Abstract
Quality Assurance of ultrasound systems is necessary to ensure the reliability of results and to check for deterioration in performance; a number of bodies have produced guidelines. Testing has traditionally been the responsibility of Medical Physics Departments but the important role of sonographers has been recognised and recent publications have included tests to be performed by ultrasound users. Since there are differences in approach between these publications the BMUS QA Working Party was established to provide a consistent set of guidelines specifically for sonographers. Three levels of testing are recommended, to include infection control and inspections for scanner and probe damage, basic display checks and further tests to assess drop-out, sensitivity and noise. These tests should form part of a programme that includes more comprehensive testing at longer intervals, perhaps by a Medical Physics Department.
Keywords
Introduction
The purpose of quality assurance (QA) of ultrasound systems is to ensure that consistent, reliable results are provided and to check for deterioration of equipment performance. A number of UK standard setting and professional bodies require or recommend QA and have produced publications relevant to ultrasound.1–7
Traditionally, QA performance testing has been seen as the domain of the Medical Physics Department, involving extensive use of tissue mimicking phantoms (TMPs) and other test devices. Over time it has been recognised that sonographers have an essential role in the QA of ultrasound scanners.
The perceived importance of such tests has been somewhat eroded by the misconception that many of the issues they look for can readily be observed during routine scanning and appropriate action taken. Whilst this may have been the case several years ago, the level of processing applied to routine presets on an ultrasound scanner often masks such issues. It is therefore necessary to undertake tests where the minimum of image processing is applied and fundamental problems can then be readily observed.
QA guidelines have been produced by the IPEM (2010) 7 the AIUM (2008) 8 and EFSUMB (2012), 9 all of which involve tests performed by sonographers. However, the three organisations suggest slightly different approaches for sonographers’ testing.
The purpose of these BMUS guidelines is to put in one place relevant guidelines for QA for sonographers including protocols, while at the same time trying to be consistent with the existing guidance above. Sonographer QA should be seen as part of a programme that includes more comprehensive testing at longer intervals, which may be provided by a Medical Physics Department.7,9 The guidelines have been trialled by sonographers in several centres, and their feedback incorporated into the final version.
Guidelines
These are guidelines for the performance of QA on ultrasound systems by sonographers. There are three levels of QA:
Level 1. Infection control and scanner damage Level 2. Basic scanner and transducer testing Level 3. Further scanner and transducer testing
Level 1 procedures have a two-fold purpose. The first is to ensure that the scanner is clean and that infection control risks to patients and staff are minimised. Secondly, checks are performed to detect any damage to the scanner, especially to the transducers and their cables. Infection control measures are relevant for every patient so that some of these actions are performed several times each day. Checks for scanner damage are performed weekly.
Level 2 procedures ensure appropriate setting of video monitor controls for consistency of imaging. They also provide a first-line evaluation of scanner performance but without the use of test tools or test objects. These tests are performed daily.
Level 3 procedures provide further evaluation of scanner performance using a very simple test tool. These checks are designed to look for scanner faults and are performed monthly.
Level 1 and 2 tests should form part of the ongoing activities of the sonographer and should not require dedicated time to be set aside, other than for simple documentation at the end of the day. Level 3 tests do require the sonographer to set aside dedicated time. Trialling of these guidelines suggest that this is no more than 15 minutes per week per scanner to perform the tests, document the results, undertake any follow-up action and return the scanner settings to their usual values.
The guidelines are contained in the tables below. These provide details of the task, the recommended frequency of performance of the task, relevant action levels and action to be taken in the event that a fault is detected. Details of protocols are provided in the appendix. Faults or results out of tolerance should be notified to the locally identified responsible person, for example the department manager or the Medical Physics Department, who will decide on further action according to local procedures, including any testing with TMP.
Level 1. Infection control and scanner damage
Weekly checks should be performed either before switching the scanner on or after switching it off.
Level 2. Basic scanner and transducer testing
Level 3. Further scanner and transducer testing
