any material.
  3. 3. The level of heat is indicated by temperature. ELECTRICAL ENERGY: it is measured by multiplying the electric charge being moved by electrical force. CHEMICAL ENERGY: it is that energy locked up in the chemical compounds and released under certain circumstances eg explosives
  4. 4. NUCLEAR ENERGY: it is that energy that is locked up in the heart of the nucleus of an atom also called, atomic energy. RADIATION ENERGY: it is that energy which is released during the process of ionization or excitation of an atom. 
  5. 5. RADIATION: it is defined as the emission and propagation of energy through space or substances in form of waves or particles. RADIOACTIVITY: it is the process by which certain unstable atoms or elements undergo spontaneous disintegration or decay, in an effort to attain a more balanced nuclear state.
  6. 6. X rays belong to a group of radiation known as electromagnetic radiation. Electromagnetic radiation is the transport of energy through space as a combination of electric and magnetic fields. Electromagnetic radiation is produced by a charged particle being accelerated. The converse is also true, that is, a charge being accelerated will emit EM radiation.
  7. 7. EM radiation is made up of an electric and a magnetic field that mutually supports each other.
  8. 8. EM radiation propagates in the form of waves. They may be compared to waves travelling down a stretched rope when one end is moved up and down in a rhythmic motion. EM radiation do not need any medium and can propagate in vacuum. Waves of all type have an associated wavelength and frequency.
  9. 9. The distance between the two successive crests or troughs is the wave length and is denoted by λ (Greek letter lambda, the initial for length).
  10. 10. The number of waves passing through a particular point in a unit time is the frequency, denoted by “ν” (the Greek letter “nu”, the initial for number.
  11. 11. If each wave has a length λ, and ν waves pass a given point in unit time, the velocity of the wave is given by: V= λ × ν EM radiations travel with the velocity of light ie 186,000 miles per second. Therefore c= λ × ν c is velocity of light
  12. 12. c= λ × ν Because all types of radiation have the same velocity, frequency of the radiation must be inversely proportional to the wavelength. All types of radiation in the spectrum differ basically in the wavelength.
  13. 13. The various parts of the spectrum are named according to the manner in which the type of radiation is generated or detected.
  14. 14. There is considerable overlap in the wavelengths of various members of the spectrum.
  15. 15.  X-rays are considered useful when their energy level is matched to the task of interest  Of the total amount of x-rays produced, only x- rays of certain energy levels are useful to diagnostic image production, these x-rays fall into the diagnostic energy range  X-rays used in dentistry have a wavelength of 0.1 to 0.5Å
  16. 16. Short EM waves, such as X rays, may react with matter as if they were particle rather than waves. These particles are actually discrete bundles of energy and each of these bundles of energy is calles a quantum or photon. The amount of energy carried by each photon or quantum depends on frequency of the radiation.
  17. 17. If the frequency is doubled, the energy of the photons is doubled. The actual amount of energy can be calculated by multiplying its frequency by a constant. E= hν ( h= Planck’s Constant) The constant has been determined experimentally to be 4.13 × 10-18 KeV sec and is called the Planck’s Constant In SI unit it is 6.62 ×10-34 Joules sec.
  18. 18. The particle concept is used to describe the interactions between radiation and matter.
  19. 19. The EM spectrum is the ENTIRE range of EM waves in order of increasing frequency and decreasing wavelength.
  20. 20. HERTZIAN WAVES: these waves are used by high altitude transmission satellites, and have wavelength of 1016 to 1013 Å.
  21. 21.  These waves can pass through most materials except that of great bulk. Wavelength varies from 1013 to 108 Å.
  22. 22. MEDICINE: radiowaves are used to transmit the pattern of the heartbeat through a monitor. OTHERS: to convey information from one place to another through media(air, space).
  23. 23. Wavelength: 3×10-2m to 3×10-4 , these overlap the wavelength of communication waves on one end and infrared on other end.
  24. 24. Transmit information to satellite. Mobile phones. Microwave ovens. These waves can penetrate tissues and cause moisturized molecules in cell to vibrate resulting in internal friction and increase in temperature of affected cell.
  25. 25. In ophthalmology. In selected cases of cancer therapy. In oral surgery, to reduce postoperative swelling and trismus arising from traumatic procedures.
  26. 26. The name infrared means “below the red”. These have wavelength ranging from 40,000 to 1,00,000 Å These occupy the part of spectrum with a frequency less than that of visible light and greater than that of radio waves. These were discovered in 1800 by Sir William Herschel.
