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TXCC Radiology
Comprehensive Review
| Question | Answer |
|---|---|
| Identify the stage of interproximal caries that is more than halfway through the enamel | Class 2, moderate |
| Identify the stage of interproximal caries that is less than halfway through the enamel | Class 1, incipient caries |
| Identify the stage of interproximal caries that extends through the enamel and more than half way through the dentin | Class 4, severe caries |
| Identify the stage of interproximal caries that extends through the enamel and less than halfway through the dentin | Class 3, advanced caries |
| Root caries may be a misdiagnosis for what radiograph occurence? | Cervical Burnout |
| If a film packet is placed in the patient's/client's mouth with the wrong side facing the x-ray beam, the resulting film will | have a thin image with a geometric pattern on it |
| The appearance of adjacent teeth being superimposed on each other and the contact areas are closed is most likely: | overlapping |
| Increasing the vertical angulation of the X-ray cone when taking a radiograph of the maxillary right second premolar will result in which of the following? | Foreshortening |
| For a client with periodontal disease (boneloss) what type of bitewing series should be exposed? | posterior vertical bitewings |
| The vertical angulation for all bitewing (interproximal) exposures is: | central ray is angled at +8?to+10? |
| When exposing the mandibular arch for periapicals, the ___________________ is parallel to the floor. | tragus-commisure line |
| A "long cone" (16-inch FFD) is used in the paralleling technique to | avoid magnification of the image |
| The facial aspect of an intraoral receptor is determined by | convexity of the embossed dot |
| Which of the following teeth should be imaged on a horizontal molar bitewing? | distal portion of the second premolar, first molar, second molar, and third molar |
| If a view of the root apex is needed, which of the following films would be selected? | Periapical |
| Which of the following describes the proper direction of the central ray in the bisecting angle technique? | 90 degrees to the imaginary bisector |
| After a receptor has been placed, how much of the receptor should show beyond the incisal or occlusal edge? | no less 1/8" and no more than 1/4" |
| Proper client position for intraoral radiographs requires the sagittal plane be... | perpendicular to the floor |
| The receptor should be placed _________the tooth in order to reduce image distortion. | parallel to the long axis of the tooth |
| A variation in the true size and shape of the object being radiographed is termed | distortion |
| Magnification can be reduced by (1)large focal-receptor distance, (2)large receptor to object distance, (3)small focal spot, (4)small focal-receptor distance, (5)small receptor to object distance | 1,large focal receptor distance 5,small receptor to object distance |
| Which of the following is the correct technique when placing bitewing films? | Place the film as close to the teeth as possible |
| Elongation and foreshortening in the paralleling technique occur because of | receptor and beam (CR) not perpendicular |
| A mandibular premolar film is exposed but the apex of the premolar root was not present on the image because of the unusual length of the root. What adjustments should be made on the retake to get the needed information? | increase the vertical angulation with beam directed toward the crown of the tooth. |
| Alveolar crest bone resorption is best detected in the | Bitewing Radiographs |
| Periapical images should include ____ millimeters of supporting tissue beyond the root apex. | 3-4mm |
| What is the name of the imaginary line, which extends from the nose to the ear? | ala-tragus line |
| One of the advantages of the paralleling technique over bisecting angle technique is that there is | an increase of anatomic accuracy |
| In taking a maxillary occlusal projection, the patient/client is positioned so that | the occlusal plane is parallel to the floor |
| A receptor is placed in contact with the lingual surface of tooth#8. Where should you direct the central ray? | perpendicular to the line dividing the angle formed by the tooth and receptor |
| The receptor should be placed _________the tooth in order to reduce image distortion. | parallel to the long axis of the tooth |
| The unsharpness or blurred edges seen on a radiographic image is termed | penumbra |
| Which of the following describes radiographic film that has MANY gradations of gray from totally white to totally black? | low contrast |
| According to federal regulations the beam for intraoral radiographs shall not exceed | 2.75" |
| What percent of kinetic energy inside the x-ray tube is converted into x-rays? | 1% |
| From what part of the negative pole of the x-ray tube are electrons emitted? | tungsten filament |
| Identify the milliamperage range for dental radiography | 7-15 mA |
| Which of the following is used as a filter? | Aluminum disc |
| What adjustment needs to be made to produce more radiation? | higher the milliamperage |
