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148 Cards in this Set
- Front
- Back
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What are 6 important darkroom requirements?
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1. Adequate safelighting
2. Free of light leaks 3. Clean 4. Temperature Controlled 5. Proper Ventilation 6. Lockable Door or Maze for unwanted light |
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What does collimation do?
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Restricts the size and shape of the x-ray beam.
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What do Film Holding Devices Do?
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Improve aiming accuracy to reduce chances of unacceptable images.
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What is this a picture of and when was it taken?
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The first medical x-ray of Roentgen's wife, Anna Bertha's, hand taken on December 22, 1895.
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How does Filtration help protect the patient?
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Removes unwanted, low energy x-rays.
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How much does F-speed film reduce patient exposure?
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60-70%
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Where does the ADA believe patient protection should be emphasized?
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Reducing exposure of the primary beam to facial structures.
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What is the Principle of Optimization?
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"It holds that dentists use every means to reduce unnecessary exposure to their patients and themselves - ALARA.
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What is so great about digital images?
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Need less radiation, able to zoom, play with contrast, image enhancement, etc.
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What are 3 important ages of Dr. Kells?
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40 - began work with x-rays
50 - has cancer of right hand which led to amputation of his whole arm 72 - committed suicide |
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What are the proper filtration thicknesses for a KVp of 50-69 or 70 and above?
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50-69: 1.5 mm Al
70 and above: 2.5 mm Al |
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What is the Principle of Dose Limitation?
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Dose limits are used for occupational and public exposures to ensure that no individuals are exposed to unacceptably high doses.
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What does proper darkroom protocol reduce?
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The need for retakes and further radiation exposure.
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Which 2 body parts does the lead apron protect most?
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1. Thyroid Gland
2. Gonads |
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Who is Dr. Edmund Kells?
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The pioneer of the application of X-rays in the United States.
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What did Dr. Walkhof do wrong when taking the first x-ray?
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Subjected himself to 25 minutes of radiation exposure!
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What is the normal range of exposure times today?
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0.01 - 0.03 seconds.
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What are the 3 guiding principles in radiation protection?
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Principle of Justification
Principle of Optimization Principle of Dose Limitation |
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What are the 5 Radiation Protection Measures for the Operator?
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1. Stand at least 6 feet away from the patient and 90-130 degrees to the primary beam
2. Stand behind a barrier 3. Never stand in the primary beam 4. Never hold films in the patient's mouth 5. Never hold or stabilize the X-ray tubehead during the exposure |
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What is the maximum permissible dose?
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The maximum dose of radiation which will not be expected to cause any significant radiation effects in a lifetime.
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What are 5 ways the dental office can reduce radiation exposure?
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1. Proper Staff Training
2. Monitoring of the X-Ray Machines 3. Darkroom Protocol 4. Film Badge Service 5. Primary & Secondary Barriers |
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What did Roentgen do on November 8th, 1895?
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First produced and detected x-ray radiation which won him the first Nobel Prize in Physics in 1901.
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What is the Principle of Justification?
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The dentist should identify those situations where the benefit to the patient exceeds the low risk of harm.
This principle determines who is examined and what examination we choose. |
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What is this, when was it taken and who took it?
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First dental radiograph
January 14, 1896 Dr. Otto Walkhoff |
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What are the mps for occupational and public exposure?
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occupational: 50 mSv/year
public: 1-5 mSv/year |
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What 3 things are important to remember about Film Mounting and Viewing?
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1. Use opaque mounts to block excess light to increase diagnostic efficiency
2. View on a light box 3. Helps to more throughly evaluate films and reduce retakes |
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What is the Federal Regulation on beam diameter?
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No greater than 7 cm when tube is operated at >50 KVp.
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When is the use of a lead apron not required?
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When all the NCRP recommendations are followed rigorously, except in children and pregnant women.
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How much is skin exposure reduced by using a rectangular vs. a round collimator?
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60% because the round cone field size is 3 times greater than necessary.
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Why is there an emulsion coat on both sides of the x-ray film?
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Increases the sensitivity of the film, so less radiation is necessary.
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What did dentists use before commercially available film?
