고려대학교 구로병원

강 대 현kangsono@naver.com

Goal of Ultrasound QA/QC ProgramGoal of Ultrasound QA/QC Program

• To make sure a system is set up correctly and performs to specified standards.

( 장비의 올바른 설치와 기준에 맞는 작동을 보장 )

• To maintain the consistency of the performance. ( 장비 성능의 일관성 유지 )

• To reveal problems at its earliest stage before it severely interferes with the clinical practices.

( 임상업무를 심각하게 방해 하기 전에 초기에 문제점을 밝혀낼 수 있다 )

• 장비의 정확하고 지속적인 성능 유지 초음파 영상의 진단능력을 항상 최고로 유지시키기 위함

Good Quality Assurance willGood Quality Assurance will

• ensure proper equipment operation

• detect gradual changes in performance

• minimize equipment down time

• reduce the number of repeat scans

• optimize operator and patient safety

When should quality assurance When should quality assurance bebe performed?performed?

• Routine preventative maintenance

( 기본예방정비 )• Performed by Sonographer on daily or weekly basis

• Routine performance testing

( 기본성능시험 )• Performed by Sonographer on weekly or monthly

basis

• Acceptance testing( 승인검사 )• Performed when new equipment arrives and is

installed.

Three Levels of Ultrasound QC Three Levels of Ultrasound QC TestingTesting

• Level 1 – Frequent QC testingLevel 1 – Frequent QC testing : Operator’s QC

• Level 2 – Semi-annual or annual QC Level 2 – Semi-annual or annual QC testingtesting

: Physicist’s QC

• Level 3 – Acceptance testingLevel 3 – Acceptance testing / baseline set-up

Guideline ByGuideline By

The Institute of Physical Sciences in Medicine (IPSM, 미국의학물리과학협회 )

Report No. 70

“Testing of Doppler Ultrasound Equipment”

Edited by PR Hoskins, SB Sherriff and JA Evans

York: ISPM, 1994

Guideline ByGuideline By

The Institute of Physical Science in Medicine (IPSM, 미국 의학물리과학협회 )

Report No. 71

“Routine Quality Assurance of Ultrasound Imaging Systems”

Edited by R. Price

York: ISPM, 1995

Guideline ByGuideline By

American Institute of Ultrasound in Medicine (AIUM, 미국 의학초음파 학회 )

“Quality Assurance Manual for Gray Scale Ultrasound Scanners (Stage 2)”

Edited by E. Madsen

AIUM, Laurel, MD, 1995

American Association of Physicists in Medicine (AAPM, 미국 의학물리협회 )

Ultrasound Task Group No. 1

“ Real-time B-mode ultrasound quality control test procedures”

By MM Goodsitt et al

Medical Physics. 25(8):1385-406, 1998 Aug.

Guideline ByGuideline By

ACR Accreditation (ACR Accreditation ( 인가인가 ))

www.acr.org• Breast Ultrasound Accreditation Program

(including Ultrasound-guided Breast Biopsy)• General Ultrasound Accreditation Program

• Obstetrical• Gynecological• General• Vascular• Combination of the above

AIUM AccreditationAIUM Accreditation

www.aium.org• Ultrasound practices in various fields:

• Breast• Obstetrical and Trimester-Specific

Obstetrical• Gynecological• Abdominal/General

ACR Accreditation QC ACR Accreditation QC RequirementsRequirements

• A QA program should be in place;• The QA program must be directed by a

medical physicist or the supervising physician ;• Routine QC testing must be done at least

semi-annually ;• Do the same tests, monitor changes over time

and take corrective actions when necessary ;• Testing results, corrective action, and the

effects of corrective action must be documented and maintained on site.

• There is currently no ACR-preferred single phantom.

ACR Recommended ACR Recommended Semi-Annual QC TestsSemi-Annual QC Tests for for Breast Ultrasound AccreditationBreast Ultrasound Accreditation

• Maximum depth of visualization• Distance accuracy (vertical and horizontal)• Uniformity• Electrical-mechanical cleanliness condition• Anechoic void perception• Ring down• Lateral resolution• Quality Control Checklist

ACR Recommended ACR Recommended Technologist’s QC TestsTechnologist’s QC Tests for for

Breast Ultrasound AccreditationBreast Ultrasound Accreditation

• Adherence to universal infection control procedures for each biopsy

• All transducers should be cleaned between patients

• Distance calibration – quarterly

• Gray scale photography - quarterly

ACR Required ACR Required semi-Annual QC Testssemi-Annual QC Tests for for

General Ultrasound AccreditationGeneral Ultrasound Accreditation

• System sensitivity and/or penetration capability

• Image uniformity• Photography and other hard copy recording• Low contrast object detectability (optional)• Assurance of electrical and mechanical safety• Vertical and horizontal distance accuracy

(recommended only when the program is initiated for a scanner)

Daily or weekly check listsDaily or weekly check lists• General Machine Cleanliness

• Keyboard and knobs clean• Monitors clean• Air Filters cleans

• Mechanical and Electrical• Wheels fastened securely and rotate easily?• Wheels locks work well?• Accessories fixed securely?• Cords attached securely?

