Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
TN-7740/PCT
1- 2~3~61
DESCRIPTION
TITLE OF THE INVENTION
Method and Apparatus for Bone Morphometry and a
Morphometric Bone Assay System
TECHNICAL FIELD
The present invention relates to an automated bone
morphometry and morphometric bone assay, and more
specifically, to an automatic bone morphometry method
using radiographs or roentgenograms and a bone-morpho-
metric apparatus for carrying out the method, and a
morphometric bone assay system connected with the
bone-morphometric apparatus by a communication system
and capable of ef~iciently carrying out a morphometric
bone assay and bone history assay.
BACKGROUND ART
Bone morphometry is applied to the confirmation of
the growth and aging of human bones, the diagnosis and
confirmation of the rate of progress of bone diseases
including osteoporosis and osteomalacia, and the confir-
mation of the effect of treatment.
Microdensitometry (MD), photon-absorptiometry and
radioscopy are generally known bone morphometric
methods. Microdensitometry (Kotsu Taisha, Vol. 13,
pp. 187-195 (1980); Xotsu Taisha, Vol. 14, pp. 91-104
(1981)) measures the tone of the roentgenogram of a
sample bone by a microdensitometer for bone morphometry;
photon absorptiometry measures the quantity o~ gamma
rays transmitted through a sample bone by a detector for
bone morphometry; and radioscopy measures the quantity
of X-rays transmitted through a sample bone by a
detector for bone morphometry. A morphometric bone
assay method disclosed in U.S. Pat. No. 4,721,112 assays
bones on the basis of bone density distribution deter-
mined by measuring roentgenographic bone patterns.
Microdensitometry has become increasingly widely
used because the method uses readily available
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roentgenograms which can be easily obtained by an X-ray
camera used widely for diagnosing bone fractures.
Photon absorptiometry has a drawback in that use of the
gamma-ray generator has not become as wide-spread as
that of the X-ray camera.
The conventional microdensitometric bone morpho-
metry, however, requires many steps of manual work.
When carrying out the conventional microdensitometric
bone morphometry, a reference point for bone morphometry
is determined in the roenkgenographic bone image of a
sample bone, an object measuring region, such as a
region on a line crossing the middle point of the
longitudinal axis of the second metacarpal bone, is
selected by a predetermined procedure with reference to
the reference point, the selected region is scanned by a
microdensitometer, the intensity or quantity, preferably
quantity, of light transmitted through the region is
measured, and the measured quantity of light transmitted
through the region or the measured quantity of light
absorbed by the region is recorded as a diagram on a
chart. On the other hand, the roentgenogram of an
aluminum standard step block, namely, an aluminum step
wedge or an aluminum slope, taken together with the
roentgenogram of the sample bone i5 scanned along its
longitudinal axis by the microdensitometer, and the
measured quantity of light transmitted through or
absorbed by the aluminum standard step block is recorded
as a diagram on a chart. Then the diagram of the
quantity of absorbed light is converted into digital
data by a digitizer, the digital data is applied to an
electxonic computer to convert the quankities of
absorbed light at points on the sample bone into
corresponding gradations of the aluminum standard step
block, and the computer calculates various indices
representing the bone-morphology of the region on the
basis of a pattern expressed by the gradations of the
aluminum standard step block.
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Thus, the conventional microdensitometry requires
manual work for the selection of the object measuring
region in the roentgenogram of the bone, which is
troublesome and time-consuming. The light absorption
diagram must be scanned by manually operating the
digitizer to give the computer the digital data, which
is an obstacle to an accurate, quick measurement of the
bone. When many sample bones must be measured and many
roentgenograms must be analyzed, in particular, the
conventional microdensitometry requires much time and
labor, which is disadvantageous from the economic
viewpoint as well that of the rapidity of a measurement.
The tone of the roentgenographic image of the
sample bone is greatly dependent on the X-ray condition
and developing condition, and the measurement of the
roentgenogram is impossible or, even if the roentgeno-
gram can be measured, the measured result includes large
errors.
