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98 Cards in this Set
- Front
- Back
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Explain how the level of the plane of focus is determined when using tomography
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The fulcrum decides object plane; decide object plane by moving fulcrum
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Explain how the thickness of the slice is determined when using tomography
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Tomographic angle/arc/amplitude
Greater angle = thinner cut |
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Define zonography
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Small angle of less than 10° (fulcrum less than 1 inch)
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Explain the relationship between tube movement & blurring
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The greater the distance ↑ or ↓ the fulcrum, the greater the blurring
Max blur occurs perpendicular to tube movement (Least- parallel to tube movement) |
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Relate the highest & lowest cuts in renal tomography to the part demonstrated
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Upper pole= lowest cut (posterior)
Lower pole= highest cut (anterior) Kidney is 3 cuts: upper, middle, lower |
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List what body parts are commonly demonstrated by panoramic tomography
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Mandible (TMJ) & Dental (teeth)
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Calculate what SOD must be used to obtain a given magnification factor when given the SID
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MF=SID/(SOD ) = (image size)/(object size)
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When given magnification factor & image size, be able to calculate object size
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object size= (image size)/MF
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When given SID, OID, & image size, be able to calculate object size
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object size= (image size)/MF
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Explain the radiographic appearance of a damaged intensifying screen
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Light/clear; ↓ density
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Explain the radiographic appearance of pressure artifacts to the film.
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Pressure artifacts will appear dark = increased density
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List & recognize the three types of static
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Crown
Tree Smudge |
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State the conditions that increase the likelihood of static production
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Cool - winter weather
Dry - low humidity climates |
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Describe the cause & appearance of guide shoe marks
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*Lines parallel to direction of film travel on the leading edge/trailing edge of film
*Caused by improperly placed crossover rollers/turn around assembly |
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Describe the cause & appearance of pi lines
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*Marks every 3.14”
*lines go against movement of travel *Caused by rollers having something on them |
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a.Vitreous humor
b.Aqueous humor c.Pupil d.Cornea e.Iris f.Lens g.retina h.Rods i.Cones |
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Describe the cause & appearance of fixer retention
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*Cause: improper washing of fixer retention
**Appearance: Yellowish |
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Explain the cause of “the curtain'' effect
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Bad squeegee rollers
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Recognize possible causes of fogged film
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*Temperature
*High humidity *Safe light too bright/close (safelight fog) *Chemical fog *Film bin not shielded from radiation (radiation fog) *Developer temp too high |
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List the cause of kink marks & explain how they will appear
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*Cause: bending of film
**Appearance: Look like a crease |
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List the cause of pressure marks & how they will appear
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*Cause: high pressure on film (stacking film)
**Will have ↑ density |
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Compare the rods & cones of the eye
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*Rods: outside retina (periphery) & Cones; Center of retina
*Rods: Night vision (Scotopic) & Cones: Day vision (Photopic) = better acuity of detail *Rods: Colorblind & Cones: see color *Rods: Sensitive to low light levels & Cones: Better for brighter light |
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a.Input phosphor
b.Photocathode c.Vacuum tube d.Electronic lens e.Output phosphor - anode |
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Explain the purpose of each part of an image intensifier
a.Input layer-4 parts- (tube window, support layer, input phosphor, photocathode) b.Output phosphor- (anode) c.Electrostatic lens d.Tube e.Electron lenses |
a.convert x-ray signal to electrons
b.converts accelerated electrons to visible light c.accelerates electrons across tube & magnifies image d.keeps the air out e.focus the electrons |
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State what types of fluorescent crystals are used in the image intensifier
a.Cesium iodide b.Cesium & antimony c.Zinc cadmium sulfide doped with silver |
a.(input phosphor) “cathode”
b.(photocathode) c.(output phosphor) “anode” |
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List in sequence the energy conversions in image intensified fluoroscopy
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XRAY>LIGHT>ELECTRONS>> LIGHT
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Calculate image magnification in fluoroscopy
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Mag=( maxfield size diameter)/(selected field size diameter)
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Explain how flux gain is calculated
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FG= (Number of OP light photons)/(Number of input x-ray photons)
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Calculate minification gain
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MG=((Input Phosphor)/(Output Phosphor))^2
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Calculate brightness gain
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BG=Minification Gain x Flux Gain
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Calculate dose changes resulting from field size selection in fluoroscopy (dose increase)
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((max size)/(selected size))^2
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Compare field size & degree of magnification in fluoroscopy
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As input field size decreases, magnification increases
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Compare field size & patient dose in fluoroscopy
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As input field size decreases, patient dose increases
(Must mA to compensate for ⇩ electrons~smaller field size) |
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Compare spatial resolution & field size in fluoroscopy
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As field size decreases, spatial resolution increases
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Compare spatial resolution and field size in fluoroscopy
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As field size decreases, spatial resolution increases
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Compare contrast resolution and field size in fluoroscopy
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As field size decreases, contrast resolution increases
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List the three types of television tubes
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*Vidicon
*Orthacon *Plumbicon |
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State how many frames per second American television tubes display
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*Used to be 30 frames/second
*NOW it is 60 frames/second |
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Know the facts associated with radiation protection in image intensified fluoroscopy
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*Bucky slot – at least 0.25 mm lead shielding device
*Image intensifier housing – at least 2 mm of lead *Dead man switch must be used (on only while holding it on) *Audible and visual signal every 5 minutes *Protective curtain/sliding panel – 0.25 mm lead minimum *Thyroid shield – 0.5 mm lead eq. |
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Define angioplasty
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*Use balloon to open occluded vessel
*Balloons filled with saline NOT air |
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Define thrombolysis
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Put catheter to occlusion & dissolve it using chemicals
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Define embolization
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Cutting off blood supply to structures you want to get rid of
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Explain the purpose of a vascular stent
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To open, or keep open, a vessel
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Give the name of the most common means of arterial access in angiographic procedures
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*Seldinger technique
*Site – femoral artery |
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Compare French sizing of catheters to the size of the catheter
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*3 Fr = 1 mm; higher French the larger the catheter
**EX: 9 Fr = 3 mm; 12 Fr = 4 mm |
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State what type of generator is used for interventional radiologic equipment
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*3Ф12p
