A method and system for ultrasound quality assurance testing

Abstract

A method of remote quality assurance for ultrasound systems comprises: receiving 16 from the user at a remote location an ultrasound image of a test object; processing the received image to determine quality assurance parameters of the ultrasound system under test; and providing a notification to the user at the remote location the results of the quality assurance determination. The testing system comprises a data store and a processor. The method may comprise receiving an ultrasound image scanning in-air, and processing the image scanning in-air and the ultrasound image of the test object to determine one or more quality assurance parameters of the ultrasound system under test. The method may further comprise performing QA tests 18, such as uniformity, drop-out, reverberation threshold or depth, B-mode noise level, grey level, pulsed wave Doppler noise threshold, colour Doppler noise threshold, cable noise, SNR and penetration depth (sensitivity).

Description

The present invention relates to a method and system for ultrasound quality assurance testing. Quality Assurance (QA) testing of all ultrasound devices is required by professional bodies such as British Medical Ultrasound Society BMUS, Institute of Physics and Engineering in Medicine IPEM and the Society of Radiographers SoR. Historically, ultrasound QA has been performed by a medical physicist using an expensive and complex test object. Testing typically takes 3-4 hours on the hospital site at a cost of £600-£1200 per scanner and must be performed annually. Handheld ultrasounds are becoming increasingly more popular. It is expected that in years to come such devices will become common for medical professionals in the same way as, sat stethoscope are currently. These devices may be referred to as "pocket ultrasound" devices and the use of them has increased significantly in recent years. It is estimated that 11,000 units were shipped worldwide in 2018 and 37,000 in 2021, with a predicted total of 59,000 sales in 2025 (OMDIA, 2021). This popularity Is not surprising given that they have a wide range of applications, are simple to use and are inexpensive. While hospital-based Ultrasound machines typically cost around £60,000, pocket ultrasound devices can be purchased for as little as £1,500 (OMDIA, 2021). The availability of ultrasound imaging is a positive outcome for patients and for medical professionals alike. However, it presents a problem regarding compliance with standards and access to QA. Generally, Diagnostic Ultrasound QA is a series of routine user and physics tests and checks that can be performed to monitor aspects of performance that are considered likely to change or deteriorate and importantly, may affect clinical efficacy. Typically, such tests can be performed daily, monthly, and annually. Testing can be performed to assess uniformity, crystal dropout, sensitivity and other image quality characteristics of the ultrasound device. Uniformity in ultrasound can be generally understood as the response or image produced being homogenous when the tissue being imaged is the same. A lack of uniformity can manifest in for example a line through an image due to a faulty component or non-functioning element which can result in image artefacts and / or affect Doppler measurements. In this context, sensitivity can be defined as the ability of the transducer elements to detect and identify weak returning echoes from background noise in an imagescanner system. A reduction or loss of sensitivity will result in reduced penetration and resolution. The present applicant specializes in ultrasound QA and has been active in this technical area for ten years. However, it has recognized that there is no technically reliable (and cost-effective) method of testing that can be scaled or used with the large increase in numbers of active pocket ultrasound devices. Current Ultrasound QA methods costing £600-£1200 are not economically viable for handheld ultrasound users where the devices cost approximately £3-6k. However, without the testing and the QA provided, users cannot be assured their device is safe and ultimately patients being scanned cannot rely on the images and data derived from scans that are undertaken using the machines or systems. Furthermore, a national shortage of ultrasound physicists means they are only found in larger hospitals (over 26% of current physicists are reaching retirement IPEM 2016). Traditional cart-based ultrasound continues to grow faster than any other imaging modality and there is a need to increase physicists to meet this demand. This is further compounded and complicated by the introduction of handheld devices, which are sometimes owned by the users and used both for private practice and within the NHS and the community. The management of these devices is crucial for patient safety (RCR 23) Despite the already significant popularity of pocket ultrasound devices, the currently available methods and systems for QA do not provide an economically viable way to test handhelds and inexpensive ultrasound systems. According to a first aspect of the present invention, there is provided a method of remote quality assurance for ultrasound systems, the method comprising: receiving from the user at a remote location an ultrasound image of a test object, an ultrasound image of the device scanning “in-air” and some camera photos of the physical condition of the ultrasound device; processing the received ultrasound images to determine quality assurance parameters of the ultrasound system under test; providing a notification to the user at the remote location the results of the quality assurance determination. In an embodiment, the method comprises providing the user with a test object