Reducing gestation time of medical systems: off-the-shelf embedded computing speeds time-to-market for medical equipment manufacturers.
* Cost containment from new competitors and industry controls
* Shorter development time for new products to capture growth market segments
* Scarce engineering resources as businesses seek to do more with less
* Higher performance products require even higher technology solutions
Additionally, these factors are interrelated in the context of a global customer base. An effective manufacturer must manage these often-conflicting requirements to develop a product that has the intended positive business impact. Thus, OEM'S are turning to off-the-shelf embedded computing solutions to meet their product requirements while managing their risk.
A little history lesson
A number of open standards have been created to address the need for embedded computing solutions, while simultaneously enabling an infrastructure to provide a wide variety of products with guaranteed interoperability. For example, VMEbus, now 20 years old, has enjoyed a wide acceptance in the medical market, providing complete compute solutions for modalities and laser imagers. However, for deeply embedded applications, a smaller platform is needed to meet size and cost constraints.
In the past five years, a new set of open standards, starting with IEEE1386 and IEEE1386.1, evolved to create the industry-leading mezzanine module called the PCI Mezzanine Card or PMC. The PMC has traditionally been used to expand I/O on computing baseboards such as VME Single Board Computers (SBCs). PMC technology further extended the functionality to enable a complete compute system in the same form factor, called a Processor PMC (PrPMC). The VMEbus International Trade Association (VITA) is the standards body for the VITA 32 PrPMC standard (see http://www.vita.com), which defines the extensions to allow a processor core, memory, as well as input! output (I/O) to reside on this module. The new standard uses the proven mounting scheme and reliable electrical connectors, resulting in a robust package.
Introducing the macro component
PrPMC technology has a number of characteristics that make it extremely attractive in a deeply embedded medical device. The overall card size is 75 x 150 mm, about the periphery of a United States dollar bill. If one assembles 100 one-dollar bills (larger denominations work, too!), one will have a good estimate of the 10 mm recommended stacking height. On each of the four corners is a hole intended for mounting, and up to four 64 bit high-density connectors can be installed to provide power, the PCI interface, some signals associated with PrPMC, and optional definable I/O. In addition, the thermal footprint has been designed to be very reliable in a convection-cooled system. This form factor results in a macro-component that may be used on an off-the-shelf baseboard, or on a baseboard built for a custom application.
Deeply embedded medical applications typically have a certain amount of I/O that is either custom or legacy. In many cases, this I/O technology is part of the manufacturer's intellectual property and must be held quite closely to maintain a business advantage. A full custom hardware solution requires the OEM to complete the design cycle for not only the application-specific I/O, but the processor, volatile and non-volatile memory devices, as well as standard interfaces such as Ethernet and serial. The PrPMC communicates to the baseboard (also sometimes called a carrier card) through the industry-standard PCI bus running at up to 66 MHz and 64 bit wide bus or 528 MBytes/sec. By creating a site for the standard PrPMC on the baseboard, the OEM design cycle is reduced since only the application specific I/O technology needs to be rendered.
While on the subject of baseboards, a large variety of off-the-shelf carrier cards is available. The cards typically will have two to five PMC sites and come in a variety of form factors such as standalone ATX (the same size as a common PC motherboard) or ready to mount in a system chassis. By attaching a Processor PCI mezzanine card onto the carrier card, one has created a fully functional compute platform on which to run a variety of Real Time Operating Systems (RTOS) and one's application. Next, one can extend the functionality by adding additional PMCs on the carrier for I/O or add additional PrPMCs for increased computing horsepower. Thus, one can have multiple PrPMCs on the same PCI bus. Wait a minute! Isn't PCI only a peripheral bus?
Monarch and non-Monarch
While it is true that the original definition of PCI only supported peripheral cards with a single processor host, this concept has been extended to allow any number of PrPMCs on a given bus subject to electrical constraints and appropriate bridging. The standard defines a Monarch PrPMC as the main processor in the system. It is responsible for handling the PCI bus enumeration (the method of determining all of the devices present in the system upon boot up) and is the PCI bus default interrupt handler. There can only be one Monarch PrPMC on a given bus although advanced architectures utilizing non-transparent bridges may have more.
The non-Monarch PrPMC acts like a compute node or a target device. It can generate interrupts to the Monarch across the PCI bus to perform synchronization. The nonMonarch PrPMC will be discovered by the Monarch upon enumeration and configured appropriately. The PRESENT signal can be used to identify which modules are installed. Another signal is available to indicate when a non-Monarch PrPMC is ready for enumeration. And here is the best part--by utilizing the MONARCH signal present from the baseboard, the PrPMC can configure itself automatically to become either a Monarch or a non-Monarch, depending on which site it was installed in. Thus, only one physical PrPMC can serve in multiple applications. By using the available building blocks of PrPMCs and baseboards, changeable systems can be created to meet the changing demands of quick development and long lived production.
