1. X-Ray Technology By: PROF. Dr. Moustafa Moustafa Mohamed
Faculty of Allied Medical Science
Pharos University in Alexandria

2. Introduction to Medical Imaging
NON Invasive
Uses of medical imaging
Obtain information about internal body
organs or the skeleton to determine a patient’s physical
Imaging Modalities:
* X-ray (plan , Dental, Panorama, Mammo, Angio, …)
* C.T * Ultrasound
* MRI * Gamma Camera
* PET SPECT

3. Medical Image Film photograph or computer display monitor
Generated by means of radiation
electromagnetic (EM)
ultrasound
electrons
Displayed for interpretation on
Film
photograph or
computer display monitor

4. Types of image
1) Projections
2) Dimensional
3D & 4D

5. 3) Slices Trans axial - plane normal to a vector from head to toe.
Coronal - plane normal to a vector from front to back
Sagittal - plane normal to a vector from left to right.
Oblique - a slice that is not (at least approximately) one of the above.

6. of PROTONS and NEUTRONS have no electrical charge.
Inside the atom
The NUCLEUS is made up
of PROTONS and NEUTRONS
PROTONS
have a positive charge.
NEUTRONS
have no electrical charge.

7. Inside the atom ELECTRONS have a negative charge.
The number of electrons in an atom usually matches the number of protons, making the atom electrical neutral.

8. Exactly what is an X – Ray?
An x – ray is a form of radiation, that is invisible
Electromagnetic waves of short wavelength with wavelengths between about 0.02 Å and 100 Å (1Å = 10‐10 meters).
Very high energy
Basically gives an “inside view”

9. The energy of X‐rays, like all electromagnetic radiation, is inversely proportional to their wavelength as given by the Einstein equation:
E = hν = hc/λ
where E = energy
h = Planck's constant, x 10‐27 erg.sec
ν = frequency
c = velocity of light = x 1010 cm/sec
λ = wavelength
Since X‐rays have a smaller wavelength than visible light, they have higher energy.

10. X‐rays can penetrate matter more easily than can visible light.
Their ability to penetrate matter depends on the density of the matter
X‐rays provide a powerful tool in medicine for mapping internal structures of the human body (bones have higher density than tissue,
and thus are harder for X‐rays to penetrate, fractures in bones have a different density than the bone, thus fractures can be seen in X‐ray pictures).

11. History
In 1895 Wilhelm Roentgen, German Physicist, was studying high voltage discharges in vacuum tubes, then he noticed fluorescence of barium platinocyanide screen lying several feet from tube end.
These rays where named
X-rays--invisible penetrating radiation,
X represent unknown in mathematics

12. William Conrad Roentgen
Wilhelm Conrad Rontgen Won the first Nobel Peace Prize for physics in 1901
                    

13. Early X- Ray Images Right: Mrs. Röntgen's hand, the first X-ray
                                    In
                        Right: Mrs. Röntgen's hand, the first X-ray
X-ray of Bertha Roentgen's
Hand

14. Types and uses of X-ray

15. Various uses of the X - Ray
Detect malformations in bones
Treats disorders such as various cancers
Security purposes
Alternatives for cancer detection
Annual physical exams
Pre-surgery evaluations

16. X-Ray
Electromagnetic Spectrum

17. Production of X-rays (1)
X-rays are produced when rapidly moving electrons that have been accelerated through a potential difference of order 1 kV to 1 MV strikes a metal target.
Evacuated
glass tube
Target
Filament

18. Production of X-rays (2)
Electrons from a hot element are accelerated onto a target anode.
When the electrons are suddenly decelerated on impact, some of the kinetic energy is converted into EM energy, as X-rays.
Less than 1 % of the energy supplied is converted into X-radiation during this process. The rest is converted into the internal energy of the target.

19. Properties of X-rays X-rays travel in straight lines.
X-rays cannot be deflected by electric field or magnetic field.
X-rays have a high penetrating power.
Photographic film is blackened by X-rays.
Fluorescent materials glow when X-rays are directed at them.
Photoelectric emission can be produced by X-rays.
Ionization of a gas results when an X-ray beam is passed through it.

20. X-ray Spectra (1)
Using crystal as a wavelength selector, the intensity of different wavelengths of X-rays can be measured.

21. X-ray Spectra (2) The graph shows the following features.
A continuous background of X-radiation in which the intensity varies smoothly with wavelength. The background intensity reaches a maximum value as the wavelength increases, then the intensity falls at greater wavelengths.
Minimum wavelength which depends on the tube voltage. The higher the voltage the smaller the value of the minimum wavelength.
Sharp peaks of intensity occur at wavelengths unaffected by change of tube voltage.

