Disruptive Technologies - Ultrasound Test Devices

Transcription

1 Disruptive Technologies - Ultrasound Test Devices G. Wayne Moore, B.Sc., MA, FASE Acertara Acoustic Laboratories Acertara Acoustic Laboratories Correspondence: G. Wayne Moore 1860 Lefthand Circle, Suite H, Longmont, CO USA gwmoore@acertaralabs.com

2 ABOUT ACERTARA: Founded by ultrasound industry pioneers, G. Wayne Moore and Jim Gessert, Acertara was created to serve the acoustic testing and quality control product development needs of ultrasound engineering and service professionals worldwide. Acertara is an independent ISO/IEC 17025:2005 accredited acoustic measurement, testing, calibration laboratory providing advanced ultrasound testing products (inventors of the probe tester known as FirstCall ) such as Aureon and Active-Z. Acertara also provides ISO9001:2008, ISO13485:2003 certified probe repairs developed and refined by over 15 years of experience in the legacy of Sonora Medical Systems founded by G. Wayne Moore. The Acertara team has authored and coauthored more than 40 United States patents and is highly published in both clinical and engineering journals. As an active member of the Medical Imaging Technology Alliance (MITA/NEMA), IEEE, and AdvaMed, Acertara and its employees are intimately involved in the development of various domestic and international diagnostic ultrasound regulatory and compliance standards.

3 INTRODUCTION: It is an axiom that significant financial waste occurs within the healthcare system due in part to the lack of high-quality and objective information concerning the operating performance of medical imaging systems in clinical use, resulting in unnecessary or delayed servicing or replacement of the devices. Historically, this lack of objective information concerning the functional health of devices can be directly linked to the absence of commercially available test equipment with the power and sophistication to test technologically intensive imaging systems and the attendant patient interface devices, such as ultrasound probes. In the hands of properly trained Medical Imaging Physicists, Biomedical, and Clinical Engineers, this type of test equipment would allow them to more effectively perform their responsibilities relative to maintaining and assuring optimal performance from the increasingly complex imaging devices in their care. Our goal at Acertara is to continue and expand our Sonora Medical Systems engineering legacy to invent, design, and develop easy-to-use and affordable test devices that provide technical hospital personnel with repeatable, objective, and quantitative data concerning the performance of medical devices. By definition, these new devices are considered disruptive innovations because they provide test results that forever change the manner in which high technology medical imaging devices are managed within a clinical environment. While at Sonora, our R&D team first began this effort with a product known as FirstCall (shown above and the test report to the right). FirstCall was developed and commercialized to address the testing needs of the diagnostic ultrasound market as it related to probes (also referred to as transducers). The FirstCall device was designed to quantitatively test the acoustic performance of each individual crystal within the probe array and each strand of co-axial wire within the transducer cable that connected the array to the ultrasound system front-end. The results of the test were output in the form shown above and stored in the FirstCall data base for archiving.

4 At the time of product introduction (2001), there was no product on the market like FirstCall that could test and report the condition of the probe. Prior to FirstCall, hospital technical personnel did not have access to a tool that could accurately test the performance of probes as a stand-alone device and were, therefore, forced to use indirect evaluation techniques such as a tissue mimicking phantom (TMP) or other subjective nonscientific testing methods such as running a dime on its edge over the length of the probe aperture and looking for drop-out in the B-mode image. FirstCall directly reveals dead and weak elements and that ability led to a first-of-kind peer-reviewed study by Weigang 1, et al, demonstrating that as many as 25% of all ultrasound probes in clinical use had some form of undiagnosed performance problem. These problems were often related to a failure process associated with the array or the lens covering the array that limited their clinical efficacy and perhaps compromised patient safety. Since the Weigang paper, multiple additional papers in the literature, on a world-wide basis, have validated and expanded upon the initial findings. The disruptive technology of FirstCall had become a de facto standard for probe testing in the hospital environment. With the widespread acceptance and use of FirstCall in the hospital, as well as by reputable after-market probe repair companies, the number of defective probes in clinical use has been steadily dropping. Further, the number of third-party companies who sold or repaired used probes and did not embrace the new testing technology also exited the market. When we first introduced the FirstCall device we thought, naively, that all third-party probe repair and used probe sales companies, independent service organizations (ISOs) companies focused on medical imaging devices, and ultrasound original equipment manufacturers (OEMs) would line-up to buy the product. After all, we reasoned, who isn t concerned with properly working transducers, patient safety, and the clinical efficacy of the ultrasound examination? Well, as we found out, not everyone. The de facto standard of acceptance for probes prior to FirstCall was: if there is no complaint from the physician or sonographer, there is no problem, so why go looking for problems. The paradox of this is that Biomedical Engineers and other technical professionals had no way of objectively testing ultrasound probes to validate performance; only the subjective opinion of the sonographer or the physician that it appears to be working. Reliance on visual acuity can be deceptive as published data has shown time and again that performance related problems may often begin in the probe long before they demonstrate obvious symptoms in the B-mode image or in the Doppler waveform. 1 The Methods and Effects of Transducer Degradation on Image Quality and the Clinical Efficacy of Diagnostic Sonography, Weigang, et al, Journal of Diagnostic Medical Sonography, Vol 19. Number 1, pp. 3-13, Jan/Feb 2002

