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Radiology Test 2
| Question | Answer |
|---|---|
| extra oral receptor is... | image receptor outside the patient such as a Panoramic |
| intraoral receptor is... | Image receptor goes inside the mouth |
| what are the three types of radiographs? | periapical, occlusal, interproximal or bitewing |
| what is the definition of a full mouth survey? | Periapical radiographs of all the tooth barring areas, bitewings as necessary |
| tube head pointing downward is... | positive such as in the maxillary periapicals |
| tube head pointing upward is... | negative such as in the mandibular periapicals |
| what happened if you get foreshortening of teeth? | too great a vertical angulation |
| what happened if you elongation of teeth? | not enough vertical angulation |
| what is the bisecting line angle technique? | x-ray beam perpendicular to the bisecting line of the long axis of the tooth, does not use a film holder, isosceles triangle for equal distortion |
| what is paralleling technique? | X-ray beam perpendicular to the long axis of the tooth, film is not angled. |
| what is the one rule that paralleling technique violates? | does not keep the film receptor as close to the teeth because bone gets in the way |
| what is the blue color on Rinn take? | anterior periapicals |
| what does the yellow color on Rinn take? | posterior periapicals |
| what does the red color on Rinn take? | bitewings |
| when do you never use cotton rolls on a Rinn device? | NEVER BITEWINGS, can for periapicals |
| Maxillary Central-Lateral incisor periapical: Maxillary Central/Lateral Incisor Projections right and left what is the LANDMARK? | the embrasure between the central and lateral incisors is centered on the biteblock. The incisal edge should be on the edge of the bite block so the film is placed in the well into the mouth |
| why do we always take anterior X-rays first? | easier to see what we are doing, makes the patient more comfortable and trusting of the clinician |
| Maxillary Central-Lateral incisor periapical: Maxillary Central/Lateral Incisor Projections right and left what is the IMAGE FEILD | include all of the central and lateral incisors and their periapical areas |
| Maxillary Central-Lateral incisor periapical: Maxillary Central/Lateral Incisor Projections right and left what is the SENSOR? | size 1 placed in a vertical position |
| Maxillary Canine Periapical: Maxillary Canine Projections LANDMARK | the crown of the canine is centered on the bite block. The cusp should be on the edge of the bite block, so that the sensor is placed well into the mouth |
| Maxillary Canine Periapical: Maxillary Canine Projections IMAGE FEILD | should include all of the canine and its periapical area, the distal of the lateral incisor and the mesial of the first premolar |
| what should we not worry about on Maxillary Canine Periapical: Maxillary Canine Projections | distal of the canine being overlapped will get that in the premolar bitewing or premolar PA |
| Maxillary Canine Periapical: Maxillary Canine Projections SENSOR | sensor #1 placed in a vertical position |
| Mandibular Central Incisor periapical: Mandibular Central Incisor Projection LANDMARK | the embrasure between the central and lateral incisors is centered on the bite block. The incisal edges should be on the edge of the bite block, so that the film is placed well into the mouth |
| Mandibular Central Incisor periapical: Mandibular Central Incisor Projection IMAGE FEILD | include all of the central and lateral incisors and their periapical areas, the mesial portions of the adjacent central incisor and canine |
| Mandibular Central Incisor periapical: Mandibular Central Incisor Projection SENSOR | size #1 placed in a vertical position |
| Mandibular Lateral Incisor- Canine Periapical: Mandibular Lateral Incisor/Canine Projections (right and left) LANDMARK | the embrasure between the canine and lateral incisor is centered on the bite block. The incisal edges of the teeth should be approximately half-way out on the biteblock with the sensor between the teeth and the tongue |
| Mandibular Lateral Incisor- Canine Periapical: Mandibular Lateral Incisor/Canine Projections (right and left) IMAGE FEILD | : include all of the canine and lateral incisor, their periapical areas, the distal portion of the adjacent central incisor and the mesial portion of the first premolar |
| Mandibular Lateral Incisor- Canine Periapical: Mandibular Lateral Incisor/Canine Projections (right and left) SENSOR | size #1 sensor is placed in a vertical position |
| Maxillary Premolar Periapical: Maxillary Premolar Projections (right and left) LANDMARK | the embrasure between the 2nd premolar and 1st molar should be centered on the bite block. The buccal cusps should be aligned with the edge of the bite block so that the sensor is placed well into the mouth |