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Glass Plates or Photographic film wrapped in black rubber dam.
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What are the two basic types of image receptors?
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1. Film - analog
2. Digital receptors |
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What are the 2 basic components of modern films?
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1. Base: made of plastic to support the emulsion
2. Emulsion: sensitive to radiation |
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What are the 3 contents of the film packet?
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1. Black, lightproof paper
2. Film 3. Lead Foil |
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What produces the sensitivity sites in the silver bromide crystals?
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Sulfur compounds and Iodides.
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What does the thickness of the base do, unfortunately?
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Allows for slight offset of the images when viewed at an angle which may appear as unsharpness.
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What does the clearing agent do?
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Ammonium thiosulfate is used to clear the silver halide grains from the emulsion.
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What are 4 important rules of processing tanks?
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1. Developer is on the left, Fixer on the right
2. Tank should have an inlet and drain 3. Made of Stainless Steel 4. Should be covered when not in use |
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What are 5 important characteristics of the silver halide crystals?
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1. Active constituents of the emulsion
2. Microscopic 3. 95% AgBr, 5% AgI 4. High atomic number compared to base 5. Silver Bromide is very energy sensitive: radiant energy, white light, & pressure |
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What are 4 characteristics of screen film?
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1. Used for extraoral imaging
2. Always used with intensifying screens 3. Decreased resolution when compared to direct film 4. Uses a lower dose of ionizing radiation to create the latent image |
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Which size in standard for kids, adults, bitewings, occlusal.
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0,1: kids
2: adults 3: bitewings 4. occlusal |
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How does the size and shape of the silver bromide crystals affect the characteristics of the film?
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Tabular grains oriented parallel to the film surface maximizes the exposed surface area, requiring shorter exposure times.
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What are the 5 film processing steps?
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1. Immerse in Developer
2. Rinse in Water Bath 3. Immerse in Fixer 4. Wash in Water Bath 5. Dry |
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What are the 3 maintenance requirements of automated processors?
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1. Changing and replenishing chemicals
2. Cleaning the roller transport 3. Keeping the machine spotless, inside and out |
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What are the 2 types of digital image receptors?
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1. Photostimuable Storage Phosphor: PSP
2. CCD/CMOS Sensors |
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What are 5 important characteristics of the gelatin?
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1. Very Pure - Made from cattle bones
2. Allows light and and energy to penetrate unattenuated 3. Keeps silver halide crystals evenly suspended over the base 4. Swells in water, not dissolves, to allow chemicals to penetrate 5. Shrinks evenly, making a smooth surface when dry |
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Where do the electrons come from that go to the sensitivity sites?
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Compton and Photoelectric interactions within the emulsion cause the removal of an electron from the bromide ion, converting it into a bromine atom. These electrons then go to the sensitivity sites.
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What are 3 characteristics of the tube side of the film packet?
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1. White
2. Matte or Slightly Pebbly to prevent mouth slippage 3. Embossed/raised indicating dot that faces the doctor when mounting |
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What is the emulsion composed of?
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A homogenous mixture of silver halide crystals, sensitive to light and photons, suspended in a pure gelatin matrix.
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What does the activator do?
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Raises the pH of the developer to alkaline and then causes the gel to swell so the developer can infiltrate and interact with the silver bromide crystals.
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How long should films be rinsed after fixing and why?
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15 minutes to remove residual fixing and ensure archival processing.
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What are 4 characteristics of the screen film?
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1. Sandwiched between 2 intensifying screens within a cassette
2. Exposed by the light and the incident x-ray photons 3. Must match the intensifying screen type 4. Screen causes photons to scatter, reducing resolution |
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What are the 2 functions of the rinse?
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1. Drops the pH and stops developer activity
2. Prevents deactivation of the fixer which acts at an acidic pH |
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What does the restrainer do?
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Potassium Bromide and Benzotriazole are used to prevent development of unexposed silver bromide crystals, preventing overall fogging.
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What are the arrows pointing to?
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Artifacts in the film made by fingernails.
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Which side of the film packet is color coded?
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The back side which faces away from the radiation source.
