Radiology (X-ray) PDF

Radiology (X-ray) Dr Gihan Omar Dr Gihan Omar 1 Objectives of the course ◼ To provide the students with basic information related to X-ray nature, production, equipments and materials used in the process of radiography. ◼ To demonstrate and train students to perform all intra oral...

Radiology (X-ray) Dr Gihan Omar Dr Gihan Omar 1 Objectives of the course ◼ To provide the students with basic information related to X-ray nature, production, equipments and materials used in the process of radiography. ◼ To demonstrate and train students to perform all intra oral radiographic examination in terms of exposing, processing, and handling radiographs. ◼ To appreciate safety procedures to avoid hazards to themselves, to the patients and to the environment Dr Gihan Omar 2  Course outline ◼ Radiation physics and production of image ◼ Image receptors and equipment ◼ IO radiography and processing ◼ EO radiography ◼ Panorama ◼ Normal landmarks ◼ Digital radiography ◼ Radiation protection Dr Gihan Omar 3  Radiation Physics By Dr Gihan Omar Dr Gihan Omar 4  Important definitions ◼ Radiology: Science dealing with the diagnosis and therapy by the use of ionizing radiation (X-ray, natural isotopes, artificial isotopes). ◼ Roentgenology: Science dealing with the diagnosis and therapy by roentgen rays (X- ray) in the field of medicine. Dr Gihan Omar 5  Important definitions ◼ Radiography: It is the production of a shadow image of a specific object by generating X-ray on a sensitized plate (film) or a digital sensor. ◼ Dental radiography: It is the production of an image of intra-oral or extra oral objects by generating X-ray on a sensitized dental film or a digital sensor. Dr Gihan Omar 6 Dental RADIOLOGY Dr Gihan Omar 7 Clinical Exam + Radiographs Diagnosis Treatment Dr Gihan Omar 8 2008 Dr Gihan Omar 9 2008 Dr Gihan Omar 10 2008 Dr Gihan Omar 11 2008 Dr Gihan Omar 12 History Wilhelm Conrad Roentgen Discovered X-rays on Nov. 8, 1895 13 Dr Gihan Omar Dr Gihan Omar 14 Dr. Otto Walkhoff First Dental Radiograph 25-minute exposure (< 0.5 seconds today) Dr Gihan Omar 15 before exposure after exposure  Dr. C. Edmund Kells He was the first dentist to use intraoral radiograph for root canal treatment. 1896 Dr Gihan Omar 16 2008 Dr Gihan Omar 17 2008 Dr Gihan Omar 18 X-ray Physics Dr Gihan Omar 19  Atomic structure: Atom (electrically neutral) K L (M, N, O, …..etc.) Atomic Number (Z) = # of protons Dr Gihan Omar 20 Dr Gihan Omar 21 ELECTROSTATIC FORCE Attraction between protons and electrons Dr Gihan Omar 22 CENTRIFUGAL FORCE Pulls electrons away from nucleus Dr Gihan Omar 23  CF EF Balance between electrostatic force and centrifugal force keeps electrons in orbit around nucleus Dr Gihan Omar 24 Binding Energy The amount of energy required to remove an electron from its orbit (= electrostatic force). Depends on atomic number (# of protons). Dr Gihan Omar 25  Free electrons ….???? ◼ Ground state: Atom in the normal or ground state is electrically neutral (no. of protons +ve = no. of electrons -ve). ◼ Excitation state: When electron ejects from its normal position to a higher energy level. Dr Gihan Omar 26 ◼ Ionizing state: When an atom loses electron number of +ve protons>number of electros so called +ve ion. ◼ Alternatively, adds electron number of –ve electrons>number of protons and becomes a -ve ion. The process is called ion pair formation. Dr Gihan Omar 27  Radiation it is the emission, transmission, and propagation of energy in space or in matter is the form of particles or waves. Types: 1- Corpuscular radiation (particulate): From radio istopes (ex: radium) or during splitting of an atom. They are not used in dentistry, only in therapeutic means. Properties: Particles , Have mass, High velocity, Have charge Ex.: alpha rays beta Rays Protons Neutrons Dr Gihan Omar Electrons 28 2- Electromagnetic Radiation The movement of energy through space as a combination of electric and magnetic fields Travel at the speed of light (3 x 108 meters/second) Pure energy Dr Gihan Omar 29  W W F Wavelength x Frequency = Speed of light Dr Gihan Omar 30 Electromagnetic Radiation ◼ X-ray ◼ Visible light ◼ Gamma ray ◼ TV waves ◼ Microwaves ◼ Radio waves Dr Gihan Omar 31  Electromagnetic Spectrum radio TV visible x-rays gamma cosmic light Dr Gihan Omar rays rays 32  ENERGY Ability to penetrate Shorter wavelength, higher energy Higher frequency, higher energy Dr Gihan Omar 33 ◼Ionizing radiation Have sufficient energy to remove