Dose Optimization Techniques (CTBC 24)

Question 1

_______ _______ produces quality images with the lowest possible radiation dose

Answer 1

Optimal dose

Question 2

Tube current (mA)
Tube Potential (kVp)
Pitch
Beam Width (Collimation)
Patient Positioning

Answer 2

5 aspects of a CT procedure affecting patient dose

Question 3

kVp controls the energy and _______ of the x-ray beam as well as the total number of x-rays in the beam

Answer 3

Penetrability

Question 4

As pitch increases, patient dose ______

Answer 4

Decreases

Question 5

As beam width increases, patient dose _______

Answer 5

decreases

Question 6

The inverse relationship of beam width and patient dose relates to the _______ outside the functional beam

Answer 6

penumbra (off-focus radiation)

Question 7

Using more detector rows (and a wide beam) results in less…

Answer 7

Exposure to penumbra

Question 8

Removing artifact-causing objects (e.g., arms) from the scan field is especially important when using…

Answer 8

Dose-modulating software (Auto mA: GE; CARE dose: Siemens; SURE exposure: Toshiba)

Question 9

Incomplete projection artifact

Answer 9

Out of field artifact

Question 10

For automatic dose-modulating scans, positioning too high in the scanner makes the patient look larger, and therefore leads to

Answer 10

increased technique (exposure)

Question 11

A technology which changes the mA during the scan based on the density of tissues imaged

Answer 11

Automatic Dose Modulation

Question 12

Automatic dose modulation technologies use the _______ to identify the densest portions of the patient

Answer 12

localizer

Question 13

Automatic dose modulation technologies which adjust the dose from superior to inferior

Answer 13

z-axis modulation

Question 14

Automatic dose modulation based on projection _______ will decrease mA in the _______ projections and increase mA in the _______ projections

Answer 14

(x- & y-axis)
AP
lateral

Question 15

AEC

Answer 15

Automatic Exposure Control (automatic dose modulation)

Question 16

ATCM

Answer 16

Automatic Tube Current Modulation
(automatic dose modulation)

Question 17

Smart mA

Answer 17

GE nomenclature for automatic dose modulation

Question 18

Auto mA

Answer 18

GE nomenclature for automatic dose modulation

Question 19

SURE exposure

Answer 19

Toshiba nomenclature for automatic dose modulation

Question 20

CARE dose

Answer 20

Siemens nomenclature for automatic dose modulation

Question 21

Dose Right

Answer 21

Philips nomenclature for automatic dose modulation

Question 22

Displayed when CTDI is set to exceed predetermined dose warning values

Answer 22

Dose notification

Question 23

Dose Notification is useful since most technologists don’t automatically recognize the CTDI values which would lead to

Answer 23

over-exposure

Question 24

The specific CTDI dose notification values are set by

Answer 24

each facility

Question 25

Displayed when the cumulative CTDI for a series of scans is set to exceed _______ mGy for any specific location in the patient

Answer 25

1000
Dose Alert

Question 26

When utilizing lead shielding, it is critically important the lead not enter the scan field d/t (2)

Answer 26

Unacceptable level of beam hardening artifact
Increased tube output–>patient dose (when using automatic exposure control)

Question 27

Unlike lead shielding, bismuth shields attenuate only _______ photons

Answer 27

Low-energy

Question 28

A relatively recent development for minimizing dose to vulnerable body tissues such as eyes, thyroid, breasts, gonads

Answer 28

Bismuth Shields

Question 29

_______ _______ may be placed in the scan field after localizer images have been acquired

Answer 29

Bismuth Shields

Question 30

A small amount of image artifact may result from use of

Answer 30

Bismuth Shield