All Exams

What exposure time is needed to create 12 mAs when using a setting of 600 mA?

.02 second 12mAs/600mA= sec

100 mA x _____ second = 40 mAs 40 mAs/100 mA

.4 second

Increasing kVp will result in increased: 1. beam energy 2. IR exposure 3. photon speed

1

grid ratio: no grid- 5:1 6:1 8:1/10:1 12:1 16:1

1 2 3 4 5 6

Which of the following will result in improved image quality? increased matrix size increased bit depth increased pixel size

1 & 2

Using a grid will result in which of the following? 1. increased image quality 2.decreased scatter production 3.decreased patient dose

1 only

An increase in which of the following will increase scatter production? 1. tissue thickness 2. kVp 3. collimation

1&2

What is the purpose of a technique chart? 1. helps ensure consistent image quality 2. helps reduce repeats due to technique errors 3. reduces scatter production

1&2

increasing kvp will result in increased: 1. beam energy 2. Ir exposure 3. photo speed

1&2

Which of the following occur when the rotor (prep button) of the x-ray machine is pressed? filament begins to heat up anode begins to spin electrons move rapidly from cathode to anode

1,2

Increasing kVp will result in which of the following? higher energy photons increased scatter production more photons created

1,2 & 3

Changing from an 8:1 grid to a 12:1 grid will result in: 1. less scatter striking the IR 2. increased radiographic contrast 3. the need to increase technique

1,2&3

which of the following may result in a repeat when using AEC? 1. poor positioning 2. tube/ IR not aligned 3. incorrect cell selection

1,2&3

Using a fixed kVp technique chart, a patient measuring 20 cm requires a technique of 60 mAs @ 85 kVp. What technique would be used for a patient measuring 24 cm?

120 mAs @ 85 kVp

Changing from an 8:1 grid to a 12:1 grid will result in which of the following? 1.decreased scatter production 2. increased image contrast 3.need to increase mAs

2 & 3

Which of the following will occur if kVp is increased? tube current decreases beam quality increases beam quantity increases

2,3

Which of the following would result in quantum mottle being seen on an image? too much mAs used insufficient kVp used SID that is too long

2,3

As kvp increases, scatter production

increases

When beam quality increases, the ability for the beam to penetrate through tissue does what?

increases

as tissue volume increases, scatter production

increases

fluid filled structures (barium filled bowel)

increases exposure time

increase SID

increases exposure time

what factors decrease size distortion?

increasing SID decreasing part thickness

lead lines run parallel to one another grid covers the IR most often used in mobile radiography

parallel grid focus

The abdomen is a structure described as having low subject contrast.

true

mAs controls only the amount of x-rays produced.

true

patient pathology may alter absorption characteristics of tissue

true

true or false: Adjusting the density controls will affect exposure to the IR

true

using a grid will improve contrast & improve image quality: T/F`

true

where does this interaction occur?

tube target

gross overexposure will cause loss of contrast

unable to see structures fully

when performing a forearm study, you should :

use a manual technique and no grid

An imaging system with a high detective quantum efficiency (DQE) produces a quality image:

using lower radiation exposure

higher grid ratios

usually have higher lead content require more mAs improve image quality as compared to a low grid ratio

what type of exposure technique chart uses a set mAs for a part, regardless of thickness

variable kvp chart

any factor change that increases scatter production :

will decrease contrast

Which of the following may be manipulated to alter image contrast?

window width

A radiographer takes an image without a grid using 8 mAs and 75 kVp. If the image is repeated using a 12:1 grid what mAs is needed to maintain exposure

〖mAs〗_1 = 〖GCF〗_1 〖mAs〗_2 〖 GCF〗_2 8 = 1 x 5

The number of lead strips per inch is called:

grid frequency

What are two ways that you can double the exposure from the x-ray tube?

1. An increase in kvp by 15% 2. Double mAs

which image demonstrates the lowest bit depth? which image is made of the largest pixels?

1. image C 2. Image B

low contrast:

1. long scale 2. many shades of gray 3. wide window width 4. high kvp 5. more scatter

As grid ratio increases:

1. scatter clean up to the IR will increase 2. radiographic contrast increases 3. Technique needed increases

High contrast:

1. short scale 2. few shades of gray 3. narrow window 4. low kvp 5. less scatter

When is higher mAs required in reference to grids?