| The step-down transformer is responsible for all of the following activities EXCEPT one. Which one is the EXCEPTION? | creates a potential difference (the step-up transformer does this) |
| What type of electrical charge does the electron carry? | negative |
| Which of the following is responsible for all collimation? | lead diaphragm |
| The focal spot is made of | tungsten |
| The energy of photons produced in an x-ray machine is dependent upon: | kVp |
| What adjustment needs to be made to produce more radiation? | higher the milliamperage |
| In order to increase contrast on a radiograph, it is necessary to | decrease the kVp and increase the mA |
| Bremsstrahlung is produced when electrons collide with the nuclei of the target atoms, creating | radiation of various lengths |
| The ability of x-rays to remove electrons from a substance is called | ionization |
| The principal factor that controls x-ray penetration is | wavelength |
| The dental radiographer can regulate the x-ray beam (kVp, mA, time) through the use of the | control panel |
| Below 70 kVp federal requirements state that filtration must be | 1.5 mm |
| Changing from 75kVp to 90 kVp will | decrease radiographic contrast |
| Ionization has occurred when | an electron is displaced from its orbit |
| Milliamperage controls | heating of the cathode |
| In digital radiography, contrast can be adjusted by ____________. | redistributing the gray levels |
| What is the major problem encountered with automatic processors? | amount of maintenance required |
| Each successive full mouth survey appears lighter than the one before. Which of the following corrections should be made? | replenish the developer solution |
| A breakdown of chemicals in the processing solution that results from exposure to air is termed: | oxidation |
| Which of the following is considered to be a disadvantage of digital radiography? | Initial cost of digital system. |
| In digital intraoral radiography, which of the following errors can be corrected without taking a retake? | Underexposure |
| Which of the following describes how gold can be distinguished from amalgam on a dental radiograph? | Gold margins are smooth and regular |
| An optical illusion created by an increased radiolucency observed at the cervical area of the tooth is called mach banding. 2. The mach banding effect increase when overlap error occurs. | The first statement is false. The second statement is true |
| Caries appear radiopaque, because more radiation is passing through the demineralization than the surrounding tissue. | The first part of the statement is false, but the second part of the statement is true. |
| If the occlusal caries lesion is seen on a radiograph it will appear | radiolucent flat line at the DEJ |
| Cemental caries is usually seen on radiographs as a(n): | ill-defined, radiolucent, saucer-shaped area just below the CEJ |
| Which of the following appears radiographically as a round radiolucency in the middle of the tooth with well-defined borders? | buccal/lingual caries |
| Which of the following appears radiographically as an ill-defined crescent-shaped radiolucency below the CEJ? | cemental caries |
| The key to successfully interpreting radiographs for proximal surface caries is to examine the contact point between adjacent teeth and just apical to the | estimated gingival margin |
| Which of the following terms describes bone loss that occurs in a plane parallel to the cementoenamel junction of adjacent teeth? | Horizontal |
| Radiographs permit the evaluation of ___________ in the detection of periodontal disease. | bone |
| The crown to root ratio is the relationship of the length of the root embedded in bone compared with the length of the rest of the tooth. true or false | true |
| 2) The greater the length of the tooth embedded in bone, the better the prognossis for support of a fixed or removable prosthesis. true or false | true |
| Which of the following combinations will result in the lowest absorbed dose for the patient from a 20-film series of dental radiographs? | Rectangular collimation with F-speed film |
| The purpose of filtering an x-ray beam is to | remove low energy photons |
| Lead aprons should be used | on all patients/clients |
| The maximum permissible dose for an occupationally exposed worker who is pregnant is | 0.005 Sv per year (0.5 rem per year) |
| Any dose of radiation may be potentially harmful. True or False | True |
| In normal dental radiography procedures, the principal hazard to the operator is produced by | scattered radiation |
| The maximum permissible whole-body dose for dental personnel is | 50mSv (5 rem) per year |
| Refers to a measurement of dose equivalents from any type of ionizing radiations that produce the same biological effects in man. | Sievert |
| Which of the following is NOT considered a critical organ? | The brain and spinal cord |
| Size Zero films are for... | smallest film, used for PA or BW for children with primary dentition |
| Size One films are for... | adult anterior PA in vertical position, anterior BW in vertical position, child posterior PA, BW mixed dentition in horizontal position |
| Size Two films are for... | Standard size, BW ... vertical and horizontal, PA.... vertical for anterior, horizontal for posterior. Sometimes used for occlusal film in primary dentition |