| Maxillary Premolar Periapical: Maxillary Premolar Projections (right and left) IMAGE FEILD | include all of both premolars, and the first molar, their periapical areas, the distal of the canine and the mesial of the second molar |
| Maxillary Premolar Periapical: Maxillary Premolar Projections (right and left) SENSOR | size #2 sensor is placed in the horizontal position |
| Maxillary Molar Periapical: Maxillary Molar Projections (right and left) LANDMARK | the crown of the 2nd molar should be centered on the bite block. The buccal cusps should be aligned with the edge of the bite block so that the sensor is placed well into the mouth |
| Maxillary Molar Periapical: Maxillary Molar Projections (right and left) IMAGE FEILD | : include all of the second and third molars and their periapical areas, all of the maxillary tuberosity, and the distal of the first molar all areas of the bone behind the tooth |
| Maxillary Molar Periapical: Maxillary Molar Projections (right and left) SENSOR | size #2 sensor is placed in the horizontal position |
| Mandibular Premolar Periapical: Mandibular Premolar Projections (right and left) LANDMARK | the embrasure between the 2nd premolar and 1st molar should be centered on the bite block. The sensor should be placed as close to the lingual alveolar ridge as practical |
| Mandibular Premolar Periapical: Mandibular Premolar Projections (right and left) IMAGE FEILD | the field should include all of both premolars, the first molar, the distal of the canine, and the mesial of the second molar |
| Mandibular Premolar Periapical: Mandibular Premolar Projections (right and left) SENSOR | Size #2 sensor is placed in the horizontal position |
| Mandibular Molar Periapical: Mandibular Molar Projections (right and left) IMAGE FEILD | the field should include all of the second and third molars and their periapical areas, bone distal to the third molar, and the distal of the first molar |
| Mandibular Molar Periapical: Mandibular Molar Projections (right and left) LANDMARK | the crown of the 2nd molar should be centered on the bite block. The sensor should be placed as close to the lingual alveolar ridge as practical |
| Mandibular Molar Periapical: Mandibular Molar Projections (right and left) SENSOR | size #2 sensor is placed in the horizontal position |
| Premolar Horizontal Interproximal (bitewing): Premolar Projections (left and right) LANDMARK | the mesial edge of the sensor is aligned with the mesial surface of the mandibular canine. The inferior edge of the sensor is placed in the floor of the mouth under the tongue ALTERNATIVE: |
| Premolar Horizontal Interproximal (bitewing): Premolar Projections (left and right) IMAGE FEILD | first premolar, second premolar and distal of the canine |
| Premolar Horizontal Interproximal (bitewing): Premolar Projections (left and right) SENSOR | size #2 sensor is placed in the horizontal plane |
| Premolar Horizontal Interproximal (bitewing): Premolar Projections (left and right) LANDMARK ALTERNATIVE | sensor between the tongue and the teeth, place the mesial edge of the sensor directly lingual to the mandibular central incisors |
| Molar Horizontal Interproximal (bitewings): Molar Projections right and left LANDMARK | distal edge of the sensor is placed posterior to the distal surface of the most posterior clinically erupted tooth |
| Molar Horizontal Interproximal (bitewings): Molar Projections right and left IMAGE FEILD | include the distal surfaces of the most posterior clinically erupted molars and an unobstructed view of the proximal surfaces of these teeth |
| Molar Horizontal Interproximal (bitewings): Molar Projections right and left SENSOR | size #2 sensor is placed in the horizontal position |
| Anterior Maxillary: Maxillary Cross-sectional Occlusal Projection HEAD POSITION | midsagittal plane is vertical and ala-tragus line is parallel with the floor |
| Anterior Maxillary: Maxillary Cross-sectional Occlusal Projection SENSORY PLACEMENT | centered on the midsagittal plane and placed as far posterior as practical |
| Anterior Maxillary: Maxillary Cross-sectional Occlusal Projection CENTRAL RAY POINT OF ENTRY | Point of entry being the bridge of the nose |
| Anterior Maxillary: Maxillary Cross-sectional Occlusal Projection DEGREES | vertical angel of the central ray is +60 to +65 degrees |
| Anterior Mandibular: Mandibular Anterior Occlusal Projection HEAD POSITION | midsagittal plane is vertical and ala tragus line is 45 degrees to the floor |
| Anterior Mandibular: Mandibular Anterior Occlusal Projection SENSORY PLACEMENT | centered on the midsagittal plane and placed as far posterior as practical |
| Anterior Mandibular: Mandibular Anterior Occlusal Projection CENTRAL RAY POINT OF ENTRY | Point of entry being the tip of the chin |
| Anterior Mandibular: Mandibular Anterior Occlusal Projection DEGREES | vertical angel of the central ray is -10 (making an overall -55 degree angle between the sensor plane and the central ray) |
