Engineering News 7639

DN Staff

June 10, 1996

21 Min Read
Engineering News

'Teledocs' treat patients remotely

Latest imaging, network, and semiconductor technologies allow doctors to diagnose problems a world away

Newton, MA--If a soldier is injured in Bosnia, the first doctor to treat him may well be in Germany--even if the patient is still in a Bosnian field hospital.

Thanks to advances in imaging, network, and chip technologies, doctors no longer need be in the same place as their patients. Some physicians believe these new capabilities could change the way medical care is delivered around the world.

"This is a leading indicator of the direction healthcare is heading," says Col. Fred Goerringer, head of the U.S. Army's Medical Advanced Technology Management Office (MATMO).

From overseas battlegrounds to small rural health clinics, medical professionals are looking at "telemedicine" as a way to bring top-notch expertise where it's needed most.

MATMO has linked medical units in Bosnia with Landstuhl Army Medical Center in Germany, allowing the transmission of full-motion video, still images, and views from laporoscopic surgery. Most of the system was put together from off-the-shelf, commercial components, according to spokesman Mark Schnur.

  • At tiny Kirby Hospital in rural Monticello, IL, a doctor at another hospital "assisted" as a Kirby medical staffer stitched up a patient's fingers. The off-site doctor had first examined the wound via telemedicine.

  • In rural North Carolina, patients were screened for skin cancer with a physician at East Carolina University's School of Medicine confirming diagnoses remotely.

Researchers are even investigating the possibility of using telemedicine to treat astronauts in space.

"There's a significant opportunity for new de-vices," says Mark VanderWerf at American Medical Development, Lowell, MA. "Telemedicine is a very immature market."

Dramatic increases in computer and telecommunications power-per-dollar have helped make telemedicine practical. "A system that probably cost $80,000 four years ago, now costs $20,000," says Dirck Goss, president and CEO of Andries Tek, Austin, TX, which develops telemedicine peripherals. "For the first time, projects are moving out of academic medicine. Telemedicine is marginally economically feasible now." He believes that in a year or two, the economics will be more viable.

Major OEMs are starting to move into the field. NEC America, for example, recently announced a 10-year agreement with Texas Tech University Health Sciences Center to jointly develop telemedicine projects. The first device from the venture: a portable, self-contained unit dubbed the TeleDoc5000, featuring an NEC video codec (coder/decoder) along with specific medical equipment such as an endoscopic color camera, X-ray light box, and digital-imaging devices.

"Most device development has been done in the past 12 months," VanderWerf says. Engineers must work to combine functions such as light sources and image processing into a single system for a viewing device, he says. For an instrument such as a stethoscope, designers must get high-quality sound captured down to 10 Hz.

Some legal and licensing as well as technical issues may need to be worked out before telemedicine becomes widespread, particularly on the civilian side. Can a specialist in one state "tele-examine" a patient in another without being licensed to practice where the patient is located? And if something goes wrong, who is legally liable--the local doctor, remote specialist, or both?

Rural medicine. For now, telemedicine is being touted for cases where transportation costs are high, such as in wartime and in space, as well as for prison medical care. Another market: well-to-do citizens of developing countries seeking access to top-notch Western expertise, Goss says.

But remote doctoring also has big appeal in small-town America. At Kirby Hospital, the smallest in Illinois, it was difficult to justify funding 'round-the-clock emergency-room physicians, according to Wayne Mathews at Rural Health Consultants, Champaign, IL.

A telemedicine program with the larger Carle Foundation Hospital allowed Kirby to staff its emergency room with lower-salaried physician's assistants (PAs), linked to doctors at Carle. In a little less than two years, 56 people received emergency care. Cases included a remote examination of a boy's eye injury and an off-site radiologist reviewing spinal X-rays from a youth's football injury.

"In all of these cases, a drive to an emergency department 30 to 40 miles away was avoided," Mathews notes. And, the hospital has treated 14% more patients while cutting costs $100,000. Last year, the program was named the Illinois Rural Health Association's "Exemplary Project of the Year."

Numerous other projects have been launched, including a state-wide system in Georgia, the High Plains Rural Health network in Colorado (also covering parts of Kansas and Nebraska), Rural Eastern Carolina Health Network in North Carolina, a hospital network in parts of Oklahoma, and the Pennsylvania Blue Shield teleradiology pilot project. But even doctors in larger facilities can use telemedicine to consult with world-renowned specialists--without requiring patient travel.

