radiation factors
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| what quantity of radiation exposure to the reproductive organs is required to cause temporary infertility? | 200 rad
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| what dose of radiation can cause menstrual changes in women and decrees the number of sperm in a man? | 10 rad
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| what dose of radiation will cause sterility? | 500 rad
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| focal spot blur is greatest where? | directly along the course of the central ray
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| what is the fx of the fixer? | * remove the unexposed silver bromide crystals
* harden the emulsion
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| darker image means more | optical density
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| as SID decreases, exposure rate _____ (inc or dec) | increases
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| as SID decreases, optical density ____ (inc or dec) | increases
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| T/F: female oogonia reproduce only during fetal life | true
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| T/F: male spermataogonia reproduce continuously | true
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| T/F: both male and female stem cells reproduce only during fetal life | false; male repro continuously, female only during fetal life.
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| what is the annual dose-equivalent limit for the skin and hands of an occupationally exposed individual? | 50 rem
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| what is the annual dose-equivalent limit for the lense of the eye of an occupationally exposed | 15 rem
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| how many rem per quarter? | 3 rem
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| no more than __ rem in a year | 5
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| which of the following will require an increase in x-ray photon energy/pemetration? * fobrisarcoma * osteomalacia * paralytic ileus * ascites | ascites: body tissue density has increased, in the others it has decreased
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| what is the formula for finding ESE? | rad / time = x / 1 min
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| what is the device that directs the light emitted from the image intensifier to varous viewing and imaging apparatus? | beam splitter
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| what influences geometric unsharpness? | OID
SOD
SID
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| as OID increases, magnification ____ (inc/dec) | increases
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| OID is directly or indirectly related to magnification? | directly
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| as focal object distance and SID are inversely proportional or directly porportional? | inversley
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| as focal onject distance and SID decrease, magnification ____ | increases
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| what is base-plus fog | small amount of measurable density on unexposed and processed film. it is a result of environmental, background radiation that is present during film manufacture, transport, and storage
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| what contributes to base-plus fog? | chemical fog
base tint
background radiation
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| which portion of the characteristic curve would most likely represent a density of 1.0 | straight-line portion
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| what is the characteristic cureve used to predict? | the speed, contrast, and exposure latitude of a particular film emulsion
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| what does the the toe of the characteristic curve represent | immediately after base-plus fog
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| what does the shoulder portion of the characteristic curve represent | Dmax
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| what effect wil a stained intensifying screen have on the finished radiograph? | decreased density:
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| patient does increases as fluoroscopic FSS increases FSS decreases FOV increases FOV decreases | FOV decreases
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| the shorter the SID, the ____ the skin dose | greater
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| high kVp _____ skin dose | decreases
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| radiation output from the diagnostic xray tube is measured in what units? | roentgen
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| what is a rad? | radiation absorbed dose
it measusres the energy deposited in any material
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| what is rem? | radiation equivalent man
it includes relative biologic effectiveness
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| Becqueral | the SI unit of measurement for radioactivity
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| if a large quantity of radiation is delivered to a body over a short period of time, the effect_____ | will be greater than if it were delivered in increments
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| exposed silver halide crystals are changed to balck metallic silver by what? | reducers
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| what keeps the emulsion swelling to a minimum? | hardner
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| what is hydroquinone and phenidone? | automatic processor developer agents
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| what provides the necessary alkalinity for the developer solutions? | activator
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| how does the use of rare earth intensifying screens contribute to lowering the pt dose? | it permits the use of lower mAs