| Anterior Mandibular: Mandibular Anterior Occlusal Projection IMAGE FEILD? | include an oblique view of the mandibular anterior teeth and the floor of the mouth |
| Cross-sectional Mandibular: Mandibular Cross-sectional Occlusal Projection HEAD POSITION | the midsagittal plane is vertical and the head is tipped backwards with the chin elevated |
| Cross-sectional Mandibular: Mandibular Cross-sectional Occlusal Projection SENSORY PLACEMENT | centered on the midsagittal plane and placed as far posterior as practical |
| Cross-sectional Mandibular: Mandibular Cross-sectional Occlusal Projection CENTRAL RAY POINT OF ENTRY | The point of entry being the center of the floor of the mouth |
| Cross-sectional Mandibular: Mandibular Cross-sectional Occlusal Projection DEGREES | vertical angle of the central ray is -90 degrees to the plane of the sensor |
| Cross-sectional Mandibular: Mandibular Cross-sectional Occlusal Projection IMAGE FEILD | include a cross sectional view of the entire mandible and floor of the mouth |
| what is horizontal angulation for a pit fall? | overlapping contacts |
| what are the X-ray film composition? | base layer, Emulsion layer, overcoat |
| what is the base layer in X-ray film composition? | it is in the center and the thickest layer Purpose is to support emulsion Uniformly translucent Blue tint improves viewing details |
| what is the base layer in X-ray film composition made of? | Polyester polyethylene terephthalate |
| what is the Emulsion layer in X-ray film composition? | present on both sides of the film purpose of suspend silver halide crystals (Br, Cl-) and absorbs processing chemicals to keep chemicals in contact with silver halide crystals |
| Why do we use tabular silver halide crystals over globular? | Sharp edges, Greater surface areas in the crystal Most x-ray films use this, more sensitive to x-ray photons and requires less exposure to create a x-ray image |
| What is the overcoat layer in X-ray film composition? | protective layer, An additional layer of gelatin vehicle to protect the emulsion from damage, harder gelatin so protect the emulsion and silver halide crystals so it can be held |
| what are the two types of X-ray films? | direct exposure and indirect exposure |
| what are direct exposure x-ray films? | Exposed by X-ray photons directly and can be used intraoraly and extraoraly. Dentistry is the only place this is used in the body |
| what are Indirect exposure (screen) film x-ray film? | Exposed by visible light- very little by x-ray photons, requires an intensifying screen, extra oral techniques only |
| What does the intraoral film packet have that is unique from extraoral | Double emulsion- layer of gelatin and silver halide crystals to make it sensitive to x-ray photons Moisture resistant packet |
| what are the components of a dental film packet? | outer wrapper: consists of moisture resistant plastic lead foil: prevents scatter radiation black paper wrapper to keep light out X-ray film |
| what is the 0 size dental film used for? | pediatric patients |
| what is the 1 size dental film used for? | anterior periapicals |
| what is the 2 size dental film used for? | posterior periapical and bitewing |
| what is the 3 size dental film used for? | long bitewing (military) replaced the two bitewing system so the military could save time |
| What is the 4 size dental film used for? | occlusal |
| Characteristic (H&D) Curve what does steep and flat mean? | steep: higher the contrast flatter: lower the contrast |
| high contrast has what kind of latitude? | low latitude because it is easier to mess up |
| low contrast has what kind of latitude? | high latitude because it is harder to mess up |
| what is Resolution | ability of radiograph to record separate structures see individual lines |
| what is Sharpness | ability of radiograph to define an edge between densities not fuzzy but really sharp |
| how are x-rays created on film? | X-ray photon hits bromine atom, ionizes and shoots of electrons electrons attracted to latent image site because of its positive charge negative charge builds at latent image site and silver is attracted silver grabs electron and becomes silver atom |
| what are the five steps in film processing? | Immerge film in DEVELOPER RINSE film in water Immerse film in FIXER WASH film in water bath DRY film |
| Emulsion changes during processing | o When it is fully developed the crystals that were exposed to x-ray photons will become grains of silver and the other crystals are not exposed and nothing is happened to them and they are removed by fixation |
| what is the purpose of developing solution? | Softens and swells the emulsion so chemical can get around silver halide crystals Reduces all Ag+ in exposed crystals to metallic Ag grains but undeveloped Ag+ are not changed |
| what are the components of the developing solution? | developer, activator, preservative, restrainer, solvent (Don't Accuse Pops Rat Sugar) |