  27. 27. To study cloud structure. The temperature of a distant object can be determined by analysis of infrared radiation from the object. Radiometers operating in the infrared range serve as the basis for many instruments, including heat seeking devices in missiles and devices for spotting and photographic persons in the dark or fog.
  28. 28. Medical uses include technique of thermal imaging of thermography. In dentistry: it is used for tooth vitality testing, surgical diathermy, altering properties of dental materials like waxes, gutta percha and for curing acrylic.
  29. 29.  Wavelength ranges from 4,000 to 7700Å.  The range of colour is often called “VIBGYOR”, with red having the longest wavelength and violet having shortest wavelength.  Red, orange, yellow, green, blue, indigo, violet.
  30. 30. In optical fibers. In dentistry it is used in dental photography and operative field illumination.
  31. 31. Wavelength ranges from 1,000 to 2,000Å. These rays have slight penetrating power and can penetrate live tissues for a depth of few mm and cause biological effects like: Photo erythema Photo pigmentation Photo chemical cornification of skin and skin carcinoma (malignant dermal changes).
  32. 32. Bactericidal effect. Aging of skin. Eyes are sensitive to UV rays which can cause cataract or keratitis. Is an agent in the production of vitamin D.
  33. 33. The UV rays can be divided into 3 categories: Between 200 and 290 nm, short or germicidal UV rays or UVC, these can cause genetic mutations, altered reproductive cycles and cell death. Between 290 and 320 middle or erythemal UV rays or UVB, these can cause skin erythema and are commercially available as sun or mercury vapor lamps.
  34. 34. Between 320 and 380 nm , long or black light UV rays or UVA, on its own it is not damaging but when used with sensitizing chemicals, it can cause extensive biological damage.
  35. 35. Photography In dentistry: Disclose plaque Photo polymerization of composite used for: Fissure sealing Splinting teeth Placing pontic in temporary bridge work Restoring teeth
  36. 36. Four types: Grenz or super soft X rays: 1-2 Å, mainly used to treat superficial lesions Soft X rays: 1-0.5 Å, used in contact therapy. Medium: 0.5-0.1 Å, mainly used in diagnostic and superficial therapy. Hard X rays: 0.1 Å , mainly used for deep X ray therapy.
  37. 37. Its properties of fluorescence is used in medicine for fluoroscopic examination and intensifying screens in extra oral radiography. Radiography and monitoring film badges. To sterilize commercial items in bulk.
  38. 38. They are high powered X rays, having wave length of 0.001 Å. These are EM radiations, but there source is from radioactive decay process. They have shorter wavelength and greater penetrating power and are used in treatment of tumors ex: Radon needles or seeds that are implanted at the tumor site, percutaneous radiotantalum wire implants.
  39. 39. These have the shortest wavelength of 0.0001 Å. They played a critical role in the scientific study of atomic nucleus and its components.
  40. 40. Light amplification by stimulated emission of radiation is a device which can operate in infrared, visible or UV region of the spectrum and which amplifies electromagnetic waves by stimulated emission of radiation. When atoms or molecules absorb energy they can emit light spontaneously or they can be stimulated to do so by a light wave.
  41. 41. If a body of atoms is raised to excited state by pumping, then an incident light wave will simulate photon emission and net amplification of the incident light beam results. The output is extremely powerful and mobilizes intense heat at close range to emit photons at an infinitely greater rate than would spontaneously.
  42. 42.  LASER light has four characteristics that distinguish it from light produced by other sources. These are:  Laser light is highly directional and travels in a narrow beam, the sides of which stay almost parallel.  Lasers produces coherent light, that is it has only one frequency.  It is of one single color.  It is very bright, powerful with very high intensity.
  43. 43. Laser concentrates and amplifies the light to a given concentrated beam of energy which can melt metals and drill holes in them. It can be used to make very accurate measurement of distance, perform delicate surgical procedure involving the eye. They have replaced many conventional techniques which have lead to shorter period of treatment.
  44. 44. It has also reduced blood loss due to its ability to seal blood vessels, less post operative infection and the fact that difficult, often inaccessible regions of the body can be reached more easily.
  45. 45. In dentistry two types of lasers are used: Soft tissue laser (800-900 nm): eg. Argon, CO2. Hard tissue laser (2500-3000nm): eg Er: YAG dental laser.
