Revision History


Documentation of quality control (QC) is required as part of the application process. All facilities applying for accreditation must comply with the minimum frequencies listed below. As part of the accreditation application, facilities must demonstrate compliance with the ACR requirements for QC by providing:

  • Report from the most recent annual survey performed by the medical physicist or designee

  • Documentation of corrective action if the annual survey and/or QC data identifies performance problems


The committees on ultrasound and breast ultrasound accreditation understand that QC is a vital part of quality imaging and patient safety. Medical physicist and radiologist members of both committees decided on the tests and frequencies to be performed, as well as who is responsible for their performance.  


The ACR strongly recommends that QC be done under the supervision of a qualified medical physicist (QMP). The QMP may be assisted by properly trained individuals in obtaining data, as well as other aspects of the program. These individuals should be approved by the QMP, if available, in the techniques of performing tests, the function and limitations of the imaging equipment and test instruments, the reasons for the tests, and the importance of the test results. The QMP should review, interpret, and approve all data. If it is not possible for a QMP to perform the tasks designated for a medical physicist, these tasks may be performed by other appropriately trained personnel with ultrasound imaging equipment experience. The ACR strongly recommends that the training be provided and documented by a QMP. If unable to acquire training by a QMP, training can be achieved through the ultrasound equipment manufacturer or through an appropriate course. These individuals must be approved by the physician(s) directing the clinical ultrasound practice.


Presentation of documentation of training is not required as part of the accreditation application. However, the facility must be sure all requirements for personnel are met when applying for accreditation with the ACR. During ACR site visits, surveyors will ask to see verifying documentation. Failure to demonstrate that personnel are qualified could adversely affect accreditation status.

 

Acceptance Testing (Optional)

Initial performance testing of newly installed imaging equipment should be performed and should be completed before clinical use. This includes purchases of new scanners and/or transducers, as well as replacement equipment obtained under warranty or service contract. Acceptance testing should be done following equipment repair and may also be warranted following major equipment upgrade. Equipment pulled from storage should also undergo acceptance testing. This testing should be comprehensive and include all tests done for the annual survey (see below) to provide complete performance baselines for comparison with future test results.


While not required, there is value to be gained by a clinical practice in doing acceptance testing, if only to verify to the practice that the equipment will perform as expected when purchasing new imaging systems. It would provide a performance baseline for comparison against the annual survey. This will also establish the timeframe for subsequent annual surveys.


Annual Survey (Required)

Annual surveys are complete tests performed once a year by the medical physicist or designee to assess the performance of the equipment. Although annual surveys include all of the same tests conducted during routine QC testing, the annual survey is intended to be more extensive. In addition, annual surveys include an evaluation of the facility’s routine QC program, if applicable.


Unless otherwise designated, the QC tests listed in the table below are required and must be performed at least annually on all machines and transducers in routine clinical use. All facilities applying for accreditation or renewal must demonstrate compliance with the ACR requirements for QC by including a copy of the facility’s most recent annual survey summary. The QMP (or designee) may use whatever forms he/she deems appropriate for the Annual Survey; however, the medical physicist (or designee) must also provide a summary of the Annual Survey pass/fail test results. He/she may complete the ACR’s Ultrasound/Breast Ultrasound Equipment Annual Survey Summary or may provide his/her own summary as long as it itemizes the pass/fail results for each required test.


The ACR realizes that surveys cannot usually be scheduled exactly on the anniversary date of the previous survey; therefore, a period of up to 14 months between surveys is acceptable. A signed report describing the results of the acceptance tests and annual equipment surveys must be provided to the physician(s) directing the clinical ultrasound practice and the responsible professional(s) in charge of obtaining or providing necessary service to the equipment. This communication must be provided in a timely manner consistent with the importance of any adverse findings.


Either subjective visual methods or objective computer-based approaches may be used to make measurements1. If subjective methods are used, it is recommended that the images used to perform the tests be retained for comparison with subsequent test images. Tests of uniformity, geometric accuracy, system sensitivity, and contrast and spatial resolutions must be made using an ultrasound phantom or test object. The ACR does not specify the phantom(s) to be used. Phantoms may be obtained from a variety of commercial vendors or may be fabricated by experienced personnel. Other approaches to performance measurement, e.g., the “paper-clip test”5 and use of transducer evaluation devices which test the electrical and acoustic characteristics of each individual transducer array element6, may also be used, but may not replace any of the required tests. Additional information may be found in the ACR-AAPM Technical Standard for Diagnostic Medical Physics Performance Monitoring of Real Time Ultrasound Equipment . 