Furthermore, the bone-morphometric examination
cannot be performed immediately after the X-ray, because
the roentgenogram must be transported from the X-ray
place to the roentgenogram examining place far ~rom the
X-ray place. Moreover, the installation of both an
X-ray apparatus and a bone-morphometric apparatus at the
same place requires a morphometric bone assay apparatus
in combination with each bone-morphometric apparatus,
which increases the cost of the system and labor for the
maintenance of the system, and thus is economically
disadvantageous.
DISCLOSURE OF THE INVENTION
Accordingly, a-first object of the present inven-
tion is to solve the problems of the conventional bone
morphometry.
A second object of the present invention is to
provide a method and an apparatus for bone morphometry,
capable of automatically and accurately carrying out a
bone-morphometric operation.
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A third object of the present invention is to
provide a method and an apparatus for bone morphometry,
capable of automatically reading the roentgenogram of a
sample bone to obtain bone-morphometric data, quickly
analyzing the bone-morphometric data, and properly
correcting the bone-morphometric data.
A fourth object of the present invention is to
provide an improved bone-morphometric apparatus capable
of efficiently reading only a specified region in the
roentgenogram of a sample bone, when automatically
reading the roentgenographic image of the sample bone to
obtain bone-morphometric data.
A fifth object of the present invention is to
provide a method and an apparatus for bone morphometry,
capable of adjusting the intensity of light for illumi-
nating the roentgenogram of a sample bone to obtain
bone-morphometric data according to the condition of the
roentgenogram.
A sixth object of the present invention is to
provide a method and an apparatus for bone morphometry,
capable of automatically and accurately reading the
roentgenographic image of an aluminum standard step
block, i.e., an aluminum standard step wedge, when
reading a roentgenogram having the respective roentgeno-
graphic images of a sample bone and the aluminumstandard step block to obtain bone-morphometric data.
A seventh object of the present invention is to
provide a method and an apparatus for automated bone
morphometry, capable of displaying the bone-morphometric
data of a sample bone as a picture, specifying a point
or a mark indicating a morphometric reference position
on the picture, and erasing the point or the mark.
An eighth object of the present invention is to
provide a bone-morphometric apparatus capable of
carrying out a more rational bone-morphometric operation
than the conventional bone-morphometric apparatus for
morphometric bone assay, based on the analysis of the
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bone density represented by data obtained by efficiently
reading the roentgenographic image of a sample bone.
A ninth object of the present invention is to
provide a morphometric bone assay system connected to a
plurality of bone-morphometric apparatuses by communica-
tion lines and capable of receiving bone-morphometric
data from the plurality of bone-morphometric apparatuses
and sending back bone-morphometric data including the
history of the sample bones to the bone-morphometric
apparatuses.
In a first aspect of the present invention, a
bone-morphometric apparatus comprises, in combination:
an automatic image read unit for reading the data of the
roentgenographic image of a sample bone through a
measurement of iight transmitted through a roentgenogram
having the respective roentgenographic images of the
sample bone and a given standard matter; an image memory
unit for storing roentgenographic image data of the
sample bone obtained by the automatic image read unit;
an arithmetic unit which processes the roentgenographic
image data for bone morphometry; and bone-morphometric
data output unit which provides bone-morphometric data
obtained through the operation of the arithmetic unit.
Preferably, the bone-morphometric apparatus further
comprises picture display means for displaying a picture
of the image of the sample bone represented by the image
data of the sample bone obtained by the automatic image
read unit, and point input for giving a point input
representing a reference position in the picture of the
sample bone displayed by the picture display means
necessary for bone morphometry.