| What does the developer do and what is in it for developing solution | Phenidone and Hydroquinone Converts exposed crystals into metallic Ag grains |
| what does the activator do and what is in it for developing solution | sodium bicarbonate Maintains alkaline pH and causes gelatin to swell |
| what does the preservative do and what is it made of for developing solution? | sodium sulfite Protects developers from oxidation and prolongs useful life |
| what does the restrainer do and what is it made of for developing solution? | Potassium bromide and Benzotriazole Restrains development of unexposed crystals, stops the reaction |
| what does the solvent do and what is it made of for developing solution? | water Maintains other components in suspension so they can be soaked up by the swollen gel |
| what is the purpose of fixing solution? | Dissolves and removes underdeveloped Ag halide crystals from emulsion hardens and shrinks emulsion |
| what are the components of fixing solution? | Clearing (fixing) agent, acidifier, Preservative, Hardener, Solvent (Cool, Agents, Peek, Haphazard, Sometimes) |
| what does the clearing (fixing) agent do and what is it made of for fixing solution? | Ammonium thiosulfate Dissolves/removes underdeveloped Ag halide crystals |
| What does the acidifier do and what is it made of for fixing solution? | Acetic acid Maintains acidic pH and inactivates any carryover developing solution |
| What does the preservative do and what is it made of for fixing solution? | Ammonium sulfite Prevents oxidation of thiosulfate and film staining from oxidized developer |
| what does the hardener do and what is it made of for fixing solution? | Aluminum sulfate Shrinks and hardens the gelatin layer, shortens the drying time |
| how do you make your dark room safe using a red bulb? | Can’t have a bulb that is greater than 15 watts and must be least 4 feet away usually safe for about 5 minutes |
| how much time should film spend in the developer for manual processing? | 5 minutes |
| how much time should film spend in the fixing solution for manual processing? | 10 minutes |
| how much time should film spend in the washing solution for manual processing | 20 minutes |
| what are the causes of the film being too light? | Developing time too short Developing solution too cold Developing solution depleted Excessive fixation |
| What are the causes of the film being too dark? | Developing time too long Developing solution too hot Developing solution concentrated Inadequate fixation Light leaks/ safelight problems |
| what is the solution temperature for a manual processor? | 68 degrees F or 20 degrees C |
| what is the solution temperature for an automatic processor? | 82 degrees F or 28 degrees C |
| what is the penny test? | used to test darkroom light leakage Leave a penny on the exposed film from the double-film pack on the working surface usually about 5 minutes if processed radiograph shows penny, the film is being fogged by inappropriate safe-lighting conditions |
| what is the reference film and step wedge? | Check processing solutions Provide accurate monitoring of day to day processing conditions Every morning exposure a film until you have 20 films and check the density and choose the middle as a reference |
| what does a panoramic image do? | extra oral radiographic projection which produces an image of a curved 3D layer |
| what are the magnification factors for panoramic x-rays? | If you go forward you will minimize the anatomic structure If you go back you will magnify the anatomic structure (especially horizontal layer) |
| In a pano, where are the lingual and the buccal projected? | lingual projected higher buccal projected lower |
| what happens in a pano image if the patient is too far forward? | too far forward, teeth too narrow |
| what happens in a pano image if the patient is too far back? | teeth are too fat (especially incisors) |
| what happens in a pano image if the patient's chin is too low? | jack-o-latern smile The “smile” line created by the interocclusal gap is exaggerated |
| what happens in a pano image if the patient's chin is too high? | Flat curved or frown curve; hard palate superimposed over apices of maxillary teeth Frown instead of smile |
| what happens in a pano image if the patient is rotated or twisted? | Teeth on one side wider with overlapping contacts; ramus on one side is much wider and condyles differ in size closer to the film is minimized further away from film is magnified |
| what is a double image in a pano? | pair of real images formed by an object lying within a zone that is intercepted twice by the beam |
| what is a ghost image in a pano? | a high attenuation object (white that absorbs more x-ray photon) is located between the x-ray source and the center of rotation |
| what are the characteristics of the ghost image? | Same morphology as the real image Appear on the opposite size Higher and more blurred Unlike double images, ghost retain the same orientation with respect to the real image |
