Chapter 13 Test Flashcards
A radiograph of the lumbar spine is produced using automatic exposure control (AEC). The exposure results in optimal contrast but low receptor exposure. Which of the following options would allow the tech to adjust IR exposure?
a.) increase grid ratio
b.) decrease density setting
c.) increase density setting
d.) increase kvp
c.) increase density setting
What is the primary function of the back up timer?
a.) prevent over exposure to the patient
b.) ensure adequate IR exposure
c.) ensure adequate contrast
d.) prevent over exposure to the IR
a.) prevent over exposure to the patient
When imaging a young child, a short exposure time is needed for an exam using AEC. The mA setting should be:
a.) any
b.) low
c.) mid range
d.) high
d.) high
___________ identifies optimal kvp values and alters the mas for variations in part thickness.
a.) variable kvp, fixed mas technique charts
b.) fixed kvp, variable mas technique charts
b.) fixed kvp, variable mas technique charts
Using fixed mAs and variable kvp technical factors, each centimeter increase in patient thickness requires what adjustment to kvp?
a.) increase 4 kv
b.) decrease 4 kv
c.) decrease 2 kv
d.) increase 2 kv
d.) increase 2 kv
What factors are important when using AEC devices?
1.) detector selection
2.) centering part to detector
3.) back up mas if set
a.) 2 and 3 only
b.) 1 and 2 only
c.) 1 and 3 only
d.) 1, 2 and 3
d.) 1, 2 and 3
Consider a technologist performing a lumbar spine series using an AEC system. After acquiring the lateral image, the technologist angles the beam 5 degrees caudad, correctly centers/positions the patient, and collimates to the area of the L5-S1 joint. Which technical parameter change will ensure proper receptor exposure?
a.) increase mA
b.) increase KVP
c.) no change is needed
d.) decrease SID
c.) no change is needed
If a radiographer is performing a PA chest using AEC at the upright bucky but the table bucky is selected:
a.) the patient will recieve no exposure because theyre no laying on the table bucky
b.) the back up time will likely be reached
c.) exposure will terminate after 5 minutes
d.) minimum exposure time will cut off at 0.5 seconds
b.) the back up time will likely be reached
Automatic exposure control (AEC) devices work by measuring:
a.) radiation that exits the patient
b.) radiation that is absorbed by the patient
c.) attenuation of primary radiation by the patient
d.) radiation exiting the tube
a.) radiation that exits the patient
When performing a lateral cervical spine using an automatic exposure control (AEC) system, the technologist activates the outer ionization chambers. How might this effect the radiographic image?
a.) decreased exposure time and decreased receptor exposure
b.) increased exposure time and decreased receptor exposure
c.) increased exposure time and increased receptor exposure
d.) decreased exposure time and increased receptor exposure
a.) decreased exposure time and decreased receptor exposure
A portable chest xray is to be performed on a patient in the ER and the technique chart suggests the exam should be performed with a grid at 120 kvp, 3.5 mAs, and a 72” SID. However, the room is too small to acheive a 72” SID and the exposure must be made at 55 inches. How should the technique be adjusted to compensate for the change in SID?
a.) 2 mAs
b.) 5 mAs
c.) remove the grid
d.) 21 mAs
a.) 2 mAs
While performing an AP T-spine, the technologist mistakenly centers 3’’ to the right of the vertebral bodies. This is likely to cause:
1.) appropriate exposure to the area of interest
2.) underexposure to the area of interest
3.) appropriate exposure to the part centered over the detector
4.) overexposure to the area of interest
5.) underexposure to the part centered over the detector
a.) 2 and 5 only
b.) 1 and 3 only
c.) 4 and 5 only
d.) 2 and 3 only
d.) 2 and 3 only
Increasing the anode angle will:
1.) decrease the anode heel effect
2.) increase the anode heel effect
3.) decrease IR exposure
4.) increase IR exposure
a.) 1 only
b.) 2 and 4 only
c.) 1 and 4 only
d.) 2 and 3 only
c.) 1 and 4 only
The AEC minimum response time may pose a problem when:
a.) a long exposure time is needed
b.) all options are correct
c.) the patient is unable to hold still for the exposure
d.) the patient can easily hold still for the exposure
c.) the patient is unable to hold still for the exposure
How much mAs is produced when the mA is 400 and the exposure time is 0.5s?