1. when going from a low grid ratio to a high grid ratio 2. going from a non grid to using a grid

As kvp increases: 1. scatter production increases 2. contrast decreases 3. IR exposure increases

1.2&3

A grid should be used whenever the anatomic part size exceeds

10cm in thickness

What is the most appropriate setting for backup time/mAs when using AEC?

150% of expected exposure time

backup time is set to

150% of expected mAs

backup time should be set by the radiographer to

150-200% of expected exposure time

200 mA x .083 second

16.6 mAs

a part measures 14cm and requires 20mAs at 75kvp, using a variable kvp tech chart, what would be used for 18cm

20 mAs @ 83 kVp

mA x .3 second = 60 mAs 60 mAs/.3 second

200mA

when using a variable mAs technique chart, how does technique change for 5cm increase in thickness

2cm per 4-5 cm

Using a grid will result in which of the following? decreased scatter production decreased patient dose increased image contrast

3 only

an image taken using 10mAs at 75kvp at 5:1 grid, what mAs would be needed if a 16:1 grid were used instead

30 mAs

An exposure of 360 mR is recorded at 40". What will exposure measure if distance is increased to 72"? I1 = 360 mR I2 = x d1= 40" d2= 72"

360/x=72^2/40^2 x = 111 mR

A person stands 3 feet from a source of radiation and receives an exposure of 160 mGy. If distance from the source is moved to 6 feet, what would exposure amount be?

40 mGy

An exposure of 20 mGy is recorded at a distance of 40". If distance is increased to 72", what will exposure measure?

6.2 mGy

Lead strips of a grid are 6.4 mm high and 0.8 mm apart. What is grid ratio? grid ratio= height of lead strips/ distance between them

6.4/.8=8:1 grid ratio

If the backup/mAs is automatically selected by the x-ray unit, exposure should end when a maximum of ______ has been reached.

600 mAs

A satisfactory image of the abdomen is taken using 20 mAs and 85 kVp at a distance of 40 inches. If distanced is increased to 72 inches, approximately what new mAs must be used to maintain exposure?

65 mAs

a patient measuring 26cm for an abdomen, requires a technique of 20 mAs at 75kvp, using a variable mAs technique chart, what technique should be used for a patient measuring 35cm

80mas 75kvp

Using a variable kVp chart, if a part measures 14 cm and requires 75 kVp, what kVp is needed for a part measuring 18 cm?

83 kVp (2 kVp per cm).

Which of the following projections utilizes distortion to better demonstrate anatomy? a.PA axial wrist, Stetcher method for the scaphoid b.PA wrist c.AP forearm d.AP abdomen

A

Which of the following will result from increasing OID? a.increased contrast b.increased resolution c.decreased magnification d.increased IR exposure

A

Converts electronic signal to a digital signal

ADC

Comparing grids of the same frequency, a higher ratio grid will clean up more scatter than one with a lower ratio. Select one: a.false b.true

B

using which of the following will reduce scatter radiation production? A. grid B. collimation C. small focal spot size D. high kvp

B

The height of lead strips in a grid divided by the distance between them is:

grid ratio

The use of a grid helps reduce scatter production. a.true b.false

B. False grids will reduce scatter production to the IR only

Increasing kVp will result in: Select one: a.decreased tube current b.increased photon speed c.increased beam penetration d.all of the above

C

Using which of the following will reduce scatter radiation production? Select one: a.high kVp b.small focal spot size c.collimation d.a grid

C

use of the airgap technique requires an increase in which of the following A. SID B. collimation C. OID D. kvp

C

Please briefly outline what happens in a CR reader once a cassette is placed in the reader.

Cassette is placed in reader, a laser beam of helium scans the plate, when scanned plate releases energy and light that was stored. Released light goes to the PMT that collects the light which then the PMT converts the light to an electrical signal the signal goes to the analog digital converter, the signal is converted to a series of numbers to the computer to an x-ray image

Which grid ratio would be best at reducing the amount of scatter striking the IR? Select one: a.6:1 b.12:1 c.8:1 d.16:1

D

Which of the following mA and exposure time combinations would result in the least chance of patient motion on the final image? a.300 mA @ .03 second b.100 mA @ .09 second c.200 mA @ .045 second d.500 mA @ .018 second

D

A grid should be used whenever an anatomic part exceeds: Select one: a.5 cm in thickness b.5 cm in length c.10 cm in length d.10 cm in thickness

D. 10cm thickness

Which of the following will occur when a stream of high speed electrons is suddenly stopped? heat is generated light is emitted electricity is generated

HEAT IS generated

what factors have no effect on spatial resolution?

grid ratio collimation mas kvp anode heel affect

Which of the following will result in elongation or foreshortening of an image? IR that is angled CR angle increased OID

IR angle CR angle

A radiograph is taken using 10 mAs @ 60 kVp. If mAs is decreased to 5 mAs, what kVp must be used to maintain exposure?

