Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Mosby's Exam Review > Dose Measurement > Flashcards

Dose Measurement Flashcards

1
Q

What term is used to describe the reconstructed CT section?

A

slice sensitivity profile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What term describes the section of tissue exposed to ionizing radiation and has a greater width than SSP?

A

dose profile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What term is used to describe the ability of x-rays to ionize a volume of air?

A

exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is “exposure” measured in?

A

roentgens (R)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What term describes the amount of x-ray energy absorbed in a unit of mass?

A

absorbed dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is “absorbed dose” measured in?

A

grays (Gy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is another term used to describe absorbed dose?

A

kerma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What describes the amount of radiation absorbed in a quantity of air?

A

air kerma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What accounts for the type of tissue radiation is deposited in?

A

effective dose (EfD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What factor determines the weighting factors that are assigned to different tissues?

A

individual radiosensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is effective dose used to calculate from exposure to ionizing radiation?

A

risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is effective dose measured in?

A

sieverts (Sv)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is also the estimation of the whole-body dose equivalent that results from the partial body exposure the patient receives during a CT procedure?

A

effective dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an approximate measurement of the dose received in a sinlge CT section or slice?

A

CT dose index (CTDI)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is calculated from the central slice of a series when 7 slices surround each side?

A

CTDI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What measurement is taken with a 100-mm-long pencil ionization chamber and makes no reference to a specific number of slices?

A

CTDI-100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What causes dose to vary within the image across the acquired FOV?

A

absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What measurement is calculated by the sum of 2/3 of periphery and 1/3 of central exposure of the field?

A

CTDI-w

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What dosimeter measures and calculates radiation exposure for CTDI-w?

A

TLD’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is measured using the axial or “step-and-shoot” method of scanning?

A

CTDI-w

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is used to measure radiation dose from the helical scan method?

A

CTDI-vol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the formula for calculating CTDI-vol?

A

CTDI-vol = CDTI-w/pitch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

As pitch increases, what happens to the dose per section?

A

decreases

24
Q

What axis planes does the CTDI-w approximate dose and what is it measured in?

A

x- and y- axis; mGy

25
Q

What axis planes does the CTDI-vol approximate dose and what is it measured in?

A

z-axis; mGy

26
Q

What is CTDI-vol similar to?

A

MSAD- multiple scan average dose

27
Q

What is a calculation of the average cumulative dose to each slice within the center of a scan consisting of multiple slices?

A

MSAD

28
Q

What does MSAD take in account for which makes the average dose higher in a single slice?

A

scatter radiation

29
Q

Are the MSAD doses from the beginning and end slices more or less than the central slice?

A

less

30
Q

What is the formula for calculate MSAD?

A

MSAD = T/I x CTDI

31
Q

What does MSAD account for when calculating dose from an axial scan?

A

image spacing or “bed index”

32
Q

Do overlapping scans in axial scanning increase or decrease dose?

A

increase

33
Q

Does having gaps between slices in axial scanning increase or decrease dose?

A

decrease

34
Q

When slice thickness is greater than image spacing, does MSAD increase or decrease?

A

increase

35
Q

When slice thickness is less than image spacing, does MSAD increase or decrease?

A

decrease

36
Q

What is MSAD controlled by during a helical scan?

A

pitch

37
Q

What is the formula for calculating MSAD of a helical scan?

A

MSAD= CTDI/pitch

38
Q

What is the MSAD dose when slice thickness is equal to image spacing?

A

equal

39
Q

What term describes the amount of table travel per tube rotation divided by the collimation?

A

pitch

40
Q

What part of a scan series is MSAD most accurate?

A

center

41
Q

What two measurements are used to calculate the average radiation dose within a scan volume?

A

CTDI-vol and MSAD

42
Q

dose amongst what scan plane is not considered in the average radiation dose calculated by CTDI-vol and MSAD?

A

z-axis

43
Q

What is the formula for DLP?

A

DLP= CTDI-vol x scan length (collimation) x No. of slices in scan volume

44
Q

What is the formula for DLP when using CTDI-vol and scan length to calculate the total dose and what is it measured in?

A

DLP= CTDI-vol x scan length; mGy-cm

45
Q

What setting controls the CTDI-vol?

A

prepatient collimator

46
Q

What object is used to determine the measurement of effective dose since calculating a direct measurement is not possible?

A

phantom

47
Q

What factor is not accounted for by CTDI-vol and DLP and typically leads to under- or over-estimation of dose?

A

patient size

48
Q

What two other ways may CTDI-vol and DLP be expressed as?

A

computed tomography air kerma index (Ca) and air kerma length product (Pkl)

49
Q

What report is included by DICOM to give information regarding tube’s radiation output during CT acquisition like: tube current and voltage, scan time, acquisition length, pitch, and collimation width?

A

RDSR- Radiation Dose Structured Report

50
Q

Does the RDSR report automatically get archived into the patient’s electronic medical record?

A

yes

51
Q

What is a new automated alert system that indicates when the anticipated dose for a given acquisition exceeds the recommended maximum?

A

dose check

52
Q

What are the two levels of check associated with dose check systems?

A

dose notification and dose alert

53
Q

Which dose check system informs the technologist when the prescribed technical settings for an individual CT acquisition may result in a CTDI-vol or DLP higher than a preset recommended value?

A

dose notification

54
Q

Which dose check system alerts the technologist when the prescribed acquisitions for an entire CT exam results in a CTDI-vol and DLP higher than preset value?

A

dose alert

55
Q

What four requirements have CT systems been designed to obtain to reduce patient exposure?

A

automated CT dose check
separate protocols for adults and pediatrics
DICOM structured reporting
AEC

Mosby's Exam Review (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions