T RRE image aquisition/processing/evaluation/criteria

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what is the exposure rate

its the intensity of the xray beam

How is source-to-image distance (SID) related to exposure rate and radiographic density?

As SID increases, exposure rate decreases and radiographic density decreases. (exposure rate is same as intensity, which we know is inversely proportional to square of the distance)

(What) describes how closely fine details may be associated and still be recognized as separate details before seeming to blend into each other and appear "as one

resolution

Which of the following terms/units is used to express the resolution of a diagnostic image?
(A). Line pairs per millimeter (lp/mm)(B). Speed(C). Latitude(D). Kiloelectronvolts (keV)

(A) The degree of resolution transferred to the IR is a function of the resolving power of each of the system components and can be expressed in line pairs per millimeter (lp/mm).

name 2 resolution test tools

star pattern and parallel-line type

The star pattern generally is used for evaluation of

focal-spot-size

parallel-line type is generally used for evaluation of

intensifying screens

Focal-spot size accuracy is related to the degree of geometric blur also known as --------

penumbra

Focal-spot size can be measured with 3 devices

pinhole camera, slit camera, or star-pattern-type resolution device

Which of the following requires two exposures to evaluate focal-spot accuracy?
(A) Pinhole camera(B). Slit camera(C). Star pattern(D). Bar pattern

slit camera-two exposures are made; one measures the length of the focal spot, and the other measures the width

Which measures focal spot size but is rather difficult to use accurately and requires the use of excessive tube (heat) loading
(A) Pinhole camera(B). Slit camera(C). Star pattern(D). Bar pattern

pinhole camera

which can can measure focal-spot size as a function of geometric blur and is readily adaptable in a QA program to monitor focal-spot changes over a period of time
(A) Pinhole camera(B). Slit camera(C). Star pattern(D). Bar pattern

both star pattern and bar pattern

what is high contrast

short scale-- more gets absorbed than makes it to the film

In which of the following ways can higher radiographic contrast be obtained in abdominal radiography?
1. By using lower kilovoltage
2. By using a contrast medium
3. By limiting the field size

all abdomen tends to have low contrast, so by adding contrast medium (barium, iodine, air) photons will be absorbed more easily causing high contrast

lower kvp results in higher contrast why?

lower energy photons get absorbed easier--less hit the film

High radiographic contrast also results when radiographing anatomic parts that have --------- subject contrast

high subject contrast---if the dont just lower the kvp so they absorb more easily

why does Restricting the size of the field increase contrast?

less scatter is produced--scatter creates a fog

Foreshortening can be caused by
(A). the radiographic object being placed at an angle to the IR(B). excessive distance between the object and the IR(C). insufficient distance between the focus and the IR(D). excessive distance between the focus and the IR

(A). the radiographic object being placed at an angle to the IR

The fact that x-ray intensity across the primary beam can vary as much as 45% describes the
(A). line-focus principle.(B). transformer law.(C). anode heel effect.(D). inverse-square law

.(C). anode heel effect-smaller percentage of photons at anode than the concentration of photons at the cathode end

Characteristics of DR imaging include
1.solid-state detector receptor plates
2.a direct-capture imaging system
3.immediate image display

(all) DR uses solid-state detector plates as the x-ray IR (instead of a cassette in the Bucky tray)

Advantages of digital radiography (DR) over computer radiography (CR) include
1.DR is less expensive.
2.DR has immediate readout.
3.Cassettes are not needed for DR.

(2-3) Computed radiography (CR) is less expensive primarily because it is compatible with existing equipment

The term windowing refers to some change made to window width and/or window level. Change in window width affects

change in the number of gray shades, that is, image contrast

The term windowing refers to some change made to window width and/or window level. Change in window level affects

image brightness, that is, optical density

Terms that refer to size distortion include
1.magnification
2.attenuation
3.elongation

magnification

Exposure factors of 80 kVp and 8 mAs are used for a particular nongrid exposure. What should be the new milliampere-seconds value if an 8:1 grid is added?