a.) 50 mAs
b.) 200 mAs
c.) 100 mAs
d.) 25 mAs
b.) 200 mAs
Increasing patient thickness while using an AEC device would result in:
a.) decreased brightness
b.) decreased mAs readout
c.) increased exposure time
d.) increased image contrast
c.) increased exposure time
An increase in the image size of an object compared with its true, or actual size is called:
a.) shape distortion
b.) size distortion
c.) sharpness distortion
d.) minification
b.) size distortion
The radiation sensitive portion of an ionization chamber is composed of:
a.) air
b.) scintillation crystal
c.) vibranium
d.) semi conductor crystal
a.) air
What is the effect of using an automatic exposure control (AEC) system to image a patient with a destructive pathology such as osteoporosis?
a.) decreased spatial resolution
b.) decreased exposure time
c.) increased contrast resolution
d.) increased receptor exposure
b.) decreased exposure time
In most AEC units, a typical detector configuration has at least ____________ detectors.
a.) 2
b.) 5
c.) 4
d.) 3
d.) 3
Xrays travel at half the speed of light. T/F
False
What competent within the automatic exposure control (AEC) system is responsible for measuring the quantity of photons exiting the patient?
a.) autotransformer
b.) rectifier bridge
c.) exposure timer
d.) ionization chamber
d.) ionization chamber
When using a radiographic unit with an automatic exposure control (AEC) , which of the following can be employed to reduce patient motion while maintaining proper receptor exposure?
a.) decrease kvp
b.) increase mA
c.) increase back up time
d.) decrease density setting
b.) increase mA
When there is a significant amount of scatter reaching the AEC detector, the exposure time will be:
a.) appropriate
b.) shorter than needed
c.) longer than needed
b.) shorter than needed
As collimation increases, the quanitity of scatter radiation decreases.
a.) true
b.) false
a.) true
Which of the following projections may be improved by using a low mA and long exposure time?
a.) lateral t spine
b.) decubitus chest
c.) supine abdomen
d.) AP axial cranium
a.) lateral t spine
Performing a KUB on a beriatric patient, using AEC results in:
a.) it depends on the type of grid used
b.) underexposure to the IR
c.) overexposure to the IR
d.) proper exposure to the IR
d.) proper exposure to the IR
When using automatic exposure control (AEC), the technologist CANNOT directly assign which of the following parameters?
a.) mAs
b.) kVp
c.) SID
d.) OID
a.) mAs
The 1st generation AEC detector is called:
a.) air filled photocells
b.) geiger counter
c.) ionization chamber
d.) phototimer
d.) phototimer
Which of the following exposure operates by ionizing air that creates an electrical charge?
a.) anatomically programmed technique
b.) none of the above
c.) phototimer
d.) ionization chamber
d.) ionization chamber
Increasing grid ratio:
1.) increases patient dose
2.) decreases IR exposure
3.) increases IR exposure
4.) increases distortion
a.) 2 only
b.) 1 and 2 only
c.) 1 only
d.) 3 and 4 only
b.) 1 and 2 only
Which of the following groups of exposure factors will produce the greatest receptor exposure?
a.) 400 ma, 70 ms
b.) 200 ma, 40 ms
c.) 600 ma, 30 ms
d.) 100 ma, 50 ms
a.) 400 ma, 70 ms
Which of the following are factors that affect contrast in digital imaging?
1.) mA and/or time
2.) windowing
3.) kVp
4.) PACS
5.) look up table
a.) 3 and 5 only
b.) 3 only
c.) 2, 3, 4 and 5 only
d.) all choices are responsible for image contrast
e.) 2, 3 and 5 only
e.) 2, 3 and 5 only
If the radiographer has the oppurtunity to set the back up time, it should be approximately _____________ of the expected exposure time.
a.) 600%
b.) 150%
c.) 275%
d.) 50%
b.) 150%
Ionization chamber AEC detectors are entrance type devices because the xrays must:
a.) enter the detector before getting to the IR
b.) enter the detector before entering the patient
c.) enter the detector after passing throught the bucky grid
d.) enter the detector after passing through the IR
a.) enter the detector before getting to the IR
A decrease in kilovoltage will result in:
1.) a decrease in image resolution
2.) a decrease in photon energy
3.) a decrease in receptor exposure
a.) 2 and 3 only
b.) 1 and 2 only
c.) 1, 2 and 3
d.) 1 only
a.) 2 and 3 only
What causes the most errors in image quality when using AEC devices?
