Update on ACR Digital Mammography QC Manual › Resources › Documents › 2015 Spring... ·...
Transcript of Update on ACR Digital Mammography QC Manual › Resources › Documents › 2015 Spring... ·...
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Update on ACR Digital Mammography QC Manual
Priscilla F. Butler, M.S.
Medical Physicist and Senior Director, ACR, Reston, VA
(with thanks to Eric Berns, Ph.D.)
Overview
• Phantom Specifications
• QC Manual
• Explain what we feel is important
• Thank you for being here today
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Digital Mammography in the US (as of 3/1/15)
• 13,493 units at 8720 facilities
• Over 96% of all units in US are FFDM
*4 accrediting bodies
*Over 30 models and mfrs approved by FDA
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Quality Control: What It and Why Is It Important?Primary Purpose
• Reduce exposure to patients and personnel
• Ensure adequate and consistent patient image
quality• Detect and correct for potential problems, before
they impact patient image quality and care
What it’s not:• Not a detailed technical evaluation of a unit• Not a detailed measure of a limits of a unit• Not the optimization of a unit
• MQSA
– Mammography Quality Standards Act
• ACR
– American College of Radiology
QC Mandates
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FDA’s Current DM QC Requirements
• Follow latest version of mfr’s QC manual procedures for unit tested– Lorad (Hologic) allows facility to follow any of their
manuals
• Meet mfr’s performance standards
• Failures must be fixed before use on patients
– Most mfrs applied for alternative standards to allow 30 days for some QC tests
ACR’s Current DM QC Requirements
• Same as FDA’s
• Which are the same as the manufacturer’s
• ACR suggests using manufacturer’s data forms
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Screen-Film QC
• Single detector technology
• Single processing technology
• First QC manual in 1990
Manufacturer’s DM QC Requirements
• Tests vary for each manufacturer and model
– Some tests same but names different
– Some tests not required by some manufacturers
• Frequencies vary for each manufacturer and model
• Procedures vary for each manufacturer and model
• Pass/fail criteria vary for each manufacturer and model
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Film Printers
• FDA recommends only using printers cleared by FDA’s Office of Device Evaluation for FFDM (but may legally use others)
• Facility must have access to a laser printer (either on-site or someplace else)
• Printer must exist and be tested by MP before the facility performs mammography
Monitors and Workstations• FDA regs require facilities to comply with a QA
program substantially the same as that of FFDM mfr(i.e., GE, Lorad, etc.) – Impractical; even impossible since tests are software-
based
• FDA says – If the monitor/workstation has been cleared by FDA’s ODE
for FFDM, the monitor’s QC manual is “substantially the same” and OK to follow
– If monitor was not cleared by FDA ODE for FFDM facilities must follow one by FFDM mfr
• FDA ODE clears monitors/workstations– Over 500 total; ? have been cleared for FFDM
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ACR DM QC Manual
VS.
All of the above may vary with QC manual revisions of same manufacturer/model
ACR DM QC Manual Project
• Subcommittee on Quality Assurance– Chair – Eric Berns, PhD – University of Colorado
• Subcommittee – all volunteers (with day jobs) – Clinical representatives
– MITA representatives (equipment and phantom manufacturers)
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ACR DM QC Manual Project
• Subcommittee Charge:– Design ACR Accreditation Phantom for FFDM
– Write QC Manual for ACR FFDM Mammography Accreditation Program
• Subcommittee Goals:– Standardize all QC tests for all digital manufacturers
– Standardize test frequencies
– Standardize performance criteria
ACR DM QC Manual Project
• QC tests:– Will apply to all manufacturers
– Tests come from a variety of sources (MQSA, SFM, ACRIN DMIST, Manufacturer’s QC programs, MITA, subcommittee clinical experience, etc.)
– Clinically relevant
– User friendly
– Eliminate non-productive testing
• Just because you can test something, doesn’t mean you should!