You can get more information about companies and projects mentioned in this article via the Internet. Please tell them that you were referred by Design News.Beckman Institute http://vizlab.beckman.uiuc.eduDefense Dept. Telemedicine Universityhttp://www.imac.georgetown.eduNEC Ling, whose poisoning was diagnosed via the Internet

Diagnoses by Internet. The Internet is also helping bring resources once confined to major medical clinics to people around the globe--regardless of how far apart doctors are from their patients.

The assistance can be as simple as a plea for help on an Internet newsgroup. In Beijing, medical student Xin Li posted a message asking for help after physicians were baffled by the case of Zhu Ling, a young woman who had mysterious symptoms of hair loss, leg pains, dizziness, and facial paralysis. Finally, she slipped into a coma, unable to breathe without use of a respirator. Several days later, experts from around the world responded that the case sounded like thallium poisoning. Xin Li credits the Internet diagnosis and subsequent advice on treatment with saving the woman's life.

The Internet is also being used for more complex data transmissions. In one pilot project, developed by Analogic Corp. of Peabody, MA, and Georgetown University Hospital, mammography images were sent over the Internet's World Wide Web. The idea is "to provide the highest quality breast-cancer diagnosis to remote areas throughout the world," according to Mathew Freedman, associate professor of radiology at the hospital.

During a medical-technology conference this spring, attendees in Washington could view digitized X-ray images--called up over a live Internet connection--from a U.S. military hospital in Tuzla, Bosnia, as well as digital mammography images

The University of Illinois' Beckman Institute is also promoting real-time, interactive imaging on the World Wide Web for medical research. Using only a PC and WWW browser software, NmrScope users can view MRI (magnetic resonance imaging) data from the institute's 170-MHz proton imaging spectrometer. "By collaborating with a center having the proper equipment, a researcher can easily carry out appropriate projects without having to invest in the latest hardware," notes Paul Lauterbur, director of the University of Illinois Biomedical Magnetic Resonance Laboratory. "The World Wide Web can be used for interactive experiments--and in real time."

If engineers can design low-cost tele-monitoring devices, predicts VanderWerf at American Medical Development, doctors may be making tele-housecalls to the bedridden. But such at-home devices must be exceptionally easy to use and clean. Says VanderWerf: "There's a lot of engineering to be done."

--Sharon Machlis, Senior Editor

Linear technology enhances tissue-slicers

Heidelberg, Germany--Microtomes are used to cut tissue specimens into thin plane sections. Sections must be reproducible from only a fraction of a micron to a few microns thick.

A microtome's knife blade must be firmly mounted for stability. Its movements must be precisely controlled to ensure that the section can be accurately reproduced. The sample must be held fixed while the microtome simultaneously advances the blade and sample by a specified thickness after each cut.

Demand for improved quality required replacing sliding guides with rigid and play-free cross roller linear bearings. Short, squat rollers show less tendency to move out of position, or creep, while long thin rollers, such as linear needle bearings, tend to creep most, explains George Jaffe, vice president of engineering applications for Schneeberger. Needle bearings' diameter-to-length ratio is less than unity, while type R guides use rollers with a diameter-to-length ratio that is approximately equal to one.

Schneeberger type R guides have been used in microtomes since the 1980s. Initial problems caused by migrating cages in the type R guides were solved by forced cage control. This was accomplished using compression or tensile springs to maintain the cage position in the center.

Now, Schneeberger offers type RNG guides. The new rollers have a diameter-to-length ratio greater than unity, eliminating the need for forced cage control.

The use of quasi-standardized Schneeberger type RNG guides in microtomy enables serial cuts with a definite, reproducible thickness down to 0.25 micron. The RNG system increases stability, and eliminates the need for cage control. A roller shape, designed to eliminate edge pressure, has enhanced error tolerance in relation to parallelism of the mounting surfaces; and treatment of the roller surface provides a noticeable reduction in noise.

--John Lewis, Northeast Technical Editor

Step motor drives breakthrough mammography system

Denver, CO--Using an off-the-shelf 5-phase step motor, engineers from Fischer Imaging have created a mammography machine that may redefine the state of the art and improve early detection of breast cancer. Called SenoSCAN, the device uses a TDI (time delay integration) CCD detector driven by an Oriental Motor model RFK-566 Vexta Nanostep motor to capture high-resolution images with superior contrast and detail.

Digital mammography machines--which offer the advantage of computer manipulation--compete with film, a media theoretically capable of high spatial resolution and contrast. In practice, however, both methods suffer degraded contrast from secondary X-ray scatter striking the media during exposure.