If mAs is cut by ½, kVp must be increased 15% in order to maintain exposure. 15% of 60 is 9. 60 + 9 = 69 kVp SO a technique of 5 mAs @ 69 kVp will maintain original exposure

A radiograph is produced using 25 mAs @ 75 kVp. What kVp would be needed to double exposure?

Increase kVp 15% to double exposure. 15% of 75 is 11.25 75 + 11.25 = 86.25 Therefore - 86 kVp needed to double exposure

When using automatic exposure control (AEC), the technologist CANNOT directly assign which of the following parameters?

Milliamp-seconds (mAs)

What projection should be performed to minimize magnification of a structure that is located anteriorly in the body?

PA

focused grid: lead lines angled to match divergence of beam most effective in cleaning up scatter uses focal range (SID)

Referring to the image above, what type of grid is depicted?

How is SOD determined?

SID - OID

tissue interactions

Signaling that typically occur between adjacent tissues.

what is the purpose of using a technique chart?

to reduce the chance of repeats due to poor technique selection

direct conversion DR

a:Se TFT

indirect conversion DR

a:Si scintillator TFT the scintillator converting x-rays to light & because of the amorphous silicon (a-si) is used in indirect conversion.

grids will a higher lead content have a greater selectivity, grids with higher selectivity

absorb more scatter

line focus principle

actual focal spot- where electrons bombard target effective focal spot- directly below tube A large target angle produces a large effective focal spot size A small target angle produces a small effective focal spot, a smaller effective focal spot results in improved image detail

The patient pathology that results in body tissue being harder to penetrate is referred to as what?

additive

In order for x-ray photons to be produced, electrons must: be released from the filament accelerate rapidly stop suddenly

all

Photons that make up the primary x-ray beam: can ionize body tissue have different energy levels travel at the speed of light

all of the above

Using an increased amount of OID will create an image that demonstrates what? magnification loss of detail increased contrast

all of the above

Added filtration is typically made of:

aluminum

What do exposure indicator numbers indicate?

amount of radiation striking the IR

calipers measure part thickness

an instrument used to measure distances or diameters

When an incident electron interacts with the inner shell of a target atom, the result is:

an x-ray photon

What are calipers used for?

anatomical part measurement

ionization chamber type devices are considered to be entrance type devices because they

are placed infront of the image receptor air within chamber becomes ionized creating an electrical charge

what do the boxes on an upright bucky represent?

arrangement of 3 AEC dectors on an upright bucky

identify what is wrong with this image

artifact

positive beam limitation is actually

automatic collimation

A low SNR results in an a poor quality digital image.

true

CR:

barium fluorohalide with europium separate reader system PSP PMT

What property of the x-ray beam influences the area of unsharpness around an image?

beam divergence

a phototimer AEC is an exit type device because it is placed

behind the IR radiation must exit the IR before it is measured by the detector

smaller pixels, the more pixels there is =

better resolution

where are the sensors for an ion chamber AEC unit located?

between the patient and IR

In order to work properly, where is a grid placed?

between the patient and the IR

Which of the following materials is a scintillator? a.barium fluorohalide with europium b.amorphous selenium c.cesium iodide (CsI) d.amorphous silicon

c

When performing an AP projection of the hip using AEC, what is the best cell configuration to select?

center cell

when using AEC for an AP shoulder, what detection selection is best?

center cell only

Which of the following is a target interaction which will result in x-ray production?

characteristic

Scatter radiation produced during diagnostic exams is primarily the result of what interaction?

comptom

lead lines run at right angles to eachother clean up scatter twice as effectively as linear grids

cross-hatch grid pattern

as collimation increases, contrast will

decrease

as tissue volume decreases, radiographic contrast will

decrease

what factors will decrease spatial resolution?