(A). 16 mAs(B). 24 mAs(C). 32 mAs(D). 40 mAs

(C). 32 mAs 8mas x 4 = 32mas
8:1=4

to adjust exposure when changing from one grid ratio to another
5:1=
6:1=
8:1=
12:1=
16:1=

5:1=2
6:1=3
8:1=4
12:1=5
16:1=6

In (PA) projection of the chest, heart measures 14.7 cm between its widest points. If the magnification factor is known to be 1.2, what is the actual diameter of the heart?
A. 10.4 cm(B). 12.25 cm(C). 13.5 cm(D). 17.64 cm

B). 12.25 cm
14.7 divided by 1.2 = 12.25

radiograph was made without grid using a 72-in. SID and 8 mAs. If distance changed to 40 in. and 12:1 ratio grid added, whats new mAs?
A. 9.5 mAs(B). 12 mAs(C). 21 mAs(D). 26 mAs

(12mas) (square law)
mas1/mas2 x d1/d2 =2.46
12:1=5xmas so 2.46x5=12.34 mAs

purpose of the thin layer of lead located behind the rear intensifying screen in an IR?
(A). To prevent crossover(B). To increase screen speed(C). To diffuse light photons(D). To prevent scattered radiation fog

D). -to absorb x-rays that penetrate the screens, strike the rear of the cassette, and bounce back toward the film emulsion, resulting in scattered radiation fog

Which will produce the longest scale of contrast?
A. 200 mA, 0.25 sec, 70 kVp, 12:1 grid
B. 500 mA, 0.10 sec, 90 kVp, 8:1 grid
C. 400 mA, 0.125 sec, 80 kVp, 12:1 grid
D. 300 mA, 0.16 sec, 70 kVp, 8:1 grid

B. 500 mA, 0.10 sec, 90 kVp, 8:1 grid---
increased kvp and low-ratio grid combination would allow the greatest amount of scattered radiation to reach the IR, thereby producing more gray tones

Using an AEC system, how will the mAs be adjusted as the film-screen speed combination is decreased?
(A). mAs increase as film speed decreases.(B). Both mAs and the kV will increase as film speed decreases.(C). The Ma will decrease as film speed decreases.(D). mAs remains unchanged as film speed decreases.

(d)mAs remains unchanged as film speed decreases. normally you would increase mas if screen speed lowered but an AEC is preset so you cant adjust for a different speed screen

Causes of grid cutoff, when using focused reciprocating grids, include the following?
1.Inadequate SID
2.X-ray tube off-center with the long axis of the lead strips
3.Angling the beam in the direction of the lead strips

(1) If the SID is above or below the recommended focusing distance, the primary beam will not coincide with the angled lead strips at their lateral edges.

which results in cutoff
1.Central ray angulation in the direction of the lead strips
2.Central ray angulation against the direction of the lead strips

2

What effect will a stained intensifying screen have on the finished radiograph?
(A). Blurring(B). Magnification(C). Decreased density(D). Increased density

Decreased density--stained area will not react to x-ray photons as completely and will emit less light, thus less density on film in stained area

Geometric blur can be evaluated using all the following devices except
(A). star pattern(B). slit camera(C). penetrometer(D). pinhole camera

C). penetrometer-- we already know the others are for focal spot, and testing penumbra

Which of the following will produce the greatest distortion?
(A). AP projection of the skull(B). PA projection of the skull(C). 37° AP axial of the skull(D). 20° PA axial of the skull

37° AP axial of the skull--mage made with the greatest tube angle will produce the greatest distortion

Resolution in CR increases as
1.laser beam size decreases
2.monitor matrix size decreases
3.PSP crystal size decreases

(1-3)

how does matrix size effect image resolution

the larger the matrix size the better the resolution---more and smaller pixels

in traditional radiography, spatial resolution is measured in

line pairs per millimeter

most things that are larger, thicker, faster, or more abundant do what to resolution

decrease resolution (ex. crystals-screen speed, phosphor thickness etc) with the exception of matrix size

A grid is usually employed
1. when radiographing a large or dense body part.
2. when using high kilovoltage.
3. when less patient dose is required.

(1-2)

Acceptable method(s) of minimizing motion unsharpness is (are)
1.suspended respiration
2.short exposure time
3.patient instruction

all

Base-plus fog is a result of
1.blue-tinted film base
2.chemical development
3.the manufacturing process

all- film emulsion has a base-plus fog, which is a result of the manufacturing process -blue tint added to reduce glare. remaining fog density is result of the chemical development process, when exposed silver bromide grains are converted to black metallic silver

An upside-down focused grid presents its lead strips in the opposite direction to that of the x-ray beam. This results in severe grid cutoff everywhere except

in the middle-- so it will be light on sides and dark down the middle

All the following statements regarding beam restriction are true except
(A). beam restriction improves contrast resolution (B). beam restriction improves spatial resolution (C). field size should never exceed IR dimensions (D). beam restriction reduces patient dose

(B) Beam restriction reduces the production of scattered radiation that leads to fog and, therefore, improves contrast resolution. Spatial resolution is related to factors affecting recorded detail, not contrast resolution

Which of the following statements regarding dual x-ray absorptiometry is (are) true?
1.Radiation dose is low.
2.Only low-energy photons are used.
3.Photon attenuation by bone is calculated.