  46. 46. Surgical excision of benign tumors and small soft tissue growths (eg: epulis) Frenectomy Nerve regeneration Cavity detection. OCT Low intensity lasers to reduce pain Treatment of TMJ for reduction of pain and inflammation.
  47. 47. For ulcerative lesions. Oral biopsies Tooth sensitivity Melanin pigmented gingiva For etching Cutting and contouring of oral osseous structures. Apicectomy.
  48. 48. X rays are weightless packages of pure energy that are without electrical charge and that travel in waves along a straight line with a specific frequency or speed. The properties of X rays can be classified into: Physical Chemical Biological physiochemical
  49. 49. Wavelength 10-0.01 Å. They travel through space in a wave motion. In free space they travel in a straight line. They travel in speed of light (186000 miles per second).
  50. 50. As they travel through space, they can produce an electric field at right angle to their path of propagation and a magnetic field to right angle to electric field.
  51. 51.  They are invisible to eye and can not be seen, heard or smelt.  They can not be focused by a lens.  They can not be reflected, refracted or deflected by a magnet or electric field as they do not possess any charge.  They do not require any medium for propagation.  They are pure energy, no mass and they transfer energy from place to place in the form of quanta (photon)
  52. 52. In free space they obey the inverse square law, which states that for a point source of radiation the intensity (I) at any given place varies inversely as the square of distance from the source to the place at which intensity is being considered. I∞i/d2 or I =k/d2 K is a constant.
  53. 53. X rays are produced by collision of electrons by tungsten atoms. Collision can be of two types: Continuous spectra (general radiation, Bremsstrahlung Radiation, Braking Radiation) Characteristic spectrum or line spectrum
  54. 54.  Also called as brems, white, or general radiation.  Derived from two German words: bremse- ‘brake’ & strahl- ‘ray’  Called as ‘braking radiation’ as the radiation is produced by ‘braking’ or deceleration of high speed electrons.  A cathode electron that completely avoids the orbital electrons may come sufficiently close to the nucleus to come under its influence.
  55. 55. The incoming electron penetrates the outer electron shell and passes close to the nucleus of the tungsten atom. The incoming electron is slowed down and deflected by the nucleus with a large loss of energy, which is emitted in the form of X rays. The amount of deceleration and degree of deflection determines the amount of energy lost by the bombarding electron and hence the energy of the resultant emitted photon has a wide range of spectrum of energies and therefore called CONTINIOUS SPECTRUM.
  56. 56. The incoming electron collides with an inner shell tungsten electron, displacing it to outer shell (excitation), or displacing it from the atom (ionization), with a large loss of energy and subsequently the orbiting tungsten electros rearrange themselves to return the atom to neutral or ground state. This involves electron jumps which results in the emission of X ray photons with a specific energy called CHARACTERISTIC SPECTRUM.
  57. 57. Generation of photons with a wide range of photon energies (continuous spectrum) This is due to : a) Continuously varying voltage difference between target & filament b) Most electrons participate in many interactions before losing their energy
  58. 58. X rays can penetrate various objects and degree of penetration depends upon: Quality (penetration power), is defined as the energy carried by the X ray beam. Quality is determined by KV, milli amperage, distance between the target and the object, time of exposure, filtration and target material.
  59. 59. Property of attenuation, absorption, scatter when passing through matter the intensity of radiation is reduced (attenuation) both because radiation energy is taken up by the material (absorption) and some is deflected from the original path to travel in a new direction(scattering).
  60. 60.  Components of the body arranged in order of their power to absorb X rays, starting from lowest value:  Air  Fat  Soft tissue, blood, body fluids  Medullary bone  Cancellous bone  Cortical bone  Dentin and cementum  Enamel
  61. 61.  When x-ray photons arrive at patient: a. Some x-rays are merely scattered with no loss of energy b. Some x-ray photons are absorbed completely in the patient (total loss of energy), & c. Some x-ray photons pass through the patient without interacting with the tissue atoms d. Some x-ray photons are scattered after loss of some energy
  62. 62. In the case of diagnostic X ray beam there are three mechanisms by which these processes take place: Coherent scattering Photoelectric effect Compton scattering
  63. 63. It is a process by which radiation is deflected without losing energy. X rays when passing close to an atom causes the bound electrons to vibrate momentarily at a frequency equal to that of incident photons.
  64. 64. The incident photon then ceases to exit. The vibration causes the electron to radiate energy in the form of another X ray photon of the same frequency and energy as that in the incident beam. Usually the secondary photon emitted is at an angle to the path of incidental X ray.