To provide the best of each method, engineers chose a slot-scan detector. It contains a narrow CCD--an array of 100 to 300 lines and 4000 pixels per line--that passes under the image area to capture the source beam through a 10-mm-wide slot. This method blocks scattered X-rays but dramatically reduces the amount of radiation hitting the CCD. That's where the TDI comes in.

"This is one of the hardest types of scanning systems to design that you can imagine," says Greg Jeffery, project engineer at Fischer. With TDI, the step motor takes about 4.5 seconds to drive the detector slowly and smoothly past the breast. Meanwhile, the CCD captures a series of complete images at one-line-width intervals as it moves. The thousands of images overlap each other by all but one line. The system integrates the CCD's multiple outputs for a given point in space to create a bright, high-contrast image, 4,000 12,000 pixels in size (18 24 mm), with little fogging from scatter.

The scanning motion and integrating of the CCD images is synchronized. "We have to transfer the charge across the TDI detector at exactly the velocity, but in the opposite direction, that the detector is moving," explains Jeffery. The proprietary, backlash-free drive system had to produce a perfect, even velocity with vibration less than 1/4 pixel (15 microns) and EMI near zero.

Jeffery expected to use special damping techniques but found Oriental Motor's step motors met their needs off-the-shelf. "The Vexta was probably ten times less noisy than any other microstepper we tried," he says.

--Mark A. Gottschalk, Western Technical Editor

High-resolution display boosts patient monitor

Beaverton, OR--A custom electroluminescent display from Planar Systems has dramatically increased the resolution and contrast of images viewed on a line of new portable patient monitors. Part of Protocol Systems' Propaq Encore, the 552- x 256-pixel display measures the same width and height as, and only a bit more thickness than, the 256- x 128-pixel display it replaces.

Protocol selected electroluminescent technology because of its 160 degrees viewing angle, &1 ms response time from to 65 degrees , and 30,000+ hour life. Those characteristics served earlier Propaqs well, and they compare to TFT LCDs with &60 degrees viewing angle, 40 ms or worse response over a narrower temperature range, and half the life.

But for the Encore, Protocol wanted improved daylight readability and image detail. The company also wanted to eliminate a circular polarizer that reduced screen reflections, but sucked half the usable luminance.

To satisfy these needs, Planar engineers turned to their patented ICE (integrated contrast enhancement) technology. It replaces the normally shiny aluminum row-electrodes with a proprietary, non-reflective material that doubles the display's contrast. They pushed the resolution to 100 lines per inch. And they developed a double-sided circuit board that keeps to a minimum the increased thickness required by the additional electronics.

Protocol engineers contributed an antireflective coating with a much higher transmission. It covers the inner surface of a filter placed over the display, and reduces internal reflections. Says Protocol hardware engineer Glenn Kustka, "Planar was the only supplier willing to work with us to give us the display we needed."

Channel-surf to Rescue 911, ER, or any of the other "real-life" TV medical programs, and chances are you'll see a Protocol monitor hanging from a bedside or stuffed into an ambulance. The 6.25- to 13-lb. units measure everything the big wall-mounted units do--heart rate, ECG, blood pressure, temperature, respiration, apnea, to name a few--except they do it in a case 8 by 4 by 4 inches built to take 50-g's.

--Mark A. Gottschalk, Western Technical Editor

X-ray instrument improves materials analysis

Huntsville, AL--A collaborative effort by NASA, X-Ray Optical Systems, Inc. (Albany, NY), and the University of New York at Albany has produced an instrument that generates the world's most intense source of commercial X-rays, according to David Gibson, president of X-Ray Optics.

"We have demonstrated more than a factor-of-10 increase in intensity, and we expect to achieve a factor of 100 increase," he says.

Using a new technology called Capillary Optics, the instrument shapes and controls the direction of X-ray beams, something never before possible because X-rays were either absorbed by or passed through glass. Capillary Optics are based on bundles of glass polycapillaries that contain numerous curved channels.

"The X-rays are controlled by reflecting them through tens of thousands of tiny curved channels," explain Dr. Walter Gibson, professor of physics at the State University of New York at Albany. "Thus, we are able to concentrate the beams to suit the particular needs of the intended research or medical procedure."

One application for this technology: better quality control in materials analysis. By using an X-ray fluorescence technique, users can examine a semiconductor wafer for contamination. The optic can identify foreign objects in the crystal wafer and detect where in the production process the crystal is exposed to contamination.

