Advanced Imaging mod 4

\_____________ is an unwanted optical density on an image

artifact

\_____________ is the density difference between adjacent areas on an image

contrast

\_____________ (aka exposure) is the degree of blackness on an image

density

\_____________ (aka spatial resolution) is the sharpness on an image which is measured in line pair per mm

detail

\_____________ is the misrepresentation of size and or shape of the object being imaged

distortion

\_____________ is when the image of an object is longer than the actual object that was radiographed

elongation

\_____________ is the range of exposure factors that will create an acceptable image

exposure latitude

\_____________ is the type of contrast available that is inherent to a particular film type

film contrast

\_____________ is when an image of an object appears shorter than what it actually is

foreshortening

\_____________ is the number of waves that pass a particular point at a given time frame

frequency

\_____________ (aka focal spot blur) is the blurred edge around the area of exposure due to focal spot not being a point source

geometric blur

\_____________ is one measurement bar and its inter-space of equal width (Old detail measurement)

Line pairs

\_____________ (aka wide dynamic range) is when a radiograph has many shades of gray

long scale contrast

\_____________ is the grainy, uneven appearance of an image caused by an insufficient number of primary x-rays (aka quantum mottle)

noise

\_____________ is the ability of x-rays to pass through structures and tissues

penetration

\_____________ is the law that density on an x-ray film should remain unchanged as long as the intensity and duration of the x-ray exposure remains unchanged

reciprocity law

\_____________ is the primary radiation that interacts with matter and changes direction based on how much energy was imparted to orbital electrons or whole atoms

scatter radiation

\_____________ (aka narrow dynamic range) is when a radiograph has few shades, mainly black and white

short scale contrast

\_____________ is the degree of differential absorption resulting from the differing absorption characteristics of the tissues in the body

subject contrast

What is the grid conversion formula?

new mAs/old mAs \= new bucky factor/old bucky factor

what kind of relationship does mAs and bucky factors have?

direct

what is the screen conversion formula?

new mAs/old mAs \= old screen/new screen

what type of relationship does mAs and screens have?

Indirect

What are the 4 essentials to radiographic quality?

exposure, contrast, spatial frequency, distortion

\_____________ is how dark an image is

exposure

\_____________ and \_____________ control exposure

time and mAs

exposure is the \_____________ of x-rays

quantity

mAs and time have a \_____________ relationship

direct

kV is an influencing factor to \_____________

exposure

\_____________ kV \= lower contrast \= \_____________ scale, \_____________ kV \= higher contrast \= \_____________ scale

higher, long, lower, short

the 15% rule means that if one increases kV by 15%, the exposure \_____________, if one lowers kV by 15%, the exposure \_____________

doubles, halves

\_____________ determines the quality of photons and controls penetration

kV

\_____________ shouldn't be used to soley control exposure due to it affecting contrast

kV

SID stands for \_____________

source to image receptor distance

SID is an influencing factor to \_____________

exposure

\_____________ kV \= more scatter

higher

don't use \_____________ to control exposure due to it also affecting magnification

SID

higher SID \= \_____________ magnificaiton

less

What is the direct square law?

mAs1/mAs2\= D1^2/D2^2

we use \_____________ law to find proper mAs to compensate for the new distance

direct square law

2x distance \= \_____________ of initial exposure, 1/2 distance \= \_____________ initial exposure

1/4, 4x

nature of tissue is an influencing factor of \_____________

exposure

more thickness of the tissue \= \_____________ photons hitting image receptor \= \_____________ exposure

less, less

less thickness of the tissue \= \_____________ photons hitting image receptor \= \_____________ exposure

more, higher

destructive pathology \= \_____________ exposure, additive pathology \= \_____________ exposure

more, less

change \_____________ if it's a volume change, change \_____________ if it's a composition change

mAs, kV

\_____________, \_____________, \_____________, and \_____________ are all less significant with affecting exposure, but it still causes a slight change in the number of photons hitting the image receptor

cellular composition, compactness of cells, status of hollow organs, respiratory phase

more empty an organ is \= \_____________ transmission

more

inspiration for chest x-ray \= \_____________ transmission

more

expiration for abdomen \= \_____________ transmission

more

the liver and kidney are compact, so \_____________ photons are going to be hitting the IR

less

\_____________ is when less photons are leaving the anode side of the x-ray tube. This is cause the target is a \_____________

anode heel affect, bevel angle

what side is the anode on in an x-ray tube 99% of the time?

