image production final
what is the leakage radiation limit
100mR per hour at 1 meter
part measuring at/or more than________require the use of a grid to offset the scatter
10cm
how do you find SOD
SID-OID
what is aec's main claim to fame
consistency and reproducity on a wide range of people. less likely to repeat image due to technique in accuracy. also less patient dose.
more absorption by the body means more_______?
contrast
window width controls ____what window level controls _____
contrast, receptor exposure/image brightness
purpose of exposure timer
controls or regulates length of exposure time
what is the function of the output phosper in the image intensfier
convert electrons sent from the photocathode into light photons
in a filament transformer when the number of turns decrease what happens to CURRENT
current increases proportionally.
subject density has a direct or indirect relationship with contrast
direct
MR value never shows its self on direct or indirect square law questions
direct ( if i value use inverse square law) REMBER BY THE LETTER I
motion has a direct or indirect relationship with shape distorion
direct ( motion may cause a body part to appear to be a slightly different shape)
what is the purpose of the electrostatic lens
direct for focus the path of electrons from the photocathode to the surface of the output phospher screen
Ei and lgm numbers have direct or indirect relationship with exposure
direct if you have a low ei or lgm number image was underexposed.
size distortion occurs because of what?
distance
size distortion can only be effected by what
distance, because distance effects magnification
how do you limit production of scatter radiation
drop kvp collimate use of compression? air gap
transformers operate on the principle of what type of induction
electromagnetic induction and require an alternating current to operate
what exposure timer is the most accurate
electronic
define latent image
electronic image of valence electrons stored in high energy traps and is made manifest by exposure to a very small beam from a high energy laser.
indirect converts x rays into light while direct converts x rays into _________
electrons
x ray tube diagram
electrons move from cathode to andoe
which are the two examples of shape distorion
elongation and foreshortening ALWAYS THE ANSWER
define isotropic
equal intensity in all directions ( x rays are produced isotropically)
what material makes up the phospher in the casete
europium activated barium flurohalide
how do you get a reciprocating or moving grid
exposure stoped at somepoint and lead strips exhibit a unfifrom appearnce across the iamge
true or false filtration is not a beam attenuator
false is a beam attenuator
with use of magnification in fluro patient dose decreases true or false
false!
true or false grids effect the production of scatter
false!! grids clean up scatter but do not produce it!
true or false kvp only effects quality and mas only effects quantity
false, kvp effects both quality and quantity while mas only effects quantity.
an image with high contrast has ________shades of grey
few (more black and white)
beam restriction can also be defined as what two terms
field size, collimation (be careful, an increase in field size moves "hands" outward as opposed to inward)
what is the main controlling factor of recorded detail
focal spot size
what is the caliper rule when using it for the variable kvp chart
for every centimeter in part thickness a 2 kvp adjustment is made.
distortion is what type of factor
geometric
focal spot size is what type of factor
geometric factor
factors that affect the degree of divergence of the x ray beam and the information recorded on the image receptor is termed what
geometric factors.
the more pixels sampled per minutes the greater or less sampling frequency
greater
what two wave forms have a 100 percent voltage ripple
half and full wave
what is does an uncrectified wave length look like
half of the wave is above the line and half is below the. an unrectified wave length can also be called the alternating current
once a wave length gets rectified the wave turns into a __________
half wave or pulse laplse because only half of the wave is showing itself.
the secondary circuit has what type of voltage
high
step up transfers is also know as high or low voltage transformer
high voltage or high tension
what does his stand for
hospital information system contain full patient inoformation
each pixel is given a numeric value called what
hounsfield
define subject density
how tightly compacted at the atomic level (moving from air to bone/thickness of a part
why does kvp and contrast have an inversely proportional relationship
if you increase kvp the amount of scatter reaching the IR will increase as well. ( scatter creates less contrast on the image)
what type of motor drives or power the anode during an exposrue
induction motor
magnification of the fluoroscopic image is a function of what component of the image intensfier
input phospher
what is the magnification factor in fluor
input phospher 1 divided by input phospehr 2
define quantum mottle (noise)
insufficient quantity of x rays to reach the IR (not enough x rays made it to the IR
what assist in cooling the x ray tube
insulating or dielectric oil (located outside glass envelope but inside protective housing
latent image is what image
invisible image
what are the two types of phototimers
ionization chamber and photomultiplier tube
what are the two main controlling factors of contrast
kvp and look up chart
a radiographic method to identify an image is ________while an electronic method to identify an image is _______
lead characteristics like r or l marker, annotation on computer after image is taken.
