By Ted Lucidi
I trust that if you, or your team, supports the ultrasound modality in any way, that you have at least heard of the Philips X5-1 transducer. In my opinion, it’s THE transducer that revolutionized modern trans-thoracic echo-cardiography. For those not so familiar, rather than producing traditional 2D cross-sectional images, X-Matrix transducers can create live-3D volumetric images. Initially released on the iE33 platform, it was one of the most technically advanced transducers of its day and after multiple iterations and design changes, and after almost 10-years, it is still one of the most popular cardiac transducers on the planet.
No doubt, if you have these transducers in your fleet, then you’ve spent tens of thousands from your service budget supporting them. But, why are these transducers more costly to support? Why do they seem to fail much more often than traditional transducers?
If, for the moment, we focus on Philips cardiac transducers, you’ll see that there’s a quantum leap in technology between the legacy S5-1 and the X5-1. The typical legacy cardiac transducer, in this case the S5-1, was designed around a traditional acoustic array, consisting of 80 acoustic elements, bonded to backing material to control the direction of and efficiency of the sound energy. The array is electronically connected to a single PCB within the scanhead via several flex-circuits. The PCB is fairly simple but handles the connection to the wiring harness (consisting of 80 miniature coax-cables, the thickness of a human hair).
The acoustic array in the X5-1 is of a newer design than traditional arrays. Although now commonplace within most Philips transducers, PureWave arrays are much more efficient and have the capability of providing greater penetration and resolution than traditional arrays. The X5-1 array boasts 3040 elements in roughly the same physical space as the 80-element S5-1. It’s mounted, not on traditional backing material, but sits atop of an Application Specific Integrated Circuit (ASIC) which handles much of the control and beamforming of the array. Beamforming and control traditionally lie within the scanner itself. There is a series of four PCBs within the scanhead to assist with array/ASIC control as well as handle the connection to the wiring harness. The cable, rather than consisting of 80 wires, now has 163 consuming roughly the same physical dimensions. 12 wires are designated for control, 151 for signal. This will be important later.
The X5-1 exhibits failures similar to other transducers … lens damage, strain relief damage, cable pulls, connector damage, premature electronic failures and, the ever-favorite, accidental trauma. For years, the primary mode of failure on almost all cardiac probes was a breakdown of the individual coax’s within the wiring harness due to the way echo studies are performed. One particular cardiac image requires the patient to rest on their left side while the probe is placed between the patient and the exam table. Besides being uncomfortable to the patient, this requires the cable to be bent at extreme angles often resulting in excessive stress and strain being placed upon the wiring harness. Even though echo labs are using specially designed exam tables to address patient comfort (and cable strain), a healthy percentage of cardiac studies are performed on traditional beds across hospital campuses. Cable/wiring failures are still common on the X5-1, but all the technological advancements in this probe have presented new modes of failure, never seen before.
Another very common mode of failure with this probe model is constant static in continuous wave (CW) Doppler mode at only specific locations within the image. The problem may or may not actually be repeatable, which makes it extremely frustrating for echo-techs as well as service personnel. A strong percentage of the X5-1 transducers exhibiting this phenomenon may actually have no problem whatsoever, however; I can confidently say that it is likely that it is THE most frequent reason for which the probe is replaced.
As today’s transducers become more advanced, you can bet that tomorrow’s breakdowns are going to be based upon obscure, non-traditional points of failure. Next month, we’ll look at the reasons WHY the constant static artifact occurs, and I’ll provide some tips to help you test for and hopefully minimize this problem for your customers.
Ted Lucidi, CBET, Customer Experience and Clinical Insights, Centers of Excellence for Ultrasound and MRI Coil Repair, Radiography, Design and Manufacturing, Innovatus Imaging.
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