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| delivery of large exposures to a cold anode, or the use of exposures exceeding the tube limit may casuse: | cracking the anode
rotor bearing damage
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| if you can't achieve a short OID, what can you do to minimize magnification? | a longer SID
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| what is the approximate intensity (quantity) of scattered radiation at 1 m from the patient? | .1% the entrance dose;
if the entrance dose for this image is 320mR, then the intensity 1m from the pt is .32 mR
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| what is the source of electrons withing the xray tube? | thermionic emissions
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| why is filtration added to the xray beam? | to porduce an xray beam with higher average energy;
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| what is the filtration on the primary beam? | 2.5mm Al
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| what amount of the filtration of the beam is accounted for in the glass envelope | .5 mm Al
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| what amount of filtration does the collimator provide? | 1.0 mm Al
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| what 3 methods of filtration are considered inherent filtration? | primary beam
glass envelope
collimarot
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| in digital imaging, xrays form an ______ ______ on the image receptor | electronic image
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| what are the 4 tanks in the processor? | 1. developer
2. fixer
3. wash
4. dryer
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| what happens in the developer tank? | the exposed silver bromide crystals are reduced to black metallic silver
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| what happens in the fixer tank? | the unexposed silver grains are removed from the film by the clearing agent
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| what happens in the wash section? | the chemicals are removed from the film to preserve the image
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| what are stochastic effects of radiation? | genetic alterations
carcinogenesis
nonthreshold and randomly occuring effevts
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| the chance occurance of stochastic effects is directly related to the ____ ____ | radiation dose
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| what are nonstochastic effects of radiation? | predictable, threshold responses; a certain amount of radiation must be received before the effect will occur, and the greater the does, the more sever the effect
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| primary radiation barriers must be at least how high? | 7'
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| off-focus or extra focal radiation may be minimized by ____ | restricting the x-ray beam as close to its source as possible
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| the annual limit for occupationally exposed individuals is valid for what type of radiations? | beta, x, and gamma radiations
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| the ratio between the height of the lead strips and the width of the distance between them | grid ratio
the thickness of the strips is unrelated to the grid ratio
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| what is the formula for grid ratio | height of strips devided by the distance apart
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| which cell type has the least radiosensitivity in the adult human? | nerve cells
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| which cell type has the greatest radiosensitivity in the adult human? | lymphocytes
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| the atomic number (Z) of the tissues is directly related to it's ______ _______ | attenuation coefficient
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| differential absorption contirbutes to the various shades of ____? | gray on the finished xray image
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| air has an effective Z number of _____ | 7.78
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| fat has an effective Z number of | 6.46
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| water has an effective Z number of | 7.51
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| muscle has an effective Z number of | 7.64
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| bone has an effective Z number of | 12.31
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| what is the formula for pixel size? | FOV / matrix size
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| if the matrix size is increased, the pixel size is ______ | decreased
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| if the FOV increases, the pizel size ______ | increases
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| pixel size is directly or inversley related to resolution | inversley
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| as pixel size increases, resolution ______ | decreases
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| grid cut off due to off centering would result in ____ | overall loss of density
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| photoelectric effect | a relatively low-energy photon uses all its energy to eject an inner-shell electron, leaving a vacancy. An electron from the shell above drops down to fill the vacancy, and in doing so gives up a characteristic ray. most harmful to patients, trsfd to tis
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| compton scatter | a high-energy incident photon ejects an outer-shell electron. In doing so, the incident photon is deflected with reduced energy, but it usually retains most of its energy and exits the body as an energetic scattered ray.