for use with the method of remote QA. The user is preferably provided with a low-cost and easy-to-use test object for generating the ultrasound image of the test object. The present method and system a thus a user-led distributed QA system, arranged which uses a simple and low-cost test object. This enables the low-cost and broadly available ultrasound QA and testing. This contrasts markedly with known and conventional ultrasound QA that is performed by a medical physicist using an expensive and complex test object. In an embodiment, the method comprises communicating captured images to the remote location from the user using a personal transmission device. In an embodiment, the personal transmission device is intrinsic to the ultrasound system or is provided by a mobile telephone separate from the ultrasound system. In an embodiment, the method comprises performing defined QA tests on images received at the remote location and providing results to the user. In an embodiment, the method comprises storing results for the user and the tested ultrasound system at the remote location. In an embodiment, the tests are selected from the group consisting of uniformity, drop-out, reverberation threshold, reverberation depth, B-mode noise levels, grey-level pulsed wave Doppler noise threshold, colour Doppler noise threshold, cable noise, signal to noise ratio, and penetration depth (sensitivity). In an embodiment, the test object is silicon-based.. In an embodiment, the test object has interface portions shaped to engage an ultrasound transducer for testing. In an embodiment, the test object has at least three interface portions, each shaped differently to engage with a respective different type of ultrasound transducer for testing. In an embodiment, the test object has a cylindrical cavity which houses removable cylindrical inserts of varying attenuation. An anechoic insert will allow measurement of B-Mode noise levels and signal to noise ratio (see the example of Figure 3B). According to a second aspect of the present invention, there is provided a testing system for remote quality assurance for an ultrasound system under test, the testing system comprising: a data store for receiving from a user at a remote location an ultrasound image of a test object, an ultrasound image scanning “in-air” and camera photos of the physical condition of the device; a processor to process the received image to determine quality assurance parameters of the ultrasound system under test and to provide a notification to the user at the remote location of the results of the quality assurance determination. In an embodiment, the system comprises a test object for imaging with the ultrasound system under test. In an embodiment, the system comprises an App on a computing device to prompt a user to capture an image of the test object and provide the image to the data store. In an embodiment, the computing device is a smart phone or a PDA. Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is schematic representation of an ultrasound QA system; Figure 2 is schematic flow diagram showing the steps in an Ultrasound QA method; Figure 3A is a schematic representations of a test object for ultrasound QA; Figure 3B is a schematic representation of another embodiment of a test object for ultrasound QA; and Figure 4 is schematic representation of the steps of obtaining and using an ultrasound QA App. As will be explained below, the present system enables the QA testing of a number of ultrasound systems, whether they are large cart-based systems or pocket ultrasound systems. In simple terms the present system enables distributed QA and remote service provision in a way that has not previously been thought possible. The combination of a particular simple test object and remote connectivity enables the ultrasound QA process to be performed and importantly scaled across any number of users or types of systems. Figure 1 is a simplified schematic view of an ultrasound QA system 1 according to the present disclosure. The system 1 comprises a user’s pocket ultrasound 3 together with a simple low-cost test object 5, to be described in greater detail below. A user’s mobile telephone or PDA 7 is included, having running in it an App 9, again to be described in greater detail below. The mobile telephone 7 is preferably connected via a network such as the internet to a data store, e.g. a database 13, in the cloud. The data store 13 contains a record or account for the user and the specific ultrasound device 3. As will be explained below the database is arranged to store images and data files provided over the network from the device 3, preferably via the mobile telephone 7. The device 3 and the mobile telephone 7 are connected by known means, e.g., Bluetooth or a wired connection. In some embodiments it is possible that the ultrasound device 3 itself has communication capability so it is able to transfer data or images directly to the cloud and database 13 without the need for the mobile telephone 7. The problems associated with the shortage of technically qualified people and the inevitable inefficiency of having them travel from site to site is addressed by the system shown in and described above with reference to Figure 1. A user is able to capture images or files such as video of the test object 5 using the pocket ultrasound 3. The captured images are transferred to the user’s account in the data store 13 in the cloud. The stored data can then be operated on and processed by skilled personnel or appropriate software to return results for storage on the mobile telephone 7, e.g. by the App 9. The method and system will now be described in greater detail. Figure 2 is a schematic view of a flow diagram showing an exemplary method 2 of remote ultrasound QA. The system will