the more magnification the less or more recorded detail
less( think of when you zoom to close in on an object, the image appears to big and is misrepresented)
how is a digital image created in indirect capture?
light from the scintillator strikes the ccd and is converted into an electronic signal. the signal is sent to an analog to digital converter where it becomes a data and forms the digital image
define edge enhancement
limiting the number of pixels in a neighborhood of the matrix. the smaller the neighborhood the greater the enhancement ( outlines an image)
how is spatial resolution masured
line paris per mm
what does lan stand for
local area network local sharing
the greater the sampling frequency the shorter or longer it takes to process a plate
longer, more information is being collected
what is the main controlling factor of contrast in the DIGITAL WORLD
look up table
the filament heating circuit has what type of voltage
low
image noise or quantum mottle is controlled by what three factors
low mas, high kvp and fast IR, probably dont need to know fast ir
the primary circuit has what type of voltage circuit
low voltage circuit
the filament transformer is also know has the _____voltage transformer
low voltage or step down
high absorption happens where there is_______kvp and low absorption happens when there is ______ kvp
low,high
what two transformers use mutual induction
step up and step down transformer
define self induction
the changing magnetic field that is created by inducing an opposing voltage in a single coil of wire
define value of interest VOI
the digital data set of information that is arranged into a histogram distribution
what are the two components that make up the cathode
the filament wires and focusing cup
define sampleing frequency
the number of pixels sampled per millimeter as the laser scans each line of the imaging plate (used when a cassete is placed into the reader)
define receptor exposure
the overall amount of x rays to reach the IR
how is a current created in a filament transformer
the power formula kick is as the number of turns decreases. voltage will decrease and current will increase proportionally which is responsible for sending the proper current to the filament wire to set electrons up for thermionic emission.
define quantization
the process of mapping a large set of input values into a smaller set
before the x ray current hits the tube it is run through a device called what
the rectificer
which anode angle gives greater spatial resolution
the smaller angle (usually 5 degree)
define minimum response time
the time it takes for a system to respond and send the signal to terminate the exposure MRT
when do you know a wave length has been rectifeid?
when the wave doesn't drop below the line anymore.
how do you et moire pattern in a grid
when two linear grids are paled on top of each other but lead lines are not aligned at right angles. wave like apperence.
define actual focal spot size
where electrons ACTUALLY strike the target
what does wan stand for
wide area network cross state sharing
what is the thinnest part of the glass envelope which reduces inherent filtration
window
the primary x ray beam comes from what part of the tube
window (all other radiation that does not come from the window is considered leakage.
what is the purpose of a ccd
with the help of scintillator material produce light for indirect capture.
what is the sequence of processing a flim on a cassette
x rays go through anatomy of interest and go on cassette. disruption of valence electrons occurs. cassette is put through reader where laser reads the disruption of electrons. at that point that signal goes from analog to digital signal through the AEC. last laser washes cassette clean.
does the oil contribute to filtration
yes
does the use of filtration create a more homogeneous beam
yes because now all they electrons in the beam are alike since the low energy electrons have been filtered out.
how do you get an upside down grid
you placed grid upside down. strips appear noraml in the middle but complet cutt off on both edges
what material is the output phosper made of
zinc cadmium sulfide.
bright lights control______While low light controls_____
cones, rods
a grid has a direct or indirect relationship with contrast
direct
additive pathology has a direct or indirect relationship with contrast
direct
angulation of the tube or part has a direct or indirect relationship with shape
direct
beam restriction has a direct or indirect relationship with contrast
direct
destructive pathology has a direct or indirect relationship with image exposure
direct
direct or indirect capture gives better spatial resolution
direct
flat panel (DEL) has a direct or indirect relationship with spatial resolution
direct
what is the main controlling factor of receptor exposrue
MAS
kvp has a direct or indirect relationship with image exposure
direct
mas has a direct or indirect relationship with receptor exposure
direct
matrix size has a direct or indirect relationship with spatial resolution
direct
number of turns and voltage always has a direct or indiect relationship
direct
the cr needs to be within what percent of the indicator
0.5
name the four beam restricter devices
1. aperture diaphragm
what are 4 factors of post processing
1. brightness-intesnity of light that represents each pixel on the monitor 2.contrast-differences in brightness 3.region of interest ROI-boundares of an object on an image 4. electronic collimation/masking-can cause small detail loss and it is accomplished by suppressing frequencies of lesser importance.