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ACR Digital QC Manual - Structure
• Radiologist’s Section
• Radiologic Technologist’s Section
• Medical Physicist’s Section
• Appendices
• **Clinical Image Quality Section (w/Patient Positioning and Compression and Clinical Image Quality Evaluation) will be revised at a later date and posted on ACR website
ACR Digital QC Manual - Tools
• Will be downloadable to computer or tablet
• Future revisions fully described (in new “Revisions” section)
• Sections and references fully linked
• Optional procedures and forms available
• Management forms available to aid organization
• Procedures liberally illustrated
• Forms in PDF and Excel formats– Excel formats contain formula and functionality– Excel forms downloadable from ACR website
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ACR DM QC Manual Project
• Subcommittee Goals:
– Standardize all QC tests for all digital Mfrs
– Standardize test frequencies
– Standardize performance criteria
What Will Be New?
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The ACR DM Phantom Prototype
Phantom Prototype Design Principles
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Phantom Prototype Design Principles
Phantom Prototype Design Principles
Based on existing ACR Accreditation Phantom
Similar imaging and scoring to current phantom
Build on experience of QC techs and physicists at ~8,700 USfacilities who already know how to use and score the existing phantom (~25,000+ techs)
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Phantom Prototype Design Principles
Can be used on both SFM & FFDM
Total attenuation matched to current SFM phantom– Similar thickness
– Similar total dose
Permits testing ofthe MQSA 3.0 mGy dose limit (single CC view)
Proposed Scoring Changes
Eliminate subtraction for artifacts
Add “Fail” for artifacts
New pass/fail criteria from
– 4,3,3
– To: 2,3,2
– **But, objects are the same (effective) size as
SFM Phantom
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Total Thickness = 4.10 + 0.03 cm
31.0 + 0.1 cm
Cover =Nominal 0.3 cm
Screws
19.0 + 0.1 cm
CNR Cavity (0.1 + 0.005 cm Deep)
Depth of CNR Cavity = 0.1 + 0.005 cm
2.0 + 0.05 cm
Centered Left to Right
2.5 + 0.05 cm
Milled out wax insert area
7.0 cm
(+0.04, -0.00 cm)
Compensator = 0.023 cm
Wax = 0.70 cm + 0.02 cm
Milled out wax insert area
13.0 cm (+0.04, -0.00 cm)1.0 + 0.05 cm
ID Tag
ACR Phantom PrototypeAir Gap = 0.027 cm Nominal
Total Insert Depth = 0.75 cm
Total Thickness Under Insert = 3.05 cm
Test object distance from base of wax = 0.35 + 0.10 cm
1.0 + 0.05 cm
1.0 + 0.05 cm
9.5 cm
Tolerances (Insert Well & CNR Cavity)• Wax insert well depth : + 0.005 cm (+ 2 mils).• Wax insert well width and length : + 0.04 / -0.00 cm.• CNR cavity depth : + 0.005 cm (+ 2 mils).• CNR diameter : + 0.05 cm.
12.98 cm (+ 0.00, - 0.04 cm)
6.98 cm
(+ 0.00, - 0.04 cm)2.0 cm
Wax Insert Specifications with Virtual “Placement Grid”
2.0 cm
0.49 cm
0.49 cm
2.0 cm
2.0 cm each0.49 cm
0.49 cm
Notes:
Test objects to be centered on their respective “placement grid” locations.
0.49 cm perimeter around test object “placement grid”.
0.635 cm (1/4 inch) radius on corners of wax insert.
