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Description  |
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TECHNICAL FIELD
The invention relates to optical data information storage and in particular
to storage of digital signals from medical diagnostic scanners, tomography
machines and the like.
BACKGROUND ART
In medical records archival data storage, it is frequently necessary to
store pictures such as digital X-ray pictures, CAT-scan pictures, digital
microscope photographs, NMR and ultrasonic scan pictures, and other
diagnostic images. These pictures originate as digital data. If digital
data is not recorded in anticipation of future image processing, it would
be lost forever. Frequently the data is converted to an enhanced eye
readable picture representing only one form of the data.
In U.S. Pat. No. 4,236,332, Domo discloses a wallet-size medical record
card to be carried by the individual containing a microfilm portion having
some data visible to the eye and other data visible by magnification. The
directly visible data is code characters pertaining to emergency medical
conditions of the patient and magnifiable data portions detail the medical
history. Such cards are not intended for achival storage and cannot be
used for that purpose. Cards cannot contain X-ray pictures, CAT-scan
pictures and the like without loss of vital image resolution.
In U.S. Pat. No. 4,110,020, Johnson et al. add bar codes along the edge of
microfilm having image areas. These codes are used by the film reader to
locate the desired frame. Bar codes are rather limited in the type and
amount of information they can represent, so their use with detailed
medical information is undesirable.
An object of the invention is to provide recording of digital image signals
from a medical scanner, such as a CAT-scanner, NMR scanner, ultrasonic
scanner, or digital X-ray scanner in a useful format.
DISCLOSURE OF THE INVENTION
The above objects have been met by recording a digital representation of a
medical picture and related medical information on a strip of laser
recordable material which is disposed next to an eye readable medical
image on a picture storage medium, such as film. Many new imaging devices
such as tomography machines and scanners provide digital outputs. By
recording a digital representation of a picture the raw data is saved.
Pictures produced from the data usually have enhancements which require
subduing unwanted signal components. In the present invention a digital
representation is combined with an eye readable picture so that the
picture can be reconstructed with other enhancements if desired. The
storage medium could be either unexposed or exposed in plates, strips, or
roll configuration. The film records visual images of a body, such as
X-ray pictures, CAT-scan pictures, NMR- and ultrasonic-scan pictures,
microscope photographs, and other diagnostic images. The data strip could
be recorded in-situ on blank optical media o pre-recorded and added to the
film.
The digital image representation of the medical scanners is recorded
directly on the data strip in digital form. Analytical or interpretive
data, such as a diagnosis, or an anatomical description, may be integrated
with the digital picture record and both stored together. A laser beam
records data on the strip of laser recordable material either by ablation,
melting, physical or chemical change, or by deformation thereby forming
spots representing changes in reflectivity. Differences in reflectivity or
transmissivity are detectable by a light detector. In this manner, data
concerning the visual image may be digitally recorded and read directly
from the strip. The digital version of the image can be analyzed by
computer techniques such as enhancement, or can be used for making
accurate photographic copies of the original image. The strip may contain
prerecorded data, concurrently recorded data or data recorded after
exposure of the photosensitive film portion of the media. The strip may be
reflective or transmissive type optical media.
No processing after laser recording is required for the recording strip
when it is a direct-read-after-write material. The uniform surface
reflectivity of this reflective strip before recording typically would
range between 8% and 65%. For a highly reflective strip, the average
reflectivity over a laser recorded spot might be in the range of 5% to
25%. Thus, the reflective contrast ratio of the recorded spots might range
between 2:1 and 7:1. When the reflectivity of the field is in the range of
8% to 20% then the reflective spots might have a reflectivity of 40%. The
reflective contrast ratio thus might range between 2:1 and 5:1.
Photographic preformatting would create spots having a 10% reflectivity in
a high reflective field or 40% in a low reflective field.
The laser scanning system records and reads using a mirror directed laser
beam and a photodetector. A photodetector array such as a CCD could also
be used. A laser light source, such as a semiconductor laser, emits a beam
which is directed to a first servo-controlled mirror. The mirror is
mounted for rotation along an axis such that the beam may be moved
laterally on the strip. The strip has data tracks running in the
lengthwise direction of the strip. The lateral motion of the beam thus
allows different tracks to be recorded and read. From the first mirror,
the beam is directed toward a second servo-controlled mirror. This second
mirror is mounted for rotation along an axis such that the beam may be
moved lengthwise along the strip. In this way the beam moves along a
track. Upon reading or writing one track, the first mirror moves an
incrimental amount so that the next track may be scanned. It is also
possible to align the tracks in a crosswise direction so that it is in the
lateral direction of the strip. Differences in reflectivity between a data
spot are detected by a light detector, such as a photodiode, which
produces electrical signals corresponding to the spots. Prerecorded
reference position information may be present on the strip to aid servo
control. The eye readable version of the image may be printed by a
commercial machine.