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What are 3 characteristics of the Lead Foil Backing?
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1. Attenuates the beam
2. Absorbs scattered radiation so it does not strike the back of the film again 3. Tire Track, Herringbone pattern will appear on the processed film if it is reversed in the mouth |
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What is direct exposure film?
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Intended to be exposed to x-rays photons only, produces high resolution images, but requires a relatively high dose of radiation.
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What is added to the emulsion to improve the sensitivity of silver?
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Trace amounts of gold or sulfur containing compounds.
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What are 3 important characteristics of the overcoat?
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1. Very thin, non-abrasive, transparent layer of pure gelatin
2. Covers both sides of the film to protect it from mechanical damage 3. Without it, the silver halide crystals would react to gentle abrasion pressure making dark spots on the film |
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How long should films be rinsed after being developed?
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30 seconds
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What does the fixer do?
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Removes unexposed silver bromide crystal, creating clear areas on the film which show as radiopacities.
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What does the developer do?
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Converts the latent image sites (exposed silver bromide crystals) into grains of solid silver which block the light in the radiograph, causing a radiolucency.
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What are 2 requirements of the safe light?
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1. At least 4 feet away
2. 15 Watt bulb or less |
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What produces the latent image, generally speaking?
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Electrons, produced as the film is irradiated, are trapped in sensitivity sites and physically alter the crystals which produces the latent image.
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What is the latent image?
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The altered silver bromide crystals that contain the information that will become the radiographic image once it is processed.
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When was the first dental x-ray film sold?
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1919 by Eastman Kodak
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What happens when the silver ions reach the sensitivity sites?
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They are reduced to neutral silver atoms.
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What does the hardening agent do?
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Aluminum sulfate combines with the gelatin to make the emulsion less prone to damage from handling.
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What does the preservative do?
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Used to prevent oxidation of the developer and the fixer, ammonium sulfate.
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What is the intensifying screen?
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A sheet of plastic coated with fluorescent phosphors such as calcium tungstate, gadolinium, or lanthanum.
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What are the 6 common OMFS projections where screen film is used?
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1. Panoramic
2. Lateral Cephalometric 3. Antero-Posterio Cephalometric/Skull Film 4. Townes 5. Waters 6. Lateral Oblique |
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What is the name of the safe light filter?
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GBX-2
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What do the fluorescent substances of the intensifying screens do?
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Glow at a specific wavelength when they are bombarded with x-ray photons. Fluoresce in proportion to the incident radiation.
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How long does it take to develop films in automatic processors?
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4.5 to 8 minutes.
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What are the 6 steps to 'get ready' to develop films manually?
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1. Replenish solutions as necessary
2. Agitate Solutions 3. Check the Temperature 4. Close the Door and Turn on the Safelight 5. Open & Mount films on Hanger 6. Set Timer |
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What is the water jacket?
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Maintains proper temperature of the developer and fixer in the water tank.
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What are the 4 downsides to automatic processors?
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1. Grainy images due to higher temperatures
2. Roller Marks 3. Mechanical Breakdowns 4. Need for meticulous care |
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How long should films be fixed for?
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10 minutes or twice as long as they were developed, and agitated every 30 seconds for 5 seconds.
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What does the squeegee action of the rollers do?
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Increase the energy of the developer, boosting resultant film speed from E to F.
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What is the maximum amount of time a film should be exposed to a safe light?
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5 minutes
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What is a Panorama?
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An unobstructed view in every direction.
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Why are the teeth so wide in this panoramic?
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The patient is too far back.
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What is the black line?
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The Image Layer/Focal Trough
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What 3 things may make patient positioning difficult?
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1. Swelling
2. Pain 3. Facial Asymmetries |
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What are 3 panoramic concepts?
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1. Anterior midline is the center of the film
2. Posterior midline is beyond the left and right edges 3. Structures appear flattened and spread out |
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What is a sliding beam transition?
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When the radiation is delivered while machine is sliding between centers of rotation.
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What are 4 instructions to give the patient?
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1. Procedure takes 1/2 minute
2. They must remain motionless 3. The machine will revolve around them 4. Tongue must be kept against the hard palate |
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What are the 2 steps to preparing the machine before the panoramic?
