Which 2 factors affect size distortion? (Select all that apply)
Select one or more:
a. OID
b. Focal spot size
c. Resolution
d. SID
e. Film screens
f. Patient motion
g. SOD
OID
SID
Name 4 ways technologists can help control patient motion.
Four ways that technologists can help control patient motion are: using a short exposure time, communicate clearly with patient about breathing, use physical immobilization tools, and use others to help immobilize when needed.
Which 3 factors affect geometric unsharpness? (Select all that apply)
Select one or more:
a. Resolution
b. Patient motion
c. OID
d. SOD
e. Film screens
f. Focal spot size
g. SID
Focal spot size
OID
SID
Which is better at spatial resolution?
Select one:
a. film
b. digital
a. film
Based on the following factors, what is the geometric unsharpness? (In mm)
FSS=0.6mm, SID=62 inches, OID=2 inches
0.02 mm
A PA projection of the hand was produced with an SID of 40 inches and an OID of 0.5 inches. What is the MF? (with 3 decimal places)
1.013
Describe how poor film-screen contact will increase image unsharpness.
Light transmitted from the intensifying screen will diverge from its origin and so it is important to have good film-screen contact. Poor film-screen contact will expose parts of the film to light that shouldn't be exposed because of that divergent light beam and the space between film and screen.
A PA projection of the chest was produced with an SID of 72 inches and an OID of 4 inches. What is the MF? (with 3 decimal places)
1.059
To increase recorded detail OID should be maximized.
Select one:
True
False
False
Radiographic images of structures are always magnified when compared to the actual structure.
Select one:
True
False
True
Why will radiographs always have some degree of unsharpness?
Radiographs will always have some sort degree of unsharpness because of all the different variables required to make an accurate radiograph including geometric unsharpness, receptor unsharpness, and motion unsharpness.
Size distortion is affected by:
1. SID
2. OID
3. Tube angulation
Select one:
A. 1 & 2 only
Which factor has the most detrimental effect on recorded detail?
Select one:
D. Motion unsharpness
What affect does resolution have on recorded detail?
Select one:
A. direct
SID is important as a photographic property and a geometric property.
Select one:
True
False
True
Based on the following factors, what is the geometric unsharpness? (In mm)
FSS=1.2mm, SID=54 inches, OID=4 inches
0.09 mm
A misalignment the central ray, radiographed part, or image receptor will cause distortion.
Select one:
True
False
True
Shape distortion can be useful in radiographic imaging.
Select one:
True
False
True
Which is better at contrast resolution?
Select one:
a. digital
b. film
a. digital
Increasing OID _________ recorded detail.
Select one:
C. decreases
Which combination of factors results in the optimal image?
Select one:
D. max recorded detail and min distortion
Shape distortion includes:
Select one:
B. elongation
Radiographic misrepresentation of the size or shape of the anatomic structure being imaged is:
Select one:
D. all of the above
Magnification always results in reduced recorded detail.
Select one:
True
False
True
Which of these factors ONLY affects recorded detail?
Select one:
a. Focal spot size
b. Film screens
c. Resolution
d. SOD
e. SID
f. Patient motion
g. OID
Focal spot size
List 2 types of additive pathologies for each of the abdomen, chest, and skeleton.
Abdomen - aortic aneurysm, calcified stones.
Chest - pneumonia, atelectasis.
Skeleton - metastases, hydrocephalus.
As compared to a patient with a 24 cm thick abdomen, imaging a patient with a 20 cm thick abdomen will result in _____________ scatter being produced and ______________ image contrast.
Select one:
B. less; higher
List 2 types of destructive pathologies for each of the abdomen, chest, and skeleton.
Abdomen - aerophagia, bowel obstruction.
Chest - emphysema, pneumothorax.
Skeleton - gout, osteoporosis.
Air – negative contrast agent
Requires no change in exposure – negative contrast agent
With film-screen imaging, for a given exposure technique, increasing part thickness decreases radiographic density.
Select one:
True
False
True
Generally speaking, what is the kVp value for a pediatric (less than 6 years old) skull compared with the adult skull?
Select one:
D. 15% less
What affect does an increased body part thickness have on scatter?
Select one:
D. increases
A misalignment in which of the following factors will cause distortion? (choose all that apply)
Select one or more:
a. body part
b. image receptor
c. x-ray tube
d. entry or exit point of the central ray
x-ray tube, body part, image receptor, entry or exit point of the central ray
With all other factors remaining the same, a patient with which body habitus would require the highest exposure factors?
Select one:
D. Hypersthenic
Generally speaking, what do additive pathologic conditions require?
Select one:
D. Increased kVp
Match the following subject contrasts to the correct terms
B – low subject contrast, Chest – high subject contrast, Abdomen – low subject contrast, A – high subject contrast
Which of the following is a destructive pathology?
Select one:
A. Emphysema
With digital imaging, the same mAs and kVp should be used for an AP lumbar spine and a lateral lumbar spine.
Select one:
True
False
False
Assuming all produce appropriate density images, which of the following would be the best exposure technique choice when performing a chest radiograph on an infant?
Select one:
D. Use 40 ms exposure time.
You should always increase your technique when imaging a body part that is stabilized by a splint.
Select one:
True
False
False
What affect does increased scatter have on contrast?
Select one:
A. decreases
Exposure factors used for adult skulls can be used for pediatric patients 6 years old and older.
Select one:
True
False
True
Which one of the following immobilizing devices requires an increase in the exposure technique?
Select one:
C. Plaster cast
In general, what should you do to your technique when imaging a body part with a cast?
