Medical Aids and Research

The Bureau's expertise in the measurement and physical sciences is brought to bear directly and in a variety of ways on the protection of public health and safety. Research in these areas is one of the more diverse efforts at NBS, involving many centers in the National Measurement Laboratory and the National Engineering Laboratory. Typical of this work are recent achievements important in the medical and health fields.

"Getting the most out of x-rays" used in medical diagnosis and treatment was the general theme emerging from several studies in the Center for Radiation Research. In one project, center researchers demonstrated that physicians and radiologists should be able to extract more information from x-ray photographs (radiographs) of patients than they now are. Like typical photographic negatives, if xradiographs are underexposed, they will appear too light to read and analyze. Consequently, doctors and radiologists use a higher x-ray exposure in order to achieve a sufficiently distinct radiograph.

Actually, the currently unusable light radiographs in many cases already contain the information needed by physicians. In order to use them, however, emerging "image processing" techniques have to be utilized. These methods allow doctors to get more information from the film than the eye can see, but they are used sparingly now because of the lengthy processing time required. Still, the fast-paced development of this technology sug

NBS has helped to foster the use of ultrasound as a diagnostic tool in the medical community. This interferometer system and the SonoChromoscope described on page 29 were developed by Melvin Linzer and his colleagues and can be used to examine tissue samples.

gests that image processing will be available for much wider use in several years.

NBS researchers analyzed the makeup of x-radiographs and the levels of x-ray exposure at which important body structures could still be revealed if image processing techniques were to supplement the usual development methods. Bureau scientists were able to relate mathematically the image content and the patient's exposure, giving estimates of the minimum exposure required for detecting particular images sought. For diagnostic examinations regularly administered to large segments of the public, such as chest xrays, the NBS researchers found that adequate information could be provided with patient exposures at less than 10 percent of current levels.

This same concept, getting more information from lower levels of x-ray exposure, was evident in studies leading to the joint development of an extraordinary new diagnostic tool by a researcher in the NBS Center for Radiation Research working with a team at the National Aeronautics and Space Administration's Goddard Space Flight Center. By coupling a variety of components not previously used in xray diagnosis and utilizing advice and equipment supplied by other Federal agencies, the researchers constructed the first small, hand-held x-ray fluoroscopic unit.

Called the "Lixiscope" (for lowintensity x-ray imaging scope), the new tool is about the size of a camera and weighs only a few kilograms, compared to the heavy, immobile units in hospitals. Although the instrument is not as powerful as conventional x-ray machines-and therefore is most useful for examining an individual's extremities rather than thicker body portions-its portability and batterypowered operation have a variety of advantages. For example, the Lixiscope may be particularly useful in emergency situations. One of its major attributes is the possibility of making certain radiographic examinations at dramatically reduced exposures compared to conventional x-ray machines.

The Lixiscope uses a low-level x-ray emitting material (a radioactive isotope) which, by itself, produces only a poor photographic image of the area being examined. However, by adding a night vision scope-widely used in military operations to "see" at night by intensifying very low light levels-even those poor images are amplified and become visible to the physician.

The device has received preliminary testing in a range of dental and medical applications. Several manufacturers

have applied for and been granted licenses to produce the governmentpatented Lixiscope, which may also find important industrial uses for the nondestructive analysis of materials and equipment components.

The Center for Radiation Research registered a number of other noteworthy achievements in fiscal year 1978 with implications and potential in the medical field. These include several projects that could aid in cancer therapy. NBS scientists developed a theoretical method for predicting certain characteristics of electron beams that will help calculate radiation dosage. Since there is a delicate threshold at which radiation will destroy cancerous cells but permit healthy cells to live, it is crucial that therapists know precisely what dosage is received by the patient. The NBS predictive method could provide a more accurate way to make that determination.

NBS also established exposure standards for iridium-192, a radionuclide often used in cancer therapy. To assure that treatment centers using this material are certain of their measurements, NBS has set up calibration services for their use.