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1. Disinfect the machine
2. Place a new bitestick |
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What are 3 features of Tomography?
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1. To view a slice of a structure
2. Useful for examining centrally located structures where overlying structures obscure conventional images 3. Pans are curved surface tomograms |
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How should the apron be positioned in panoramics?
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1. High in front to protect the thyroid
2. Lower in the back to expose the neck |
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What will be the real image and the ghost image?
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Real: Mandible
Ghost: Condyle |
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What is a panorex?
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Brand name of the original machine - NOT the name of panoramic radiographs.
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What is the cause of these white artifacts?
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The lead apron is up too high in the back.
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What are 3 common double images?
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1. Hard Palate
2. Soft Palate 3. Hyoid Bone |
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What is the image layer (5 characteristics)?
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1. Volume of tissue seen clearly on tomographic image
2. 3d curved volume 3. Called the Focal Trough in panoramic radiology 4. Can vary in thickness 5. Usually pre-set on panoramic machines with variable settings for different size dental arches |
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What are the 5 rules for proper patient placement?
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1. Patient must be as straight as possible
2. Patient's neck should be extended 3. Anterior teeth in bitestick notch 4. Tragus of ear aligned with plastic guides 5. Ala-Tragus line should be 5 degrees from level |
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When are real images formed?
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When an object is radiographed between the center of rotation and the film.
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How many centers of rotation do modern panoramics use?
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3
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When are ghost images formed?
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When an object is radiographed between the x-ray source and the center of rotation.
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What are the 5 advantages of panoramics?
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1. Well-tolerated by patients
2. Minimal time to expose when compared to intraoral radiographs 3. Broad anatomical coverage 4. Relatively low patient dose 5. Useful for patient education |
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What is the correct order of structures to check in panoramics?
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1. Mandible
2. Maxilla 3. Zygoma 4. Soft Tissue 5. Air Spaces 6. Teeth |
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What 2 things combine to make the continuous image?
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1. Stationary Rotation Center
2. Moving Rotation Center |
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What are these?
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Occlusal Views, size 4 film, use to get a 3d aspect of panoramic.
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What will a sphere look like on a panoramic if its between the focal trough and the image receptor.
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A narrow elliptical.
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What are the 6 indications for Panoramics?
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1. Evaluation of Trauma
2. Third Molars 3. Large Lesions 4. Generalized Disease 5. Inability to Tolerate intraoral films 6. Assessment for surgical procedures |
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Why does the dumbell piercing look like this?
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1. The top ball looks different because it is further away from the focal trough.
2. It looks wider because it is closer to the x-ray source and further from the image receptor. |
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What 3 ghost image scan you see in this picture?
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1. L
2. R 3. Earring |
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What are the 3 disadvantages of panoramics?
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1. Resolution not as good as intraoral films
2. Only objects in focal trough are seen clearly 3. Distortion of image |
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What are the 2 types of images seen in panoramics?
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1. Real: Single & Double
2. Ghost |
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What are the 6 steps for interpreting panoramics?
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1. Examine borders of bone
2. Examine medullary bone 3. Check internal structures: canal, foramina, sinuses 4. Check soft tissue shadows 5. Examine air spaces 6. Save the teeth for last |
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What are 3 qualities of ghost images?
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1. On opposite side of radiograph
2. Superior to real image 3. More blurred but have same morphology. |
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What are the 2 steps to preparing the patient for the panoramic?
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1. Remove all jewelry, piercings, hairclips, and removable appliances
2. Explain the procedure to the patient |
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What kind of collimation does every panoramic machine have?
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Double Slit Collimation
1. collimator in source 2. collimator in lead plate in front of cassette |
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What are the 4 distortions of panoramics?
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1. Overlapped Teeth
2. Magnification 3. Minification 4. Objects of interest outside the focal trough |
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What are 4 common soft tissue structures seen in panoramics?
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1. Dorsum of tongue
2. Soft palate 3. Lips 4. Nasolabial fold |
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How does the panoramic machine compensate for the fact that the dental arches are not true arcs?
