1. Physics Testing for ACRIN 6678 Protocol version 3.0 QIBA Group 1C

2. Goal
Determine Scanner Performance for Spatial Resolution and Noise under protocol specified by ACRIN 6678.
These will be compared with results from Performance Based Protocol Testing

3. ACRIN 6678 Protocol(hyperlink)

4. General Outline of Testing Protocol
Using protocol specified by ACRIN 6678
Scan ACR phantom spatial resolution section
Record visible bar pattern size
Scan ACR phantom uniformity section
Place ROI in center of phantom and record std. deviation

5. Testing Protocol (Details)
Record required data on accompanying spreadsheet,
On accompanying spreadsheet, record:
Scanner Manufacturer (e.g GE)
Model (e.g. VCT)
Site id (e.g Scanner 95)
Software version
Testing date ( )
All scanners use 120 kVp, record 120 in kVp field.
Record Scan Field of View or Patient Size (or equivalent) setting used.
Record Slice thickness between 0.75 to 1.25 mm (depending on scanner’s available reconstructed slice thickness)
Record nominal beam collimation (NxT such as 16 x 0.5mm, or 128x0.6mm, 320 x 0.5 mm) rotation time and pitch such that scan can cover a 35 cm thorax in 15 seconds or less
Values near pitch 1 are preferred.
Record reconstruction kernel.
Record mAs or effective mAs setting

6. Specific Instructions for Testing Protocol
2. Using parameters specified in ACRIN 6678, Scan phantom once through section 4 of ACR CT accreditation phantom.
Reconstruct images, display with Level =1100, Window=100
Record the name of recon filter
Record the size of the line pair object (e.g. 6 lp/cm etc.) observed for that filter
Provide image (DICOM AND jpeg)
Zoomed in
B30
6 lp/cm
7 lp/cm
ACR Spatial Resolution Section (Module 4)

7. Specific Instructions for Testing Protocol
3 Using parameters specified in ACRIN 6678, Scan phantom once through section 3 of ACR CT accreditation phantom.
Reconstruct images, display with Level =100, Window=100
From Reconstructed image, measure standard deviation by placing an ROI of approximately 400 mm2 at the center of the image
Record standard deviation on spreadsheet
Provide image (DICOM AND jpeg)

8. Example of Testing Protocol
Step 3 – Example on Siemens Sensation 64.
100 eff. mAs
Tech. Params:
120 kVp
1mm
Pitch 1
0.5 sec
B30
100 eff. mAs; std dev = 17

9. RESULTS Of Testing Protocol
For Siemens Sensation 64, using ACRIN 6678 parameters:
120 kVp
Reconstructed Slice thickness 1.0 mm
Nominal beam collimation 64x0.6 (actually 32x0.6 with flying focal spot)
Rotation time 0.5 seconds
Pitch 1.0
Recon kernel B30
Effective mAs setting 100
CTDIvol = 7.7 mGy
PERFORMANCE
Spatial Resolution = 6 lp/cm
Standard Deviation = 17 HU

10. Next Scanner?