Revision History


The phantom is evaluated in 3 areas: protocol evaluation from the phantom data form; image quality evaluation; and dosimetry. One or more major deficiencies and/or 7 or more minor deficiencies total will fail the phantom review. Each required protocol will be evaluated for major and minor deficiencies.


Protocol Evaluation from the Phantom Data Form

Minor

Major

Detector configuration (N and T) recorded in the phantom data form is inappropriate for the submitted protocols

X


kVp recorded in the phantom data form is inappropriate for the submitted protocol

X


Rotation time recorded in the phantom data form is inappropriate for the submitted protocol

X


Table increment or table speed (pitch) recorded in the phantom data form is inappropriate for the submitted protocols

X


Reconstruction algorithm recorded in the phantom data form is inappropriate for the submitted protocol

X


Other technical parameters recorded in the phantom data form are inappropriate for the submitted protocols

X


Phantom Image Evaluation

Minor

Major

Parameters on the submitted images do not match the protocols recorded in the phantom data form

X


Submitted image thickness is more than 1.5 mm thicker than what is recorded in the phantom data form


X

kVp used is different than what is recorded in the phantom data form


X

mAs is more than 10% greater than what is recorded in the phantom data form


X

mAs is more than 10% less than what is recorded in the phantom data form

X


Pitch is more than 10% greater from what is recorded in the phantom data form

X
Pitch is more than 10% less from what is recorded in the phantom data form (unless effective mAs is equivalent)
X

Each ROI measurement outside the criteria for HU

X


Low contrast detectability (Contrast-to-Noise Ratio)

X


Uniformity (any difference between 5 and 7 HU)

X


Uniformity (any difference of more than 7 HU)


X

Artifacts (could be major or minor depending on severity)

X

X

Dosimetry

Minor

Major

Helical scans performed


X

Incorrect dosimetry phantom used


X

Parameters used on the dosimetry images do not match the protocols recorded in the phantom data form

X


kVp used on the dosimetry images does not match what is recorded on the phantom data form


X

Total beam width used is larger (under-estimates dose) than what is recorded in the phantom data form (exclusive of scanner limitations)


X

Total beam width used is smaller (over-estimates dose) than what is recorded in the phantom data form (exclusive of scanner limitations)X

Non-chamber holes are not filled

X


CTDIvol exceeds the pass-fail criteria


X

CTDIvol exceeds the reference level

X


CTDIvol not calculated correctly but can be recalculated

X


CTDIvol not calculated correctly but cannot be recalculated


X

Percent difference between calculated CTDIvol and CTDIvol reported by scanner*

n/a

n/a

SSDE for 35 or 18.5 cm water equivalent diameter (mGy) for adult and pediatric abdomen protocols*

n/a

n/a

*Please note that the percent difference between calculated CTDIvol and CTDIvol reported by scanner and SSDE calculations for the adult and pediatric body and Dose Notification Values are for informational purposes only and do not contribute deficiencies at this time.


Artifact Evaluation (can occur on each required series)

Scored starting at the slice with Module 1 BBs to the slice just before the transition to Module 4 using the window and level specified for each module


Minor

Major

Artifacts that could affect clinical interpretation
X
Artifacts that obscure the test objects in the phantom
X
High contrast streak artifacts
X
High contrast ring artifacts
X
Low contrast ring artifacts that are as prominent or more prominent than the 25 mm LC insert on the adult abdomen scan or the highest CNR scan if an adult abdomen was not submitted. NOTE: If only a pediatric abdomen is submitted, then major versus minor deficiency is left up to reviewer discretion
X
Low contrast ring artifacts that are less prominent than the 25 mm LC insert on the adult abdomen scan or the highest CNR scan if an adult abdomen was not submitted
X

Low contrast streak artifacts
X

Artifacts that are present but do not meet the Major Deficiency criteria
X

The following would be No Deficiency Artifacts:
  • Streak Artifacts caused by the "bone" insert, wire ramps, BBs, high contrast resolution patterns, or the phantom stand
  • Artifacts that occur at the transition between modules
  • Artifacts due to defects in the phantom or phantom construction (e.g., filler)
  • Minor bleed through artifacts on volume scans
  • Artifacts on CTDI phantom images



Revision History for this Article

Date

Section

Description of Revision(s)

12-12-19

All

Article created; FAQs incorporated; No criteria changes

12-7-2021Protocol Evaluation from the Phantom Data Formclarified detector configuration, changed kV to kVp

Phantom Image Evaluationclarified pitch more or less than 10% of recorded in phantom data form deficiency

DosimetryRemoved dosimetry images not submitted deficiency, clarified total beam width deficiencies
12-21-2021Artifact EvaluationAdded artifact evaluation section



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