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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to the field of medical instrumentation, and more
specifically to the field of microscopic analysis of fluids.
Suppliers of medical instrumentation have adopted computer technology to a
high degree, offering complex and expensive equipment capable of providing
rapid analyses and calculations. Such equipment has proved its worth in
many situations, and indeed has paved the way to more exact, efficient
diagnosis. Computerized axial tomography, for example, literally has
revolutionized diagnositic techniques.
This trend, however, has bypassed some of the more mundane but essential
tasks faced by the medical laboratory. Urinalysis presents an excellent
example of this phenomenon. The task is relatively straightforward: a
technician must view a sample through a microscope and count the number of
white blood cells in a given area. Following traditional methods, the
technician places a drop of sample on a microscope slide, covers that
slide with a cover slide, and clips the assembly on the viewing stage of a
microscope. After making the count, the two-slide assembly usually is
discarded.
The answer offered by equipment suppliers is complete automation of
urinalysis, combining computer-controlled chemical testing with optical
scanning and pattern recognition to generate a complete report in a matter
of seconds. In an era when rising medical costs are a matter of national
concern, however, new equipment must not only be technically sophisticated
but also cost effective. Many laboratories have rejected the automated
approach after carefully weighing the savings provided versus the costs
associated with the high level of capital expenditure required.
Yet, laboratories recognize that tasks such as urinalysis are expensive,
labor-intensive, and repetitive. A 300-bed hospital, for example, will
perform almost 23,000 urinalyses per year; at a cost of about $0.25 in
disposables for each analysis, this testing results in an expenditure of
almost $5700, plus the cost of technicians and microscopes, etc. This
level of spending certainly does not justify the purchase of equipment
priced over $100,000, but the clear requirement exists to reduce costs.
What laboratories need is an approach that offers the benefits of
automation without travelling as far as the fully computerized systems
provided by the instrumentation industry.
The art has failed to provide effective solutions to this problem. U.S.
Pat. Nos. 3,864,564, to Adkins, and 3,397,656 disclose automated systems
for positioning and viewing samples, employing sophisticated logic
circuitry and complex mechanisms for driving the slide in selected
patterns to insure full scanning. Such approaches typify the problem
rather than the solution. Similarly, Negersmith, in U.S. Pat. No.
4,300,906 presents an improvement to an automated analysis system designed
to provide a constant flow of sample through the analytical portion of the
system. Again, such systems do not meet the needs of the laboratories for
a urinalysis system.
An optical counting system is disclosed in U.S. Pat. No. 3,511,573, issued
to Isreeli, stated as being particularly useful for counting red blood
cells. There, a flow cell is employed in conjunction with means for
focusing a light beam, the particles being detected by utilizing
photocells and photomultipliers to sense occlusions of the beam. The flow
cell of this invention is itself somewhat of a complex device, requiring
the machining of bores and passageways and the inclusion of a special
fitting to accomodate the washing function. In like manner, a flow cell is
also disclosed in U.S. Pat. No. 3,515,491, to Emary, in which the sample
is retained in a machined block, within a cylindrical insert having fluid
passages and a viewing bore.
What none of these devices provide is an inexpensive, easy-to-use system
that will allow a laboratory to automate its urinalysis without high
capital expenditure. It was left to the inventor of the present invention
to solve this problem.
SUMMARY OF THE INVENTION
An object of the present invention is to provide apparatus for
microscopically analyzing fluids.
A further object of the invention is to provide apparatus that will enable
urinalysis to be performed rapidly and conveniently.
Yet another object of the invention is a urinalysis system that allows a
technician to perform urinalysis rapidly, eliminating danger of spillage
and the eyestrain associated with conventional microscope equipment.
These and other objects are achieved by the present invention. In one
embodiment of the invention, a urinalysis system is provided, consisting
of subsystems for providing fluid flow and for acquiring and displaying an
image. The fluid flow subsystem pumps a portion of fluid sample from a
sample container to a flow-through cell, where a thin planar portion of
sample is presented for viewing. The flow-through cell includes a
three-part lamination, the two outer members being generally flat and the
center member having a display chamber cut out of its central area. The
fluid system also includes means for washing the system between samples,
by pumping a quantity of solvent (pure water in the instance of a
urinalysis system) through the flow-through cell, the pump, and associated
tubing. A light beam is passed through the flowthrough cell, enabling a
video camera to acquire a magnified image of a portion of the sample,
which image is displayed on a monitor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an embodiment of the invention;
FIG. 2 is a pictorial showing the embodiment of FIG. 1 mounted in a
housing;
FIG. 3 is a pictorial of the flow-through cell of the embodiment shown in
FIG. 1;
FIG. 4 is an exploded pictorial of the laminated display cell of the
flow-through cell of FIG. 3.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
FIG. 1 schematically depicts an embodiment 10 of the invention. Preferably,
the system is contained within a unitary housing 12, as shown in FIG. 2,
with accessible control and display features as described below.
The invention generally can be thought of as two cooperating subsystems--a
fluid handling system and an imaging system. The former subsystem includes
the components required to bring a portion of the sample into position for
viewing, to dispose of the sample after analysis, and to purge the system
between samples. The imaging subsystem consists of those elements needed
to generate a magnified image of the sample and to display that image for
analysis.
The fluid subsystem begins at one of two fluid sources--the sample
container 14 or the wash reservior 16. The latter can be a small tank,
fabricated of a convenient inert plastic or other suitable material,
carried within the housing. For urinalysis applications, distilled water
serves as an excellent washing medium, and the reservoir preferably is
connected to a water supply. Other analytical tasks might require
different solvents, and those in the art will appreciate the best manner
of selecting a particular solvent for individual requirements.