| Size Three films are for... | bitewing only |
| Size Four films are for... | Occlusal films |
| Film speeds: List from slowest to fastest. E speed, F speed, D speed | D, E, F |
| How is film speed determined? | Size of silver halide crystals. Larger the crystals the faster the speed. |
| At what temp must film be stored? | 50-70 degrees F (in refrigerator) |
| What happens to film if stored at a temp that is to warm? | film fog |
| What is thermionic emission? | release of electrons from the hot tungsten filament. |
| Line Focus Principle (has to do with focal spot and sharpness) | The smaller the focal spot the sharper the image will be |
| Exposure time is calculated by what formula? | Number of impulses/60=seconds |
| what does kVp control in the tubehead? | regulates the voltage across the x-ray tubehead |
| The higher the kVp the __________ the electrons will travel from the filament to the target | faster |
| What three things does kVp control? | Quality, wavelength, and energy |
| What controls the voltage entering the Step-Down Transformer? | mA setting |
| What does the Step-Down Transformer do? | It reduces the voltage of the current before it reaches the filament to prevent it from burning up |
| What does the Autotransformer do? | It determines how much voltage goes to the Step-Up Transformer. |
| What does the Step-Up Transformer do? | Dramatically Increases the voltage |
| Current pass from cathode(-) to anode(+) or anode(+) to cathode(-)? | cathode(-) to anode(+) |
| Federal, State, Local, or Municipal government regulates the manufacture and installation of dental x-ray equipment? | Federal |
| X-ray are high or low energy waves? | high energy |
| X-rays are short or long wavelengths? | short wavelengths |
| x-rays have mass or no mass? | no mass |
| x-rays are visible. TorF | false you dummy |
| x-rays travel in straight lines. TorF | true |
| x-ray beams stay focused to a point. TorF | false. the beam diverges(spreads out) as it travels |
| More Dense material will absorb more or less x-rays? | more |
| How is Bremsstrahlung Radiation produced? | (aka braking or general radiation) produced when high speed electrons are slowed down as they pass close to or strike the nuclei of atoms. (primary source of x-ray photons) |
| How is Characteristic Radiation produced? | Produced when a high speed electron from the filament collides with an electron in one of the orbits of a target...electron knocked out of orbit. |
| What are 5 x-ray beam modifiers? | kVp mA Exposure time filtration collimation |
| If you increase mA you ___________ electrons | increase |
| if you increase exposure time you___________ number of x-rays | increase |
| what does filtration accomplish? | removal of low energy x-rays increase average energy of x-rays (the quality) but decreases the quantity. |
| What is inherent filtration? | Materials present in the x-ray tube that filter- the beryllium window and oil. |
| What constitutes external filtration? | aluminum discs at andhigher 70 kVp= 2.5mm lower 70kVp= 1.5mm |
| What does the collimator do? | it restricts the area of the head that the x-rays will contact |
| The collimator does not change the energy or the number of x-rays in the beam. TorF | true |
| The collimator does not limit the size and shape of the x-ray beam. TorF | false. it does limit the size and shape |
| by reducing the PID from a 7cm to a 6cm radiation is reduced by how much? | 25% |
| by changing the PID from a round to a rectangular shape radiation is reduced by how much? | 55% |
| If distance is increased definition is______________ | improved |
| if distance is increased magnification is______________ | lessened |
| if distance is increased, exposure time is______________ | increased |
| Formula for new exposure time when distance is changed: | new distance (squared)/old distance(squared) x old mAs = new mAs |
| What two types of radiation are emitted from the x-ray tubehead? | Bremsstrahlung and Characteristic radiation |
| The beam of x-rays strengthens as it passes through matter. TorF | False. it weakens and gradually disappears |
| What is the disappearance of x-rays referred to as? | absorption. ionization is the basic method of absorption. |
| What is beam attenuation? | low energy photons are more likely to be absorbed decreasing the intensity but increasing the mean energy of the resultant beam (has more high energy) |
| What are the three types of scatter radiation? | Coherent, Photoelectric, Compton |
| What is scatter radiation? | photons are ejected from the primary beam as a result of interation with orbital electrons of the absorber atom |
| Which radiation is most detrimental to the patient? | scatter radiation |
| what is Coherent scattering? | about 8% incoming x-ray interacts with the outer shell electron by causing the electron to vibrate at the same frequency as the incoming x-ray |
| what is photoelectric absorption? | about 30%. incoming x-ray interacts with an inner shell electron and causes it to fly from orbit with speed and combine with a free electron to form a positive ion. |
| what is compton scatter? | 62% xray photon interacts with loosely bound electron and ejects it. causes film fog and degrades image. |