what are the two sub sections of dr
1. direct capture 2. indrect capture
the filament circuit contains what three structures
1. focal spot selector 2.ma selector 3. step down transformer EVERYTHING ELSE IS PRIMARY CIRCUIT
what three factors effect the production of scatter radiation
1. high kvp 2. large thick part? 3. large field size
what are the 6 types of exposure timers
1. mechanical 2. synchronous 3.electronic 4.mas 5.impulse 6.aec
what makes an image legal
1. name/medical record number 2. date performed 3. institution name 4.right or left marker patient age and DOB is optional
the secondary circuit contains what three structures
1. rectificer 2.ma meter 3. tube
image receptor exposure and contrast are inversely proportional except for in what two times?
1. screen and image receptor speed. 2. beam filtration
what are the 6 types of compensator filters
1. wedge- mounted on collimator 2. supertech/trough- mounted on collimator 3. bboomerang- placed on patient 4.ferlic swimmers-collimator 5. ferlic shoulder- patient and collimator 6.supertech/full lenght-collimator
sampling frequency has a direct or indirect relationship with spatial resolution
direct
the aec backup timer should be set to ________% of the anticipated manual exposure time.
150
which of the following SNRs give greates spatial resolution 2,1 4,1 8,1 16,1
16:1 (more signal greater resoltuion) or lower ratio more noise greater ratio less noise
on a pa projection of the chest what two ionization chambers will be selected
2 outer chambers
image plates that have been unexposed for longer than how many hours should be erases
24-48 hours
what wavelength has a 4 percent voltage ripple
3 phase 12 pulse.
what wavelength has a 13 percent voltage ripple
3 phase six pulse
indrect capture is a ____step process while direct is a ____step process
3, 2
what is the angle capacity of the anode?
5-15 degree angle
at what angle in a transformer is the greatest emf produced
90
define attenuation
Attenuation is the reduction in intensity of an x-ray beam as it passes through an object due to the absorption and scattering of photons. (clean up scatter)
who own image
INSTITUTION OWNS THEM, NOT TECH OR PATINET
sid has a direct or indirect relationship with recorded detail
direct
is spatial resolution related to exposure amount
NO!
what has a greater effect on magnification SID or OID
OID
what is a hysterogram
a graph of exposure information
define look up table
a histogram of the luminance values derived during image acquisition. each pixel is changed to a new gray value where the resultant image will have the appropriate brightness and contrast. a there is a lut for every body part.
define spatial resolution
ability of the system to record adjacent small structures equipment related
define windowing
ability to alter the receptor exposure and contrast of a digital image following processing. (post minipulation)
if image exposure decrease the more photons will be _________?
absorbed by the body
what current must the x ray tube always be supplied with
ac or alternating current for the process of induction
what focal spot size is larger actual or effective
actual
how do you calculate total resistance in a series circuit?
add the the respective resistance together if the three resistances are 1, 4, 5. total resistance is 10
list from least to greatest attenuation factors
air, fat, muscle, bone,
what ionization chamber would you use for apelvis
all three
rectifiers creates wave from and change the current for ______to_______
alternating current to direct current.
direct capture uses what materials
amorphous selenium
define radiographic receptor exposure
amount of blackness of an area of a radiograph
analog signals or electric pulses are converted to digital signals via what
analog to digial converter
what does apr stand for
anatomically programed radiographY( NOT THE SAME AS AEC ( when you select hand and the control panel is set to 50@ 2)
name four factors that effect shape distortion
angulation of the tube,part,image receptor and motion
define focal spot size
area of anode surface which receives electrons ( smaller the focal spot the better!)
define umbra
area of sharpness
what is the purpose of a compensating filter
at attenuate varying amoounts of the x ray beam baseson filter type and exam being performed. produces an EVEN receptor exposure of anatomical structures.
what is the source for kvp not relating to contrast
autotransformer
what transformer uses self induction
autotransformer
define contrast resolution
better visibility of detail
short scale contrast is ________while long scale contrast is _______
black and white, many shades of gray
define penumbra
blurring around the edges or geometric unsharpness
how does the fluro image become magnified
by reducing the size of the area of the input phospher focused to the output phospher screen
inverse square law is used for ________while direct square law is used for _________.