PrPMC and medical
Eastman Kodak Company's Health Imaging Group and Motorola's Computer Group worked together to provide an embedded solution for the new Kodak DryView 8900 laser imager. A laser imager is a device that prints diagnostic quality films from a range of medical imaging devices, such as Computed Radiography or Digital Radiography (CR/DR) systems, or MRI and CT scanners. These films are read by a radiologist for patient diagnosis. The DryView 8900 combines several unique technologies to attain performance of more than 180 films per hour. By using PrPMC technology from Motorola, Kodak was able to meet its embedded system requirements.
Per Doug Jensen of Kodak's Health Imaging Group, in order to reduce the development time of the DryView 8900, his company needed a vendor that would provide other "soft" features outside of the hard technical requirements of CPU, RAM, serial port, etc, such as:
* A system with a Board Support Package ready to go, allowing software work to begin prior to any hardware being complete. This setup included software in the form of the BSP, but also the availability of PMC carrier boards allowing software folks to exercise the PrPMC600 on a bench.
* Long life hardware that would be supported for many years.
* Flexibility for customization (through depopulation or other means) and the willingness to control this custom product with ECO control that would not allow changes without Kodak's approval.
What is yet to come
The PrPMC600 was able to provide these technical solutions. It simplifies design of medium-performance applications, handling the complexity of 250MHz architectures. Because of existing business relationships with Motorola, Kodak was comfortable knowing the other requirements were part of Motorola's standard operating procedure. The customized board provided Kodak with a prescription-fitted board with the 12C bus brought out to an external connector and bus arbitration permanently enabled, as well as being able to depopulate the Ethernet circuitry (used only during the product debug phase) and the front panel of the board for extra cost savings in production.
Because medical product lifetimes are relatively long, an OEM must be concerned about the longevity of any given technology. Today, over a hundred vendors provide PMC related products and the market is continuing to evolve. This breadth will allow an OEM to select from an array of PrPMC upgrade choices. The PrPMC standard is continuing to evolve with a number of vendors participating in VITA 42 working groups. This work will add speed, functionality and I/O to PrPMCs. By selecting an open standard, risks and design time are minimized, allowing the manufacturer to concentrate on their application needs and, ultimately, gain market share.
Circle 237--Kodak Health Imaging, or connect directly to their website via the Online Reader Service Program at www.rsleads.com/307df-237
Circle 238--Motorola Computer Group, or connect directly to their website at www.rsleads.com/307df-238
RELATED ARTICLE: Improving the Image
Medrad Inc, Indianola, PA, is a manufacturer of a range of products for the medical marketplace, as certainly suggested by their name. Part of their catalog includes magnetic resonance surface coils and endorectal coils for use with MR scanners produced by major imaging manufacturers like GE, Siemens and Hitachi. Several coil units distributed through Medrad were designed by WL Gore & Associates, Elkton, MD, who, long before their fame for outdoor clothing, was known as a manufacturer of wire and cable with PTFE coatings (still a core product).
Earlier Gore coils included Torso and Cardiovascular phased arrays for the GE I 5T MRI systems. The torso unit contains 4 coils--2 in an anterior pad, 2 in a posterior pad--that can be individually phased for high-resolution images of the abdominal, thoracic and pelvic regions. The later cardiovascular unit extended the torso array to accommodate heart and vasculature imaging, and could contain up to 10 coil elements in a lightweight, flexible panel that conforms to the patient's body. The panel's size could produce an image of the entire aorta, from arch to iliac bifurcation.
This year, GE introduced the Signa 3T body imaging system, the highest field now offered under FDA guidelines. Gore, responding to the market need, produced a new torso array, a receive-only phased array coil consisting of an anterior and posterior paddle, each with two overlapping coil elements. According to Alex Czernik, director of global MR products at Gore, the largest problem was that at the higher Tesla level, coil and cable heating was a major concern. Gore's solution was to add, during the manufacture of the cables, a quarter-wave choke directly in each of the coaxial cable lines going to the coils, to minimize external currents riding on the outer shield of the cable.
Besides improved resolutions, the new system takes away one element of discomfort for some patients--when imaging the prostate, 1.5T MRI systems require use of a small coil on a probe that must be inserted into the patient and maneuvered close to the gland. The 3T MRI system, in combination with the Gore torso array, eliminates the coil/probe, and still produces a higher-resolution image of the region than its predecessor.
Circle 239--Medrad Inc, or connect directly to their website via the Online Reader Service Program at www.rsleads.com/307df-239
Circle 240--WL Gore & Assoc. Inc, or connect directly to their website at www.rsleads.com/307df-240
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|Date:||Jul 1, 2003|
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