| what effects overall darkness of film? | density |
| quantity refers to the ____________ of xrays produced | number |
| high kVP = | low contrast long grey scale |
| low kVp= | high contrast short grey scale |
| how does focal spot size influence sharpness? | decrease focal spot size and you increase sharpness |
| how does crystal size influence sharpness? | decrease the crystal size and you increase the sharpness |
| how does movement influence sharpness? | decrease movement and you increase the sharpness |
| how does target-receptor distance effect magnification? | increase target-receptor distance you decrease magnification |
| how does object-receptor distance effect magnification? | increase object-receptor distance you increase magnification |
| how does object-receptor alignment influence distortion? | object-receptor parallet and distortion decreased |
| how does x-ray beam angulation influence distortion? | beam perpendicular to object and receptor and distortion is decreased |
| what is penumbra? | shadow, zone of unsharpness around edge of radiograph |
| what are the 5 rules of shadow casting? | 1.radiation source small as possible 2.source-object distance large 3.object-film distance small 4.object and film parallel 5.xray beam perpendicular to object and film |
| Bitewings should be taken on a routine basis. TorF | False. Taken based on diagnostic need |
| If a patient has gingivitis and low caries risk which interval can be followed for BWS: 24-36mos, 12-24mos, 12-18mos | 24-36mos |
| If a patient has perio with mild bone loss, low risk caries which interval can be followed for BWS; 24-36mos, 12-24mos, 12-18mos? | 12-24mos |
| If a patient has high caries history, perio with moderate to severe boneloss which interval can be followed for BWS: 24-36mos, 12-24mos, 12-18mos? | 12-18mos |
| The PID should be positioned at what vertical angulation for BWX? | +0 to +10 degrees, optimal +8 to +10 |
| What plane is parallel and which perpendicular to the floor for Maxillary Periapical films? | Ala-tragus line is parallel, sagittal plane perpendicular |
| What plane is parallel and which is perpendicular to the floor for Mandibular Periapical films? | Tragus-commisure line is parallel, sagittal plane is perpendicular |
| Is the PID + or - for maxillary periapicals? | positive |
| IS the PID - or + for mandibular periapicals? | negative |
| how is film placed for paralleling? | film is parallel to the long axis of the tooth and central ray directed perpendicular to the film and long axis of tooth |
| In Paralleling the Object-Film distance is increased to keep film parallel to the long axis of the tooth. TorF | true |
| Magnification occurs in paralleling technique due to the increased Object-Film distance, what is done to compensate for that? | An increased target-receptor distance |
| What is Cieszynski's Rule of Isometry? | two triangles are equal if they have two equal angles and share a common side |
| In what radiographic technique is the rule of isometry used? | bisecting angle |
| How is the central ray positionied in Bisecting angle technique? | Perpendicular to the imaginary bisector formed by the long axis o the tooth and the film |
| Bisecting Angle technique is more accurate than paralleling. TorF | false |
| Tissue radiation decreased with bisecting angle technique. TorF | False, increases due to sharper vertical angulation |
| Bisecting Angle technique is less accurate in showing bone level and caries depth. TorF | true |
| Bisecting Angle Vertical Angulation for Maxillary | Incisors +40 to +50 Canines +45 to +55 Premolars +30 to +40 Molars +20 to +30 |
| Bisecting Angle Vertical Angulation for Mandible | Incisors -15 to -25 Canines -20 to -30 Premolars -10 to -15 Molars -5 to 0 |
| Overlap is more likely in Bisecting Angle (BA). TorF | true |
| Subgingival Calculus may be superimposed on alveolar bone and thus not detected in Bisecting Angle technique. TorF | true |
| Occlusal Radiographs are used in conjunction with PA or BW. TorF | True |
| What size receptor is used for and adult occlusal radiograph? | size 4 |
| How do you position the patient and PID for a Anterior Maxillary Occlusal? | Mx arch parallel to the floor, sagittal plane perpendicular, Central Ray directed through the tip of the nose and at a +65 degree angle. |
| How do you position the patient and PID for Maxillary Topographical Posterior or Lateral Occlusal radiograph? | Right or Left side. CR +45. Point of entry of PID beam is ala-tragus line below the outer canthus of the eye. |
| How do you position the patient and PID for Mandibular Topographical Occlusal? | Mandibular arch parallel to the floor. Central Ray directed at -55. Central Ray come from below mandible. |
| What side of the film is facing the PID? | white. |
| How do you position the patient and PID for Mandibular Cross Sectional Occlusal? | Mandibular arch is perpendicular to floor. Central Ray is 90 degrees. |
| What is a sialolith? | a salivary stone. soft tissue opacity |
| what is SLOB? | same lingual opposite buccal |
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talithakuttler
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