calculate for change ,maintaining a constant exposure by compensating
what determines how much you vary the kvp on a variable kvp chart
caliper,
is penumbra greater on the cathode or anode side of tube
cathode
__________is negative and ______is positve
cathode, andoe
what cell should be used for ap projection of hip
center
what ionization chamber will be used on a lateral chest
center chamber
what material is the input phosphor made of
cesium iodine
ccd stands for what
charged couple device
x- x rays interact with input phosepr and get converte to light. l-light interacts wtih the photocathode and get converted to electrons e-electrons run through anode and interact with output phospher and get converted back into light. L-light goes through ace and analog Digital converter get broadcast on the monitor m- monitor
chasing the flow of the image intensfier
which recording system device gives the greatest patient dose
cine fluoroscopic device.
grid clean up definiton
cleanup of scatter raditon
cr stands for what, dr stands for what
computed radiogrpahy, digital radiography
a decrease in mas will do what to image exposure
decrease
an increase in kvp will do what to contrast
decrease contrast. (less shades of grey more black and white)
a decrease in kvp will do what to image exposure
decrease image exposure
filtration increases or decreases skin dose
decreases because it absorbs low energy x rays
minification formula
diameter of the input phosphor squared divided by the diameter of the output phosphor squared.
for both thorax and abdomen where do you place the cathode over
diaphram (upper abdomen) (lower thorax and tspine)
how do you exchange images through different modalities
dicom
define contrast
difference in adjacent areas
what is subject contrast
difference in different organs
define radiographic contrast
differences in densities on adjacent areas on a radiograph
what does dicom stand for
digital imaging and communication in medicine
define rescaling
digital processing technique that is used to modify and under or overexposed image.
OID has a direct or indirect relationship with size distortion
direct
explain the 15 percent rule
if you increases or decrease kvp by 15 percent you have to double or cut receptor exposure in half. DO NOT TOUCH MAS, YOU ARE CHANGING EXPOSURE BY CHANGING KVP (remember kvp can effect mas but not vice versa)
high kvp means more penetrating x rays through the body parts creating what type of image
image with more shades of grey/less contrast
where is the electrostatic lens located
in the image intensfier along the ful lenth of the tube
what is the greatest disadvantage when using aec?
inaccurate or improper positioning.
an increase in mas will do what to image exposure
increase
as field of view increases you will get an in increase or decrease in pixel size
increase
if more x rays get absorbed contrast will increase or decrease
increase ( more x rays getting absorbed means a better photographic picture)
does a increase in atomic number increase or decrease attenuation
increase because an increase in atomic number means atoms are more closely packed and can attenuate or absorb more x rays.
a decrease in kvp will do what to to contrast
increase contrast ( more shades of grey)
an increase in kvp will do what to image exposure
increase image exposrue
define anode heel effect
increase in beam intensity toward the cathode end of the beam and a decrease on anode end of beam (hint fat cat fattest or thickest part goes under cathode because there is more intensity. or compensate with a wedge.
how do you minimize quantum mottle
increase mas, drop kvp
if you increase image receptor size does the matrix increase or decrease
increase, now there are more rows and columns
as number of turns in a transformer increases voltage increases or decreases
increases
sampling frequency increase or decreases spatial resoluton
increases
decreasing pixel size increase or decreases spatial resolution
increases spatial resolution (m&ms) also increases visibility of small structures and recorded detail
OID has a direct or indirect relationship with recorded detail
indirect
SID has a direct or indirect relationship with receptor exposure
indirect
a grid has a direct or indirect relationship with image exposure
indirect
additive pathology has a direct or indirect relationship with receptor exposure?
indirect
angulation of the tube or part has a direct or indirect relationship with recorded detail
indirect
beam filtration has a direct or indirect relationship with contrast
indirect
beam filtration has a direct or indirect relationship with image exposure
indirect
beam restriction has a direct or indirect relationship with receptor exposure
indirect
destructive pathology has a direct or indirect relationship with contrast
indirect
focal spot size has a direct or indirect relationship with recorded detail
indirect
kvp has a direct or indirect relationship with contrast
indirect
motion has a direct or indirect relationship with recorded detail
indirect
subject density has an direct or indirect relationship with image exposure
indirect
psp plate size has a direct or indirect relationship with spatial resolution
indirect ( think of the same amount of peanut butter being spread over an 8 by 10 plate and a 14 by 17 plate. you get more coverage (or in this case spatial resolution the the smaller plate)
field of view has a direct or indirect relationship with spatial resolution
indirect ( larger the field of view the larger the pixel size)
pixel size has a direct or indirect relationship with spatial resolution
indirect ( think of a jar of m&ms in a jar compared to a jar full or golf balls) the golf balls are greater in size and dont pack together as nicely as the m&ms )
sid has a direct or indirect relationship with size distortion?