involve the actions of a user 4 shown schematically as remote from a QA service provider 6. It is, for the purposes of this example, assumed that the user is a medical practitioner in possession of a pocket ultrasound system, such as any commercially available system including the GE Vscan Air, Philips Lumify or Butterfly iQ. Initially at step 8 the user will have registered 8 their device with the QA service provider 6. Examples of how this can be done will be described in greater detail below. the user receives 10, or is provided with by the QA service provider, a specialised test object which is provided as a simple and low-cost silicon imaging test object.. At step 12, having decided that a QA process is desired or required to comply with a safety standard, the user initiates the QA process at step 12 by performing an ultrasound imaging process of the provided test object. This can involve any typical interactions with the test object or can be according to some prescribed sequence of imaging steps. The pocket ultrasound system will have captured and stored images of the test object and is then arranged automatically to transmit 14 the captured image or video files to the remote QA service provider. This can be via any known communication method and typically might be via a network such as the internet. At step 16, the transmitted data files are received by the remote QA service provider. The QA service provider 6 then performs 18 known QA tests on the captured images, with knowledge of both the test object that has been imaged, and the system used to perform the imaging. The QA testing itself is thus done remote from the user and the system and this enables a centralisation of the QA processing. Importantly it removes the need for specialist highly trained and expensive medical physicist to travel to the location of each of the ultrasound operators or medical practitioners who are signed up to the QA service provider. The QA tests performed can be any one or more of known QA tests such as uniformity, drop-out, reverberation threshold, reverberation depth, B-mode noise levels, grey level, pulsed wave Doppler noise threshold, colour Doppler noise threshold, cable noise test, signal to noise ratio and penetration depth (sensitivity). The process of QA has thus been performed remotely which is a distinction from known methods of QA and significantly enables a scaling of the QA process which is not possible given current restrictive availability of trained personnel. An important feature of the system is the provision of a known but simple test object which is used for imaging. This enables a standardisation of the imaging and of the tests performed which enables the QA method to detect deterioration of the ultrasound device. As will be explained below, an important aspect of the present is the provision of an App which a user can use to store data and records of QA processes performed on their ultrasound system. The present system is thus a user-led distributed QA system, arranged in preferred embodiments to operate with an app together with the referred to test object. The system is arranged to be accessed 24 / 7 and to enable low-cost ultrasound testing. The present method thus allows a reversal of the known systems; instead of taking the ultrasound physicist to the device, the user can send some images to the physicist. Without the cost of travel and expensive equipment, handheld ultrasound can be made viably safe for regulated medical devices on a global scale, democratizing ultrasound safety worldwide. All records of a user’s ultrasound will be stored via the app ensuring compliance with Managing Medical Devices (MHRA, 2021), and national guidelines on ultrasound testing. The solution meets this need and gives users accessible proof of compliance ready for regulatory inspections, removing one of the principal problems often faced by healthcare professionals. An important aspect of the present system is the use of an inexpensive, simple-to-use test object which enables healthcare professionals globally to test their own ultrasound devices. The test object is smaller and more user-friendly than those typically used in imaging calibration or QA. The present test object preferably enables measurement of the most important parameter (sensitivity) that is traditionally only measured with a high-cost tissue mimicking test object (TMTO). The present test object uses inexpensive silicon material to validate the proposed novel test method. By removing the more complex components which were important for legacy ultrasound testing, a test object which allows the measurement of sensitivity can be made at a fraction of the cost. Thus far, the test has been performed across 8 ultrasound probes from four different manufacturers and shows excellent agreement with the equivalent test performed on the high cost TMTO referred to above. The capability to test for noise levels, an important secondary measure (Dudley, 2020), will be added to the Multi-Medix test object. Crucially, this enables poorer or more remote areas to benefit from an innovative QA system. Approximately 37% of ultrasound probes in clinical use are faulty (Dudley, 2020). The present QA system would have identified 100% of these defects, reducing the risk of misdiagnosis. It will be understood that to perform a QA measurement, the user will take prescribed camera photographs of their handheld pocket ultrasound machine. They will preferably be instructed to: 1. capture an image of the handheld scanning in-air; and, 2. capture an image of the machine scanning in the test object. The captured images (in any appropriate file format, but typically JPEG files) are sent to a remote, preferably cloud-based, database where they can be accessed and reviewed by a technical review