5 Further, at these early stages of failure, the clinician would really have had no way of knowing that any changes had occurred in the performance of the probe that may be affecting the clinical results. For example, spectral broadening may occur in the Doppler waveform as a result of two or three consecutive dead elements in the array; a result that can mimic a clinical hemodynamic condition. However, because of the significant amount of imaging processing that is used in the construction of an image, the effects of two or three dead elements may not be readily seen in B-mode. Consequently, prior to FirstCall, undiagnosed defective probes were being sold to and being used by hospitals. As FirstCall technology began to diffuse into the hospital market it became the new de facto standard for probe testing. Early adopters of this technology quickly recognized the value to the hospital of consistently and regularly testing ultrasound probes to insure they were in proper working order. Defects were discovered earlier in the failure process and were repaired for a fraction of the cost of an unnecessary replacement. Downtime was kept to a minimum and patient dissatisfaction related to rescheduling went down. With the disruptive technology of FirstCall, hospital technical personnel were able to effectively manage the ultrasound assets under their care, rather than reacting to an event. The big winner is the patient. As mentioned, published data from around the world has clearly shown that performance issue with probes can lead to a misdiagnosis or under diagnosis. Patients deserve the best possible outcome from a diagnostic ultrasound study, and the best way to insure that is by regularly testing the performance of both the probes and the system mainframe. Creating the new advanced and disruptive technologies to do this is both the passion and the mission of your partners at Acertara Acoustic Laboratories.

6 TECHNOLOGY ADVANCEMENTS Over the past 14 years, since the commercialization of FirstCall, there have been dramatic technology leaps in probe materials and design. By way of example, when FirstCall was introduced, the probe with the highest element count on the market was 288 elements. Today there are 2D matrix array probes on the market with more than 9,000 elements (Philips X6-1). In 2001, the most complicated electronics in a probe was the multiplexing circuit in the probe s connector. Today we have ASIC devices that function as a minibeamformer integrated into the array s acoustic stack. Our research and development team concluded that the simple ping-and-response technology of FirstCall was not going to be enough to adequately and thoroughly test these newer advanced technology probes. We needed to create a new paradigm for testing probes and analyzing their performance. To insure a level playing field between sellers and buyers of ultrasound devices, we needed to again create disruptive technology in the legacy of FirstCall that would keep pace with the advances being made with ultrasound systems and probes. The definition we have adopted at Acertara relative to disruptive technologies and innovations is: A disruptive innovation is an innovation that helps create a new market and value network, and eventually disrupts an existing market and value network, displacing an earlier technology. In that spirit we have created a new generation of probe testing devices designed to replace earlier technology. The complexity of diagnostic ultrasound transducers continues to increase. In newer models even the cable has been done away with, as in the Acuson/Siemens Freestyle device shown to the right. Other portable devices are using various USB connectors, as in the recently introduced Philips VISIQ, shown below, as well as other non-traditional connectors (e.g., cartridge-type connectors). When FirstCall was originally designed, there were only a few types of probe connectors being used and making adaptors for them was not overly complex. However, the divergence from the standard 260 pin ZIF connectors (zero insertion force) over the last several years resulted in the re-thinking at Acertara about the use of adaptors and designing a test tool that would be right for every model probe being manufactured irrespective of the connector used. In addition to the wide variety of probe connectors currently being used, is the overall increase in the complexity of both arrays (e.g., 2D matrix arrays and single crystal arrays) and the array control electronics (e.g., ASICs and multiplexing circuitry) resident within the probe housing or probe connector.