indirect (think of the heart being done at 72 to decrease magnification)
which dr system converts x ray photons into light
indirect capture
define mutual induction
inducing a current through a secondary coil by varying the current through the primary coil
if you increase OID what happens to magnification
magnification goes up and recorded detail decreases
what has the greatest effect on quantum mottle
mas
variable kvp chart always used the same kvp or mas
mas, kvp varies by
number or rows X number of columns is term what (number of squares aligned in rows and columns, the greater the amount of the squares the greater the matrix)
matrix size ( this shows a large matrix with with small pixels. )
what is the brightness gain formula
minification gain multiplied by flux gain
distortion is __________of an image
misrepresentation
the focusing cup is made up of what material
molybdenum or nickel
more rows and more columns/matrix size gives you more or less pixels
more pixels
why does an increase in kvp decrease contrast
more scatter radiation reaches the IR
an image with low contrast has _____shades of grey
more shades of grey
when using aec device how do you change the rate of exposure?
new equipment select the large or small person on control panel old days before new technology - adjust density control ANSWER IS ADJUST DENSITY CONTROL
does SID have an effect on shape distorion
no because you are not angling the tube.
SID has a direct or indirect relationship with contrast
no relationship
angulation of the tube or part has a direct or indirect relationship with size
no relationship
focal spot size has a direct or indirect relationship with size distortion
no relationship
mas has a direct or indirect relationship with contrast
no relationship
motion has a direct or indirect relationshp with size distortion
no relationship
focal spot size has a direct or indirect relationship with shape distoriton
no relationship, focal spot size only has a relationship with recorded detail
does OID have any effect on shape distoriton
no, because you are not angling the tube.
does a fixed kvp chart means you always use 50 for a hand
no, it means 50 is a good starting point and can be appropriately adjusted according to part thickness and pathology. GENERALLY SPEAKING MAS CHANGES KVP STAYS THE SAME FOR THE MOST PART
a decrease in mas will do what to contrast
nothing
an increase in mas will do what to contrast
nothing
how do you get lateral off centering of a grid
off centering central ray. lead strips will appear more frequently on one side of the image.
autotransformers use self induction meaning they have how many wires
one
what is another term for degree of blackness
opacity
what is the magnification factor
or image size over object size, depends on what information is in question
what ionization chamber would you use for wings of pelvis
outer two cells
caliper is a device used to measure what
part thickness
what is the purpose of using a back up timer when using aec device
patient safety in case of malfunction, terminate exposure in case aec exposure fails. not the primary means of terminating aec exposure.
what is aec or automatic exposure control
photo timer, can only be used in upright and table buckey not table top. terminates X-ray exposures when a reference level is reached
bright light is also knows as _______while low light is also knows as________
photopic,scotopic
define pacs
pictures archival and communication systems
loss or resolution around the outside or pheripheal of an image is called what
pin cushion effect or vignetting
the filament transformer has more primary or secondary turns
primary
step up transformer has two coils left is ______right is _______
primary, secondary
define aquisistion
process of acquirring and reconstructing an image on a digital system
where does the cathode go over when x raying extremities
proximal jonint
what is the active material used in the cr cassette
psp photostimuable phospher plate.
the glass envelope in composed of what type of glass
pyrex glass which is heat resistant and has a high melting point
kvp controls______while mas controls _____
quality, quantity
define leakage radiation
radiation emitted through the metal protective housing
what does ris stand for
radiology information system contains radiology information only
define dynamic range.
range of acceptability in techniques. you dont need to be as precise with you techniques in digital imaging because dynamic range is included
define signal to noise ratio
ratio between signal or meaningful information and noise or background info
density is also referred to as what
receptor exposure
what are the two photographic factors
receptor exposure and contrast
degree of sharpness is termed what
recorded detail/spatial resolution
wht does a beam restriction device do
reduce pateint does
define line focus principle
reduction in the size of the focus directed toward the image receptor versus the size of the actual area on the surface of the anode bombarded with electrons.