Select one:
D. Increase technique
In order to image a structure that is located anteriorly in the body, it is best radiographed to minimize magnification by doing a(n) _____ projection.
Select one:
C. Posterior-anterior
What is the purpose of technique charts? (Give at least 2 reasons)
The purposes of technique charts are: to help produce consistent images, satisfy ALARA, and to expand the life of the tube.
What is the appropriate setting for backup time/mAs?
Select one:
D. 150% of the expected mAs
A variable kVp-fixed mAs chart may be most effective with:
Select one:
C. Pediatric patients
When the radiographer is considering whether to repeat an image using AEC, it is important to determine the reason the first radiograph failed.
Select one:
True
False
True
AEC devices directly control the:
Select one:
B. exposure time
What is the purpose of setting a backup time/mAs?
Select one:
B. To prevent excessive exposure of the patient
Exposure time will ______ using AEC when patient thickness decreases.
Select one:
C. decrease
Why was automatic exposure control (AEC) originally developed?
Select one:
B. To reduce repeats and improve image quality
List and BRIEFLY discuss 4 technical considerations when using AEC.
Four technical considerations when using AEC are: proper centering of the part, correct detector selection, kVp and mA selections, and your density selection.
Why are calipers used?
Select one:
D. Measure body part thickness
What would the result be if a film-screen radiographic examination required an exposure time shorter than the minimum response time of the AEC sensors?
Select one:
D. Image density would be excessive.
Select the correct 2 types of technique charts.
Select one or more:
a. Variable kVp/variable mAs
b. Variable kVp/fixed mAs
c. Fixed kVp/fixed mAs
d. Fixed kVp/variable mAs
Variable kVp/fixed mAs, Fixed kVp/variable mAs
Technique charts should follow which principle?
Select one:
D. ALARA
In order to become familiar with manual technical factors (i.e., setting mAs and kVp and not using AEC), it is very helpful to pay attention to the:
Select one:
B. mAs readout
It is correct to call all AEC devices phototimers.
Select one:
True
False
False
If a part measures 14 cm and requires the use of 75 kVp, how much kVp would a part measuring 18 cm require when using a variable kVp-fixed mAs technique chart?
Select one:
C. 83 kVp
When using a fixed kVp-variable mAs technique chart, if part thickness increases by 5 cm, what needs to happen to the mAs?
Select one:
A. It should be doubled.
Technique charts help in which of the following areas? (Choose all that apply)
Select one or more:
a. Provide uncertainty in radiographic factors
b. Reduce exposure
c. Reduce repeats
d. Increase patient dose
e. Produce consistency in image quality
Produce consistency in image quality, Reduce repeats, Reduce exposure
Where is the sensor located in an automatic exposure device that converts light into an electrical signal?
Select one:
D. Behind the image receptor
Match the following descriptions to the proper type of AEC device.
More sophisticated – Phototimers
Less prone to failure – Ionization chambers
More accurate – Phototimers
Most common AEC device – Ionization chambers
Which automatic exposure device works by converting x-ray photons first into light and then into an electronic signal?
Select one:
B. Phototimer
When using AEC with film-screen, what should the radiographer adjust to manipulate the overall density of the image?
Select one:
D. Density control
With digital imaging, AEC can be used with tabletop exams.
Select one:
True
False
False
Where is the sensor located in an automatic exposure device with a gas-filled chamber?
Select one:
D. In front of the image receptor
What is the appropriate change in kVp when using a variable kVp-fixed mAs technique chart for a 1 cm change in tissue thickness?
Select one:
A. 2 kVp
What kind of chart uses a kVp value that is high enough to adequately penetrate the part but does not diminish radiographic contrast?
Select one:
C. A fixed kVp technique chart
When comparing how radiation exposure is converted into electrical energy, what is the difference between phototimers and ionization chambers?
Phototimers make light with photons which converts into electrical signals. Ionization chambers are cells containing air that interacts with photons to create an electrical charge.
Technique charts are still needed when using AEC.
Select one:
True
False
True
Briefly list and explain the 5 steps in technique chart development.
Step 1 - Determine phantom and radiographic factors
Step 2 - kVp and mAs using 15% rule
Step 3 - Eliminate unacceptable radiographs
Step 4 - Choose optimal radiograph
Step 5 - Extrapolate chart based on optimal image
Each body part requires these steps. Pick your part and make multiple images with varying techniques and choose the optimal image/technique. Use that as you technique on the chart.
AEC devices help control:
Select one:
A. density
A technique chart should be established for:
Select one:
D. Each radiographic tube
A good time to use AEC is when the radiographer is unable to accurately center the x-ray beam
Select one:
True
False
False
Accurate patient measurement is most critical for the:
Select one:
A. Variable kVp-fixed mAs technique chart design
What describes the shortest exposure time required for the AEC device to operate?
Select one:
C. Minimum response time
When doing a CR study using AEC, what will happen to the patient exposure when changing from the -1 to +1 density setting?
Select one:
A. Patient exposure will increase
When exposure factors are selected using APR, the variables should not be adjusted.
Select one:
True
False
False
Which automatic exposure device works by using a gas-filled chamber?
Select one:
A. Ionization chamber
Which factors on a technique chart are standardized? (Choose all that apply)
Select one or more:
a. SID
b. Measuring point
c. IR
d. Grid ratio
e. mAs
f. FSS
g. kVp
Measuring point
SID
IR
Grid ratio
FSS
When doing a film-screen study using AEC, what will happen to the density in the area of interest when changing from 70 kVp to 90 kVp?
