What is an X ray? Parts of an X ray Machine AN INTRODUCTION TO RADIOLOGY X RAYS ARE USED IN DENTISTRY TO: 8/18/2016. Tubehead (PID) Number Scale

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1 AN INTRODUCTION TO RADIOLOGY What is an X ray? o Energy created when an atomic particle changes its speed or direction o That energy is called a Photon o Examples of photons in everyday life are: TV, Microwave, Radio, Cell Phone, and Light The greater the change the more energy the photon has X-rays have so much energy they can damage tissues In dentistry photons are called x-rays; x- rays are created in the x-ray tubehead X RAYS ARE USED IN DENTISTRY TO: Detect lesions, diseases and conditions that cannot be seen clinically Confirm or classify suspected disease Locate lesions of foreign objects Obtain information during dental treatment Determine growth and development Identify any changes Document conditions at a specific point in time Extension Arm Control box On/off switch Parts of an X ray Machine Parts of an X ray Machine Tubehead Positionindicating device (PID) Tubehead Activation Switch (Outside the room) Number Scale 1

2 Opening film Parts of an X ray Film Dental X Rays Low energy, long wave length photons are undesirable X-rays with only HIGH energy desired Low energy x-rays produce scatter radiation which is damaging Scatter is the radiation created when low energy x-rays interact with subject matter (tooth, bone, skin, etc...) and scatters Interaction creates ionized subject matter Ionized subject matter may not function properly Filters are used to remove low energy x-rays Need to remove by filtration- (they cause tissue damage because of scatter radiation in tissue) High energy, short wavelength photons are preferred They pass through tissue without interacting X Ray Image Latent Image the latent image is defined as the invisible image that is produced in the film by x-rays and then converted into a visible image when processed Silver Halide crystals the latent image is produced in the film emulsion, which contains silver halide crystals and gelatin Plastic X-ray Question: If all x-rays leave tubehead with the same energy, why do some x-rays have less energy when they reach the film? 2

3 Image Characteristics Visual Characteristics RADIOLUCENT Lots of energy reached crystals because object lacked density and did not absorb x-rays RADIOPAQUE Very little energy reached crystals because object was dense and absorbed all the energy Film Density- the overall blackness or darkness of a radiograph Object Density (Subject thickness)- the degree of hardness of the object being x-rayed Contrast- various degrees of blackness (film densities) between adjacent areas on a radiograph Which has more film density? Which object has more density? Which one is radiopaque? Which one is radiolucent? Factors Affecting Density Milliamperage (MA s) - intensity of the x-ray tube current (# of x-rays= QUANTITY) Kilovolts (KVP s) - maximum or peak voltage used during exposure- energy or QUALITY Exposure time- the time interval during which x-rays are produced (60 impulses per second) Why would we want to change KvP, ma. or impulses? Changing KvP, ma or impulses (exposure time) can all affect the density of the radiograph For example, increasing the KvP will increase the beam intensity and increase the film density- (therefore the film becomes darker) Increase kilovolts (KvP) Increase milliamperage(ma) or time (impulses) 3

4 If you increase the KvP, the resulting film will have lower contrast (lots of gray); this is termed long-scale contrast If you decrease the KvP, the resulting film will have higher contrast (lots of black & white); this is termed short-scale contrast FILM SIZES Size 0- Used for very small children Size 1- Used primarily for anterior teeth in adults or bitewings for children Size 2- Bitewing film used for posterior teeth in adults Size 3- A longer and narrower film used ONLY for bitewing films (rarely used) Size 4- Used for occlusal films Intraoral film (goes inside the mouth) Periapicals Bitewings Occlusals Extraoral film (goes outside the mouth) Panoramic (panoral) Periapical Film Examines the entire tooth (crown and root) and supporting bone. A full mouth series (FMS) includes periapicals of the entire mouth TYPES OF X RAY FILMS Bitewing Film Occlusal Film Examines large areas of the maxilla or mandible. The patient bites on the entire piece of film Used to detect interproximal caries 4

5 Panoramic film Film Holding Devices Used to hold and align the x-ray film in the mouth Used to detect bone pathology and evaluate Growth and tooth eruption patterns BWtab XCP Stabe biteblock EEZEE-Grip FILM SPEED D E & F **Faster film (E and F) have larger silver halide crystals, takes less radiation to expose Types of film speed used in intraoral radiography: D-Speed (should NOT be used) E-Speed- requires ½ the exposure time of D-speed and has comparable image contrast and resolution and is less exposure to the patient (no longer on the market) F-Speed- newest; 50% less radiation than D and 20% less radiation than E The processor It contains developer that changes the latent image to a permanent image It also contains fixer and keeps the new image from reverting to a latent image Mounting After the film is developed and fixed, it is mounted in a film holder 5