radio final

• Dental radiographs are a critical diagnostic tool. They can help to detect teeth conditions and/or abnormalities, check supporting structures, and monitor changes in a patient's health.
• Dental hygienist's role


  Exposing, developing, and mounting radiographs
• Knowing how to properly perform these duties is essential, not only for the safe use of ionizing radiation, but also for the appropriate development of the patient's treatment plan.
• ADA recommendation on radiographs

  Radiographs be taken on an individual basis, as per a patient's dental needs
• Radiographs were first discovered

  1895
• Hittorf-Crookes cathode ray tube

  • Partially evacuated tube with an anode and a cathode at both ends
  • When high voltage electricity was passed from the anode to the cathode, Roentgen observed a fluorescent glow on a barium platinocyanide-coated screen across the room
  • When he shrouded the tube in a heavy black box, he could still see the greenish fluorescent light on the platinocyanide-coated screen
• Roentgen's discovery


  1. Passing the radiation through several objects

  2. Using his own hand and seeing the bones projected onto a fluorescent screen
• Electromagnetic radiation


  Comes in varying levels of energy, wavelengths, and frequencies, which determine if the rays are visible or invisible
• 1. rays


  • Varying wavelengths (length of wave) and frequencies (how many times the wave appears from point x to point y) that determine if the x-ray penetrates an object
  • X-rays that penetrate more effectively have a shorter wavelength with a high frequency rate
  • Less penetrating x-rays will have low frequency with longer wavelengths
• Particulate radiation


  Bundles of energy that consist of particles and waves of electromagnetic radiation, called x-ray photons, that move at the speed of light
• Bremsstrahlung or braking radiation

  The sudden deceleration a negatively charged electron experiences when it passes near a positive nucleus, becoming attracted to it
• Radiological effects


  • X-ray photons interact with the patient's tissues, and may be absorbed or scattered
  • Some photons are attenuated or absorbed by the patient, resulting in radiopaque areas on the radiographic films
  • Other photons exit the patient, and are exposed on radiographic films as radiolucent areas
• Absorbed x-ray photons


  Can have biological effects, as ionizing radiation can alter the DNA of the nucleus of a cell, causing a disturbance with cell division or mitosis, resulting in future tissue mutations
• Classic scatter radiation


  Also called coherent or Thompson effect, occurs when a low-energy x-ray photon that is unable to eject an electron from an atom excites the electron instead, producing a new photon to be ejected from the atom
• Characteristic radiation or photoelectric effect

  Occurs when a high-speed photon ejects a tightly bound inner orbit electron from an atom, causing an outer orbit electron to drop down into the space left empty, emitting energy, with the ejected electron called a recoil electron
• Compton effect


  The result of a high-energy photon ejecting a loosely bound outer orbit electron after the two collide, with energy being absorbed
• Free radicals


  Produced when X-ray photons intermingle with water and oxygen of biological molecules or human tissue, having a high likelihood of interacting with human biological tissue and causing damage to the biological cells
• Tissue sensitivity to radiation

  • High: Lymphocytes, Bone marrow, Reproductive cells, Thyroid glands in children, Intestines, Endocrine glands, Skin, Oral mucosa
  • Moderate: Developing bone & cartilage, Mature bone & cartilage, Connective tissue, Salivary glands, Small vasculature, Thyroid glands in adults
  • Low: Kidneys, Liver, Muscles, Nerve tissue
• Operator and patient protection

  • Standard ADA and CDC precautions must be taken, including plastic barriers, decontamination, and protective equipment for dental personnel
  • Lead apron with thyroid collar should be placed over the patient to protect reproductive organs and thyroid gland
• Lead apron thickness


  0.25 mm thick
• Clinician positioning during film exposure

  1. Remain behind a lead barrier, or cover any exposed anatomy with a lead apron 0.25 mm thick

  2. Safest area to stand is within 90-135 degrees at the side of the patient and away from the primary beam
• Distance from beam


  At least 6 feet of distance from the direction of the beam is best
• Dental personnel occupational exposure monitoring


  Wear film badges
• Maximum permissible dose (MPD)

  • For dental personnel, 5.0 rem (.05 Sv) per year
  • For the general public, 0.5 rem per year
  • MPD does not use the age-based formula
• Maximum accumulated exposure formula

  5 (N-18) R, where N is the patient's age
• Radiation measurements


  • Traditional units: Roentgen (R), rads (radiation absorbed dose), rems (roentgen-equivalent-man)
  • SI units: Gray, Sievert, coulombs/kg
• 1. ray tube


  Contains a protective housing with a lead lined-casing and an anode and cathode, surrounded by an oil bath cooling system
• Cathode


  Contains the filament that produces electrons through thermionic emission, controlled by milliamperage
• Anode


  Contains a focal spot on the tungsten target that is inundated with electrons from the cathode, generating excess x-rays
• Beam filtration


  Aluminum filter must be 1.5 mm for x-ray exposure below 70kVp, and 2.5 mm for x-ray exposure greater than 70kVp
• Collimation


  Lead diaphragms restrict the size of the beam through a round or rectangular aperture of the position indication device (PID) or beam indication device (BID)
• PID or BID size regulations

  • Circular tube heads: 23" (7 cm) in diameter
  • Rectangular tube heads: 13" by 13" (3.5 x 4.4 cm)
  • Length: 8", 12", or 16"
• Digital radiography


  • Direct digital imaging uses a wired sensor that transmits an electronic image to the computer monitor
  • Indirect digital imaging scans and digitizes a radiographic film onto the monitor
  • Storage phosphor imager uses a reusable imaging plate that captures an image and is transferred to the computer monitor
• Radiographic quality


  • Milliamperage (mA) controls the quantity of radiation
  • Kilovolt peak (kVp) controls the quality of radiation
• Dental x-rays are black, white, and shades of gray, with more radiation absorbed onto the film during exposure of soft tissue resulting in more film emulsions being exposed.
• Plate


  Placed onto a laser scanner that transfers the image to the computer monitor
• Imaging plates


  Reusable, can be recycled by placing face down under a white light to erase the latent image
• Ampere


  Unit of electrical current
• 1. ray cathode units


  Operate on a smaller amount of electricity than most other appliances, measured in milliamperes (mA)
• Cathode


  Controls the milliamperage (mA)