radiology

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radiology
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2014-05-04 20:34:47
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radiology in vet tech 247 surgical nursing
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  1. DLPMO
    dorsolateral palmeromedial (planteromedial) oblique
  2. positional aids
    keep animal in place for radiographs
  3. kVp
    • kilovoltage peak
    • intensity of xray -- how powerful beam is
  4. mAs
    • milliamps per second
    • how much power over given period of time
  5. pneumocystogram
    inject air into bladder to show borders on radiograph
  6. CT
    • computerized (Axial) tomography
    • special test uses x-radiation to take a series of views while tube head rotates (360 or less), opposite detector which catches photons forms detailed view of many angles
    • number of photons that make it through indicates density
  7. kVp and mAs of CT
    kVp 120, variable mAs
  8. prep for CT
    • take regular rads so you know where to shoot
    • general anesthesia
    • place on cradle in relation to gantry
  9. cradle
    surface animal lies on in CT
  10. gantry
    doughnut where the tube head is in CT
  11. pixel
    • picture element
    • what numbers (photons) in CT turn into
    • representation of a signal corresponding to the intensity of the beam
    • The smaller the pixel, the better the detail
  12. voxels
    • volume or body elements
    • layers of 2D pixels in CT that form a 3-dimensional appearance
  13. lighter color in xRay
    fewer photons make it through, denser material
  14. adjusting CT
    • digitial image, can be enhanced, tilted, rotated
    • contrast material can be used (barium, iodine)
    • has calipers to measure
  15. quality of CT picture
    • very high--serial images average out fat, etc and superimposition
    • Lots of contrast
    • good for skull, extremities, abdomen, bony lesions
  16. MRI
    • magnetic resonance imaging
    • does NOT use X-rays
    • magnet makes each cell move slightly to line up with magnetic pole. Magnet off, switch back.  This is what is read (radiofrequency), series of slices.  NO METAL
    • Known for SOFT TISSUE
  17. uses of MRI
    • good for soft tissue
    • contrast studies
    • can be rotated and enhanced including false color
  18. time and prep of MRI
    • ~45 minutes
    • General anesthesia
  19. fluoroscopy
    • fluorescent screen, x-radiation from underneath patient onto screen, monitoring of movement
    • Good for swallowing studies.  REAL-TIME images
    • Increased radiation for patient and examiner
  20. scinitigraphy
    • small amount of radioactive material IV, IN or transcolonically
    • more sensitive but less specific than CT, nut a true image, but good for ID of lesions
    • used to ID tendonitis, thyroid scans, etc.
  21. bone scan
    • technetium 99m(radioactive) linked to MDP, which makes bone absorb it.  
    • Shows "hot spots" (bright=inflammation, dark=bone death or hypoactivity)
    • 2 phases (soft tissue and bone)
  22. thyroid scans
    • radioactive material (technetium 99 pertechnetate) is taken up y thyroid, best in hyperthyroid cats.
    • ectopic thyroid tissue also visible
    • huge red thyroid = overactive
  23. digital radiographs
    • relatively new
    • images recorded via computer, MORE LATITIDE (range of grey)
    • can be enhanced, rotated, printed, etc.
    • can take over and over if necessary
    • analog can be converted, probably not financially worth it
  24. latitude
    • range of greys
    • digital has more than film
  25. spatial resolution
    • ability to tell the size and shape of an object
    • analog<digital<CT<MRI
  26. contrast resolution
    • ability to distinguish things in very small scale
    • analog<digital<CT<MRI
  27. benefits of digital radiographs
    • more latitude, better resolution
    • faster results
    • no chemicals
    • can zoom, brighten or darken, etc
    • rare to need retakes
    • pictures recorded to CD, DVD, email, saved to hard drive
    • stored useing RIS (radiology information system, connects terminal to hospital, allows upload)
  28. RIS
    • radiology information system
    • connects digital terminal to computer system, allows upload of digital radiographs
  29. PACs
    • picture archiving and communication systems
    • type of software processing for digital film
    • allow conversion to conventional pictures so can be uploaded and evaluated
  30. Matrix
    Rows and columns of pixels
  31. doppler phenomenon
    • as wavelength decreases, pitch/color changes
    • For heart valves, flow should all be one way/one color.
  32. digital monitors
    • grey-scale, CRT (unless using color doppler)
    • LCD acceptable
  33. Technique chart and how to create one
    • a chart detailing the mAs and kVp settings for each body part and measurement
    • 1. measure thickest part of lat abd
    • 2. kVp calculation using Sante's Rule - kVp = 2*tissue thickness (cm) + FFD (in) + grid factor.  
    • 3. take 3 radiographs at 1mAs, 3mAs and 6mAs (or a range)
    • 4. develop and choose best soft tissue visualization.  This is abd setting, then conversions.  
    • every cm below yours = -2 kVp
    • every cm above yours = +2 kVp
    • >80cm = +3 kVp 
    • >100cm = +4 kVp
  34. conversions for different body parts on technique chart
    • start with abdomen.  
    • high speed screen (400)  grid = *3
    • thorax = *0.5
    • slow speed screen (100)  *4, grid *3
  35. electromagnetic radiation
    method of transporting energy through space and is distinguished by its wavelength, frequency and energy.
  36. electromagnetic spectrum
    (short wavelengths, easier to penetrate) cosmic, gamma, x-rays, ultrasound, visible light, infrared, TV and radiowaves (long wavelength)
  37. 4 factors that effect xrays
    • kVp: kilovoltage peak
    • power = peak of energy of xrays.  
    • determines quality of xray beam
    • mA: millamperage.  Quantity of xrays (#)
    • s: seconds.  Time
    • FFD: film focus distance/SID source image distance
  38. physical properties of xrays
    • wavelength is variable and related to the energy of the radiation
    • travels in a straight line (can be altered but is always straight)
    • short wavelength allows xrays to penetrate materials that absorb or reflect visible light.  The amount of absorption depends on atomic number (lead has a high number)
    • certain substances have properties of fluorescence
    • xrays produce a visible image on photographic filter
    • xrays can cause biologic changes, have ability to excite or ionize atoms (important molecular structure of cells)
  39. parts of an xray machine
    • xray tube, high-voltage generator, control tower
    • on-off switch, voltage compensator, kV selector (sets power, letting electrons through), mA selector (current to cathode, number of electrons through filament), timer, exposure button, warning light
  40. what penetrates body in xray
    photons
  41. sante's rule
    • how we figure kVp settings
    • 2 x thickness of target organ (cm) + area density factor (ADF) (aka FFD, usu 40cm)
  42. incident photons
    organized, penetrate the target.  Everything else is scatter
  43. plate/cassette sizes
    8x10, 10x12, 14x17
  44. properties that determine efficiency of screen
    • high level of absorption
    • high xray to light conversion
    • little to no afterglow
  45. screen types for film
    regular, fast and fine
  46. layers of intensifying screen
    • plastic base, reflective layer, phosphor crystal layer, protective coating.  
    • Scrape or scratch is bad
  47. bucky
    under table, moving grid that holds the cassette
  48. intensifying screens
    sheets of luminescent phosphor crystals in emulsion, bound together, mounted on plastic base.  Give off phsophorescent for exposure.  Reduces amount of radiation required by 95%
  49. cassette
    • a light-tight film-holding case which positions the x-ray film & intensifying screens in intimate contact.  
    • rigid film-holder.  Light-tight, prevent unwanted exposure.  Must be strong and radiolucent to xrays.  
    • inside is intensifying screen.  Yellow outside gives info, grey side goes under animal.
  50. how an xray machine works
    glass envelope with anode at one end and cathode at the other.  Cathode has a filament like inside of a lightbulb, electrons come from filament and hit tungsten target, go down through window.  Become photons when exit window, go through organ and hit screen, crystals phosphoresce and expose film.