As urine specimens usually are provided to the laboratory in small
containers, a sample well 20, sized to accept such containers, is formed
in the front panel of the housing. A portion of the tubing 18 extends
downward into the well, so that a sample container may be placed into the
well with the tubing extending into the container. It should be noticed
that the technician is not required to pour or remove any of the sample
from the container, an advantage of the present invention. This convenient
method not only results in a time savings, but also it prevents
contamination of the work area resulting from spillage.
Only one of the two sources is connected to the remainder of the system at
any given time. A two-way valve 22, selected from among the many suitable
components available to the art, is actuated by front panel buttons 24 and
26 to select the appropriate alignment. From the two sources, the tubing
18 esxtends to the input end of the flow-through cell 30, discussed in
greater detail below. Further tubing runs from the output end of the
flow-through cell to a pump 40, which provides fluid pressure to the
system. This pump should be capable of rapidly transporting a quantity of
sample from its container to the flow-through cell, and it is preferred to
employ a small peristalic pump, selected from among those commercially
available in this role. For ease of service, the pump may be mounted on
the front panel, as shown in FIG. 2. The pump output line 42 carries fluid
to a waste container 44, which may further communicate with a drain line
(not shown). Alternatively, the output line can feed directly to a drain
if desired.
The imaging system consists of those elements required to produce a
magnified image for analysis. As with conventional microscopes, a source
of light is needed, and here that light is provided by lamp 46, which may
be halogen or other suitable source of illumination known to those in the
art. The beam emitted by this lamp passes through the portion of the
specimen disposed in the flow-through cell and continues to camera 50.
Size considerations of this embodiment dictated that the beam be reflected
90 degrees using mirror 48, but other in other applications the user may
find that the beam can be passed to the camera in a straight line. Either
method can be used.
Camera 50 can be a television camera, known to the art, fitted with a lens
capable of providing magnification. It is preferred to offer two degrees
of magnification, at 200 and 400 diameters, and the camera is selected to
provide an optical system consistent with that requirement. The camera
lens system should be of the "zoom" adjustable type, and is controlled
from the front panel by selector buttons 28. Signals from the camera are
connected to monitor 60, mounted in the front panel, where they are
electronically processed to produce an image. To obtain an image that most
exactly replicates the view observed directly through a microscope, it is
preferred to employ a color camera and monitor having good optical
resolution.
The intersection of the two subsystems is occupied by flow-through cell 30,
better seen in FIG. 3. The cell body 32 is generally in the form of a flat
letter "U", with upstanding end portions 31 and a central well 33. The
body may be formed of any convenient material, but it has proved effective
and economical to fabricate it from aluminum, which is readily available,
light, and easy to work. A circular viewing aperture 34 lies at the center
of the central well, extending completely through the body at that point.
This opening may be sized according to the analysis task to be performed.
A sample viewing assembly 35 is carried in the central well. This device
accepts a portion of the sample and disposes it for optimum viewing by the
camera. As shown in the exploded view of FIG. 4, this element is a
lamination of three parts. Upper and lower retainers 36 and 37 are
generally flat, transparent members that form the outer walls of the
assembly. It has been found that these members can most conveniently be
formed of glass slides commonly available, but of course those in the art
will understand that other materials, such as any of a number of clear
plastics, can be employed. The central element 38 has a cutout area in its
central portion, display chamber 39. Utilizing a glass slide for this
element insures that the sample will be presented to the imaging system in
a thin planar form, allowing the technician to gain a clear view of the
material within the sample.
Hollow connector pegs 45, secured in mounting holes 43 in upper retainer 36
and extending upward, allow for connection to fluid input and output
tubing. It should be noted that the mounting holes are located at the
extreme ends of the display chamber, to insure that fluid does flow
throughout the chamber, with no portions of fluid being trapped behind an
inlet or outlet port. The pegs are preferably fabricated of hollow metal
tubing, and are secuered in the mounting holes with an appropriate cement.
Cement also is applied to the retainers and to the center element to seal
the display chamber and to maintain the assembly as a single unit. To
prevent the application of sidewise stress to the connector pegs by the
tubing, support passages 47 may be formed in the upstanding ends of the
cell body, sized to accept the tubing.
Analysis of a sample proceeds straightforwardly. First, of course, the unit
is turned on and the monitor adjusted, in a manner known to those in the
art. A technician then places a sample container in the sample well 20
(FIG. 2), insuring that tubing 18 extends into the sample. When "Sample"
button 24 is depressed, two-way valve 22 cycles to connect the fluid
subsystem to the sample container 14, the pump 40 operates, drawing a
portion of the sample into the flow-through cell 30. A portion of the
sample enters the display chamber 39 as a relatively thin film of fluid.
The beam of light emitted by lamp 46 passes through the sample, is
reflected by mirror 48, and enters video camera 50, which generates a
video image displayed on monitor 60. The technician can choose between two
levels of magnification by appropriate selection of buttons 28.
When analysis is complete, the technician presses "Wash" button 26. Two-way
valve 22 cycles to connect the fluid subsystem to the wash reservoir 16,
and the pump operates to draw a quantity of pure water through the tubing,
the flow-through cell and the pump, removing all traces of the previous
sample. Both the excess sample and the wash water are pumped into the
waste container. At this point the technician can perform another analysis
by replacing the sample container with another such container and
repeating the steps outlined above. It should be noted that after each
analysis, the pump propels a sufficient quantity of sample into the
flow-through cell to displace completely the wash water introduced during
the wash cycle.
Those familiar with the art will understand that various modifications can
be made without departing from the spirit of the present invention. For
example, the embodiment disclosed above deals with a system for performing
urinalysis. An adaptation of the invention to other forms of analysis may
require different means for introducing the sample into the system,
different solvents, etc. These and other changes may be made within the
scope of the invention, which is defined solely by the claims appended
hereto.
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