team. For example, the present applicant has teams of engineers and medical physics specialists who are able to review the received images from the cloud-based database. The outcome of the test is then delivered back to the user’s app and stored so they have access to results and a testing history of the device. Importantly, as well as keeping a record of the tests themselves, a record is generated of the QA history which can be used to demonstrate and evidence that independent QA has taken place, thus satisfying many independent compliance thresholds. Of course, in the event the ultrasound is identified as faulty, the central physics team can advise on repair / replacement options. The method as described may typically be performed with the use of low-cost test object, such as a silicone-based test object. Examples are shown in Figures 3A and 3B. Referring to Figure 3A, The test object or test object 20 is formed of a material such as silicone and has plural surfaces shaped for engagement with different standard types of ultrasound transducers. The test object 20 is shaped simply in this example as a cuboid having dimensions roughly between 6 and 20 cm. Preferably the test object is 15cm long, 9cm high and 6 cm deep. The sizing is selected such that it is convenient and easy for an operator to handle and to. The test object has at least one flat planar side 22 with a shallow rectangular recess. . At least two of the other surfaces are provided with shaping to enable interaction with common ultrasound transducers. The upper surface 25 (“upper” in the configuration shown in Figure 2) has a curved recess 24 which is shaped and sized so as to be able to receive a curvilinear array transducer. The bottom side surface 28 has an end domed recess 26 which is shaped and sized so as to be able to receive an endocavity array transducer. The at least one flat surface 22 has a shallow rectangular recess 29 which is able to interact and engage with a linear and sector array transducer. Accordingly, in a preferred example, the test object is a silicon test object. The test object has interface portions shaped to engage an ultrasound transducer for sensitivity testing. Preferably, the test object has at least three interface portions, each shaped differently to engage with a respective different type of ultrasound transducer for sensitivity testing. In the example shown in Figure 3B, the test object has at least one cavity 30, e.g., a cylindrical cavity, which houses a removable insert of varying attenuation. An correspondingly shaped anechoic insert 31 enables noise level and signal to-noise testing. The present inventors have recognised that, surprisingly, low cost silicon-based test object such as that shown in Figure 2 can function as a test object that provides a speckle image when scanned with an ultrasound transducer. Although the speed of sound in silicone is not matched to human tissue, the image produced is similar to homogeneous human soft tissue. The image is also similar to the more sophisticated, speed of sound matched, TMTOs traditionally used for sensitivity measurements. The system described can be accessed and used in the form of an App that a user can have on their mobile smart phone or any appropriate digital device. Figure 4 shows a schematic simplified series of steps by which a user can download the App and set it up for running on their mobile telephone or digital device (referred to hereinafter simply as “phone” for brevity). Initially a user will download the App from the Google Playstore ® or Apple’s Appstore ® or any other provider of mobile Apps from which the app will be available. The user is required to provide information such as the model of the ultrasound device that they have, serial number, the year of manufacture and any information regarding software versions running on it. Next, they are prompted for information relating to how often they would like to use the App, i.e. how often do they want to perform QA on their ultrasound device. They are given the option of subscribing which can offer repeat service or of paying for a one-off QA process. An instructional video is shown, or some other form of instructional material may be provided. For example, the App could provide a download of a written or audio instruction manual. Finally, once this information has been gathered and stored the user can select when to perform a QA test by clicking on a selector “Take a Test Image”. The App will guide the user on which images to take together with the provided low cost simple test object, and how to upload them to the App and from there to the remote database in the cloud. Once the images have been received in the cloud-based database and stored in a user’s account, tests or checks can be run on the images to determine the QA status of the ultrasound machine under test, the tests can be performed by a human operator or using computer or Al based testing methods. The results of the tests are stored in the user’s database in association with the ultrasound machine in question. Thus, a record and historical store of the timing and details of QA process is built up. Over time and repeated tests, it will be appreciated that a historical record is built up of all QA tests that have been done. These can be used when the user is required to demonstrate, say to a regulator, that the ultrasound machine has undergone the required QA testing over its active lifetime. The tests review can be done entirely independently of the user, even without their knowledge of the precise time that the QA testing is done. The only role of the user in the testing is to perform that image capture of the test object when prompted by the App or when they decide that QA is required. Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.