  51. larger crystals in intensifying screen
    faster screen, less detail, grainy image
  52. smaller crystals in intensifying screen
    slower, more detail, cleaner
  53. absorption
    process by which the # of photons is reduced as it passes through matter
  54. ALARA
    an acronym used to express the concept that levels of radiation exposure should be As Low As Reasonably Achievable
  55. Anode
    the positive electrode in the x-ray tube that contains the target
  56. cathode
    the negative electrode in the x-ray tube that contains the filament from which free electrons are produced by thermionic emission
  57. caudocranial (CaCr)
    a method of describing the direction of the x-ray beam with the entrance audal and the exit cranial prior to exposure of the x-ray film.
  58. collimator
    an attachment to the tube-head that restricts the size & shape fo the primary beam
  59. cone
    the metallic cone shaped structure that functions as a beam restrictor
  60. craniocaudal (CrCa)
    a method of describing the direction of the x-ray beam with the entrance cranial and the exit caudal prior to exposure of the x-ray film
  61. density
    mass/unit volume
  62. dorsopalmer (DoPa)
    a method of describing the direction of the x-ray beam with the entrance dorsal & the exit on the palmar surface prior to exposure of the x-ray film
  63. dorsoplantar (DoPl)
    a method of describing the direction fo the x-ray beam with the entrance dorsal and the exit on the plantar surface prior to exposure of the x-ray film
  64. dorsoventral
    a method of describing the direction of the x-ray beam with the entrance dorsal & the exit ventral prior to exposure of the xray film.
  65. dosimeter
    • film badge
    • an instrument used to detect and measure an accumulated dosage of radiation
  66. focal film distance (FFD)
    distance from the target of the x-ray tube to the plane of the radiographic film
  67. glass envelope
    the houseing for the cathode and anode of the x-ray tube that permits the creation of a vacuum
  68. heel effect
    • a consequence of the angle of the target of the tube which results in greater radiation intensities on the cathode side as compared to the anode side of the radiation field
    • So point the thicker side of the P toward the cathode side
  69. intensifying screen
    a device for converting the energy of the x-ray photons into light photons, thereby increasing the efficiency of radiographic image formation and reducing the x-ray exposure necessary to produce an image
  70. layers of film
    base, adhesive, emulsion, protective coat
  71. cleaning of screens
    • use cotton gauze and screen cleaner, 4x/year minimum, dry standing upright to avoid dust.  
    • Don't clean all at once in case of emergency
  72. How to develop film
    • 5 minutes in developer, 1 minute in water bath, 5 minutes in fixative (hardens), another wash in water bath for 15-20 minutes.  (68%, increased temp, decreased time)
    • safe-light, low wattage red b/c film is sensitive to white light.
  73. chemical maintinence for film
    • mix chemicals before use (settling)
    • change frequently, gets weakened.  
    • watch for bio growth
    • drain tanks ONE AT A TIME, developer and fixative causes noxious gas
  74. film identification
    • legal record.  label (NO SHARPIE), EZ printer blacks out one corner
    • 1. name/address of hospital/vet
    • 2. date taken
    • 3. patient ID, name, O; +/- age, sex, breed
    • 4. R/L markers (digital before close).  Lead markers, lead tape, EZ printers, pre-printed labels
  75. kilovoltage (kV)
    the potential difference applied across an x-ray tube to accelerate electrons emitted by the cathode toward the anode
  76. kilovoltage peak (kVp)
    the maximum potential difference applied between the anode and cathode by a pulsating voltage generator (power)
  77. maximum permissible dose (MPD)
    level of radiation exposure above background level that has been established for those working with radiation
  78. milliamperage (mA)
    a measurement of the # of electrons that flow across the x-ray tube during an exposure
  79. milliampere-seconds (mAs)
    a combination unit which is the product of the tube current expressed in milliamperes and the exposure time expressed in seconds (how much power given @ given time/second)
  80. palmardorsal (PaDo)
    a method of describing the direction of the x-ray beam with the entrance on the palmar surface & the exit on the dorsal surface prior to exposure of the x-ray film
  81. plantardorsal (PlDo)
    a method of describing the direction of the x-ray beam with the entrance on the plantar surface & the exit on the dorsal surface prior to exposure of the x-ray film
  82. phosphorescence
    the emission of light radiation from a substance after a time delay of greater than 10^-8 seconds following absorption of radiation from some other source (if the time delay is less than 10^-8 seconds see fluorescence)
  83. radiodense