define shuttering
removes or replaces background information
a low s number means you under or over exposed an image
s stands for sensitivity and has an indirect relationship with exposure so that image was over exposed.
what is the only component that sits outside the glass or metal enclosure of the x ray tube.
sator
what materials are used in the indrect sub section of dr
scintillator, cesium iodide, or gadolinium oxysulfide ( indirect is a three step system therefore there are three materials)
in a step up transformer there are always more primary or secondary turns
secondary
in a turns ratio the number on the right is _______while the number on the left is _______
secondary, primary
what are the two different types of circuits
series and parallel
what is the simplest type of transformer and what is the most effeicent
simplest most efficient shell
what are two types of distortion
size(magnification) and shape(elongation/foreshortening)
increasing sampling frequency causes the laser over a smaller or shorter distacne
smaller
what is the difference between spatial resolution and contrast resolution
spatial resolution is the ability to distinguish between adjacent small structures while contrast resolution is better visibly in general .(or able to make an image lighter or darker for better visibility)
what is the reciprocity law
states that receptor exposure on a radiograph is proportional only to the total number imparted to the radiograph image receptor ( mas 1 = mas 2 ) ( it doesnt matter what combination of ma and time you use as long as it equals the same mas you will get the same result) example: 100ma x 1 sec =100 mas is the same as 200ma x .5 sec=100 mas
what two componets make up the induction motor
stator and rotor
what is the function of the input phosper of the image intensfier
to convert incoming x ray photons into light
what is the function of the photocathode in the image intensfier
to convert light photons from the input phospher into free electrons.
what is the function of an image intensfier
to convert x ray beam into visible light( increase brightness) used in fluro
what is the parallel circuit rule regarding total resistance
total resistance will be less than the least resister and be about half of that least resister.
cr and dr are both conisdered forms of digital imaging true or falase
true
filtration hardens beams and removes soft x rays true or false
true
if more x rays get absorbed in the patient and dont hit the ir then contrast will increase true or false
true
if more x rays go through the patient and reach the IR receptor exposure will increase true or false
true
true or false grids are attenuators
true
true or false digital world gives greater exposure latitued and provides better contrast
true because you can post minipulate
true or false image receptor exposure and contrast are inversely proportional
true, as image exposure increase contrast decreases. the number of different shades of grey decrease so a more black and white image is achieved.
true or false kvp and contrast have an inversely proportional relationship
true, as you increase kvp you get more black and white/less shades of gray
true or false if you increase mas you will increase receptor exposure
true, mas and receptor exposure are directly proportional ( if you double mas you will double receptor exposure.
true or false the smaller the angle the greater the spatial resolution
true, the smaller the angle the smaller the focal spot which means greater resolution
what is the disadvantage of using a small focal spot
tube damage, pitting, cracking, filament burning CANNOT WITH STAND HEAT. large can withstand the heat but with less spatial resoluton
the filament wires are made of what material
tungsten
anode target surface is made up of what material while the neck and the base of the target are made up of what material
tungston, copper/molybdenum
step up and step down use mutual induction meaning they have how many wires or coils
two
grid cut off definition
unintended absorption of the remant beam
is there a tool you can use to limit thickness part
use of compression
how do you get grid cuttoff
using a grid outside of the established focal spot range will exhibit uniform cutoff along the lateral edges.
define voltage ripple
variation in peak wave form
manifest image is what image
visible
electromotive force (EMF) or potential difference is the same thing as what
voltage
how is the secondary coil induced in a step up transformer (mutual induction)
voltage and current are sent to primary coil, and by virtue of position a flow is induced in the secondary coil
volume of tissue imaged is given a value called volume element or_______?
voxel
if you have a wet cast what do you do to kvp? dry cast fiberglass cast
wet cast increase kvp the most 8-10 increase dry cast inceease kvp the second most 5-7 increase fiberglass cast increase kvp the least 3-4 increase a wet cast creates more thickness due to adding water. when you have a thicker cast you need more kvp to get through the cast. also more attenuation takes place on a thicker cast creating a higher contrast image
define effective focal spot size (also called useful or projected)
what gets projected down onto the patient
when does the reciprocity law fail to exist
when exposure times are less than 10 miliseconds or longer than 5 seconds
where and when does voltage become kilivoltage
when it gets to the step up transformer