This new optic can also be used in medical imaging and for industrial-processing applications. Currently, the inability to control a standard beam's direction causes companies to use expensive parallel beams. Using capillary optics, these lithography systems could be smaller and less expensive.

Miniature controller oversees distillate recycler

Menomonee Falls, WI--Pope Scientific selected the Z-World, Davis, CA, Little Giantminiature PLC to run its new Distillation Controller 3000(TM). The alternative, an embedded PC, would have required special I/O circuit boards and extensive custom programming, according to Pope engineers. In contrast, the Little Giant supplies on a single 4.8 x 5.6-inch pc board the analog and digital I/O channels required to interface to the distiller, as well as high-current drivers for the solenoids.

Hospital histology departments distill and recover solvents, such as alcohol, water, and xylene, that they use when preparing slides of human tissue. In the process, the xylene becomes contaminated with traces of water and alcohol.

The Little Giant's high-current digital outputs energize and de-energize fluid-control solenoid valves, under program control, in the distiller. The solenoid valves direct material back to the bottom of the distiller for redistilling, route distillate to the appropriate fluid-output container, and apply cooling water to the condenser.

A computer-controller motor rotates a stainless-steel fixture inside the distillation column. This fixture opposes the flow of vapor to the head of the column, admitting only the most volatile components to the condenser. The distiller can separate several different volatile fluids in only one distillation run because the rotating band makes the distiller 15 times as efficient as a passive distiller would be.

The Little Giant's analog-input channels monitor the state of the distiller's heating mantle, drive motor, condenser-water flow, and access door. To ensure safe operation, the Little Giant's analog-input channels also detect potentially dangerous gas vapors and the fluid level in the fluid-output containers. A printer attached to the controller generates a time-stamped running record of the distiller's vapor temperature.

Liquid-crystal polymer cuts waste, cost for surgical instrument

Research Triangle Park, NC--Surgical manufacturer Pilling Weck overcame the design challenges of a "reposable" (reusable-disposable) instrument for minimally invasive and open surgeries by drawing on the strength and precise dimensional control of a liquid-crystal polymer (LCP).

In a surgeon's hand, the long, slender HemoclipEcoSystemligation device reaches through a 10-mm incision to clamp off vessels and ducts with titanium wire clips. Once the clips are fastened, the throwaway cartridge saves time and money but the handle can be sterilized and reused to reduce waste 30-fold.

Engineers at Pilling Weck designed a long, stiff track to guide the clips accurately down the cartridge. The injection-molded part incorporates complex features that are tough to mold and must carry heavy mechanical loads. The material needed to have compressive strength, dimensional stability, and high flow in thin walls. The designers found those ingredients in VectraLCP from Hoechst Celanese, Summit, NJ.

The single-use ECO cartridge has a lower housing or track of Vectra and a polycarbonate upper housing. Both components are wrapped in a stainless-steel jacket for added strength. "We cut the hospital cost by loaning the handle," says Jeff Haggerty, Pilling Weck materials manager. "The customer then buys the disposable portion repeatedly."

The basic cartridge for open surgery measures 7.75 inches long but a 5.07-inch-long insert and longer steel jacket extend the reach of the instrument for endoscopic procedures. A clear polycarbonate window near the tip lets the surgeon see advancing Hemoclip fasteners.

Each ECO cartridge has a bayonet plug that locks into the handle with a quarter-turn. "We made the handle like a traditional stainless-steel, reusable surgical instrument, then had to develop a cartridge that could withstand some pretty significant loads," says Tony Hudson, Pilling Weck disposables engineering manufacturing manager. For instance, the 0.125-inch-diameter pins supporting the bayonet plugs in the Vectra molding are loaded to more than 100 lb.

The bottom housing presents a study in thin-section, highly detailed molding. It has a thin-walled, semi-tubular cross section measuring 0.396 inch in diameter, walls down to 0.012-inch-thick, and some posts and stops just 0.020 inch in diameter. It mates with a 1.88-inch-long plug carrying the bayonet attachment. "This cartridge is definitely an injection-molded part," explains Hudson. "Had it been a machined part, it would have cost us $50 or $60 dollars apiece."

To keep the parts together under compressive loads, the long housing halves were jacketed in a pre-cut, stainless-steel tube. The internal parts consequently had to be molded precisely for easy assembly.

