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Imaging
Vet Dentistry
| Question | Answer |
|---|---|
| What is the speed of light? | 186,000 miles per second in a vacuum |
| What spectrum do x-ray wave energy belong to? Why? | electromagnetic they have electric and magnetic fields associated with them |
| What material is typically used in an x-ray generator filament and target? | tungsten |
| What is focal film distance? FFD | distance from the focal spot on the tube's target to the film |
| What is Object-film distance? OFD | distance from the object being x-rayed to the film |
| What are 3 main premises to decrease magnification/image distortion? | 1: use as great an FFD as possible 2: use the minimal OFD as possible 3: place the film and object parallel to each other's long axis and perpendicular to the central useful primary beam |
| What are the more radiosensitive cells in the body? | lymphatic young bone cells skin blood-forming tissues immature cells rapidly reproducing cells cells w/increased metabolism |
| What are 3 general radiation safety techniques? | 1: avoid the primary beam 2: stand at least 6 feet away from the source to avoid contact with scatter radiation 3: schedule regular testing of the unit to prevent leakage radiation |
| What FFD should be used for optimal radiation safety? | Short cone, because they require shorter exposure time |
| With what type of film can you reduce exposure time requirements further? | E-speed |
| Do dental films use intensifying screens? | no |
| What determines film speed? | the size of the silver bromide (halide) crystals in the film emulsion larger crystal-->faster speed |
| What is the trade-off for faster speed film? | coarser image, loss of fine detail |
| What are two manipulations of the position indicator device PID? | vertical angulation horizontal angulation |
| What is the inverse square law? | states that the intensity of radiation required varies inversely with the square of the distance from the source |
| according the inverse square law, if the FFD is doubled, and mAP and KVp remain constant, the exposure time must be _____ to maintain the same image | quadrupled |
| what is the premise of definition evaluation? | structures ling closest to the film will show better definition than those farther from the film |
| What is the SLOB rule AKA Clark's rule regarding tube shift technique? | when the horizontal angulation is adjusted, lingual objects move toward the head and buccal objects move away from the head |
| What is the contrast resolution of standard film radiography? Computed tomography? JVD Summer 2013 | 5% vs. 1% |
| What is the result of a better contrast resolution of CT compared to standard film radiography? JVD Summer 2013 | CT is more fine tuned, able to ID smaller resolution tissue differences |
| What are the 3 main enhancement patterns seen when using IV iodinated contrast medium for a CT scan? JVD Summer 2013 | homogenous, peripheral, & heterogenous |
| When comparing MR & CT, what is MR better at? JVD Summer 2013 | provides more accurated info regarding tumor size and invasion of adjacent structures |
| When comparing MR & CT, what is CT better at? JVD Summer 2013 | provides best visualization of calcification and cortical bone destruction |
| What is a disadvantage of standard film radiography --compared to CT-- when used to evaluate oral tumor? JVD Summer 2013 | extent of bony change is underestimated |
| What regional structure is CT particularly good at identifying when tumor involves it, which standard radiography tends to miss? JVD Summer 2013 | orbit |
| What is the advantage of CT when evaluating oral tumors? JVD Summer 2013 | CT shows better anatomical detail, structural resolution, & greater bone involvement sensitivity compared to standard radiographs |
| In Small dogs, what 2 teeth are most likely to show radiographic abnormalities? JAAHA 2013 | maxillary PM4, mandibular M1 |
| In small dogs, what is the most commonly detected radiographic abnormality? JAAHA 2013 | bone loss of any type |
| In what age category of small dogs was it most common to see radiographic findings which were not noted on oral exam? JAAHA 2013 | older dogs |
| What is the value of 18F-FDG PET/CT as a staging tool for feline oral SCC? Vet Comp Oncol 2013 | soft tissue infiltrative tumors that were subtle and ill defined on CT were highly visible and more extensive on PET/CT. mets were seen as hypermetabolic on PET/CT |
| How many shades of gray can the human eye differentiate? How many shades of gray can CTdistinguish? JVD Fall 2013 | Human:20-30. CT 32-60 |
| CT is superior for imaging ___ tissues, while MR is superior for imaging ___ tissues when compared to plain film radiology. JVD Fall 2013 | CT: hard/bony, MRI: soft |
| Does CT or MRI provide a diagnostic advantage over intraoral rads for detecting periapical abscess? JVD Fall 2013 | no |
| What are 2 types of Cone Beam CT detector designs? JVD Spring 2012 | IIT/CCD (image intensifyer tube, charged coupled device) & FPD (flat panel detector) |
| What scanning and reconstruction parameters influence imaged quality in CBCT? JVD Spring 2012 | kVp, mA, scan field of view (FoV), patient positioning in the machine |
| Which type of CBCT detector design is less complicated, offers greater dynamic range, and has less distortion? JVD Spring 2012 | FPD |
| What image artifacts are problematic when using CBCT? JVD Spring 2012 | scatter, beam hardening, metal streaks, increased image noise level, increased inhomogeneity, image density variability, poor soft tissue visibility |
| Why was CBCT image quality for cats inferior? JVD Spring 2012 | increased noise level |
| What is the typical radiographic finding in puppies with periostitis ossificans? JVD Fall 2010 | double layered ventral mandibular cortex |
| Which modality was shown (by Bar-am et al) to be more useful for visualizing the mandibular body and occlusion--CT or RAD? 2008 Vet Surg | Radiography |
| Which modality was show to be more useful for IDing anatomic skull structures and maxillofacial injuries in dogs/cats? 2008 Vet Surg | CT |
| How much less radiation is used for digital dental radiography compared to traditional dental radiography? JVD spring 2014 | 50-80% less |
| EQ: what is the sensitivity and specificity of radiography to diagnose equine dental disorders? | 52-69% and 70-95% (Weller et al 2001, Barakzai 2010) |
| What is the gold standard imaging modality for TMJ analysis (in humans)? | MRI |
| What are the most common radionuclides used in sku. scintigraphy (for bone tracers)? | Methelene diphosphanate & hydroxymethelene diphosphanate (MDP & HDP) Technetium bound to phosphates |
| What is the sensitivity and specificity of scintigraphy? | 95% & 86% |
| What is scintigraphy? | The use of a gamma-ray emitting radio isotope which is bound to a tissue seeking molecule |
| What is the most commonly used radioisotope in equine scintigraphy? What is it’s half life? | Technetium: Tc-MDP, 6hrs |
| What are the two different types of scintigraphic studies? What is the matrix size of each? | Static: 256X 256 Dynamic:128 X 128 |
Created by:
lamarron
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