decrease SID (short sid) increase OID increase focal spot size increase part thickness higher the angle motion distortion

destructive diseases

decrease absorption less difficult to penetrate pneumothorax emphysema

scatter on an image will

decrease contrast

air-filled structures (bowel gas)

decrease exposure time

an increase in kvp will

decrease exposure time

increase in mA will

decrease exposure time

when using AEC, an increase in mAs will

decrease exposure time

larger pixels =

decrease in resolution

what factors increase contrast?

decrease kvp increase OID increase collimation increase grid ratio decrease part thickness size increase atomic # use of contrast material decrease window width

what factors decrease IR exposure?

decrease mAs decrease kvp increase SID decrease OID increase collimation increase grid ratio increase patient part thickness increase in filtration SID changed from 40" to 72" (but technique remains the same) mA is reduced by half. Exposure time is reduced by half.

How is exposure affected when distance from a source of radiation is doubled?

decreased by a factor of 4

When a matrix size is fixed (stays the same), what will decreasing the field of view (FOV) result in?

decreased pixel size

as collimation increases, scatter production

decreases

as kvp increases, radiographic contrast

decreases

high mA, ______________ exposure time

decreases

what factors increase size distortion?

decreasing SID increasing OID increasing part thickness

Which type of digital imaging equipment has the highest DQE?

direct conversion DR

factors that affect resolution: (2)

distance - SID/OID motion- voluntary/involuntary

____________ will result in reduce spatial resolution

distortion

an AEC system is preprogrammed to end an exposure when a certain amount of exposure has been reached, this means

equipment determines exposure time & determines total amount of mAs used in an exposure

identify what is wrong with the image

excessive collimation

visiblity

exposure contrast

when using an AEC unit, what occurs once a predetermined amount of radiation is transmitted through the patient to the detector?

exposure terminates

when using AEC, the equipment determines which of the following?

exposure time

When using an AEC device, how is exposure time affected when kVp is increased?

exposure time decreases

what would happen if AEC were use for an AP chest on a stretcher?

exposure time would be too long

AEC and APR are essentially the same thing.

false

AEC can and should be used for tabletop examinations:

false

Which tube component provides the electrons needed for x-ray production?

filament

what determines focal spot size?

filament size

IR used in DR imaging systems

flat panel detector

what factors have no effect on IR exposure?

focal spot size

what factors have no effect on distortion?

focal spot size

identify what is wrong with the image

grid artifact

parallel grid shown

grid covers the IR mobile/portable exams use this

The number of lead lines per inch or centimeter in a grid defines:

grid frequency

positive contrast material:

high atomic number barium/iodine increases absorption seen as white or bright on images requires an increase in Kvp more kvp needed for barium

positive contrast

high atomic number radiopaque barium/iodine

When looking at a digital image, what is window level used to adjust?

image brightness

when collimation increases ___________ increases

image contrast

increasing OID has what affect on image contrast?

image contrast increases

what factors increase shape distortion?

improper CR alignment part alignment IR alignment CR angle and direction

using a grid will

improve image quality increase contrast improve recorded detail

Where are the sensors (cells) located with an ionization chamber type AEC device?

in front of the IR

As grid ratio increases, radiographic contrast will:

increase

what factors will increase resolution?

increase SID decrease OID decrease focal spot size decrease part thickness decrease in magnification

Additive diseases

increase absorption more difficult to penetrate pleural effusion atelectasis

grids are used to improve contrast and absorb scatter before it hits the IR, use of a grid will also:

increase contrast improve image quality improve the ability to see recorded detail

an increase in patient thickness will

increase exposure time

increase collimation will

increase exposure time

what is the result when switching from a grid with 8:1 ratio to 12:1 grid?

increase image contrast

what factors decrease attenuation

increase in beam energy

what factors decrease contrast?

increase kvp decrease OID decrease collimation decrease grid ratio increase part thickness decrease atomic # fog increase window width

Exposure time decreases:

increase kvp increase mA

when using a kvp variable technique chart, what is the appropriate changed needed for 1 cm increase in tissue thickness?

increase kvp by 2

what factors increase IR exposure?

increase mAs increase kvp decrease SID increase OID decrease collimation decrease grid ratio decrease part thickness mAs is doubled kVp increased by 15%

higher kVp will:

increase number of compton interactions/increase scatter increase energy of scatter created

exposure time increases:

increase pt thickness increase SID

what factors increase attenuation?

increase tissue density atomic # tissue increase increase tissue thickness

A larger bit depth will result in images that display what?