45o + 5o
Fiber
45o + 5o
Fiber
Fiber specifications
Fiber Length = 1.0 cm + 0.1 cm
Fiber Diameter = See Table
Fiber Placement specs
Speck Placement & Specs
1. Specks to be placed at points on star and middle of star
2. Speck Size (spherical) = See Table
3. Center speck placement to be within + 0.1 cm of center of virtual grid
4. Distance from center speck to center of speck on perimeter = 0.5 cm + 0.1 cm
Mass Placement & Specs
1. Mass pre-cut sphere diameter = 5/8 inch
2. Mass placement to be within + 0.1 cm of center of virtual grid
ID TagID Tag
ID Tag Specs
Virtual Box: height = 0.5 cm, length = 1.8 cm
Location of Virtual Box 1.5 cm
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Test Object
Fiber DiameterSpeck Diameter(Glass Spheres)
MassThickness
mm mm mm
1 0.89 + 0.05 0.33 + 0.0100 1.00 + 0.05
2 0.75 + 0.03 0.28 + 0.0083 0.75 + 0.05
3 0.61 + 0.03 0.23 + 0.0069 0.50 + 0.05
4 0.54 + 0.03 0.20 + 0.0059 0.38 + 0.04
5 0.40 + 0.03 0.17 + 0.0084 0.25 + 0.03
6 0.30 + 0.03 0.14 + 0.0070 0.20 + 0.02
Wax Insert Test Object Specifications
Test Object
Fibers (mm)
Specks(mm)
Masses (mm)
ACR 156 FFDM ACR 156 FFDM ACR 156 FFDM
1.56
1.12 0.54 2.00
0.89 0.89 0.40 1.00 1.00
0.75 0.75 0.32 0.33 0.75 0.75
0.61 0.28 0.50 0.50
0.54 0.54 0.24 0.23 0.38
0.40 0.40 0.20 0.25 0.25
0.30 0.16 0.17 0.20
0.14
Summary of Test Object “Visual Equivalency”
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Test Object
Fibers (mm)
Specks(mm)
Masses (mm)
ACR 156 FFDM ACR 156 FFDM ACR 156 FFDM
1.56
1.12 0.54 2.00
0.89 0.89 0.40 1.00 1.00
0.75 0.75 0.32 0.33 0.75 0.75
0.61 0.28 0.50 0.50
0.54 0.54 0.24 0.23 0.38
0.40 0.40 0.20 0.25 0.25
0.30 0.16 0.17 0.20
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Pass/Fail Criteria
Pass
Fail
4 32 23
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The ACR DM Phantom Prototype
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Serial Number
*Note: Gray dot in lower left corner of wax insert is an artifact due to a bubble in wax insert.
Image of Entire Phantom
Wax Insert
Serial Number
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Expanded View of Wax Insert
Pass Criteria: 2 Fibers, 3 Specks, 2 Masses
Equivalent to SFM Phantom: 4 Fibers, 3 Specks, 3 Masses
Serial NumberPass
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•New FFDM phantom equalizes attenuation inside and outside wax insert.
•This permits evaluation of artifacts over entire phantom area with same
WW and WL used to score test objects.
Effects of Thickness Equalization
Serial Number
Benefits of Prototype Phantom Design
Provides view of entire detector – artifact evaluation
W/L optimized for test objects optimizes for artifact evaluation
Finer gradations and smaller sizes of test objects
AGD measurement & limit same as SFM – meets MQSA
Provides single image/exposure for evaluation(s)
Minimal training
Provides basis for monitor and printer QC
ACR Physics Reviewers– Can see scores and artifacts on single submitted film (or image)
– Do not need different WW/WL settings
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TechnologistSection
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Also:
Tally sheet
Daily Counting Sheet
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Technologist ManagementForms
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Facility Room ID
MAP ID-Unit# (00000-00) Unit Mfr & Model
AW & RW Monitor QC
Procedure: Display the AAPM TG 18-QC or SMPTE test pattern.
(Another pattern that allows relevant measurements may also be used.)
Check the monitor screens to verify they are clean.
Verify that 0%-5% and 95%-100% boxes are visible (red circles).
Verify that line-pair images are sharp and distinguishable (red rectangles).
Score the ACR DM Phantom & evaluate for artifacts (RW only).
If applicable, perform monitor calibration tests per manufacturer's recommendations.
Monitor manufacturer instructions for finding & viewing TG 18-QC test pattern:
SMPTE Test Pattern TG 18-QC Test Pattern
ACR Technique and Procedure Summaries (continued)
Facility Room ID
MAP ID-Unit# (00000-00) Unit Mfr & Model
Film Printer QC
Procedure: Required equipment - ACR DM Phantom image and densitometer
Print image acquired in "ACR DM Phantom Image Quality" test.
Print from workstation/computer/PACS used for printing most clinical films.
Do not adjust window and level settings prior to printing.
Evaluate the phantom for artifacts & score.Note: If possible, print phantom image from same x-ray unit each time for this test.
Note: Use film size most commonly used for mammography.
Note: For each printer, only print a single image from a single x-ray unit or workstation.
Date:
Dmax Note: Dmax to be measured on perimeter of film.
If not available, print a clinical image and measure
in the non-breast area.
