Study RAD Technique Test 2 Flash Cards

 
Pile Management Card
RAD Technique Test 2

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where do you measure the body part with the calipers and what unit of measure is used
measure along the course of the central ray in centimeters
what type of radiographic rating chart contains: tube model type, Efs size, power supply, maximum allowable heat units generated per exposure, total # of exposures, number of exposures per second
angiographic rating chart
what is the target material for a mammo machine
molybenum
what is the max mA for fluoro
5mA
what is the purpose of the tube rating charts
it conveys what techniques are safe and what techniques are dangerous
an elementary particle consisting of a charge of negative electricity
electron
what is the formula for frequency and wavelengths(speed of electromagnetic radiation)
c = f × λ
speed of xrays in vacuum of air(3x10 to the eigth m/s) = frequency in hz x wavelength in meters
what is the formula for photon energy
E=hv
E= photon energy
h= plancks constant (4.15x10 negative 15th power)
v= frequency (hz)
what are the three thickness ranges specified for fixed kV systems
thin
average
thick
what are the four principal charts for technique
variable kV / fixed mA
fixed kV / variable mA
high kV
automatic exposure
how do you fix the radiograph if the density is too light if using the 15% rule
increase kVp by 15%
how do you fix the radiograph if the density is too dark if using the 15% rule
decrease kVp by 15%
a decrease of kVp by 15% is equivalent to what mAs
half mass
an increase of kVp by 15% is equivalent to what mAs
doubling the mAs
technique changes involving kVp affect
penetration
scatter
patient dose
kVp secondarily affects what
beam quantity
what are the image quality factors
optical density
contrast
image detail
distortion
does SID have an affect on radiation quality
no
what is the primary control of mA
radiation quantity
what is the primary control of kv
beam quality
mAs primarily affects what on a finished radiograph
density
kV primarily affects what on a finished radiograph
contrast
what are the three technique factors that affect radiographic technique
exposure technique factors
patient factors
image quality factors
what are the advantages of a fixed kV system
patient recieves lower doses
greater exposure latitude
more consistency with exposures of same anatomic part
measurement is not critical
what is the method of selecting exposures that produce radiographs with longer scale of contrast
fixed kV xray exposure system
what are the four phases of standardization in xray exposure systems
exposure factors (kVp, mAs, SID
radiography (screen vs grid/bucky)
positioning
processing
a device that converts the energy of the xray beam into visible light
intensifying screen
an extremely effective device for reducing the level of scatter radiation
grid
the blackening of the finished radiograph
density
the degree of difference between the light and dark areas of a radiograph
contrast
what type of radiographic rating chart contains the similiar information as a angiographic rating chart
cineradiographic chart
what is the other radiographic rating chart that contains the same information found in the anode cooling chart
housing heat storage chart
what type of radiographic rating chart contains: heat units, time (minutes)-cooling time
anode cooling chart
what type of radiographic rating chart contains:focus size, type of rectification, exposure in time seconds, kV, mA station, tube design, cold vs hot tube, & power supply
total anode heat loading chart
what is the equation for figuring out heat units
HU = kV x mA x s x constant
single phase- 1
triple phase, six pulse- 1.35
triple phase, twelve pulse- 1.41
high frequency- 1.45
what measures the heat capacity of the anode
heat units
what is the most frequent cause of tube failure
open filament
what is the percentage of decrease in diameter resulting from overheating of the filament that will cause filaments to break
10%
what is the common method used in radiography of infants that results in overheating of the filament
boost and hold method
what is a result of the boost and hold method
overheating the filament
in housing heat overload what is the effects of continuous heat delivery
bearings fail
glass envelope cracks
tube housing failure
the side of a right angled triangle that lies opposite the right angle
hypotenuse
what is the intensity or exposure rate of radiation at a given distance from a point source that is inversely proportional to the square of the distance
inverse square law for fixing adjustments to the technique do to SID change
what are the two exposure factors affected by beam restricting devices
1.decrease field size = increase exposure factors