a.) improper patient centering
b.) failure of the back up timer
c.) selecting the wall bucky for a table exam
d.) density control errors
a.) improper patient centering
The reason to have a back up time is to:
1.) protect the patient from excessive exposure
2.) make sure the right mAs is used
3.) keep the tube from excessive heat loading
4.) assist techs when a short exposure time is needed
a.) 1, 2, 3 and 4
b.) 1, 3 and 4 only
c.) 1 only
d.) 1 and 3 only
d.) 1 and 3 only
A lateral coccyx was made using AEC but is overexposed. this is most likely the result of:
a.) incorrect selection of the small focal spot
b.) incorrect centering of the part
c.) insufficient back up time
d.) selection of the center photocell
b.) incorrect centering of the part
What is the primary purpose of an automatic exposure control (AEC) system?
a.) to automatically module the kvp
b.) to maintain optimal image receptor exposure
c.) to enhance image contrast
d.) to increase spatial resolution
b.) to maintain optimal image receptor exposure
In which of the following systems does the radiographer select the anatomic part from the console menu?
a.) TFT
b.) CCD
c.) AEC
d.) APR
d.) APR
Aluminum filtration has its greatest effect on:
a.) high energy scattered photons
b.) low energy scattered photons
c.) low energy x ray photons
d.) high energy xray photons
c.) low energy x ray photons
When performing a lateral thoracic spine radiograph with an automatic exposure control (AEC) system, what technical change will increase the total exposure time without increasing the receptor exposure?
a.) decrease mA
b.) increase kvp
c.) increase density setting
d.) decrease back up timer
a.) decrease mA
On AEC systems, using the plus or minus density controls should be done frequently to produce optimal images.
a.) true
b.) false
b.) false
A technologist is performing a PA chest radiograph on a bariatric patient using an automatic exposure control (AEC) system. Which of the following changes will be rooted if the technologist increases the mA?
a.) increased patient dose
b.) decreased contrast
c.) increased receptor exposure
d.) decreased exposure time
d.) decreased exposure time
The smaller the area of xray exposure, the lower the patient dose.
a.) true
b.) false
a.) true
Which of the following factors have an effect on image receptor exposure?
a.) mAs
b.) SID
c.) kVp
d.) motion
e.) tube, IR, and or patient angle
f.) focal spot size
g.) filtration
h.) patient factors
a.) mAs
b.) SID
c.) kVp
g.) filtration
h.) patient factors
If a duration of 0.05s was selected for a particular exposure, what milliamperage would be necessary to produce 30 mAs?
a.) 600
b.) 300
c.) 500
d.) 900
a.) 600
Which of the following grid patterns will result in an image with the least amount of grid cutoff?
a.) cross hatched grid
b.) parallel grid
c.) focus grid
d.) non focused grid
c.) focus grid
Which of the following patient conditions require a change in technical factors? choose all that apply.
a.) decreased tissue thickness
b.) prosthetics
c.) destructive diseases
d.) plaster casts
e.) contrast media
b.) prosthetics
c.) destructive disease
d.) plaster casts
e.) contrast media
APR is a system in which the radiographer selects:
a.) settings based on the size of the patient
b.) AEC settings
c.) mAs and kVp settings
d.) settings based on the part being imaged
d.) setting based on the part being imaged
A technologist performing an AP pelvis projection unintentionally places gonadal shielding over two of the three active automatic exposure control (AEC) ionization chambers. How will this affect the exposure time and patient dose?
a.) decreased exposure time and increased patient dose
b.) decreased exposure time and decreased patient dose
c.) increased exposure time and decreased patient dose
d.) increase exposure time and increased patient dose
e.) no change to exposure time and patient dose
d.) increased exposure time and increased patient dose
When using AEC, the radiographer is responsible for determining the:
a.) exposure time
b.) mAs
c.) kVp
d.) kVp and mAs
c.) kVp
If the AEC detectors are not completely covered by the part being imaged, exposing the cells to primary radiation, what is likely to occur?
a.) the exposure will terminate very quickly
b.) none of these choices are correct
c.) the IR will be exposed to the proper amount of radiation
d.) the patient will be over exposed
a.) the exposure will terminate very quickly
What technical change is required to increase receptor exposure when using automatic exposure control (AEC)?
a.) increased mA
b.) increase density setting
c.) decrease density setting
d.) decrease back up timer
b.) increase density setting
An increased focal spot size will:
1.) increase IR exposure
2.) decrease spatial resolution
3.) increase spatial resolution
4.) increase distortion
5.) decrease contrast
a.) 1, 2, 4 and 5 only
b.) 1, 2 and 3 only
c.) 1 and 2 only
d.) 2 only
d.) 2 only
The AEC density control usually adjusts the xray beam intensity by what increment?
a.) 25%
b.) 35%
c.) 50%
d.) 10%
a.) 25%
When performing an AP lumbar spine using an automatic exposure control (AEC) system, the technologist inadvertently positions the patient with the active ionization chamber under a gas pocket in the abdomen. How will this affect the radiographic image?