Claims

1. A method of remote quality assurance for ultrasound systems, the method comprising:Receiving from the user at a remote location an ultrasound image of a test object; processing the received image to determine one or more quality assurance parameters of the ultrasound system under test;providing a notification to the user at the remote location the results of the quality assurance determination.

2. A method according to claim 1, comprising in addition, receiving an ultrasound image scanning “in-air”, and processing the received ultrasound image scanning “in-air” and the ultrasound image of the test object to determine one or more quality assurance parameters of the ultrasound system under test.

3. A method according to claim 1 or 2, comprising providing the user with an inexpensive, easy-to-use test object for use with the method of remote QA.

4. A method according to any of claims 1 to 3, comprising communicating captured images to the remote location from the user using a personal transmission device.

5. A method according to claim 4, in which the personal transmission device is intrinsic to the ultrasound system or is provided by a mobile telephone separate from the ultrasound system.

6. A method according to any of claims 1 to 5, comprising performing defined QA tests on images received at the remote location and providing results to the user.

7. A method according to claim 6, comprising storing results for the user and the tested ultrasound system at the remote location.

8. A method according to claims 5 or 6, in which the tests are selected from the group consisting of uniformity, drop-out, reverberation threshold, reverberation depth, B-mode noise level, grey level, pulsed wave Doppler noise threshold, colour Doppler noise threshold, cable noise, signal to noise ratio and penetration depth (sensitivity).

9. A method according to any of claims 1 to 8, in which the test object is a silicon-based test object.

10. A method according to claim 9, in which the test object has interface portions shaped to engage the transducer of the ultrasound system for sensitivity testing.

11. A method according to claim 9, in which the test object houses an anechoic insert or anechoic area for B-Mode noise level and signal to noise ratio testing.

12. A method according to claim 10, in which the test object has at least three interface portions, each shaped differently to engage with a respective different type of ultrasound transducer for sensitivity testing.

13. A testing system for remote quality assurance for an ultrasound system under test, the testing system comprising:a data store for receiving from a user at a remote location an ultrasound image of a test object;a processor to process the received image to determine quality assurance parameters of the ultrasound system under test and to provide a notification to the user at the remote location of the results of the quality assurance determination.

14. A testing system according to claim 13, comprising a test object for imaging with the ultrasound system under test.

15. A testing system according to claim 13 or 14, comprising an App on a computing device to prompt a user to capture an image of the test object and provide the image to the data store.

16. A testing system according to claim 15, in which the computing device is a smart phone or a PDA.5

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