| what are the inches for standard skull projection? | 40 inches |
| what are the inches for Cephalometric projections? | 60 inches |
| what is the Cantomeatal line for landmark? | Central point of external auditory canal to outer canthus of eye |
| what is the ala-tragus line for landmark? | Fleshy part of the ear to the middle of the nose |
| what is the lateral cephalometric projection position? | Beam is directed at the center of the head at about the level of the nose, left side towards image receptor |
| What is the Posteroanterior (PA) projection position? | patient faces the plate looking forward in natural head position, x-ray tube head behind patient so that the mouth is in focus |
| what is the Submentovertex: SMV projection position? | X-ray source comes at the chin, head tilted back towards the plate, patient facing away from the plate |
| what is the modified submentovertex projection see? | jug handles or zygomatic bone |
| what is the waters projection position? | patient faces plate, Tip their head so chin closer to imaging plate than their nose or forehead, Head looks round and primary purpose is to look at what is going on in the sinuses |
| what is the Reverse-Towne projection position? | patient faces plate, Forehead is closest to plate, closer than the forehead and chin, open mouth technique |
| what is the Mandibular oblique projection position? | patient holds film to cheek |
| what is an important factor to remember for panoramic images? | Lingual objects, being further from imaging surface, will be magnified and less sharp |
| what does SLOB mean? | same, lingual opposite, buccal |
| In order to verify where the location of an object is you need... | at least two images |
| ALARA Principle | As Low As Reasonable Achievable |
| what is unique about Computed Tomography (CT)? | whole body scan, uses X-rays but does not use film |
| what is the dense metal Hounsfield Unit? | +3,000 HU |
| what is the cortical bone Hounsfield Unit? | +1,000 HU |
| what is the water Hounsfield Unit? | 0 |
| what is the air Hounsfield unit | -1,000 HU |
| what is bad about Cone Beam Volumetric Tomography (CBVT or CBCT)? | poor soft tissue contrast |
| what is the Magnetic Resonance Imaging (MRI) image based on? | Images based on H+ concentration of tissues bone does not give a signal |
| T1 weighted images in MRI are | fat weighted images |
| T2 weighted images in MRI are | water weighted images |
| what studies are in nuclear medicine? | SPECT, PET, scintigraphy |
| what does nuclear medicine use? | gamma radiation |
| what does MRI use | Radiowaves |
| what does Sonography use? | radiowaves |
| a piezoelectric crystal is associated with... | ultrasonography |
| a Hounsfield unit are used in what type of imaging? | computer tomography |
| at Baylor a typical full mouth radiographic survey includes | 15 periapical and 4 bitewings |
| which radiographic projections is the mouth typically wide open? | Towne's |
| the top of the head is placed closest to the film cassette when making... | sunmentovertex |
| the exposure time for intraoral digital radiographs is usually about how much less than techniques using D-speed film | 80% |
| T1 and T2 images are associated with... | MRI |
| linear and complex motion are terms associated with... | conventional tomography |
| a wide tomographic angle will result in a ___ image layer | thin |
| which chemical agents are responsible for changing exposed silver halide crystals into metallic silver | phenidone and hydroquinone |
| the ___ safelight filter which is red in color is recommended for use in darkrooms when processing both intraoral and extra oral radiographic film | GBX-2 |
| panoramic radiography units create an image layer similar in shape to the patients jaw, what is the image layer called? | focal trough |
| fixer solution contains the preservative sodium sulfite, how does it function | prevents oxidation of the thiosulfate clearing agent it prevents oxidized developer solution from staining the film |
| the activator int he developing solution serves to | maintain the alkaline pH and makes the gelatin swell to increase developer |
| which of the following uses radiation source inside the body | nuclear medicine |
| silver halide crystals are found in what layer? | emulsion layer of radiographic film |
| What is the fastest speed of dental film available | F Speed |
| which of the following imaging techniques typically provides the best resolution for of soft tissue | MRI |
| the patient is positioned in the Frankfurt plane parallel to the floor when making the following image | lateral and straight PA |
| for dental purposes, CT is typically acquired in the... | axial |
| which ions are able to move about within the silver halide crystals and are important in latent image formation | interstitial silver |
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