• ALI Workstation• Contrast and Brightness between scanner and workstation

• Transducer Inspection (for each probe)• Cables• Transducer Cracks • Matching layer delaminations

Assurance of Electrical and Assurance of Electrical and Mechanical SafetyMechanical Safety

The equipment related physical checks are also worth attention. These include:• Checking for any cracks or delamination in the

transducers• Noting for loose and frayed electric cables, loose

handles or control arms• Checking the working condition of the wheels and

the wheel locks• Making sure all the accessories (such as VCR, printer,

etc.) are fastened securely to the system• Making sure the image monitors are clean and the

air filter are not dusty

General Machine CleanlinessGeneral Machine Cleanliness /PhilipsPhilips

System Power Switch

Filter

Main Power Switch( 장비 뒷 편에 위치 )

Monitor Control

Filter

Power Switch

IU 22 SystemIU 22 System Envisor SystemEnvisor System

HDIHDI®®

5000 System 5000 System

SystemPower Switch

MainPower Switch( 장비 뒷 편에 위치 )

Filter

Monitor Control

Philips Philips

ACCUVIX System Track ballACCUVIX System Track ball

MedisonMedison

ACCUVIX Filer

MedisonMedisonACCUVIX System FilterACCUVIX System Filter

제품 뒤쪽 화살표 부위를 청소한다 .

MedisonMedisonSA8000 System FanSA8000 System Fan

Accuvix

AcusonAcusonSequoia 512 System Sequoia 512 System

Filter : 장비의 후면에 위치

System Power switch

Main Power switch

Key board

AcusonAcusonAntares System Antares System

System Power switch Main

Power switch

Filter : 장비의 후면에 위치

AcusonAcusonG50/ G60SG50/ G60S

Both Filter : 본체 전면 하단 다리측 2 개

System Power switch : 장비 좌측하단

Mechanical and Electrical checkMechanical and Electrical check

Transducer Inspection checkTransducer Inspection check

Transducer Cleaner

Annually or semi-annually check Annually or semi-annually check listslists

• Performance test• Dead zone test • Vertical Measurement accuracy test• Horizontal Measurement Calibration• System sensitivity test • Uniformity test • Grayscale photography test • Axial resolution test • Lateral resolution test • Functional resolution, Definition and Fill-in

• Doppler QC tests • Doppler signal sensitivity• Doppler angle accuracy• Color display and Gray-scale image congruency• Range-gate accuracy• Flow readout accuracy

Ultrasound QC PhantomsUltrasound QC Phantoms

B-mode:1. Multi-purpose or general purpose

tissue/cyst phantom2. Low contrast resolution phantom3. Spherical lesion phantom4. Beam profile and slice thickness phantom5. Prostate QC phantom

Doppler-mode:1. Flow phantom2. String phantom

Multipurpose Phantom Multipurpose Phantom Model Model 539539

Specifications of Multipurpose Phantom Model 539

1.Tissue-mimicking 1.Tissue-mimicking materialmaterial

- Speed of sound: 1,540m/sec

- Attenuation : 0.7 ㏈ / ㎝ / ㎒

- Freezing point: 0℃ (32℉)

- Melting point: 78℃(174℉)

2. Containers2. Containers- Wall : 3/8"Acrylic

- Scanning surface : 0.4mm

(0.015")polyurethane(saran)

3. Targets3. Targets- Cyst speed of sound :

1,540m/sec

- Cyst attenuation :

0.05 ㏈ / ㎝ / ㎒

- Nylon lines: 0.3mm

(0.012") diameter

- Phantom size and weight:

15×18×5Cm, 2.5Kg

Multipurpose Phantom Model 539

Scanning Scanning Target Target

DiagramDiagram

측정항목측정항목

• Dead zone test • System sensitivity and/ or penetration

capability test • Image Uniformity test • Grayscale photography and other hard copy

recording test • Axial and lateral resolution test • Functional resolution, Definition and Fill-in• Vertical and horizontal distance accuracy test

(recommended only when the program is initiated for a scanner)

측정 시 주의사항측정 시 주의사항

Scanning : vertical to Scanning : vertical to phantom surfacephantom surface

Dead Zone (Ring down)Dead Zone (Ring down)

A group of 9 reflectors consisting of fibers are placed at different separations from the top of the phantom(~2-10mm). As the transducer scan across the top, the distance from the transducer to the first reflector completely imaged is equal to the dead zone (ring down)

distance.

Dead Zone (Ring down)Dead Zone (Ring down)

• Reduced near field resolution by Transducer-skin interface

Dead Zone (Ring down) Dead Zone (Ring down) test

Dead zone testDead zone test

2mm ~ 10mm , 9 targets

Distance Accuracy testDistance Accuracy test

• Scan the phantom with vertical column and a horizontal row of reflectors;

• The digital caliper readout on screen is checked against the known distance between reflectors (10cm);

Criteria• Vertical : 1,5% of the actual distance or 2mm,

whichever is greater.• Horizontal : 3% of the actual distance or 3mm,

whichever is greater.