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It uses several centers of rotation to maintain the arches in the focal trough as it turns around the patient.
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Why were panoramics split images in the early machines?
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The machine had a stationary center of rotation, so the patient had to move to get the image of the different sides.
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What are the 3 air spaces seen in panoramics?
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1. Maxillary Sinuses
2. Glossopharyngeal Air Space 3. Nasal Fossa |
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What are 4 common ghost images?
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1. L & R from machine
2. Spine 3. Earrings 4. Inferior border of mandible |
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Who was the first person to discover the x-ray?
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Wilhelm Conrad Roentgen on November 8, 1895 in Germany.
Roentgen also published 3 papers on his findings about x-rays. None of his conclusions have been yet proved false! |
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Who was the inventor of the bitewing radiograph?
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Howards Riley Raper in 1924
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Who produced the first American dental x-ray?
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Dr. Edmund Kells.
Due to his constant contact with radiographic material he developed severe cancer in his hands & subsequently committed suicide. William Morton is also credited (by some) with this title. |
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Who is the dentist who called for radiation protection in an article on radiation effects & safety?
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William H. Rollins
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Who made the first dental radiograph?
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Dr. Otto Walkoff made the first dental x-ray in Germany in January 1896
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Who discovered the atom?
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Niels Bohr
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How are cathodes & anodes configured in the x-ray tube?
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As a diode
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What is the Cross Vacuum Scale?
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It is a scale the demonstrates the phenomenon of discharge at different pressures (vacuum) inside the tube.
The highest vacuum is .03 Torr. X-rays will be produced in this high vacuum |
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What is the forerunner of rectangular collimators?
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The Rollins Collimator.
Discovered by William H. Rollins for added radiation protection |
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What are the relative sizes of an atom's contents?
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Protons=Neutrons>Electrons
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What is kinetic energy?
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The extra energy a particle possesses due to its motion/velocity
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Where is binding energy highest?
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In inner electron shells
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What form of energy are x-rays composed of?
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Electromagnetic energy.
E=hν h-Planck's constant; ν-frequency |
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What is rest-mass energy?
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The energy needed to keep particles together.
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What happens if you remove parts of the nucleus?
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Rest-mass energy will be released from the atom. Nuclear energy takes advantage of this huge burst of energy
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What is electromagnetic radiation?
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The movement of energy through space as a combination of electric & magnetic fields.
Also called non-particulate radiation. |
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What is an electron volt?
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The energy an electron will acquire if it is accelerated by a potential difference of 1 volt.
This is a very small amount of energy. |
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What occurs during ionization?
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An electron is removed from an atom & the atom becomes unstable. It will instantly begin to form chemical unions with any nearby atoms. This leads to the production of an ion pair.
X-rays cause a huge amount of ionization. This leads to the harmful effects of radiation |
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What is the rule for finding the # of electrons in each shell?
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# electrons= 2(n)(n)
n values: K=1; L=2; M=3; N=4 |
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What is potential energy?
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The energy every particle has (due to its location), which can be converted to other forms of energy
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What types of x-ray beams have the best diagnostic results?
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High energy x-ray beams. They have high frequency & low wavelength.
(Remember: E=hν) |
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What is radiation?
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The transmission of energy through space & matter
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What is the equation for speed of light?
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c= λν
λ-wavelength; ν-frequency wavelength & frequency are inversely proportional |
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Do x-rays or visual light have higher energy?
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X-rays have higher energy and lower wavelength. Because of this they also cause more damage.
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What is particulate radiation?
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"The use of small particles as a means of transferring energy.
Using: alpha particles (He nucleus) beta particles (pos. charged) cathode rays (electrons) protons neutrons |
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What is the Law of Conservation of Energy?
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Energy can be transformed from one form to another, but cannot be created or destroyed.
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What is the exception to the electron formula?
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A normal, stable atom has an external shell with either 8 or 2 electrons
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What is the atomic #? atomic mass?
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Atomic #: # of protons present in an atom
Atomic mass: total # of particles in the nucleus (# of protons & neutrons) Often expressed in atomic mass units. |
