Introduction To Dental Radiology PDF

Introduction To Dental Radiology Prepared by : Dr. Rowa’a Yasin  Outlines Terminology History of X-Ray Importance of Dental Radiograph Atom Radiation Types and Nature Electromagnetic Spectrum X- Ray Machine X- Ray Production X- Ray Interaction wi...

Introduction To Dental Radiology Prepared by : Dr. Rowa’a Yasin  Outlines Terminology History of X-Ray Importance of Dental Radiograph Atom Radiation Types and Nature Electromagnetic Spectrum X- Ray Machine X- Ray Production X- Ray Interaction with matter Dr. Rowa'a Yasin  Terminology Radiology A branch of medical science that deals with the use of X-ray , radioactive substances and other form of radiant energy in the diagnosis and treatment of diseases Dental Radiology The science that deals with the use of radiation in the diagnosis of dental disease Dr. Rowa'a Yasin Roentgenology Science that deals with the application of X-ray on any field Radiation It is the process of emission, propagation and transmission of energy by atoms in the form of waves or stream of particle Dr. Rowa'a Yasin X – Radiation High energy radiation produced by the collision of a beam of electrons with metal target in an x-ray tube X-Ray A form of pure energy belong to electromagnetic radiation have a power to penetrate substances and record image shadows on photographic films or digital sensors Dr. Rowa'a Yasin Radiograph A photographic image ( shadow ) produced on receptor ( sensitive film , phosphor plate or digital sensor ) by the passage of x-ray through an object It is basically dependent on the differential absorption of radiation directed through heterogeneous media Dental Radiograph A photographic image produced on receptor by the passage of x-ray through teeth & related structures 2D representation of 3D objects Dr. Rowa'a Yasin Image A picture ( shadow ) or likeness of an object Image Receptor A recording medium examples ( sensitive film , phosphor plate or digital sensor ) Dr. Rowa'a Yasin Radiography The art and science of making radiographs by the exposure of film to X-ray Dental Radiography It is the art of producing an image or picture for intra- or extra-oral structures on a dental film using X-ray Dental Radiographer Any person who positions , exposes and processes X-ray film Dr. Rowa'a Yasin  History X-rays were first discovered in 8 November 1895 by Wilhelm Roentgen professor of physics He won a Noble prize for his discovery of X-ray Dr. Rowa'a Yasin  The term ROENTGEN RAYS often applied to mechanically generated X-rays Roentgen called them X-rays after the mathematical symbol X for unknown Dr. Rowa'a Yasin X-ray of Bertha Roentgen's Hand When the image was developed the bones of her hand & rings were clearly visible Dr. Rowa'a Yasin Pioneers in Dental X-Radiation 1896 German dentist Otto Walkhoff made the first dental radiograph he placed in his own mouth small glass photographic plates wrapped in rubber dam and exposed them for 25 minutes W.J.Mortan a New York physician made the first dental Radiograph in US using a skull Dr. Rowa'a Yasin  Importance Of Dental Radiographs History + Clinical Exam + Radiographs Diagnosis Dr. Rowa'a Yasin Treatment Detection of diseases in the teeth or adjacent structures e.g. Caries , Periodontal disease , Jaw lesions , TMJ lesions and others Detect anomalies or injuries within the teeth , their supporting structures & adjacent facial structures Determine the presence or absence of teeth Localize unerupted teeth Locate lesions or foreign bodies Dr. Rowa'a Yasin Provide information during dental procedures Evaluate Growth & Development Preoperative Assessment Postoperative Assessment of bone healing & surgical treatment effectiveness Dr. Rowa'a Yasin  Atom Atom consists of two parts ▪ Central Nucleus Composed of particles Protons , Neutrons ▪ Orbiting Electrons Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin  Electrons are maintained in their orbit by the Electrostatic Force or Attraction between the positive nucleus and the negative electrons This is known as the Binding energy The strongest binding energy is found closest to the nucleus in K shell whereas electrons located in the outer shells have a weak binding energy Dr. Rowa'a Yasin  Atoms can exist in a neutral state or in an electrically unbalanced state Normally most atoms are neutral containing an equal number of protons (+ charge ) and electrons ( - charge ) Dr. Rowa'a Yasin  If the atom gains an electron it has more electrons than protons and neutrons and therefore it has a negative charge Similarly the atom that loses an electron has more protons and neutrons than electrons and thus it has a positive charge An atom that gain or loses an electron and becomes electrically unbalanced is known as Ion Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin  Radiation A type of energy that can travel through space - When travels in the form of waves called Electromagnetic Radiation - When travels as a beam of fast moving particles called Particulate Radiation Dr. Rowa'a Yasin Nature Of Radiation 1) PARTICULATE OR CORPUSCULAR RADIATION It is that type of radiation given off from radium radioisotopes and during splitting of the atom It is composed of solid subatomic particles These particles include Alpha (α) , Beta (β) , Protons , Neutrons and Electrons Dr. Rowa'a Yasin  Having mass and charge It travels in straight lines Not used in dental diagnostic filed but in Therapeutic means Dr. Rowa'a Yasin 2) ELECTROMAGNETIC RADIATION Formed of units of pure energy which are propagated in the form of waves Doesn’t have a mass or charge They travel in straight lines or wavy motion Dr. Rowa'a Yasin  Has the same speed of light As they propagate in a form of waves they have a wavelength and frequency Not affected by electric or magnetic field They are invisible ( Undetectable by human senses ) Dr. Rowa'a Yasin  Are differentially absorbed by materials they pass through More dense material will absorb more X-ray like amalgam restoration than less dense material like skin They affect photographic film by producing a hidden image , made visible by processing