Image artifact

Question 1

What CT artifact may result from excessive absorption of the x-ray beam?

Answer 1

Beam hardening artifact

Question 2

While imaging a CT chest, leaving an EKG line in t he exposure field may result in:

Answer 2

beam hardening artifact

Question 3

Out of field artifact is caused when a part of the patient is outside of the:

Answer 3

Scan field of view (SFOV)

Question 4

Positioning the patient comfortably on the CT table is important in order to prevent which type of image degradation?

Answer 4

Patient motion

Question 5

Adjacent areas with significant density differences can cause an artifact called:

Answer 5

Edge gradient artifact

Question 6

If ring artifact is identified in a scan, this might be prevented in future scans by:

Answer 6

cleaning the detector array

Question 7

When scanning a patient’s chest, the axial images demonstrate ring artifact. This might be prevented in the future by:

Answer 7

Correctly calibrating the detector array

Question 8

During a CT of the abdomen and pelvis, using fluoroscopy-grade barium rather than CT grade barium for rectal contrast will likely result in an image degradation called:

Answer 8

beam hardening artifact

Question 9

While imaging a large bariatric patient, you notice the patient’s abdomen is touching the gantry in several areas. This might result in what of artifact

Answer 9

out of field artifact

Question 10

Dark streaks extending from the interface between the contrast and air in the GI tract is called

Answer 10

Edge gradient artifact

Question 11

During a CT (CTA) of the neck, the patient is instructed not to swallow in order to avoid

Answer 11

motion artifact

Question 12

When scanning a patient’s chest, beam-hardening artifact can be prevent by:

Answer 12

placing the patient’s arms above his/her head

Question 13

When imaging a patient’s paranasal sinuses, which of the following procedures may help prevent beam-hardening artifact?

Answer 13

angle the gantry to avoid dental implants

Question 14

Consider this scenario: when reviewing the standard algorithms of a patient’s head, you see what look like a subdural hematoma. However, when reviewing the bone images you see the hematoma is just a double image of the patient’s cranium bone. this error is most likely the result of:

Answer 14

motion artifact

Question 15

While acquiring the scout images for a bony pelvis CT, you notice the patient has a hip prosthesis. the axial images may have

Answer 15

beam hardening artifact

Question 16

Centering the patient too high or too low in the gantry can result in which image artifact

Answer 16

out of field artifact

Question 17

Consider this scenario: when reviewing 2.5 mm slices of a CT CTA abdomen, you see what looks like an embolism. However, when reviewing the 1.25 mm slices the embolism is not visible. This is most likely an error called

Answer 17

partial volume averaging

Question 18

An overly concentrated bolus of IV contrast may result in an error called:

Answer 18

beam hardening artifact

Question 19

The use of thick reconstruction slices can result in an error called

Answer 19

partial volume averaging

Question 20

out of field artifact might be prevented by:

Answer 20

compressing the patient with straps

Question 21

How does cone beam artifact affect the appearance of the CT image?

Answer 21

shape distortion of anatomy