*Multiply by 1.41 |
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Calculate heat units for single and serial exposures and compare them to heat capacity for an x-ray tube
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*1Ф2p: kVp x mA x sec
*3Ф12p:kVp x mA x sec x 1.41 *If there’s more than one exposure, multiply it by how many exposures where performed. *Divide if you want to figure out how many exposure it would take to have a given number of (HU) heat units. |
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Know how mass density affects the degree of x-ray absorption
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The denser it is, the more Compton & photoelectric (Proportional)
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Know how atomic number affects the degree of x-ray absorption
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↑ atomic # = ↑ Compton, but a LOT more photoelectric
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State the appropriate range of kilovoltage for mammography
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23-28 kVp
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State the type of generator used in mammography
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High frequency
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State the frequency range of electricity produced by a high frequency generator
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5-10 kHz
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State the ripple of the electricity produced by a high voltage generator
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1% ripple
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State the two main anode target materials that used in mammography
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*Rhodium
*Molybdenum |
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Give the atomic number for tungsten, rhodium and molybdenum
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Tungsten - 74
Rhenium - 45 Molybdenum – 42 |
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Explain how the anode heel effect is used in mammography
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Cathode side closest to chest wall
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State the limit for total filtration in a mammographic tube
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> 0.5mm Al eq.
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List the benefits of compression for mammography
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Creates more uniform thickness
Consistent OD over entire image ↓ OID of tissues ↑ spatial resolution Reduces scatter Increases contrast resolution Reduces patient dose |
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State the purpose of a grid in mammography
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Used to increase contrast
Increase visibility of detail |
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Compare AEC in diagnostic radiography to AEC used in mammography
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*Diagnostic radiography AEC located on top of IR
*Mammography AEC located under IR to reduce OID |
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Define differential absorption
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Different degree of absorption (in different tissues) as pass through body
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Define magnetic resonance
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Creates images of structures through the interaction of magnetic field and radio waves with tissue.
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Define the gyro-magnetic ratio
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Ratio of magnetic moment to the moment of inertia (rate it spins: magnetic field)
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Define precession
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Battle between inertia & gravity (wobbling top)
Spinning nucleus with a magnetic moment subjected to a magnetic field will align with the field and then begin to wobble |
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Define proton density
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How many precessing nuclei are in a given volume of tissue
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List the three types of magnets used in MR
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Resistive
Superconductive (cryogenic) Permanent |
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Convert tesla to gauss and gauss to tesla
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1 Tesla = 10,000 gauss
1 gauss = 0.0001 Tesla |
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Express the potential hazards of MR
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EKG leads (burns from metal)
Claustrophobia Metal inside patients body **Must screen patients!! Superconductor dangers: rapid centering |
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Know the difference between CT and MR in terms of image plane acquisition
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CT: acquired axially, then reconstructed
MR: obtained as 3D block, then displayed in any plane |
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Compare acquisition of thin slices and thicker slices in MR
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Thicker slice: less noise, may miss small lesions
Thin slice: more noise, show lesions better |
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State the effect of acquisition time upon image quality in MR
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Longer acquisition time: better signal, longer scan, motion
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Know the type of contrast agents used in MR
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Gadolinium containing compounds (Rare earth element)
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Know the dangers of contrast used in MR
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Bad batch may cause kidney function problems
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Define magnetic resonance spectroscopy
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Analysis of molecular structures (produces a graph, not an image)
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State what type of tissue structures are best imaged with sonography
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Soft tissue; muscles
Fluid-filled organs Solid organs |
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Explain the source of the term SONAR
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SOund NAvigation & Ranging
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State the differences between sound waves and electromagnetic radiation
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*Sound waves: mechanical; have to transmit through a medium (solid, liquid, gas)
*EM: pure energy; can travel thru a vacuum |
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Give the significance of the amplitude of a sound wave
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Way we measure its volume
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Give the unit of measurement for sound volume
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Decibel
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Give the frequency of ultrasound
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> 20,000 Hz
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List the known biological effects of ultrasound
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NONE
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Define transducer
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Any device that converts one form of energy to another
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Define the piezo electric effect
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Ability of a substance to produce voltage when a mechanical stress is applied to it
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Explain the relationship between frequency and penetration of ultrasound
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↑ frequency; ↓ penetration (lower frequency penetrates better)
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Explain the relationship between frequency and resolution of ultrasound
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↑frequency; ↑ resolution (detail better b/c more sound waves from sound waves)
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List and define the four types of echoic characteristics of masses
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*Hypoechoic (low level echos)
*Hyperechoic (bright echo) *Isoechoic (same texture as surrounding tissue) *Anechoic (no internal echoes) |
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Name the artist who painted
the Mona Lisa? |
Leonardo Da Vinci
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State the traditional significance of red and blue in color Doppler
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*Red - flows toward transducer (arteries)
*Blue - flows away from transducer (veins) |
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mAs
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Increases density ONLY!!
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kVp
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Increases density and contrast
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SID
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Increases density, recorded detail and distortion
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Grids
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Increases density and contrast
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Filtration
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Increases density and contrast
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Film/screen combination
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Increases density and recorded detail
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Beam restriction
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Increases density and contrast
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Anode heel effect
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Increases density ONLY!!
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Patient factors
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Increases EVERYTHING
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Generators
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???
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