electron from an atom ex.: cosmic rays X-ray -rays ◼Non ionizing radiation Have insufficient energy to remove electron from an atom ex.: U V Infra red light Radio &TV cell phones Dr Gihan Omar 34 A B C Dr Gihan Omar 35  X-ray Characteristics ◼ No mass ◼ No charge (neutral) ◼ Travel at speed of light ◼ Invisible ◼ Travel in straight line ◼ Cannot be focused to a point Dr Gihan Omar 36 ◼ High energy waves (Very short wavelength ) Ranges from 0.1 – 1 Angstrom ◼ Differentially absorbed Penetration….liquids, soft tissues Absorption…..lead Deflection……heavy metals Dr Gihan Omar 37  X-ray Characteristics ◼ Cause fluorescence ◼ Affect photographic films ◼ Harmful to living tissue (through ionization) Somatic and genetic Dr Gihan Omar 38 X-ray Machine Dr Gihan Omar 39  X-ray Machine Tube head (tube +accessories) Support arms Control panel Dr Gihan Omar 40  support arms tubehead control panel 2008 Dr Gihan Omar 41  Control Panel kVp readout mA control (50-100) kVp control (10-15) exposure time (3 impulses-5 minutes) Dr Gihan Omar 42 Control Panel Dr Gihan Omar 43  X-ray Tubehead 2008 Dr Gihan Omar 44 X-ray Tubehead PID, BID X-ray tube (cone) PID = position indicating device Dr Gihan Omar 45 BID = beam indicating device  X- ray tube vacuum bulb of glass with 2 electrodes (cathode and anode) extending in opposite directions. Why vaccum?! Dr Gihan Omar 46  Cathode Filament (tungsten) Focusing cup (molybdenum) Dr Gihan Omar 47 Thermoionic Emission Release of electrons from hot filament Increase current, increase heat Increase heat, increase # electrons Dr Gihan Omar 48  Tungsten….why? (as Filament material) ✓ High atomic number (Z=74) ✓ High melting point (3370º C) ✓ Can be drawn into fine wire Dr Gihan Omar 49 Step-Down Transformer 220 volt 3 – 5 volts Filament Circuit Dr Gihan Omar 50 Step-Down Transformer Primary Secondary Dr Gihan Omar 51  Anode Dental x-ray machines have stationary anode Target (tungsten) Copper stem Dr Gihan Omar 52 Step-Up Transformer 65,000 - 90,000 V (65 kVp - 90 kVp) kVp = kiloVoltage peak Dr Gihan Omar 53 Step-Up Transformer Primary Secondary Dr Gihan Omar 54  Exposure Switch You cannot overexpose by holding the exposure switch down too long! Dr Gihan Omar 55  Tungsten….why? (as Target material) ✓ High atomic number (Z=74) ✓ High binding energy ✓ High melting point (3370º C) BUT low thermal conductivity Dr Gihan Omar 56  auto 65-90 mA 8-12…15 Dr Gihan Omar 57 X-ray Tube Dr Gihan Omar 59  X-ray Tube Beryllium Window Focusing cup Target Why vaccum tube?! 2008 Dr Gihan Omar 60 X-ray Tube Components beryllium Dr Gihan Omar window 61  X-ray Machine Components X-ray Control Panel Tubehead 110, 220 line Timer Exposure switch mA selector Step-down transformer kVp selector Step-up transformer X-ray Tube Wires Dr Gihan Omar Oil 62  timer Step-up transformer PID 110 220 oil filter Step-down collimator transformer exposure switch Dr Gihan Omar 63 ◼ Glass tube is evacuated……why??? Remember…….. ◼ Tungesten is perfect as filament material…….why?? ◼ Tungesten is almost perfect as target material…..why???? ◼ Cooling system………..what?? ◼ Leaded glass…. Why??? Dr Gihan Omar 64 Glass tube evacuated to maintain maximum speed of electrons to allow x-ray production. Extra heat is controlled by: ▪ High melting point of tungsten ▪ Conductive properties of copper stem ▪ Oil surrounding x-ray tube Leaded glass to protect against X-rays that are generated in all directions. Dr Gihan Omar 65  Electromagnetic Spectrum 1. Which type of radiation has the highest energy? 2. Which type has the longer wave length? 3. Which type has the highest frequency? visible x-rays cosmic light Dr Gihan Omar rays 66 GIVE US A BREAK 2008 Dr Gihan Omar 67 X-ray Production Dr Gihan Omar 68 Machine turned on ◼ Electric current passes through the tungsten filament of the cathode ◼ Heating and release of electrons in every direction termed thermionic emission ◼ Focusing cup helps to focus the electrons in an electron cloud Exposure switch pressed ◼ The potential difference between the cathode and anode attracts the electrons with very high speed hit the target of the anode. ◼ The electron kinetic energy is converted into 99% heat and only 1% x-rays 69  The X-ray Spectrum X-rays are produced as a result of interactions of the accelerated electrons with tungsten atoms of the target. The energy and wavelength of the produced x-ray varies based on how the electrons interact with the tungsten atoms of the anode. Two types of X-ray are generated: Bremsstrahlung radiation (70% of produced x-rays) Characteristic radiation (30% of produced x-rays) 70 Bremsstrahlung Characteristic Dr Gihan Omar 71  Bremsstrahlung Radiation (Braking radiation, general radiation) X-rays produced when high-speed electrons from the filament are slowed down as they pass close to, or strike the nuclei of the target atoms Dr Gihan Omar 72  Bremsstrahlung X-ray Production Maximum energy high-speed electron + maximum energy x-ray Dr Gihan Omar 73  Bremsstrahlung X-ray Production high-speed x-ray electron + decelerated electron continues to next atom Dr Gihan Omar 74 Characteristic Radiation X-rays have energies characteristic of the target material (energy = difference between binding energies of target electrons involved, e.g., K & L, K & M, etc.) The energy of the high-speed electron from the filament must be higher than the binding energy of the target electron (inner shell electron) with which it interacts in order to eject the target electron Dr Gihan Omar 75  Characteristic X-ray Production Ejected electron High-speed electron (at least 70 keV) M L K Dr Gihan Omar Recoil electron 76  Characteristic X-ray Production Characteristic x-ray (59 kev) Outer-shell electron drops into vacant spot M L K Dr Gihan Omar 77 M L K Dr Gihan Omar 78 High-speed Ejected Characteristic electron electron X-ray M M LK LK Recoil electron What is the energy of the characteristic x-ray produced above? Dr Gihan Omar 79  X-ray Spectrum results from: Varying electron/nucleus distances Multiple electron interactions Dr Gihan Omar 80 Electron interactions with target atoms 1 % produce x-rays 99 % produce heat Dr Gihan Omar 81 The excess heat is controlled by high melting point of tungsten, conductive properties of copper sleeve, and cooling from oil surrounding x-ray tube Dr Gihan Omar 82 Machine Accessories Dr Gihan Omar 83  Machine Accessories 1- filter 2- collimator 3- cone 4- timer Dr Gihan Omar 84  1- Filter remove low-energy x- rays from the x-ray beam Dr Gihan Omar 85  timer Step-up transformer PID 110 220 oil filter Step-down collimator transformer exposure switch Dr Gihan Omar 86  Total Filtration Aluminum filter (s) Added 2.5 mm Glass window Total 70 kVp Oil/Metal barrier 1.5 mm of x-ray tube Inherent Dr Gihan Omar 87  PID The filter is usually located in the end of the PID which attaches to the tube filter head. Material: Al Dr Gihan Omar 88  Advantages ◼ 1. Improve quality of the beam by allowing only the short wave length photons of high penetration power to pass through. ◼ 2. Patient’s and dentist protection by preventing the long wave length photons of high absorption from passing. ◼ 3. Improves the quality of the image. Dr Gihan Omar 89  2- Collimation The collimator is a device that regulates the size and shape of the x-ray beam. It is made of lead with an aperture in the middle. The size of the beam should not exceed 2.75” or 7cm diameter) area covered (less patient exposure) scatter radiation Dr Gihan Omar 90  Collimator 2008 Dr Gihan Omar 91  Collimator 2.75 inches (7 cm) (maximum diameter at end of PID) Dr Gihan Omar 92  Functions: 7 cm 6 cm 1- Make the 7 cm round x-ray beam just cover the film. 6 cm round If you switch from a film 7 cm round PID to a (4.5 cm long) 6 cm round PID, the patient receives 25% less radiation. entrance entrance exit exit Dr Gihan Omar 93 Functions 2- Reduce facial exposure of the patient. 3- Reduce the total body exposure of the patient Dr Gihan Omar 94  Types 1- Diaphragm 2- Tubular 3- Rectangular * Material: Lead. Dr Gihan Omar 95 3- Cone [PID] position indicating device Device used to adjust and direct the beam of X-ray. ◼ Functions: 1. Indicate point of entry. 2. Direct the x-ray beam. 3. Fix target - film distance. ◼ Types: Acc. to material: * Plastic * Glass * Metal (lead) Dr Gihan Omar 96 Dr Gihan Omar 97 2008 Dr Gihan Omar 98  4- Timer 2008 Dr Gihan Omar 99 Dr Gihan Omar 100  Exposure Switch Automatic timer You cannot overexpose by holding the exposure switch down too long! Dr Gihan Omar 101 ◼ Primary radiation: Radiation coming out of the target most of it absorbed by the metal housing. ◼ Useful beam: Radiation coming out of the aperture of the machine. ◼ Secondary radiation: Radiation generated from the surrounding objects with no change in direction. ◼ Scattered radiation: type of secondary radiation deviated in direction. ◼ Stray radiation: radiation scattered due to passage through heavy metals. Dr Gihan Omar 102  Thank you 2008 Dr Gihan Omar 103