22. Minimum wavelength in the X-ray Spectra
When an electron hits the target its entire kinetic energy is converted into a photon.
The work done on each electron when it is accelerated onto the anode is eV.
Hence hf = eV and the maximum frequency
Therefore,

23. Continuous (Bremsstrahlung) X-Ray Production

24. Characteristic X-ray Spectra
Different target materials give different wavelengths for the peaks in the X-ray spectra.
The peaks are due to electrons knock out inner-shell electrons from target atoms.
When these inner-shell vacancies are refilled by free electrons, X-ray photons are emitted.
The peaks for any target element define its characteristic X-ray spectrum.

25. Characteristic X-Ray Production

27. Anode Heating
This occurs when projectile electrons excite an atoms outer shell electrons but do not eject them from the atom.
For most X-ray machines, about 99% of the projectile electrons lose energy this way.
Infrared EM radiation (observed as heat energy) is produced when the excited electrons relax and fall back into the original energy level
The amount of anode heating can be reduced by increasing the energy of the projectile electrons so that they cause more ionization rather than excitation.

28. Uses of X-rays In medicine In industry To locate cracks in metals.
To diagnose illness and for treatment.
In industry
To locate cracks in metals.
X-ray crystallography
To explore the structure of materials.

29. Conditions for x ray production
Separation of electrons
Production of high speed electrons
Focusing of electrons
Sopping of high speed electrons in target

30. COLD GAS CATHODE TUBE
glass tube with partial vacuum with small amount of gas,
two electrodes, one negative (cathode)
& another positive (Anode).

31. Hot Cathode Diode tube
In 1913 W.D. Coolidge invented new type of tube on Edison principal called
Hot Cathode Diode tube.
It made possible the control of mA and kV independently and there by controlling the quantity and quality of x-rays.

33. PARTS OF X RAY TUBE Glass Tube Cathode Anode Filament Supporting wires
Focusing cup
Anode
Stationary
Rotating

34. Main components of x-ray unit are:
·        X-ray tube
·        X-ray electrical power generator
·        Control unit
·        Film or digital system
In addition to:
·        Table unit
·        Bucky film tray and grid system
·        Suspension system

41. Introduction Image contrast is (((proportion with)))
X-ray image is a shadow picture produced by x-rays emitted from a point source
Image contrast is (((proportion with)))
1- Mass attenuation coefficient of the imaged part
2- Density
3- Thickness

42. Principles of X-ray tube
Battery

44. Main components of a modern x-ray tube
A heated filament releases electrons that are accelerated across a high voltage onto a target.
The stream of accelerated electrons is referred to as the tube current.
X rays are produced as the electrons interact in the target.
The x rays emerge from the target in all directions but are restricted by collimators to form a useful beam of x rays.
A vacuum is maintained inside the glass envelope of the x-ray tube to prevent the electrons from interacting with gas molecules.

45. X-Ray Tubes

46. X‐ray Absorption
When the x‐rays hit a sample, the oscillating electric field of the electromagnetic radiation interacts with the electrons bound in an atom.
Either the radiation will be scattered by these electrons, or absorbed and excite the electrons.
A narrow parallel monochromatic x‐ray beam of intensity I0 passing through a sample of thickness x will get a reduced intensity I according to the expression:
I = I0 e‐μ x or Ln (I0 /I) = μ x
where μ is the linear absorption coefficient, which depends on the types of atoms and the density ρ of the material.

47. How X‐ray Lose Energy within Matter?
• Photoelectric effect
X‐ray interacts with an electron by giving all its energy to the electron near the nucleus.
It is the most probable way of losing energy
X‐ray energy must be greater than or equal to the electron binding energy to the nucleus

48. • Compton effect
X‐ray (of energy at least 511 KeV) colloids with a loosely bound outer electron.
The electron receive part of the energy and the rest goes in different direction as a scattered photon radiations each of 511 KeV

50. Pair production
X‐ray (of energy at least 1.02 MeV) penetrates the intense electric field of nucleus. It is converted to an electron and a positron each of 511 KeV.
The positron will then colloids with one electron and results in the production of two annihilation

52. Bragg's Law
According to Bragg, X‐ray diffraction can be viewed as a process similar to reflection from planes of atoms in the crystal.
In Bragg's construct, the planes in the crystal are exposed to a radiation source at a glancing angle θ and X rays are scattered with an angle of reflection also equal to θ. The incident and diffracted rays are in the same plane as the normal to the crystal planes.
Bragg reasoned that constructive interference would occur only when the path length difference between rays scattered from parallel crystal planes would be an integral number of wavelengths of the radiation.
When the crystal planes are separated by a distance d, the path length difference would be 2d sin θ. Thus, for constructive interference to occur Bragg’s law must be fulfilled.