left

\_____________ is when the tungsten anode blocks photons being angled off which causes them to be absorbed and lost in the tungsten anode

anode heel affect

anode heel affect is an influencing factor to \_____________

exposure

due to anode heel affect, there is higher % of radiation at \_____________ side of x-ray tube

cathode

anode heel affect is best seen using \_____________ SIDs with a \_____________ IR

short, large

\_____________ is the extra exposure that hits the IR, it is accidental

fog

\_____________ can be caused by comptom scatter radiation

fog

fog is an influencing factor to \_____________

exposure

grids and filters are influencing factors to \_____________

exposure

\_____________ reduces scatter radiation and fog but they require a compensation of exposure factors

grids

central ray angle is an influencing factor to \_____________

exposure

adding an angle can cause the x-rays to go through more or less tissue and going through more or less tissue will affect the \_____________

the number of photons hitting IR or exposure

beam filtration is an influencing factor to \_____________

exposure

\_____________ and \_____________ are types of beam filtration. \_____________ is what's in the x-ray tube that isn't meant to filtrate, but it does. It is equivalent to \_____________ mmAl. \_____________ is added by manufacturer with the main purpose of filtration and is \_____________ mmAl eq.

inherent, added, inherent, .5, added, 1

adding filtration requires \____________ mAs to compensate (+3mm of Al \= 50% \_____________ exposure)

more, more

when going through a cast, add \_____________ kV to have more transmission

5-10

\_____________ can also affect exposure because you need to scan the correct view/exam so that the image is normalized correctly

histogram correctness

\_____________ contains perfect histograms that the computer uses to automatically rescale digital images

LUT - look up table

\_____________ screen speed \=. more mAs required

lower

\_____________ changes detail not mAs

focal spot

\_____________ OID \= less photons hitting IR due to scatter clean up happening

higher

screens \_____________ radiographic density

increase

\_____________ is the computer term for contrast

dynamic range

\_____________ is the range of visible differences of adjacent densities

contrast/dynamic range

short scale contrast \= \_____________ dynamic range, long scale contrast \= \_____________ dynamic range

narrow, wide

you need to know \_____________ to know the number of available shades

bit depth

changing bit depth to number of shades is done by doing what?

2^(x) x\=bit depth

low bit depth \= \_____________ contrast, high bit depth \= \_____________ contrast

high, low

\_____________ is what the x-rays are going through and affects image contrast

subject contrast

\_____________ has to do with composition differences, not technique

subject contrast

higher subject contrast \= \_____________ image contrast

higher

\_____________ is the average atomic number of all the elements a part is made of.

effective atomic number

low kV can mimic \_____________ subject contrast, high kV can mimic \_____________ subject contrast

high, low

high subject contrast causes \_____________ contrast, low subject contrast causes \_____________ contrast

high, low

use of contrast produces a \_____________ subject contrast

high

iodine's atomic number is \_____________, barium's is \_____________, air's effective atomic number is \_____________

53, 56, 7.6

\_____________ is the controlling factor of contrast because it controls the differential absorption of parts

kV

mAs affects \_____________ only slightly (except if extreme change)

contrast

what 4 accessories reduce scatter radiation fog?

grids, beam restrictors, filter, Pb blocking

\_____________ contrast with grids.

higher

\_____________ beam restriction \= more contrast due to beam restrictor reducing scatter

more

\_____________ filtration \= less edge burnout \= \_____________ contrast on edges

more, higher

\_____________ is when different parts absorb x-rays differently than other parts due to compactness of parts

differential absorption

SID affects \_____________ only in relation to density (extreme long distance \= \_____________ contrast or white on white, extreme short distance \= \_____________ contrast or black on black)

contrast, low, low

more OID \= \_____________ contrast

higher

extreme changes in either direction for SID \= \_____________ contrast

lower

\_____________ can affect contrast due to barcoding the wrong part will make the contrast off due to the wrong normalization taking place

histogram correctness

\_____________ is the ability of a recording system to record sharp edges

resolution