An advantage of the invention is that laser recorded data, particularly
digital image data, will be saved and will not be separated from
corresponding image data. Both will have similar archival properties. The
strip may be placed directly on the photographic film or on the film
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a first embodiment of the recording medium of the
present invention.
FIG. 2 is a top view of the second embodiment of the present invention.
FIGS. 3-6 are alternate sectional constructions of the medium of FIG. 1
taken along lines A--A in FIG. 1.
FIG. 7 is a partial sectional view of an alternate embodiment of the medium
of FIG. 1.
FIG. 8 is a plan view of optical apparatus for reading and writing on the
data strip portion of the medium illustrated in FIG. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
With reference to FIG. 1, the data medium used in the present invention may
be seen to compromise a photographic medium 11 having a planar major
surface 13 which is divided into a photographic image areas 15 and a data
strip 17. Photographic medium 11 is preferably film in sheet form, for
example X-ray film, plate film, microfiche film or high resolution
photoplates of the type used in the semiconductor industry. The
photographic image areas 15 are conventional photographic images produced
by usual photographic techniques, typically by exposure and development of
the medium. The image areas 15 may occupy the entirety of the photographic
medium, except for the data strip, or discrete areas as shown in FIG. 1.
The discrete areas may resemble motion picture film or roll film or
microfiche film where several images may be disposed on the photographic
medium. Alternatively, only a single image may be on the medium.
The present invention features an optical data strip 17 which may be a
direct read-after-write (DRAW) material which may have either prerecorded
information or user-written information, or both. The type of DRAW
material that may be used is relatively high reflective material which
forms a shiny field against low reflectivity spots such as pits, craters,
holes or dark spots in the reflective surface which tend to be absorbtive
of light energy. The contrast differences between the low reflectivity
spots and the shiny reflective field surrounding the spots cause
variations at a detector when the spots are illuminated by light of lesser
intensity than the light that originally created the spots. These are also
laser recording materials which create reflective spots in a dark field.
Data strip 17 is intended to provide an archival data record accompanying
the photographic images on the same material just as a movie sound track
accompanies a sequence of frames of film. Data is written in individual
tracks extending in a longitudinal direction, as indicated by the spot
patterns 19 and these spot patterns are analogous to sound track on a
film, except that the data tracks contain a much higher density of
information and are usually read in reflection, rather than in
transmission. The information density is greater because each of the spots
in the spot pattern is approximately 5 microns in diameter with a spacing
of about 5-20 microns between spots. A one inch (25 mm) piece of 16 mm
wide data strip holds three million bits of information, which is adequate
for one digitized image. The spots may be either digital or analog data,
but in either case are recorded by a laser in the usual way, for example
as shown in U.S. Pat. No. 4,278,756 to Bouldin, et al.
FIG. 2 is similar to FIG. 1 except that a larger photographic medium 21 is
used with a plurality of rows of images 23, 25, and 27. Accompanying each
row of images is a corresponding data strip 33, 35 and 37. These data
strips are analogous in construction to the strip of FIG. 1. Once again,
it is not necessary that each row have individually different images. Each
row may consist of either multiple images or a single image. The
embodiment of FIG. 2 is a microfiche type medium where each row of images
would have corresponding data on a data strip. The images are such that
they can be viewed with the naked eye or with low power (magnification)
optical systems. On the other hand, the data strips are not usually read
with the naked eye, but require either microscope inspection or preferably
reading by reflection of a scanning laser beam as explained below.
FIG. 3 illustrates a first construction of the recording medium shown in
FIG. 1. The sectional view includes a substrate 22 which is transparent
and may be glass or one of the many polymeric substrate materials known in
photographic arts. Applied to the substrate 22 is a subbing layer, not
shown, and an emulsion layer 24. This emulsion layer has a photographic
image area 15 made by exposure and development in the usual way. The wavy
lines 26 represent filamentary black silver particles which characterize
normal photographic black and clear images. Data strip 17 is one of many
laser recording materials. It may, for example, be made from silver-halide
emulsion having fine grain size, less than 0.1 microns, by a silver
diffusion transfer process described in U.S. Pat. No. 4,312,938 (Drexler
and Bouldin), incorporated by reference herein.