  65. 65. Contributes to 8% of the total no. of interactions. Is of little importance in radiography as the it involves low energy x-rays.
  66. 66. At energy levels employed in diagnostic radiology, the effect of coherent scattering is negligible in production of fog. This property is used to investigate internal molecular structure of materials by method of X ray diffraction, called X ray crystallography.
  67. 67. It is a process of interaction of the incident photon ant the bound electron leading to emission of characteristic radiation. It occurs when an incident photon collides with a bound electron in the atom of the absorbing medium. The incident photon ceases to exit and its energy helps to eject a bound electron from its shell to become a recoil electron or a photo electron.
  68. 68. The kinetic energy imparted to the recoil electron is equal to the energy of the incident photon minus that required to overcome the electron binding energy. The orbital vacancy caused by the electron reshuffle and the neutrality is obtained by attracting an electron from outside. During this rearrangement characteristic radiation is emitted.
  69. 69. In diagnostic radiography the characteristic radiation generated is of no significance as the X ray photons which are absorbed by the patient are of low energy.
  70. 70. Or inelastic scattering is an interaction of photons with free or loosely bound outer shell electron.
  71. 71. The photon gives some of its energy to the electron and it, itself continues in a new direction, but with reduced energy and hence with increased wavelength. The ejected outer shell electron is called compton or recoil electron.
  72. 72. If scattered through a small angle, very small amount of energy is lost to the outer electron. The recoil electrons further ionizing interactions with the tissues, and gradually lose energy along their tracts by causing secondary radiations and consequent biological damage.
  73. 73. This creates a serious problem as photons that are scattered at narrow angles have an excellent chance of reaching the film & producing film fog. Contributes to 62% of the x-ray scattering.
  74. 74. Due to their energy, rays can emit photoelectrons from metals, when allowed to fall on them. HEATING EFFECT: the production of heat is due to slowing down of the primary electrons, it also arises as an end product of the chemical reactions induced by radiation.
  75. 75. FLUORESCENCE: when X rays fall upon certain material, visible light is emitted called fluorescence. IONIZATION: this is a process of converting atoms into ions.
  76. 76. The outer electron of the atoms play an important role in chemical combinations and therefore any disturbance in the outer electron configuration of an atom brings about chemical changes.
  77. 77. X rays induces color changes in several substances: Methylene blue gets bleached Sodium platinocyanide which is apple green turns to darker shades then light brown and finally dark brown. Brings about molecular changes in biological molecules. Organic compound gets oxidized to carbon dioxide with release of hydrogen.
  78. 78. Water in organic substances undergo oxidation and reduction reactions when irradiated. X rays can cause oxidation of ferrous sulphate to ferric sulphate and this is used as a method of measuring X ray dosage (Frickle dosimeter).
  79. 79. X rays can cause destruction of the fermentation power of enzymes, which are vital substances for metabolism of cells of all living materials.
  80. 80. When X rays are incident on an atom, one of the reaction it produces is excitation. this property is used in: Treatment of malignant lesions. Germicidal or bactericidal effect and are used for sterilization and preservation of food. Effects can be of two types: Somatic effect Genetic effect
  81. 81. The effect is cumulative and depends upon the type of tissues and intensity of the radiation. It may range from simple sun burn to severe dermatitis.
  82. 82. This is due to radiation induced mutation of genes and chromosomes. These are usually seen in off springs of irradiated parents. The fetus is more sensitive to radiation in early stages of development.
  83. 83. PHOTOGRAPHIC EFFECT: Photographic film when exposed to X rays and developed will turn black. This blackening is known as film density.
  84. 84. RADIOLOGY: Diagnostic use in dentistry and medicine. Medico legal cases. RADIOTHERAPY: Used to destroy malignant cells and cure skin disease. RADIOBIOLOGY: Alteration of cells and tissues for experimental purpose. CRYSTALLOGRAPHY
  85. 85. In industries Photochemistry.
  86. 86. Oral Radiology Principles and Interpretation, 2nd Edition, Gaoz and White. Oral Radiology, Principles and Interpretation, 4th Edition, White and Pharooh. Christinsen’s Introduction to the Physics of Diagnostic Radiology, 3rd Edition, by Currary T.S., J.E. Dowdry, R.C. Murry. Eric Whaites: Essential of Radiology and Radiography, 2nd Edition.

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