In another area of medical research, scientists in the NBS Center for Analytical Chemistry have pioneered the special use of a technique which could well become an invaluable tool in biomedicine and pathology. The technique utilizes a laser-excited microRaman spectrometer not previously used to test biological tissues and cells. The Raman microprobe, as it is called, is likely to be of special significance in detecting occupational or environmental diseases for which existing techniques are inadequate.

When medical researchers and doctors find or suspect that foreign material has been introduced into body tissue, they need to know the distribution and identity of the particles or dissolved material. Conventional microanalytical tools cannot reveal as much information about the material as medical researchers would like. Having heard about NBS work using the Raman microprobe, an instrument used to characterize microscopic samples, a pathologist at the University of California, San Diego, approached the Bureau about its possible application to the analysis of living tissue. NBS agreed to try out the technique. The pathologist supplied NBS with thin sections of lymph node believed to contain foreign particles of silicone polymer. It was suspected that the particles were related to a silicone finger joint prosthesis implanted in the patient.

Research confirmed this suspicion and supported other previously

undocumented medical indications that microparticles can migrate from an intact and normally-functioning implant to a distant lymph node. Many possibilities have been opened up by the NBS application of the microprobe. The technique should make it possible to obtain much needed information about the identity, precise distribution, and relative abundance of certain constituents within tissues and cells and thus contribute significantly toward understanding many essential tissue and cellular processes. The experiment also raises the possibility that the

technique can be used to detect, pinpoint, and characterize a number of environmental and occupation-related contaminants within individuals.

Scientists in the Center for Materials Science also made progress last year in the areas of synthetic implants and dental research. Companies fabricating plastic synthetic implants-used to replace damaged or diseased parts of the body, such as hip, knee, and ankle joints-need reliable means for specifying and testing the plastics in order to guarantee the long-term safety and durability of this product.

Fire Research

Fires take more than 7,500 lives, cause 310,000 injuries, and result in billions of dollars of property damage in this country each year. As the Federal government's prime fire research laboratory, the NBS Center for Fire Research seeks to reduce that toll by improving our knowledge of the way fire works and what we can do to prevent, forestall, or minimize its destructive effects. In fiscal year 1978, this center:

⚫ developed a new device that can test any installed smoke detector to see whether it is sufficiently sensitive and in good working order. The NBS instrument is intended for use by fire departments and maintenance personnel in periodic tests and has been used successfully in several demonstrations.

⚫ examined in laboratory and full-scale tests the role of various mobile home interior finish materials in fires as part of a program sponsored by the Department of Housing and Urban Development.

presented several new test methods for assessing the flammability of thermal insulation and saw them adopted for Federal insulation procurement specifications. (See page 34.)

prepared a system for grading health care facilities in terms of fire safety. The system offers flexibility to the designers of new facilities and to those remodeling existing health care buildings. It can be used to determine how combinations of fire safety equipment and building construction features may provide a level

of safety equivalent to that specified in the widely accepted National Fire Protection Association Code. The Center for Building Technology and the Center for Applied Mathematics also worked on this joint project. Several Federal agencies have asked NBS to prepare a similar evaluation system for application to housing for the developmentally disabled and to multi-family residences. • sponsored the preparation of audiovisual training aids for health care personnel in the basics of smoke spread and control and fire "flashover," the point at which a small, nonthreatening fire suddenly becomes a violent force which can envelop an entire room in flames. The film and slide presentations are based on NBS research for the De

partment of Health, Education, and Welfare.

saw an NBS test for judging the flammability of corridor flooring systems adopted by both the National Fire Protection Association and the American Society for Testing and Materials.

• developed a model for routing people from buildings under emergency situations. This work was performed with the assistance of the Center for Building Technology and the Center for Applied Mathematics. Designed to minimize evacuation time and bottlenecks, the model will provide valuable information to architects, municipal building code officials, and safety officers.

NBS is helping to develop a test method for assessing the potential toxicity of combustion products generated when household materials burn. Left to right, chemist Susan Womble, physiologist Dolores Malek, and biologist Barbara Levin measure amounts of toxic materials in the blood of research animals and in their immediate environment.