1-3 two photon energies used, one for bone to calculate density and detect osteoporosis, and one for soft tissue

The purpose of the automatic processor's transport system is to
(A). monitor and adjust temperature(B). agitate, mix, and filter solutions(C). move the film and change its direction(D). monitor the solution and replace it as necessary

(C)move the film and change its direction

The purpose of the automatic processor's circulation system is to
(A). monitor and adjust temperature(B). agitate, mix, and filter solutions(C). move the film and change its direction(D). monitor the solution and replace it as necessary

B). agitate, mix, and filter solutions

The purpose of the automatic processor's temperature control is to
(A). monitor and adjust solution temperature(B). agitate, mix, and filter solutions(C). move the film and change its direction(D). monitor the solution and replace it as necessary

(A). monitor and adjust solution temperature

The purpose of the automatic processor's replenishment system is to
(A). monitor and adjust temperature(B). agitate, mix, and filter solutions(C). move the film and change its direction(D). monitor the solution and replace it as necessary

D). monitor the solution and replace it as necessary

A radiograph made with a parallel grid demonstrates decreased density on its lateral edges. This is most likely due to
(A). static electrical discharge(B). the grid being off-centered(C). improper tube angle(D). decreased SID

D). decreased SID (example of off focus-sid problem)

An exposure was made using 600 mA and 18 ms. If the mA is changed to 400, which of the following exposure times would most closely approximate the original radiographic density?
(A). 16 ms(B). 0.16 second(C). 27 ms(D). 0.27 second

27 ms--just change ms to seconds and find mAs. which is 10.8. then multiply 400ma with all the given times till u get 10.8mas

All the following are related to recorded detail except
A. motion
B. focal-spot size
C. OID
D. scattered radiation

Scattered radiation is not related to recorded detail

how does focal spot size affect recorded detail

Focal-spot size affects recorded detail as a result of blur—the smaller the focus, the less is the focal-spot blur and the better is recorded detail

--------is said to be the greatest enemy of recorded detail because it completely obliterates image sharpness

motion

how does a decrease in OID improve recorded detail

reduces magnification

Which of the following is most likely to occur as a result of using a 30-in. SID with a 14 x 17 in. IR to radiograph a fairly homogeneous structure?
(A). Production of quantum mottle(B). Density variation between opposite ends of the IR(C). Production of scatter radiation fog(D). Excessively short-scale contrast

(B)Density variation between opposite ends of the IR--Because shorter SIDs and larger IR sizes require greater divergence of the x-ray beam to provide coverage, the anode heel effect will be accentuated

Which of the following can affect the amount of developer replenisher delivered per film in an automatic processor?
(A). Developer temperature(B). Amount of film exposure(C). Film size(D). Processor capacity

C). Film size--Replenisher is added according to the length of the x-ray film

The x-ray tube used in CT must be capable of
1.high-speed rotation
2.short pulsed exposures
3.withstanding millions of heat units

all--

Which of the following is (are) characteristic(s) of a 16:1 grid?
(1).It absorbs more useful radiation than an 8:1 grid.
(2).It has more centering latitude than an 8:1 grid.
(3).It is used with higher-kilovoltage exposures than an 8:1 grid.

1-3 centering is even more critical in higher ratio grid

A wire-mesh test is performed to evaluate screen
(A). lag(B). contact(C). resolution(D). intensification

contact

A radiograph exposed using a 12:1 ratio grid may exhibit a loss of density at its lateral edges because the
(A). SID was too great.(B). grid failed to move during the exposure.(C). x-ray tube was angled in the direction of the lead strips.(D). CR was off-center

(A). SID was too great--(off focus)If the SID is above or below the recommended focusing distance, the primary beam at the lateral edges will not coincide with the angled lead strips

How would the introduction of a 6-in. OID affect image contrast?
(A). Contrast would be increased.(B). Contrast would be decreased.(C). Contrast would not change.(D). The scale of contrast would not change

A). Contrast would be increased--the air gap will cause scatter, which will miss the film

The tiny minus-density artifacts seen on radiographs that look like white little pinholes are often caused by

dust/dirt on the PSP

Which of the following can impact the visibility of the anode heel effect?
1.SID
2.IR size
3.Screen speed

1-2

Which of the following materials may be used as grid interspace material?
1.Lead
2.Plastic
3.Aluminum

2-3 The interspace material must be radiolucent; plastic or sturdier aluminum usually is used

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