Annual Survey (System Performance Evaluation)

QC Test

Description

Physical and Mechanical Inspection

Assures the mechanical integrity of the equipment, and the safety of patient and operator.

Image Uniformity and Artifact Survey

Identifies the presence of artifacts, often axial or lateral streaks in scans of uniform sections of a phantom. The use of “in-air” images (i.e., images acquired without the use of gel or phantom) may also be useful in detecting superficial artifacts; however, the potential limitations to the “in-air only” approach (e.g., limited sensitivity, especially for sector/vector probes) do not support use of in-air images only as a valid approach. In-air images could be used in this evaluation along with other assessment data, e.g., phantom images.

Geometric Accuracy (Optional)

Commonly involves use of the scanner calipers to measure known distances between phantom test targets in the axial and lateral directions and also in the elevational direction for 3D probes. Other tests of geometric accuracy are acceptable, e.g. verifying accuracy of the pixel size calibration in the image header.

System Sensitivity

Methods relying on visual determination of the maximum depth of visualization of speckle patterns or phantom targets, and quantitative measurements of signal-to-noise ratio (SNR), have been reported.

Ultrasound Scanner Electronic Image Display Performance

Maintaining the performance of the image display is critical for providing the greatest diagnostic benefit of the scanner. Display characteristics that are evaluated may include gray scale response and luminance calibration, presence of pixel defects, and overall image quality. These evaluations are typically performed using specialized test pattern images, and may also require photometric equipment. See ACR-AAPM-SIIM Technical Standard for Electronic Practice of Medical Imaging.

Primary Interpretation Display Performance (Only required if located at the facility where ultrasound is performed; otherwise optional)

Primary diagnostic displays may be electronic soft-copy displays on a PACS workstation or hard-copy films. They should also include worklist monitors only if used for primary interpretation (other than color analysis). Display characteristics that are evaluated may include gray scale response and luminance calibration, presence of pixel defects, and overall image quality. These evaluations are typically performed using specialized test pattern images, and may also require photometric equipment. See ACR-AAPM-SIIM Technical Standard for Electronic Practice of Medical Imaging for additional information on tests and testing methods.

Contrast Resolution (Optional)

The use of both anechoic and low contrast echogenic targets has been suggested, as has the use of 2D cylindrical targets and 3D spherical targets.

Spatial Resolution (Optional)

Should be measured in the axial, lateral, and elevational directions. Various approaches have been described for these measurements via visual interpretation of groups of phantom pin/fiber targets and using computer-based algorithms to measure pin dimensions(1-4).

Evaluation of QC Program (if applicable)

Provides an independent assessment of the QC program, checks that appropriate actions are taken to correct problems, identifies areas where quality and QC testing may be improved, and enables a comparison of QC practices with those of other ultrasound sites.

References

  1. Goodsitt MM, Carson PL, Witt S, Hykes DL, Kofler JM, Jr. Real-time B-mode ultrasound quality control test procedures. Report of AAPM Ultrasound Task Group No. 1. Med Phys 1998; 25: 1385-1406.
  2. Gibson NM, Dudley NJ, Griffith K. A computerised quality control testing system for B-mode ultrasound. Ultrasound Med Biol 2001; 27:1697-1711.
  3. Thijssen JM, Weijers G, de Korte CL. Objective performance testing and quality assurance of medical ultrasound equipment. Ultrasound Med Biol 2007; 33: 460-471.
  4. Skolnick ML. Estimation of ultrasound beam width in the elevation (section thickness) plane. Radiology 1991; 180: 286-288.
  5. Goldstein A, Ranney D, McLeary RD. Linear array test tool. J Ultrasound Med 1989; 8: 385-397.
  6. Moore GW, Gessert A, Schafer M. The need for evidence-based quality assurance in the modern ultrasound clinical laboratory. Ultrasound 2005; 13: 158-162.