2. loss of scatter results in loss of density
what are the causes of tube failure
1.temperature of anode is excessive during single exposure
2.rapid temperature increase
3.maintaining elevated anode temperatures for long periods
4.housing heat overload
5.overheating filament
what do the xray tube rating charts convey
which radiographic techniques are safe and which techniques are hazardous to the tube
tube life is shortened how
with inconsiderate use
the length of xray tube life is primarily under control of who
xray tech
what are the factors that extend tube life for each exam
mA
kVp
time
a sustained luminous discharge of electricity across a gap in a circuit or between electrodes
arcing
what is the formula for using the pythagorean theorem to figure out the requirements for film coverage
(A)2 + (B)2 = (C)2
in any right triangle the square of the length of the hypotenuse equals the sum of the squares of the length of the two sides
pythagorean theorem
what is the formula used for figuring out the radiographic coverage of an xray beam
RC = SID x tangent of target angle
what is direct square relationship when talking about target angle
decrease SID, decrease coverage using same target angle
increase SID, increase coverage using same target angle
what is the direct relationship when talking about target angle
decrease target angle, decrease xray coverage at the same SID
increase target angle, increase xray coverage at the same SID
the area of exposure by the primary beam where technical factors affect that coverage which is normally shown by the collimated light field
xray coverage
what is required on all non mobile radiographic equiptment by federal law
PBL - positive beam limiting device
what is the best all around beam restrictor
collimator
what are the types of beam restrictors
aperature diaphragm
cones & cylinders
collimators
what are the advantages of a smaller field
1.smaller area of the patient exposed
2.decrease of 1/2 in xray beam diameter=decrease patient exposure
3.less scatter radiation
4.improves film quality
what does the beam restricting device do
regulate size and shape of xray beam
what is the most common sheets of metal used for filtration
aluminum
what is the total filtration required for diagnostic radiology
2.5mm of aluminum
what is the formula for total filtration
inherent filtration + added filtration = total filtration
what are the types of added filtration
collimator mirror
aluminum sheets
special purpose filters
what are the types of inherent filtration
tube window
immersion oil
tube housing
anything built into the machine
what are the types of filtration
inherent filtration
added filtration
what are the effects of filtration
decreases low energy photons in the primary beam
increases the average energy in the primary beam
increases the HVL
used to reduce patient dose by beam modification
filtration
penetrating ability of xrays is decreased how
by decreasing the kV
penetrating ability of xrays is increased how
by increasing the kV
what are the factors that affect beam quality
kVp
filtration
beam restriction devices
the ability to penetrate matter
quality (xray)
energy associated with motion
kinetic energy
the thickness of a specified material which reduces the exposure rate to one half its initial value
half value layer
process of shaping the xray beam to increase the ratio of photons usefull for imaging to those photons that increase patient dose or decrease image contrast
filtration
what is the equation for xray efficiency
E = K x Z x KVP
E- efficiency in percent
K- constant = 1x10 to the -4
Z- atomic # of the target
KVP
what is the efficiency of xray production
a percentage of the kinetic energy of electrons is converted to xrays, the remainder is converted to heat
to raise to a higher energy level
excite
how much is the exposure reduced when the kV and mAs are held constant
1/4
what is the formula for the inverse square law for fixing adjustments to the technique do to SID change
I x d2 = i x D2

i / I = (D)2 / (d)2
what is the relationship of frequency and wavelength
frequency is inversely proportional to wavelength
what is planck's constant in relation to electromagnetic radiation
photon energy is directly proportional to frequency
a unit of length equal to one ten-billionth of a meter
angstrom
the entire range of wavelengths or frequencies of electromagnetic radiation extending from gamma rays to the longest radio waves and including visible light
electromagnetic spectrum
the number of complete oscillations per second of an electromagnetic wave
frequency
a quantum of radiant energy
photon
one of the very small increments or parcels into which many forms of energy are subdivided
quantum
the distance in the line of advance of a wave from any one point to the next point of corresponding phase
wave length
wavelike flucuations of electric and magnetic waves. they fluctuate perpendicular to thier direction as well as to each other
electromagnetic radiation
what is the composition of xrays
1.belongs to the general category of electromagnetic radiation
2.behaves as waves and particles
what is the usefull energy range for xrays
25-120kV
can xrays be deflected by electric or magnetic fields
no
how do xrays travel
in a straight line
what are highly penetrating, invisible rays that are electrically neutral
xrays
what two chemical and biological changes do rays produce
ionization
excitation
what are the groups that the electromagnetic spectrum consists of
gamma
xray
ultra violet
visible light
infrared
microwave
what are the wavelengths of an xray measured in
angstroms
what is the frequency of an xray measured in
hertz
what are the size of the focal spots of a mammography tube
.8mm-2mm
what is the molybdenum anode used for in a mammographic tube
to obtain high intensity within a narrow band of wavelengths
what type of tube has closer anode-cathode spacing
mammographic tube
what type of tube produces an xray beam of soft radiation and low kV
mammographic tube
what type of tube produce heat in a relatively small amount over a long period of time
fluoroscopic tube
what type of xray tube uses a high speed anode, must allow for increased tube loading, and must withstand more heat
angiographic xray tube
what is the function of a angiographic xray tube
provides for multiple exposures during a short period of time
what happens when the exposure switch is activated
1. grid bias is reduced to almost zero
2. applied kV drives space charged electrons to the anode
3. preselected mAs value is reached
what happens to the grid bias when the control switch is activated
it is instantaneously dropped to zero
what are the two characteristics of grid bias in a grid controlled xray tube
acts as a switch
voltage applied to the grid is -2kV
what are the four functions of a Grid Controlled xray tube
1. start/stop discharge of capacitors
2. applied grid bias prevents electrons from passing to the anode
3. exposure switch is activated
4. exposure is stopped
process of stopping the discharge of the capacitor at some preselected point on the discharge curve
wave tail cutoff
a radiography procedure which makes possible the visualization of organs in motion, positioning of the patient for the spot filming, instillation of an opaque media into hollow organs, insertion of catheters into artieries, and a variety of other procedures
fluoroscopy
the radiographic visualization of the blood vessels after the injection of a radiopaque substance
angiography
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