7 System electronics are also being migrated into the probe so smaller smart devices like phones that house the ultrasound operational software can also be used as a point-of-care diagnostic ultrasound device. These devices typically have acoustic output levels lower than cart-based systems and are generally used for a specific clinical purpose. They also normally use a USB µ-b port to attach the probe to the smart phone. Even though these devices may have a limited diagnostic role, they too should be tested periodically to insure proper performance. General Electric Healthcare recently upgraded its pocket-sized ultrasound device known as Vscan (shown below) with a novel probe design that incorporates two arrays into one probe housing (one at either end of the housing). One array operates at a higher frequency emphasizing near-field resolution, and the array at the other end operates at a lower frequency emphasizing depth-of-penetration. This device is also used as a point-of-care diagnostic tool for physicians. As with all ultrasound FDA cleared devices, the product must prove to be safe and efficacious. Therefore, all of these hand-held units need to have a regularly scheduled PM and testing protocol to make sure the physician is getting the diagnostic information he expects. It was clear to the Acertara R&D team that novel new testing devices would be required to accommodate all of these various new ultrasound system and probe design approaches. Our two newest solutions are devices we call Aureon and Active-Z, both of which are shown and described in detail on the following pages.

8 DISRUPTIVE TEST TECHNOLOGY Aureon represents the first in a new generation of sophisticated ultrasound testing devices designed to keep pace with the advancing technology of both ultrasound probes and systems. Utilizing 2D matrix array technology, Aureon directly captures, analyzes and displays the acoustic energy emanating from the face (aperture) of the probe under test. The captured energy is displayed as both a realtime B-mode image and as a graphical representation of the energy amplitude per pixel as shown in the image below left. The Aureon does not require an adaptor of any kind and works with every commercially available diagnostic ultrasound probe. Aureon presents side-by-side images of the real-time test with a previous archived test (see image below right), so that any changes in output can be detected and noted. 2 Dead elements are seen as black voids in the image and as drop-out in the graphical format. Shown below is the Aureon test comparing a functional Philips X6-1, 2D matrix array probe (top) to an X6-1 with two dead zones. The resolution is so sensitive with Aureon that it can detect and differentiate a single dead element within a 192 element array. Bubbles under the lens, or delamination of the lens are also easily detected, and the geometry of the defect will be clearly seen in the Aureon s B-mode image. In addition to the extensive on-board database, Aureon also generates a complete test report for documentation. A sample of this report is shown on the following page.

9 Aureon Sample Report Page

10 Acertara has also recently introduced another unique test device, Active-Z, shown to the right. Active-Z is a handheld battery operated point-of-measurement device, slightly larger than a contemporary smart phone. Touchscreen operated, the Active-Z is easy and quick to use. The Active-Z device was designed to test both the complex impedance between the connector pin and the element in the array, and the acoustic pulse output through the lens, and to inject an acoustic signal back into the lens. These two tests performed by the Active-Z, the electrical test and the acoustic test will provide the user with confidence that the elements are functional. The electrical test uses an impedance probe and the acoustic test uses a specially designed acoustic probe. Both of these probes are configured to be connected to the Active-Z device via a USB µ-b port. The electrical test results recorded in the Active-Z test report (shown to the right), will inform the user if there is a break in the wire anywhere within the probe cable, or if there is a problem in the acoustic stack, e.g., a dead element, a delaminated lens, or a short. The acoustic test will detect if acoustic pulses are leaving the probe through the lens, and will then inject an acoustic signal back into the lens that will be displayed on the system monitor (as shown below) if all is functioning along the signal path. Active-Z was designed to be a low cost high-value ultrasound test device that could be used as a quick but effective test to insure probe and system functionality. Injected Acoustic Signal

11 CONCLUSION The explosion of technological advances in general electronics and materials has greatly benefitted the field of diagnostic ultrasound. The diffusion of this medical imaging technology into virtually every soft-tissue clinical imaging application has truly been astounding. The dramatic improvements in B-mode image (see below) quality and Doppler performance have transformed ultrasound from its humble qualitative beginnings to a true quantitative modality that challenges both CT and MRI in terms of performance for various complex clinical applications. From the perspective of a test equipment design team our on-going challenge is to match those technologies in the systems we build and create novel, robust test devices that can quantitatively measure the performance of ultrasound probes and system mainframes, insuring safe and efficacious ultrasound examinations. Creation of innovative and disruptive technologies will be our path forward. We look forward to taking the journey with you, our customers. Neonatal Head circa 1976 Apical 4 chamber View of Heart circa 2008

12 Acertara Acoustic Laboratories 1860 Lefthand Circle, Suite H Longmont, CO sales@acertaralabs.com