53. For constructive interference: nλ = 2a From trigonometry: a = d sin θ
or a = 2 d sin θ
thus, nλ = 2d sin θ
What it says is that if we know the wavelength ,λ , of the X‐rays going in to the crystal, and we can measure the angle θ of the diffracted X‐rays coming out of the crystal, then we know the spacing (referred to as d‐spacing) between the atomic planes.
d = nλ /2 sin θ

54. Checkpoint Question 1 What are x-rays?
X-rays are high-energy waves that travel at the speed of light. X-rays can penetrate fairly dense objects, such as the human body. They cannot be seen, heard, felt, tasted, or smelled.

55. Checkpoint Question 2
Why is it important to schedule a barium enema before an upper GI or barium swallow?

56. Answer
Barium enemas involve filling only the large intestine with barium. Because the large intestine is the last part of the GI tract, this barium can be eliminated more quickly. If an upper GI examination is performed first, it may be days later before barium can be eliminated, thus delaying other examinations.

57. Radiation Safety
X-rays have potential to cause cellular or genetic damage
At highest risk
Pregnant women
Children
Reproductive organs of adults

58. Radiation Safety Procedures for Patients
Reduce exposure amounts as much as possible
Avoid unnecessary examinations
Limit area of body exposed
Shield sensitive body parts
Evaluate potential pregnancy status

59. Radiation Safety Procedures for Clinical Staff
Limit amount of time exposed to x-rays
Stay far away from x-rays
Use available shielding
Avoid holding patients during exposure
Wear individual dosimeters
Ensure proper working condition of equipment

60. Diagnostic Procedures
Routine radiographic examinations
Named for part of body involved
Performed for viewing bone structure or abnormalities

61. Mammography Specialized x-ray examination of the breast
Screening tool for breast cancer
Breast compressed in specialized device
Has become vital adjunct to biopsy procedures

62. Contrast Media Examinations
Radiographic contrast media helps differentiate between body structures
Used to evaluate structure and function

63. Contrast Media Introduced into body in several ways
Swallowing
Intravenously
Through a catheter
Medical assistant must ensure that patients understand preparation instructions

64. Checkpoint Question 3
How do contrast media help in differentiating between body structures?

65. Answer
Contrast media help differentiate between body structures by artificially changing the absorption rate of a particular structure so that it can be seen clearly instead of blending in with adjacent structures. For example, barium sulfate absorbs radiation and shows up as white areas on a radiograph.

66. Fluoroscopy Use x-rays to observe movement within the body
Barium sulfate through the digestive tract
Iodinated compounds showing the beating of the heart

67. Computed Tomography (CT, CAT scan)
X-ray tube and film move in relation to one another, blurring all structures except those in focal plane.
CT uses x-rays from a tube circling the patient, analyzed by computers to create cross-sectional images

68. Checkpoint Question 4
How does fluoroscopy differ from computed tomography and sonography?

69. Answer
Fluoroscopy uses x-rays to show movement within the body. CT uses a combination of x-rays and computers to create cross-sectional images of the body. Sonography uses high-frequency sound waves to create cross-sectional still or real-time (motion) images of the body.

70. Radiation Therapy
High-energy radiation is used to destroy cancer cells
Treatments must be planned carefully by radiologist
Most patients have some side effects

71. Transfer of Radiographic Information
Radiographic images remain part of permanent record
Digital images saved on disk
X-ray films belong to site where study was performed
Examining physician or radiologist writes summary of the examination
Medical assistant obtains patient’s permission to have summary sent to office physician

72. Teleradiology Use of computed imaging and information systems
Provides new benefits in medicine
Digital images can be transmitted via telephone lines to distant locations
Allows for consultation with experts on difficult cases

73. Dental X- Rays What is the purpose of dental x- rays
What does the assistant giving the x- ray look for
What is the educational requirements of the person giving the x- ray
Specific shots that are taken when in the “chair”

74. Purpose of dental x - rays
To help the dentist reach a correct diagnosis.
Help to provide the patient with proper care and treatment.

75. What is found through x – rays?
Tooth Decay
Periodontal disease
Extra Teeth
Bone cancer (cysts)
Osteoporosis
Root fragments( configuration)
Abscesses of the teeth or gums
Tooth position
Tatar below the gum line
Jaw joint irregularities
Facial bone composition

76. Reported problems
Table systems
- mechanical system for positioning tabletops
Wires and cables may break ---- tabletop to jam
Control unit
Control levers jam (MA, KV, Time, …)
Collimator (Levers)
Light Localizer
Tube
PCB Control
Mechanical jam of film tray
Collimator loss from its x-ray tube
****** LOSS X-RAY TUBE SUSPENSION ******

77. Purchase Considerations
Tube
(focal spot of the tube determine the resolution of images)
Generator
(High frequency generator needs less space and smaller HV cables)
Table
(Fixed, floating top, tilting, or elevating which is suitable for
traumatic and emergency patients).
Digital radiography
Image quality, storage space,
Digital Imaging and Communication in Medicine (DICOM),
remote control,