If the annual survey test results fall outside of the acceptable limits, corrective action must be taken. Appropriate action must occur immediately if there is imminent danger to patients or staff using the equipment due to unsafe conditions. However, for other cases there is no specific timeframe required by the ACR. You should consult your medical physicist/service person regarding the seriousness of the failure to determine how quickly corrective action should be implemented. The ACR will not grant accreditation if documentation of compliance with ACR QC requirements is not provided; if any tests fail, you must provide documentation of corrective action with your accreditation material.

 

Quality Control Tests (Optional)

A continuous QC program is essential to assure the proper functioning of all ultrasound equipment and to identify problems before the diagnostic utility of the equipment is significantly impacted7,8. Routine QC tests are outlined in the table below and unless otherwise noted, should be conducted semiannually, at minimum. Routine QC is typically performed by appropriately trained sonographers or equipment service engineers. The lead sonographer is not required to conduct routine QC, and you do not need to notify ACR of the designated staff performing QC. At this time, the ACR does not provide forms to record data from routine QC tests. We suggest working with your qualified medical physicist to help develop your own forms or contacting the equipment manufacturer.


If any test results (acceptance tests, annual survey, QC) fall outside of the acceptable limits, corrective action must be taken. This is typically accomplished by an equipment service engineer. Appropriate action and notification must occur immediately if there is imminent danger to patients or staff using the equipment due to unsafe conditions. After a problem has been addressed, acceptance testing should be performed to assure adequate resolution of the problem, and these test results should be documented.



Routine QC

QC Test

Description

Physical and Mechanical Inspection

Assures the mechanical integrity of the equipment, and the safety of patient and operator.

Image Uniformity and Artifact Survey

Identifies the presence of artifacts, often axial or lateral streaks in scans of uniform sections of a phantom. The use of “in-air” images (i.e., images acquired without the use of gel or phantom) may also be useful in detecting superficial artifacts (an in-air only approach to uniformity assessment for the routine QC test is reasonable and acceptable; a good implementation would provide baseline images of the reverberation/interference pattern for comparison to aid in detecting potential uniformity problems). All transducer ports on each scanner should be tested using at least 1 transducer. In the case of single probe, it is likely left plugged into the same port all the time, and other ports are not used. In this case, not testing the other ports would be acceptable for accreditation purposes.

Geometric Accuracy (Mechanically scanned transducers only)

Commonly involves use of the scanner calipers to measure known distances between test targets. Measurement is required only in the mechanically scanned directions.

Ultrasound Scanner Electronic Image Display Performance

Maintaining the performance of the image display is critical for providing the greatest diagnostic benefit of the scanner. They should also include worklist monitors only if used for primary interpretation (other than color analysis). Display characteristics that are evaluated may include gray scale response, presence of pixel defects, and overall image quality. These evaluations are typically performed using specialized test pattern images. See ACR-AAPM-SIIM Technical Standard for Electronic Practice of Medical Imaging for additional information on tests and testing methods. 

Primary Interpretation Display Performance (Only required if located at the facility where ultrasound is performed; otherwise optional)

This test should be performed semiannually, or as judged appropriate based on the specific display technology, or prior QC testing data. Primary diagnostic displays may be electronic soft-copy displays on a PACS workstation or hard-copy films. Display characteristics that are evaluated may include gray scale response and luminance calibration, presence of pixel defects, and overall image quality. These evaluations are typically performed using specialized test pattern images and may also require photometric equipment. See ACR-AAPM-SIIM Technical Standard for Electronic Practice of Medical Imaging for additional information on tests and testing methods.

References

7. Mårtensson M, Olsson M, Brodin LÅ. Ultrasound transducer function: annual testing is not sufficient. Eur J Echocardiogr. 2010 Oct; 11(9): 801-5.

8. Hangiandreou NJ, Stekel SF, Tradup DJ, Gorny KR, King DM. Four-year experience with a clinical ultrasound quality control program. Ultrasound Med Biol. 2011 Aug; 37(8):     1350-7.


The ACR will not ask for documentation of routine QC performed by the sonographer as part of the accreditation application. Although strongly recommended to ensure continual acceptable performance of US equipment, semiannual QC is no longer required for submission for ACR US accreditation.

 

Preventative Maintenance

Regular preventive maintenance should be performed and documented by a qualified equipment service engineer following the recommendations of the equipment vendor.



Revision History for this Article

Date

Section

Description of Revision(s)

12-12-19

All

Article created; FAQs incorporated; No criteria changes



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