Background OD Cavity OD
ACR Technique and Procedure Summaries (continued)
Fil
m P
rin
ter
Set
up
ID of x-ray unit or workstation for printed phantom:
Film Size (8 x 10 or 10 x 12):
Dmax
SN-1234
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Medical PhysicistSection
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2. ACR DM Phantom Image Quality
Facility Name Room ID, Mfr & Model
ACR DM Phantom Mfr and S/N MAP ID-Unit# (00000-00)SID (cm) Survey Date
Equipment: ACR DM Phantom (required) Phantom Setup: AEC mode:
Follow procedure in the Technologist's ACR Technique & Procedure Summaries: Paddle size (IR size):
• Use clinical technique for typical screening exam of 4.2 cm 50/50 breast Paddle type (reg or flex):
• Largest IR & paddle, 5 daN or 12 lbs, Score on AW View or selected image:
• Adjust W/L to optimize test objects, zoom & pan entire image Compression force:
• For Config 2 & 3 using kVp & mAs closest to phantom techniques AEC cell position (if avail):
Phantom patient name: Target/filter (if app): kVp (if app):
Phantom patient ID: Density setting (if app):
Image sent to which PACS? Mag factor (mag mode only):
Image receptor size
Analysis
Required: ACR DM Phantom image must be free of clinically significant artifacts.
Fiber score must be ≥2.0;; speck group score must be ≥3.0;; mass score must be ≥2.0.
SNR must be ≥40.0;; CNR must be ≥2.0;; measured wax insert distance must be 70.0 ± 14.0 mm.
Timeframe: Failures of required items must be corrected before clinical use.
Initiated (or updated) technologist's ACR Technique and Procedure Summaries form
SNR ≥40.0 (P/F)
Unit-indicated AGD (mGy)
#DIV/0!
Std dev of background
Calculated CNR
#DIV/0!
Mean background signal
Mean cavity signal
Imaging Facility Room 1, Unit Mfr, Unit Model
December 1, 2015
12345-xxPhantom Mfr 1234
70
Contact Mode
Manual - Target/Filter
Config 2
Manual - Target/Filter
Config 3
Phantom Setup
Target/filter
Manual - Target/Filter
Config 3
Clinical - ACR DM Phantom
Mag Mode
Clinical - ACR DM Phantom
Manual - Target/Filter
Config 2
largest
Phantom P/F
Mass score
Speck group score
Action Limits
Overall Pass/Fail
Meas = 70.0 ±14.0 mm (P/F)
Calculated SNR
CNR ≥2.0 (P/F)
SN
R &
CN
R
R
aw I
mag
e
Fiber score
Artifacts P/F
mAs
DC offset (if applicable)
AC
R D
M P
han
tom
E
valu
atio
nR
esu
ltin
g
Tec
hn
iqu
es(if
ava
ilabl
e)
kVp
≥ ¾ border
4 - 6 specks
≥8 mm long
Full Point
≥ ½ & < ¾border
2 - 3 specks
≥5 & <8 mm
Half Point
Parallel to A-C axis (mm)Distance Measurement
Fibers
Specks
Masses
Distance
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Serial Number
Mean = 542.3 Mean = 498.5
St. Dev = 7.8
CNR
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D = KgcsD = Mean Glandular Dose
K = Entrance surface air kerma
g = glandularity of 50%
c = corrects for difference in composition (age dependent)
s = X-ray spectrum correction (Target/Filter)
Note: g and c depend on thickness, glandularity, and HVL.
Primary Ref: D.R. Dance, et al. Additional for the Estimation of Mean Glandualar Breast Dose Using the UK Mammography Dosimetry Protocol. Physics in Medicine and Biology 45, 3225-3240, 2000.
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ACR DM QC Manual – Status
In September 2014, draft sent to manufacturers, select technologists and medical physicists for review– We hope manufacturers will adopt this manual
Extensive comments received in October– Reviewed and incorporated as appropriate
Updated draft sent to FDA in February 2015
Comments and instructions for implementation received from FDA late April 2015
ACR DM QC Manual – Status (continued)
ACR will respond to comments
ACR must apply for FDA alternative standard under current regulations– Alternative standard will allow facilities to use this instead
of the manufacturer’s manuals
– Tomosynthesis QC to be added as Appendix after FDA approval
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Top Strengths & Take Home Points
• QC Manual is comprehensive
• Phantom is of major importance
• Most failures are artifacts
• Includes most “legacy” tests
• Includes most “current” manufacturer tests
• Accommodates mfr specific test (where app)
• Accommodates growth of QC program
• Manual can realistically be implemented
End of Presentation
Questions?