Dr. Rowa'a Yasin  Can be harmful to living tissues Large amounts can cause necrosis ( cell death ) Also destructive effects on somatic and genetic levels You must keep the number of films taken the minimum number needed for proper diagnosis Dr. Rowa'a Yasin Non Ionizing Radiation Ionizing Radiation Dr. Rowa'a Yasin  There are many different forms of EMR Radio waves have the lowest energy and the longest wave length X-ray is part of EMR have high energy , high frequency and short wave length Gamma Rays have the highest energy , highest frequency and the shortest wave length You can only sense two parts of EMR ✓ Feel Infrared ✓ See Visible Light Dr. Rowa'a Yasin  Radiation can be : ❖ Non Ionizing Radiation ✓ Radiation doesn’t have enough energy to ionize atoms or molecules ✓ These type aren’t completely Harmless ✓ Examples Radio transmission , Cell phones Microwaves , Infrared and visible light Dr. Rowa'a Yasin ❖ Ionizing Radiation ✓ Ionization is the process of converting atom into ions ✓ Any radiation that produces pairs of ions ✓ Requires high energy to overcome the binding force that binds the electron to the nucleus This energy enough to remove electrons ✓ Atoms that gain or loses electron are electrically Unbalanced ✓ Harmful can cause cancer , kill cells Dr. Rowa'a Yasin Dr. Rowa'a Yasin Ionizing Radiation Dr. Rowa'a Yasin Dr. Rowa'a Yasin Number of wave cycle / second Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin X – Ray Machine Dr. Rowa'a Yasin The more important equipment involved in the production of final dental radiographic image X - RAY GENERATING EQUIPMENT Required to produce x – rays IMAGE RECEPTORS ( RADIOGRAPHIC FILMS ) Required to detect x- ray PROCESSING EQUIPMENT Required to produce the visual black , white and grey image Dr. Rowa'a Yasin  IDEAL REQUIREMENTS The equipment should be 1. Safe and accurate 2. Capable of generating x – rays in the desired energy range and with adequate mechanism for heat removal 3. Small 4. Easy to maneuver and position 5. Stable , balanced and steady once the tube head has been positioned 6. Easily folded and stored 7. Simple to operate Dr. Rowa'a Yasin  Dental X- ray Generating Equipment Fixed ( Wall mounted ) Mobile ( Portable ) Consists of 3 main components : 1. Tube Head 2. Positioning / Extension arms 3. Control panel (Timer) Dr. Rowa'a Yasin Components of Control Panel The on / off switch and indicator light The timer there are 3 main types 1. Electronic 2. Impulse 3. Clockwork (not accurate , no longer used ) Dr. Rowa'a Yasin  An exposure time selector mechanism either : ▪ NUMERICAL Time selected in seconds ▪ ANATOMICAL Area of mouth selected and exposure time adjusted automatically Warning lights and audible signals to indicate when x-rays are being generated Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin  Voltage / Kilovoltage Determines the speed with which the electrons move When voltage increased the speed of electrons increased The electrons strike the target with greater force and energy Resulting in penetrating X-ray beam with short wave length The Quality of X-ray beam is controlled by kilovoltage The Kilovoltage regulates the speed and energy of electrons and determine the penetrating ability of X-ray beam Dr. Rowa'a Yasin  Amperage / Milliamperage Determines the amount of electrons passing through the cathode filament An increase in the number of electrons available to travel from cathode to anode results in production of increased number of X-ray The Quantity of X-ray is controlled by milliamperage As the milliamperage is increased , more electrons pass through the filament and more X-ray are produced Dr. Rowa'a Yasin Components of Tube Head Dr. Rowa'a Yasin PID an open ended device extended from the tube head for indicating the direction of beam and setting the ideal distance from focal spot on target to the skin Dr. Rowa'a Yasin X – Ray Tube Components A. X-ray Tube B. Cathode C. Anode Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin ❑ The smaller the focal spot the sharper the Radiographic image Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Alter the voltage of incoming electricity Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin 1. Focusing Cup focuses electrons on target 2. Filament releases electron when heated 3. Electron Stream electrons cross from filament to target during length of exposure 4. Vacuum no air or gases inside the tube to prevent electron interaction with other materials 5. Target x-ray produced when electrons strike target Dr. Rowa'a Yasin 6. Copper stem helps remove heat from target 7. Leaded Glass absorbs unwanted X-ray as radiation protection measures since X-ray produced in all directions 8. X- Ray produced in target are emitted in all directions 9. Beryllium Window non leaded glass Allows x-rays to pass through PID would be located directly in line with this window Dr. Rowa'a Yasin  X-Ray Production The Tungsten filament is electrically heated and a cloud of electrons is produced around the filament (cathode) by thermionic emission The high voltage ( potential difference ) across the tube accelerates the electron at very high speed towards the anode Dr. Rowa'a Yasin  The focusing device aims the electrons stream at focal spot on the target The electrons bombard the target and brought suddenly to rest The Kinetic energy lost by the electrons is transferred into either ✓ HEAT 99% ✓ X-RAYS < 1 % Dr. Rowa'a Yasin  The Heat produced is removed and dissipated by the copper block and surrounding oil The X- Rays are emitted in all directions from the target those emitted through the small beryllium window constitute the beam used for diagnostic purposes Dr. Rowa'a Yasin X-RAY BEAM Cone shaped Travel in diverging straight line as they radiate from focal spot Primary Beam Original useful beam of X-ray Originates at focal spot and emerges through tube head Central Ray is the X-ray at the center of the primary beam Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin X-Ray Interaction with Matter Absorption of X-ray Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Reference Dr. Rowa'a Yasin