In the referenced patented process, silver-halide emulsion is exposed to a
non-saturating level of actinic radiation to activate silver halide. The
activated emulsion is then photographically developed to a gray color of
an optical density of 0.05-2.0 to red light, forming an absorptive
underlayer. There is no fixing after this first development step. The
surface of the emulsion strip is then fogged by a fogging agent such as
borohydride to produce silver precipitating nuclei from the part of the
unexposed and undeveloped silver-halide emulsion. The strip is then
contacted with a monobath containing a silver-halide solvent and a silver
reducing agent to complex, transfer and reduce the remaining unexposed and
undeveloped silver to reflective non-filamentary silver at the nuclei
sites on the surface. The reflective layer contains from 20% to 50% silver
particles of which 1% to 50% may be filamentary silver formed in the
initial development step. Beneath the reflective layer is an absorptive
underlayer.
The reflective surface layer is characterized by non-filamentary particles
28 overlying a concentration of filamentary particles which form the
absorptive underlayer. Separating the data strip from the image area is an
unprocessed silver-halide buffer area 30 which would remain generally
clear since it is neither exposed nor developed. The buffer area 30 is not
necessary, but is desirable because chemical processing of data strip 17
differs from the processing of image area 15. The buffer area 30 may be
fixed to remove silver halide so that the area will remain clear. This is
optional. Both processes may occur by spraying of chemicals onto the
surface of the film, with a mask covering buffer area 30. Such spray
processing is well known in the photolithography. However, in the present
case it may be necessary to proceed in two steps. In the first step,
conventional photographic processing of image area 26 takes place.
Subsequently, the image area, together with the buffer area 30 is masked
to allow seperate processing of the data strip 28. After processing is
complete, a transparent layer 32 is applied to the emulsion, forming a
protective layer. Layer 32 may be any of the well known protective
coatings, including a layer of clear gelatin. The remainder of the film,
apart from the data strip 17, need not have fine grain size. Data strip 17
can also be added to the photographic material in the form of an adhesive
tape which is bonded to the photographic material either before or after
the film is developed.
FIG. 4 is similar to FIG. 3 except that substrate 34 is coated only with
silver-halide emulsion to the right of line 36. The image area 15 is
exposed, developed and fixed. A protective coating 38 may then be applied.
A preformed strip 40 of laser recording material may then be disposed on
the substrate. This may be a strip of Drexon material. Drexon is a
trademark of Drexler Technology Corporation for reflective silver based
laser recording material, such as that described in the aforementioned
U.S. Pat. No. 4,312,938. Such a preformed strip of laser recording
material would have its own thin substrate 39 carrying the emulsion layer.
Alternatively, the recording material could be any of the other
direct-read-after-write laser recording materials, for example such as
that described in U.S. Pat. No. 4,230,939 issued to De Bont, et al. where
the patent teaches a thin metallic recording layer of reflective metal
such as Bi, Te, Ind, Sn, Cu, Al, Pt, Au, Rh, As, Sb, Ge, Se, Ga. Materials
which are preferred are those having high reflectivity and low melting
point particularly Cd, Sn, Tl, Ind, Bi, and amalgams. These materials may
be deposited directly on substrate 34, as by sputtering, or may be
premanufactured on a very thin substrate and adhered to the substrate by
means of a subbing layer. After adhering the DRAW material to the
substrate, a transparent protective coating 44 is applied. This coating
material may be the same as protective material 38.
With reference to FIG. 5, substrate 52 has a notch or groove 54 which
allows placement of a DRAW material 56 therin. This laser recording
material may be processed in situ from silver-halide material previously
existing in the groove, as in the case of FIG. 3, or preexisting laser
recording material which is placed in the groove, as with the the
preexisting laser recording material of FIG. 4. In either case, the
photographic image area 15 is exposed and developed in the usual way,
while an unexposed and undeveloped area 58 protects data strip 56. Since
emulsion area 58 is unexposed and undeveloped, it remains clear and forms
a protective layer over the data strip.
In the embodiment of FIG. 6, no groove exists in substrate 60. Rather, a
photographic image area 15 is exposed and developed in the usual way, with
the remainder of the substrate being covered with emulsion which is masked
and protected from exposure and development, forming a protected region
62. On top of the protected region 62 a strip of laser recording material
64 is positioned. This laser recording material may be formed in situ by
application of a silver-halide emulsion strip which is then processed, as
data strip 17 in FIG. 3 is processed, or may be a preformed strip which is
applied as in FIG. 4. The strip is then covered with a protective coating
66.