a.) decrease spatial resolution
b.) decreased image contrast
c.) decreased receptor exposure
d.) increased receptor exposure
c.) decreased receptor exposure
The greatest detail sharpness is obtained by using:
1.) a small focal spot
2.) the longest SID
3.) the smallest OID
4.) longer exposure times
a.) 1 only
b.) 1, 2 and 3
c.) 1, 2, 3 and 4
d.) 4 only
b.) 1, 2 and 3
When used correctly, which of the following is an important benefit of an AEC system?
a.) minimize image artifacts
b.) minimize patient motion
c.) minimize heat accumulation in the tube
d.) to minimize patient dose
d.) to minimize patient dose
The actual amount of exposure used for an image when using AEC is the:
a.) density control
b.) minimum response time
c.) mAs readout
d.) back up time
c.) mAs readout
The shortest exposure time that a radiographic tube with AEC can have is the:
a.) minimum response time
b.) mAs readout
c.) density controls
d.) back up time
a.) minimum response time
Types of detectors used in AEC are:
1.) image intensifiers
2.) phototimers
3.) geiger counters
4.) ionization chambers
a.) 1, 2 and 4 only
b.) 1, 2, 3 and 4
c.) 2 and 4 only
d.) 1 and 2 only
c.) 2 and 4 only
When using AEC, which of the following special considerations may require the tech to make technique adjustments?
1.) bariatric patients
2.) small bowel follow through (SBFT)
3.) osteoarthiritis
4.) hyposthenic patients
a.) 2 and 3 only
b.) 1, 2, 3 and 4
c.) 1 and 4 only
d.) 2 and 3 only
a.) 2 and 3 only
A technologist is performing an AP abdomen radiograph on a geriatric patient using an automatic exposure control (AEC) system. Which of the following changes will be noted if the technologist decreases the kvp?
a.) increased exposure time
b.) decreased patient dose
c.) decreased contrast
d.) increased IR exposure
a.) increased exposure time
When performing a PA chest radiograph using an automatic exposure control (AEC) system, the technologist engages only the center AEC ionization chamber. How might this affect the radiographic image?
a.) increased exposure time and increased receptor exposure
b.) increased exposure time and decreased receptor exposure
c.) decreased exposure time and decreased receptor exposure
d.) decreased exposure time and increased receptor exposure
a.) increased exposure time and increased receptor exposure
By law, the back up timer on an AEC system must terminate exposure when the total mAs has reached:
a.) 600 mAs
b.) 150 mAs
c.) 100 mAs
d.) 300 mAs
a.) 600 mAs
Which of the following modifications may be used to decrease the total exposure time when using an automatic exposure control (AEC) system?
a.) decrease kvp
b.) increase density setting
c.) increase mA
d.) decrease back up timer
c.) increase mA
Which of the following special considerations may require an increase in milliamperage (mA)?
1.) pediatric exam
2.) geriatric exam
3.) barium studies
4.) exams that use breathing techniques
a.) 1 and 2 only
b.) 1, 2, 3 and 4
c.) 1, 2 and 4
d.) 3 only
a.) 1 and 2 only
Which detector or combination is best used for imaging a right shoulder?
a.) right
b.) center
c.) right and left
d.) left
b.) center
The maximum length of time that an exposure lasts when using AEC is the:
a.) back up time
b.) mAs readout
c.) density controls
d.) minimum response time
a.) back up time
Practices that enable the radiographer to reduce the exposure time required for a particular include:
1.) use of a higher millamperage
2.) use of a higher kvp
3.) use of a higher grid ratio
a.) 2 and 3 only
b.) 1 only
c.) 1 and 2 only
d.) 1, 2 and 3
c.) 1 and 2 only
Which of the following exposure factors us controlled by the automatic exposure control (AEC) system?
a.) kvp
b.) ma
c.) SID
d.) time
d.) time
What potential effect does EXCESSIVE BOWEL GAS have on IR exposure?
underexposure
What potential effect does PROSTHETICS have on IR exposure?
overexposure
VWhat potential effect does part not being centered over the detector have on IR exposure?
underexposure
What potential effect does too much collimation have on IR exposure?
over exposure
What potential effect does excessive scatter have on IR exposure?
underexposure
What potential effect does CONTRAST MEDIA have on IR exposure?
overexposure
What potential effect does part superimposing ion chambers have on IR exposure?
appropriate exposure
What potential effect does increased patient thickness have on IR exposure?
appropriate exposure
