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Fundamentals of Diagnostic Imaging Study Guide Week 4 Slideshow 05 – X-Ray Production -Pressing the “prep” button starts rotation of the anode and runs current (mA setting) across cathode filament -Cathode filament heats up and electrons are “boiled off” filament via _____________________________ -Pressing “exposure” button applies kVp across the tube (at 90 kVp cathode is _______, anode is _______) -Boiled off electrons then move from cathode to anode at ________________________ (not a perfect vacuum) -1 _________ (A) = 6.3 x 1018 e-/second (at 100 mA (0.1 A) 6.3 x 10 17 e-/second run through cathode) -Actual Focal Spot = size of _________ beam incident on anode -Effective Focal Spot = size of ________ beam coming off anode -Line Focus Principle = actual focal spot > effective focal spot

-Small filament : _______ focal spot : better spatial resolution -Large filament : _______ focal spot : higher heat capacity

- ____________ : effective focal spot size : potential beam size

-To make full-spine x-rays anode angle cannot be less than ____ (beam would be too small for full-spine film)

-99% of energy applied to anode results in _______ because outer shell electrons become temporarily elevated from their orbits then fall back into their original orbit

-These electrons release infrared radiation (heat) as they return to their original orbit -Heat Units kVp x mAs = heat (____________); kVp x mAs x 1.45 = heat (__________________) -Anode Heat Capacity (kHU) is determined by anode thickness and diameter -150 kHU is standard; busy family practice with full-spine x-rays upgrade to 400 kHU -Thermal Shock = extreme heating of anode (cold crystal in hot water) to avoid use a ___________________ -Electric Power P (power in ________) = I (current in Amperes) x V (electrical potential in volts) -25 kW x-ray tubes are standard; to accommodate large patients upgrade to 40 kW tube

-Anode Heel Effect = beam is weaker on the ______ side of the tube than the ________ side (put anode side of tube by ________ body part in the beam full-spine: anode on top for c-spine, cathode on bottom for l-spine)

- FFD : anode heel effect - anode angle : anode heel effect -17” film at 40” gives a 24° “cone” of x-ray that __________________________ from anode side to cathode side

-Strongest part of the beam is not the central ray; it is a ray that’s ___ toward the cathode from the central ray

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-Penumbra = fuzzy, blurry edges of shadows - penumbra at mA (200) - large focal spot (large filament); also, penumbra on _________ side - penumbra at mA (50, 100) - small focal spot (small filament); also, penumbra on ________ side - OFD : penumbra - OFD : penumbra

-Characteristic Radiation = projectile cathode electron _______ with inner (K) shell electron of _______ atom -Anode atom inner (K) shell electron flies off and is quickly replaced by an electron from _____________ -As outer shell electron fills in inner shell it releases an ______ -X-ray’s energy is _______________ of atomic number (# protons) of anode atom involved -Tungsten (W) anodes characteristic x-rays are ____ kiloelectronVolts (keV) -kVp < 69.5 do not produce ____ characteristic radiation -kVp > 70 produce a ____________ of characteristic radiation (tiny minority of total x-ray production) -Bremsstrahlung Radiation = projectile cathode electron ______________ near nucleus of _______ atom -As projectile electron changes direction it releases an ______ -X-ray’s energy is ___________ and depends on magnitude of change in direction of projectile electron -Any kVp will produce a __________________ of Bremsstrahlung radiation (vast majority of x-ray production) -Single Phase = x-rays only produced in bursts every 1/120 second (ripple factor = _____)

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-Three Phase = x-rays produced more frequently than single phase (ripple factor ~ ____)

-Medium Frequency (6 kHz) = x-rays produced more frequently than three phase (ripple factor ~ ____)

-High Frequency (40-100 kHz) = x-rays produced almost constantly (ripple factor ~ ___)

-Unfiltered Beam = large amount of useless harmful __ energy Bremsstrahlung x-rays; HVL

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-Filtered Beam = _____ block in beam path removes unwanted __ energy Bremsstrahlung x-rays; HVL

- beam filtration : low energy Bremsstrahlung x-rays : __ average x-ray energy

- mA : quantity of x-rays : __________ in average x-ray energy

- kVp : quantity of x-rays : __ average x-ray energy