Vertical Distance accuracy testVertical Distance accuracy test

Horizontal Distance accuracy testHorizontal Distance accuracy test

System Sensitivity/PenetrationSystem Sensitivity/Penetration

This test should be done with following setting:• Maximum transmit power• Proper receiver gain and TGC that allows echo

texture to be visible in the deep region• Transmit focus at the deepest depth

The maximum depth of visualization is determined by comparing the gradually weakening echo texture to electronic noises near the bottom of the image.

Do this test with the same setting and monitor the changes over time.

System Sensitivity/PenetrationSystem Sensitivity/Penetration

3.5 MHz

12 MHz

7 MHz

Axial and Lateral ResolutionAxial and Lateral Resolution

Spatial resolution may be evaluated by either of the following ways:

• Count the number of the pins distinguished without overlap in lateral and axial direction; thus the minimum target spacing is documented

• Measure the size of the pin in lateral and axial direction

Axial resolution testAxial resolution test

Axial Resolution ArrayAxial Resolution Array

3.0 mm3.0 mm

2.0 mm2.0 mm

1.0 mm1.0 mm0.5 mm0.5 mm

0.25 mm0.25 mm

1.0 mm1.0 mm

0.25mm

Lateral resolution testLateral resolution test

Lateral Resolution ArrayLateral Resolution Array

3.0mm

2.0mm

1.0mm

0.5mm

0.25mm

3.0mm

3 mm

Image UniformityImage Uniformity

Adjust the TGC controls and other sensitivity controls to obtain an image as uniform as possible

Inspect the image to detect any kinds of• Vertical or radially oriented streaks( 수직 또는

방사형태로 출현하는 줄무늬 )• Dropouts• Reduction of brightness near edges of the

scan( 주사면 끝부분의 밝기 저하 ) • Brightness transitions between focal zones (

초점 영역 사이의 밝기 변화 )

Image UniformityImage Uniformity

Functional resolution, Definition Functional resolution, Definition and Fill-inand Fill-in

• QA Phantom 에서 anechoic structure 의 spherical targets 를 명확하게 detection 할 수 있는 능력• 2, 3, 4, 6, 8mm diameter spherical targets

Functional resolution, Definition Functional resolution, Definition and Fill-inand Fill-in

1 1/2D (Matrix) Transducer1 1/2D (Matrix) TransducerConventional array TransducerConventional array Transducer

• 초음파 영상은 단면초음파 영상은 단면 data data 가 아니라가 아니라 volume data volume data 이기 때문이기 때문임임 ..

Soft and/or Hard Copy Recording ⅠSoft and/or Hard Copy Recording ⅠThe shades of gray, weak, and strong echo

texture should be optimized and consistent between the image display on the ultrasound scanner and the photographic hard copies or soft copy displays on the workstation in the reading room.

For quick follow-up testing, the Gray-scale bar pattern on the clinical image display can be used

Soft and/or Hard Copy Recording ⅡSoft and/or Hard Copy Recording Ⅱ

• Use the SMPTE test pattern and other patterns if they are available on the ultrasound scanner.

• Workstation monitor display should be included in QC tests.

Soft and/or Hard Copy Recording Soft and/or Hard Copy Recording ⅢⅢ

• Film processor QC needs to be done daily.• Darkroom fog test needs to be done at least

semi-annually.

Sensitometry

Low Contrast Object DetectabilityLow Contrast Object DetectabilityScan of a low contrast resolution phantom

can reveal the low contrast object detectability which is an optional test on the ACR semi-annual QC test list for general ultrasound accreditation.

Ultrasound Doppler QC TestingUltrasound Doppler QC Testing

• Doppler QC tests include• Doppler signal sensitivity• Doppler angle accuracy• Color display and Gray-scale image

congruency• Range-gate accuracy• Flow readout accuracy

Doppler String PhantomDoppler String Phantom

Doppler Velocity Accuracy: Variations among 6 clinical units, each with transducers of 3.5MHz, 5MHz and 7 MHz.

Flow Rate (ml/min)

Frequency

100

237

398

611800

1093

AVG

3.5MHz 5.7% 10.2% 6.7% 8.0% 10.2% 13.0% 9.0%

5 MHz 17.4% 7.7% 10.6% 6.9% 13.9% 13.0% 11.6%

7 MHz 8.2% 8.2% 4.1% 9.2% 7.1% 12.5% 8.2%

Average 10.4% 8.7% 7.1% 8.0% 10.4% 12.9% 9.6%

DiscussionDiscussion

• The guidelines for ultrasound QA/QC programs are descriptive.

• Maintaining an ultrasound QA/QC program is straightforward and testing consistency. However, we need to know that the tissue mimicking material can only mimic some of the properties of tissue in real clinical situations.

• Assessment of the efficacy and relevance of ultrasound QA procedures is rare.

• The guidelines need to be updated periodically as ultrasound technology develops.