Ultrasound is one of the most widely used diagnostic tools in modern medicine. In the late 1970s ultrasound required specially trained physicians to interpret the results from technically driven analog equipment. Some research equipment featured realistic two dimensional grey scale images, but the complexity and excessive tuning requirements to keep the equipment functioning correctly restricted its use to very specialized applications. Nevertheless, the benefits in diagnostics, especially in gynecological exams, caused ultrasound to become widely used.
Ultrasound is technically any sound above 20kHz, but practical medical ultrasound is often targeted between 1 and 2 MHz with some systems working as high as 50MHz. The high frequency sound is generated by ultrasonic elements, configured in an array for some types of equipment. The Phased Array probe is made of many ultrasonic elements, each of which is independently pulsed. Varying the timing, by pulsing the elements in sequence along a row, creates a pattern of interference which creates a beam at a specific angle, that can be steered electronically. The beam is swept through the body’s tissue, and the data from multiple beams are assembled mathematically to create an image showing a slice through the body.
A Phased Array system can be very powerful, but the probe is fairly expensive. Even though the probe costs more than alternative technologies, the benefits are significant. Having an electronically steerable acoustic beam enables massive amounts of data to be gathered quickly. Large amounts of data means that there is a significant computational load placed on the central processor. A key problem with this type of imaging is that it’s impossible to make the sound beams thin enough to resolve structures directly. Overlapping sound sources means that each bit of output data must be derived from the interaction of reflections in a small volume around the point being scanned. The result is a specific type of blurring in the output images called “specklation” or “speckle”.
Recovering an image from the data set is computationally intensive. Intel processors like the ATOM™ processor can run a library of real world signal processing routines to recover and deblur the ultrasonic image. In addition, more processing power can be achieved by employing a multicore processor. Alternatively, multiple multicore processors may be used to divide the application into distinct functions.
Advantech’s (1) AIMB-210 board was selected to form the base of a medical ultrasound system.
According to the company, the ATOM™ board was chosen because the customer was looking for a special type of reliable industrial-grade computer. Product support and reliability were important, as were medical grade features. The Advantech board was selected as a powerful and reliable computing platform, supporting I/O connectivity and performance to control other devices. One feature, often overlooked when considering office environment based equipment, is fan noise. Physician offices require low noise levels, making low dissipated power key.
Mathematical libraries suitable for image reconstruction are available from many sources, including The Math Forum. If you’re looking for a way to learn more about ultrasound for medical applications, there’s an application for a mobile phone called MobileUS. It’s a program to use industry standard USB-based ultrasound probes with a cell phone. The C# software may be licensed under the BSD license. (licensing was the topic of a recent blog)
USB Ultrasound (USBUS) is another ultrasound program that uses USB to interface to probes from Interson. These probes and associated software do not provide full imaging, with the image processing performed in the probe itself.
Real ultrasound equipment has other system requirements that can be satisfied by Intel technology. One example of Intel-enabled technology is fastboot from QNX Software Systems(2). QNX fastboot technology is a specific feature of the QNX Neutrino® RealTime Operating System. It eliminates the need for a BIOS on Intel ATOM platforms, reducing system costs while improving instant-on performance. Systems designers can use fastboot technology to deliver fast boot times for a wide variety of medical and other applications.
Considering the image of the Advantech-based ultrasonic equipment, there are a number of systems requirements that are not directly related to the technical requirements of controlling or displaying the results from a phased array ultrasonic system. A LAN interface is a typical data communications requirement for modern medical diagnostic equipment. In another blog we’ve studied several systems that use Ethernet for LAN connection. USB interfaces are specified for controlling a printer, DVD recorder/player, and ultrasound probe. USB support is a fundamental part of many packages including those from Green Hills Software (3) and Wind River Systems (4).
Fortunately, the traditional data processing systems functions are a part of offerings from Intel, Green Hills, and Wind River. But, the lion’s share of code that needs to be developed is outside of commercial offerings – an issue for products outside of the norm for large volume applications.
When your applications are not “mainstream” for commercial vendors, how will you make the choice of tool/library vendor?
1. Advantech is a Premier Member of the Intel® Embedded Alliance
2. QNX is an Associate Member of the Intel® Embedded Alliance
3. Green Hills Software is an Affiliate Member of the Intel® Embedded Alliance
4. Wind River Systems is an Associate Member of the Intel® Embedded Alliance
Roving Reporter (Intel Contractor)
Intel(r) Embedded Alliance