With reference to FIG. 7, a substrate 70 is shown which carries a
photographic image in a substrate portion not shown. This image may be
above the substrate surface or within a groove of the substrate, as
previously mentioned. The substrate carries a secondary substrate 72 which
is a thin flexible material, only a few mils thick carrying a laser
recording material 74. The secondary substrate 72 is adhered to the
primary substrate 70 by means of an adhesive or sticky substance, similar
to dry adhesives found on tape. The laser recording material may be any of
the materials previously discussed, such as DREXON material, except that
the secondary substrate 72 is substituted for the substrate previously
mentioned. A protective coating 76 is applied over the laser recording
material. Using this embodiment, photographs of the prior art may be
converted to the optical data and image medium of the present invention.
In this situation, not shown in the drawing of FIG. 7, a portion of an
image area is converted to a non-image area by application of the sticky
laser recording material. The laser recording material rests above
developed silver-halide emulsion, resembling FIG. 6, except that the
emulsion is completely exposed and developed in the region underlying the
secondary substrate.
In all of these embodiments, a strip of laser recording material is
positioned adjacent one or more photographic images for providing archival
data storage of a similar quality as for the photo image. Digital image
data, and remarks in the form of alphanumerics or voice may be recorded
adjacent to the photographic image. By this means these two forms of
communication will not be separated. This arrangement is of particular
value to add analytical information to X-rays used for medical purposes,
or for non-destructive testing or to add to photomicrographics of
biological objects or metallurgical structures.
Of course, while the photo images may be read by conventional means,
low-powered laser or a photodetector array apparatus must be used to read
the data strip. A laser apparatus is illustrated in FIG. 8, which
illustrates the side view of the lengthwise dimension of the medium of
FIG. 1 consisting of a data strip in combination with photo images. The
data strip portion 41 of the medium is usually received in a movable
holder 42 which brings the strip into the trajectory of a laser beam. A
laser light source 43, preferably a pulsed semiconductor laser of infared
wavelength emits a beam 45 which passes through collimating and focusing
optics 47. The beam is sampled by a beam splitter 49 which transmits a
portion of the beam through a focusing lens 51 to a photodetector 53. The
detector 53 confirms laser writing and is not essential. The beam is then
directed to a first servo controlled mirror 55 which is mounted for
rotation along axis 57 in the direction indicated by arrows B. The purpose
of the mirror 55 is to find the lateral edges of the data strip in a
coarse mode of operation and then in a fine mode of operation identify
data paths which exist predetermined distances from the edges.
From mirror 55, the beam is directed toward a mirror 61. This mirror is
mounted for rotation at pivot 63. The purpose of mirror 55 is for fine
control of motion of the beam along the length of the data strip. Coarse
control of the lengthwise portion of the data strip relative to the beam
is acheived by motion of the movable holder 42. The position of the holder
may be established by a linear motor adjusted by a closed loop position
servo system of the type used in magnetic disk drives. Reference position
information may be prerecorded on the card so that position error signals
may be generated and used as feedback in motor control. Upon reading one
data path, the mirror 55 is slightly rotated. The motor moves holder 42
lengthwise so that the path can be read again, and so on. As light is
scattered and reflected from spots in the laser recording material, the
reflectivity of the beam changes relative to surrounding material where no
spots exist. The beam should deliver sufficient laser energy to the
surface of the recording material to create spots of changed reflectivity
in the data writing mode, but should not cause disruption of the surface
so as to cause difficulty in the data reading mode. The wavelength of the
laser should be compatible with the recording material to achieve this
purpose. In the read mode, power is approximately 5% to 10% of the
recording or writing power.
Differences in reflectivity between a spot and surrounding material are
detected by light detector 65 which may be a photodiode. Light is focused
onto detector 65 by beam splitter 67 and focusing lens 69. Servo motors,
not shown, control the positions of the mirrors and drive the mirrors in
accord with instructions received from control circuits, as well as from
feedback devices. The detector 65 produces electrical signals
corresponding to pits. Other optics, not shown, could be used to observe
the photo images, while data is being read or written on the data strip.
A photodetector array such as a CCD could also be used. It could be either
a linear array or area array. The number of detector elements per track
would be approximately three elements to create a reading redundancy. The
surface would be illuminated with low-cost light-emitting diodes
generating power primarily in the near infra-red to match the sensitivity
spectrum of the photodetector array.
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