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| thompson scatter | another name for classical scatter
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| what are examples of primary barriers? | lead walls and doors
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| primary barriers must be how high, and how many inches thick? | 7' high, 1/16th" thick (1.5mm)
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| what is secondary radiation? | leakage or scattered radiation
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| what are examples of secondary radiation barriers? | portions of the wall above 7'
the control booth
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| what is the required thickness of secondary radiation barriers? | 1/32th" o
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| what is the single most important factor regulating rad contrast is? | kVp
the lower the kVp, the shorter the scale of contrast
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| the lower the kVp, the _____ the scale of contrast | shorter
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| what is the primary source of scattered radiation? | the patient
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| as the size of the irradiated field decreases, scattered radiation production and patient hazard ______ (inc or dec) | decreases
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| if the amount of scattered rad decreases, then the radiographic contrast is ____ (ligher or lower) | higher
(shorter scale)
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| long scale | low contrast
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| short scale | high contrast
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| what voltage ripple is produced by single-phase equipment? | 100% voltage ripple
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| what is a photon | the smallest quantity of any type of electromagnetic radiation
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| the Hz stands for ___ and represents _____ | Hertz
cycles per second
1 Hz = 1 cycle/s
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| what determines the quantity of flourescent light emitted from a flourescent screen? | thickness of phosphor lyer
type of phosphor used
kV range used
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| effective dose | equivalent whole body dose
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| spinning top test | to test timer efficiency
full wave = 12 dots at 1/10s, 6 dots at .05s 10 dots at 1/12s, 3 dots at .025s
for 3 phase, the size of the arc is measured and equated to exp time
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| rare earth phosphurs | gadolinium
lanthanum
yttrium
(musch faster than calcium tungstate)
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| using a rare earth phosphors allows the radiographer to use _______ | significantly lower mAs
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| what unit of measure expresses the amoung or energy deposited in tussue? | Rad (Gy)
the unit of absorbed does
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| quantity of ionization in the air | roentgen
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| radiation dose to biologic material | rem
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| inverse square law | as the distance btwn the radiation source and the IR decreases, the exposure rate increases
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| inverse square law formula | old mAs/new mAs = old distance / new distance
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| Voltage ripple | the percentage drop from maximum voltage each pulse of current experiences
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| controlled area | 1. that is occupied by people trained in radiation safety.
2.that is occupied by people who wear radiation monitors.
3.whose occupancy factor is 1.
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| The use of which of the following is (are) essential in magnification radiography? 1. High-ratio grid 2. Fractional focal spot 3. Direct exposure film | Fractional focal spot
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| Pair production | an interaction that occurs only at energies of 1.02MeV, and therefore it does not occur in daig rad
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| classical scatter | a low-energy photon interacts with an atom but causes no ionization; the incident photon disappears into the atom, and is then immediately released as a photon of identical energy but changed direction.
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| Occupational exposure received by the radiographer is mostly from | Compton scatter.
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| The high-voltage, or step-up, transformer functions to | increase voltage to the necessary kilovoltage
It decreases the amperage to milliamperag
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| one of the biggest advantages of CR/Dr is | lattitude
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| CR relationship between the exposure given the photostimulable phosphor (PSP) and it's resulting luminescence | linear
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| what affects recorded detail on traditional film/screen imaging | FSS
SID
OID
film/screen speed
motion
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| the effect of focal spot size is principally on ____ ____ | radiographic sharpness
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| according to the NCRP, the whole body dose equivalent limit is | 50mSv
5 rem
5000 mrem
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| according to the NCRP, the annual whole body dose equivalent for students under the age of 18 yrs | 1 mSv
100 mrem
.01 rem
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| The annual occupational dose equivalent limit for the lens of the eye, a particularly radiosensitive organ, is | 150 mSv (15 rem or 15,000 mrem)
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| The annual occupational dose equivalent limit for the skin and extremities is | 500 mSv (50 rem or 50,000 mrem
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| The total gestational dose equivalent limit for embryo/fetus of a pregnant radiographer | 5 mSv (0.5 rem or 500 mrem
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| The device used to test the accuracy of the x-ray timer is the | spinning top
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| line focus principle | illustrates that as the target abgle decreases, the effective focal spot size decreases, providing improved recorded detail
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| steep, small target angle increases or decreases the heel affect? | increases
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| LET refers to | the rate at which energy is transferred from ionizing radiation to soft tissue
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| as screen speed in increased, exposure factors must be ______ to maintain the original image dinsity? | decreased.
a change from 100 to 200 speed usually requires the mAs be halved.
400 to 200 would require twice the mAs
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| As the CR laser scanner recognizes various tissue densities, it constructs a graphic representation of pixel value distribultion called a | histogram
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| sensitometry | method of quality control for daily monitoring of the automatic film processor
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| densitometer | a device used to read optical density
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| crossover rollers should be cleaned daily to prevern | accumulation of crystallized solution on the rollers
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| what is needed to construct a sensitometric curve | pentrometer
densitometer
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| pentrometer | aluminum step wedge used
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| brensstrahlung radiation | A high-speed electron entering the tungsten target is attracted to the positive nucleus of a tungsten atom and, in the process, is decelerated
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