    that characteristic of tissue that permits few of the x-ray photons to pass unaffected and causes a reaction on the radiographic film that enables light to be transmitted through the film
  84. radiographic contrast
    the differences in optical densities between different portions of the radiographic which enable image details to be visualized dependent on subject contrast and film contrast that are independant
  85. radiolucent
    that characteristic of tissue that permits most of the x-ray photons to pass unaffected and causes a reaction on the radiographic film that prevents light from being transmitted through the film
  86. radiopaque
    that characteristic of tissue that permits few of the x-ray photons to pass unaffected and causes a reaction on the radiographic film that enables light to be transmitted through the film
  87. REM
    an acronym for Roentgen Equivalent Man that was devised to allow for the fact that the same absorbed dose in rads delivered by different kinds of radiation does not produce the same degree of biological effect
  88. scatter radiation
    radiation generated as a result of interaction of the photons with in the primary beam with tissue or matter which travels in a different direction & is composed of photons of lower energy than the incident photons which created them
  89. secondary radiation
    radiation generated as a result of interaction fo the photons within the primary beam with tissue or matter which travels in a different direction & is composed of photons of lower energy that the incident photons which created them-at the energy used in diagnostic energy it is composed of Compton electons, characteristic x-rays & photoelectrons
  90. sievert (Sv)
    • a unit of dose equivalence in man or mammals resulting from the absorption of x or gamma radiation.  
    • 1 sievert equals 100 rem
  91. tungsten
    the metal used to form the filament and the target in the xray tube because of the high melting point, thermal conductivity, and high atomic number
  92. ventrodorsal (VD)
    a method of describing the direction of the xray beam with the entrance ventral and the exit dorsal prior to exposure of the xray film.
  93. causes of film being too dark
    • overexposure due to too much kVp or mAs
    • overdevelopment due to too much time in developer or increased developer temperature
    • overmeasurement of part under examination
    • SID not correct for grid use
  94. causes of film too light
    • underexposure due to insufficient kVp or mAs
    • underdevelopment due to decreased temperature or time of development, developer exhausted or diluted, or not stirred
    • x-ray tube failure, didn't rotor long enough
    • incorrect film-screen combination
    • drop in incoming line voltage
  95. film grey/lack of contrast
    • too much kVp
    • radiation fog due to exposure of film to radiation other than desired
    • light leak in darkroom, incorrect bulb wattage or filter for safelight in darkroom
    • storage fog due to old chemicals, increased chemical temperature or increased time of development
    • film out of date
    • lack of a grid with use of high kVp
    • double exposure
  96. lack of detail
    • increased object-film distance
    • blurring due to poor screen-film contact
    • blurring due to patient motion
    • blurring due to x-ray tube motion
    • distorted image due to central x-ray not directed at center of film
    • double exposure
  97. heavy lines on radiograph (generalized)
    • grid lines due to: grid out of focal range
    • grid out of alignment to x-ray central beam
    • grid upside-down
    • damaged grid
    • roller marks: result of film jammed in automatic processor
  98. inconsistent film density
    • collimation of primary beam
    • bucky tray not positioned directly under primary xray beam
    • cassette not locked into bucky tray correctly
    • light leak into cassette
    • quantum mottle
    • target damage (pitted anode)
    • variable screen-film contact
  99. black marks (not generalized)
    • crimping or folding of film
    • two films sticking together during development
    • static electricity
    • developer on film before processing
    • fingerprints as a result developer on hands while loading or unloading cassette
  100. clear areas on film (white marks, not generalized)
    • hair in cassette
    • scratch in film emulsion
    • line due to scratch on screen surface
    • contrast medium on cassette or table
    • air bubble on film during developing procedure
    • film toughing side of tank during manual processing
    • fingerprints due to film handling with contaminated hands
    • fixer splashes on film before developing
  101. yellow radiograph
    • premature age due to improper fixation
    • film sticking together during fixing process
    • incomplete washing so that residual fixer oxidizes to yellow powder while destroying the image
  102. OFA
    • orthopedic foundation for animals (non-profit, worldwide), largest breed database in world.  