The Pilling Weck EcoSystem cartridge provides a new approach to ligation devices. It's still finding its place in a market dominated by totally disposable instruments. With time, Pilling Weck engineers feel, the reposable concept should make its mark in the medical marketplace.

CAD helps redesign cancer equipment

Palo Alto, CA--Using CAD, engineers at Varian Oncology Systems quickly and efficiently redesigned their cancer-treating, 52-leaf modular multileaf collimator (MLC). The new design allows users to easily upgrade a 52-leaf to an 80-leaf collimator.

Collimators adjust the shape of a beam during radiation treatment. The MLC enables physicians to program its intersecting metal leaves so that the radiation beam rapidly conforms to the tumor's shape, while minimizing damage to surrounding tissue. With the 80-leaf MLC, therapists can treat larger field sizes than the 52-leaf, while automatically adjusting the beam to hit only cancerous areas.

Because the original 52-leaf MLC was designed in 2-D, Varian's design team could not associate on-screen representations of its original parts to the overall assembly. This resulted in drawing errors and mismatched parts that had to be redesigned using a physical prototype.

For the redesign, Varian equipped its engineers with Parametric Technology Corp.'s Pro/ENGINEER CAD software. This allowed the design team to view and manipulate a 3-D image of the MLC prototype before the physical prototype was constructed. Several engineers worked concurrently on the virtual prototype.

With Pro/ENGINEER, engineers resolved many manufacturing issues early in the design process. For example, a study of structural deflection was done on computer, allowing the team to examine different design scenarios and analyze the results. According to Stan Mansfield, mechanical engineering manager for Varian: "The whole design process using Pro/ENGINEER saved months of work."

Latch aids walker maneuvers, cuts assembly time

Bay Shore, NY--Lumex has introduced a walker with special locking latches that let users maneuver in tight spaces.

Unlike other collapsible walkers, the Sure-Gaithas latches integrated into a structural crossbar on each side. A user can easily reach the latch, which is conveniently located just below the support grip.

To gain room for turning in a small bathroom or other confined space, the user squeezes the latch bar, releasing the lock. This allows the side of the walker to be swung inward. When the turning maneuver is complete, returning the side to the open position relocks the latch.

The latch mechanism has five parts molded from DuPont Zytel(R): a structural crossbrace, a spring-loaded latch bar, a snap-fit pin that holds the latch, and two collars. One collar caps the assembly and holds it against a walker leg. The other, which is pressed over the frame tube, has a recess that mates with the latch to secure the walker sides in the open position.

The Zytel latch replaces a metal assembly. The metal latch was manufactured in house and required significant off-line assembly efforts. The new mechanism's main components are put together by the molder, and Lumex installs the latches on frames on the walker assembly line. "The new design gives us significant labor savings," says Alan Spiegel, technical manager for Lumex.

Another benefit of the design is more consistent latch operation, says Spiegel. "We can hold tighter tolerances with Zytel than we could with metal," he explains.

Autronic molds the latch components from Zytel 72G33L, a 33% glass-reinforced copolymer formulation combining high stiffness and strength with excellent surface appearance and gloss.

Adhesives bond nasal device

Irving, TX--You've probably seen sports celebrities wearing nasal dilators on television. The narrow adhesive bandages surround a plastic spine that acts as a spring, and the resulting force widens nasal passages and makes it easier to breathe.

But did you ever wonder how the dilators stay affixed to the athletes' faces? To answer that need, dilator manufacturer Bolligner Industries, Inc. approached InsulFab of Texas Inc., Dallas.

InsulFab provides the in-house laminating and rotary-die-cutting capabilities needed to convert the base materials into the form and shape required for the AirFlodilator, according to co-founder Bob Bollinger. InsulFab, in turn, contacted Avery Dennison Specialty Tape Division, Painesville, OH. Avery supplies the WETSTICKmedical tape used on the dilator.

Choosing the right adhesive tape was a critical factor in the design of the AirFlo, says Bollinger. Because the tape adheres directly to the wearer's nose, the adhesive requires FDA approval. The adhesive must pass skin-sensitivity tests, and it also has to stay firmly attached to the wearer's nose for up to four hours. In selecting the adhesive, designers had to consider perspiration, since the athletes would be active while wearing the AirFlo.

Skin is a porous surface, and as a substrate, it poses several challenges. It stretches, breathes, perspires, and absorbs--not to mention that it isn't a flat surface. WETSTICK medical tapes form an aggressive bond that resists high moisture conditions yet is comfortable, Bollinger says.

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