increased contrast resolution

The speed of electrons moving from cathode to anode during x-ray production is controlled by:

kvp

What factor actually controls the speed of electrons moving from cathode to anode in the x-ray tube?

kvp

AEC eliminates the need for the radiographer to set the exposure time, but you must still select

kvp mA proper IR gird, if needed

performing which projection on a patient would result in the most scatter? 1. AP lumbar 2. Oblique lumbar 3. Lateral lumbar

lateral lumbar

What unit is resolution expressed in?

line pairs/mm

lead lines that run in 1 direction

linear grid pattern

negative contrast material:

low atomic number air/gas dark or black images

negative contrast

low atomic number radiolucent air/gas

The number of electrons that flow from cathode to anode during x-ray production is directly proportional to what?

mA

Which technical factor directly controls the number of x-ray photons created?

mAs

when using AEC, paying attention to the ______ __________ will help you become more familiar with the manual technique factors

mAs readout

Size distortion on an image is also known as what?

magnification

What is the formula SID/SOD used to calculate?

magnification factor

Converts x-ray photons into an electric signal Answer 2

photoconductor

Converts visible light to electric signal

photodector

Which of the following is a tissue interaction which results in the total absorption of an x-ray photon within the body?

photoelectric

converts visible light into electrical energy

photomultiplier (PM) tube photodiode (solid-state device)

Which component of a CR reader collects visible light and converts it to electrical signal?

photomultiplier tube (PMT)

Which of the following impacts contrast resolution of a digital image?

pixel bit depth

Which of the following immobilization devices requires an increase in exposure?

plaster cast

grids will:

prevent scatter from hitting the IR allow you to see detail better require more technique

AEC controls the ________________ of radiation reaching the image receptor.

quantity no effect on contrast

AEC works by measuring

radiation exiting the patient

light paddles coated with fluroscent material serve as detectors

radiation interacts with the paddles, producing visible light light is transmitted to remote PM tubes or photodiodes that convert the light to electricity

AEC operation & types of systems:

radiation through the patient converted to electrical signal exposure terminated phototimer system ionization chamber system

what is placed between the lead strips?

radiolucent

What is placed between the lead strips of a grid?

radiolucent material

what type of grid is shown? what does focal range mean

range of SID that can be used with the grid focused grid

What is the focal range of a grid?

range of SIDs that may be used with a grid

IR exposure stays the same if the mAs stays the same

reciprocity 100 mA x .1 second = 10 mAs 200 mA x .05 second = 10 mAs All above mA/time combinations = 10 mAs All should result in same amount of IR exposure

Collimation, what does the beam restriction do?

reduce amount of tissue being exposed reduce PT dose reduce scatter production increase image quality (contrast)

using good collimation will

reduce scatter production

grids will not:

reduce scatter production increase detail reduce pt dose

If you go from not using a grid to using a 16:1 grid, how are the following image quality characteristics effected? detail/spatial resolution will

remain unchanged

how is spatial resolution of an image affected when the grid ratio is increased

remains unchanged

Focal spot size is determined by the pixel and matrix size, the larger the matrix, the smaller the pixels, the overall better

resolution

decreasing kvp has what affect on scatter production

scatter decreases

Decreasing kVp used has what affect on scatter production?

scatter production decreases

Converts x-ray photons to light

scintillator

Elongation and foreshortening are examples of what?

shape distortion

Angling of the IR, body part or tube when creating an image results in which of the following?

shape distortion (elongation or foreshortening)

Accuracy

spatial resolution distortion

When pixel density increases, how is image spatial resolution affected?

spatial resolution increases

alignment and positioning

spine- center cell selected abdomen- all 3 cells selected pelvis; 2 outer cells

1. When a predetermined level of ionization is reached at an ionization chamber, what happens?

the exposure is terminated

the higher the kvp value, the shorter

the exposure time high kvp with AEC decreases the exposure time & mAs, reducing pt exposure

what is the greatest source of scatter during a radiologic exam?

the patient

higher grid ratios remove more scatter than lower grid ratios IF

they have the same frequency

Which DR system component is divided into square detector elements known as DELs?

thin-film transistor

purpose of the back up timer:

to limit unnecessary x-ray exposure

what is the purpose of setting backup timer when using AEC?

to prevent patient overexposure if the AEC fails

What is the reason for have filtration in the x-ray tube?

to reduce pt skin dose