    • disseminate scientific info on genetic disease.  Hip dysplasia, elbow, thyroid, knees, cardiac, eye disease
    • VD pelvis, one view.  Anesthesia recommended, must include patellas and wings of ilium
    • Prelim at 18 months but won't rate.  24 months preferred/accredited, growth plates closed.
    • Excellent, good, fair are passing
    • registration info from P (pedigree etc), $ to OFA, type of restraint used, cone down on 2 edges
  103. Penn Hip
    • specific training required (certified) to take radiographs, specific equipment.
    • most reliable method, anesthesia required.  
    • min 16 weeks preliminary
    • 3 views, extended hip VD, compression, distraction
    • 0 is tight hips, 1 is very loose hips
  104. radiopaque contrast
    • white, lets few photons through.  Radiodense
    • barium, iodide compounds, renografin, gastrographin
    • Give more for faster metabolism (smaller)
  105. contrast media
    used to check veins, blockages in kidneys, first take flat film without contrast, then add contrast media.  Use positive or negative or both to further differentiate target areas with better definition or detail
  106. radiolucent contrast
    • transparent, black.  Lets most/all photons through.  (lungs)
    • negative contrast media includes air, nitrogen, oxygen, carbon dioxide
    • fasted, enema, anesthetized, air, dye, roll animal to coat, more air, then shoot
  107. BIPS
    barium impregnated poly...spheres capsules with number of spheres.  Sterile, okay if perforated because you know how many you have and can get them out.
  108. side effects of positive contrast medium
    • nausea, vomiting, skin erythema, pulmonary edema, facial swelly, hypotension, dyspnea, irritation at IV site, vascular collapse, seizures, laryngeal edema, death.  
    • Like vaccine reaction
  109. side effects of negative contrast medium
    • if using air oxygen, nitrogen or carbon dioxide, can get absorbed or cause gas embolism and death.  
    • history of bladder stones, hematuria, irritation in bladder, engorged blood vessels.  Absorb more, gas embolism more likely
  110. 5 basic radiographic opacities
    • gas      atomic humber   1.8      black
    • fat                              6.5
    • muscle                        7.6
    • bone/mineral               12.3       white
    • metal                      higher       bright white
  111. pitted anode
    as tungsten target wears it becomes not flat, so reflects elsewhere, increases secondary radiation
  112. electrons become photons when
    they leave the glass envelope
  113. higher mA causes
    more electrons, centrifugal force keeps them together so less loss
  114. cells and tissues in most danger from radiation
    • growth cells
    • gonadal cells
    • neoplastic cells
    • metabolically active cells
    • Bone
    • lymphatic tissue
    • leukopoietic tissue
    • hemopoietic tissue
    • epithelial tissue (sunburn)
  115. 2 types of biological damage that occur from overexposure to radiation
    • somatic damage: damage ot body that becomes manifest in body of recipient
    • genetic damage: damage to the genes of reproductive cells
  116. maximum permissible dose (MPD)
    • maximum amount of radiation a person may receive in a given period
    • 5 rems per year
    • 1.25 rems/quarter
    • 0.027 rems in a 2-view chest rad
    • 600 rems will cause death in 3 days
  117. PPE for radiographs
    • lead gown, gloves, glasses, thyroid shield >/= 0.5mm thickness, dosimeter badge worn at collarbone level over apron
    • DON'T FOLD LEAD
    • use tools to prop animals so don't need to be in room

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