In a second aspect of the present invention, a
morphometric bone assay system comprises a bone-morpho-
metric apparatus for measuring the morphology of a
sample bone, a first transmission unit for sending out
bone-morphometric data obtained by the bone-morphometric
apparatus, a morphometric bone assay unit for storing
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the bone-morphometric data and for assaying the sample
bone by using the bone-morphometric data, previously
obtained bone-morphometric data corresponding to the
bone-morphometric data and, if necessary, other stored
data, and a second transmission unit for transmitting
the results of the morphometric bone assay to the
bone-morphometric apparatus.
In a third aspect of the present invention, a
bone-morphometric method, which uses the quantLty of
transmitted light measured by illuminating a roentgeno-
gram having the roentgenographic image of the sample
bone and that of a given standard matter having a
gradational thickness and X-rayed together with the
sample bone for the measurement of the sample bone,
comprises: selecting a region of the roentgenographic
image of the standard matter, the quantity of light
transmitted through the region meeting predetermined
conditions, making a first decision to see if the
quantity of light transmitted through a measured portion
is within the range of the quantity of light transmitted
through the standard matter, making a second decision to
see if the quantity of light transmitted through the
measured portion and the corresponding quantity of light
transmitted through the standard matter meet a predeter-
mined resolution, and adjusting the quantity of lightfor illuminating the roentgenogram on the bases of the
result of the second decision.
In a fourth aspect of the present invention, a
bone-morphometric method comprises a reading step of
reading a transmitted radiographic image obtained by
exposing a sample bone to radioactive rays, a smoothing
step of obtaining a first smoothed pattern by obtaining
the density pattern of the sample bone along a plurality
of substantially parallel scanning lines in the vicinity
of an object portion of the transmitted radiographic
image and smoothing the density pattern at the corre-
sponding positions, a pattern converting step of
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convexting the smoothed density pattern into a thickness
pattern represented by the thickness of the standard
matter, and an operating step of processing the thick-
ness pattern for bone morphometry.
When necessary, the bone-morphometric method may
comprise a step of obtaining a second smoothed pattern
by smoothing the data of a plurality of points in areas
extending along the measuring lines.
In a fifth aspect of the present invention, a
bone-morphometric method, which uses the quantity of
transmitted light measured by illuminating a roentgeno
gram having the roentgenographic image of a sample bone
and that of a given standard matter having a gradational
thickness and X-rayed together with the sample bone for
measuring the sample bone, comprises: a detecting step
of detecting one end of the roentgenographic image of
the standard matter corresponding to the thicker end of
the standard matter by applying a predetermined small
quantity Lo of light to a region around the end of the
roentgenographic image of the standard matter and
measuring the quantity of light transmitted through the
region, and determining the relationship between the
gradational thickness of the standard matter and the
gradation of the roentgenographic image of the standard
matter from the relationship between the quantity of
transmitted light measured by applying a quantity L of
light greater than the quantity Lo to the
roentgenographic image of the standard matter and the
distance from the end of the roentgenographic image
corresponding to the thicker end of the standard matter.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advan-
tages of the present invention will become more apparent
from the following description taken in connection with
the accompanying drawings, in which:
Figure 1 is a perspective view of a bone-mor-
phometric apparatus in a preferred embodiment according
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to the present invention;
Figure 2 is a plan view illustrating the
arrangement of objects, namely, a sample bone and an
aluminum standard step wedge, i.e., a standard step
S block, for X-ray;
Figure 3 is a block diagram of the functional
configuration of the bone-morphometric apparatus of
Fig. 1 including an internal bone-morphometric data
processing unit;
Figure 4 is a plan view of a picture of a
sample bone displayed on a display unit included in the
bone-morphometric apparatus of Fig. 1;
Figure 5 is a graphical view typically
illustrating an arithmetic process in accordance with
the present invention for bone morphometry;
Figure 6 i5 a perspective view of an example
of a focusing rod lens;
Figures 7A and 7B are graphical views of
assistance in explaining the effect of a linear detector
on the correction of detected values;
Figure 8 is a block diagram of a radiographic
apparatus for bone morphometry, embodying the present
invention;
Figure 9 is a plan view, similar to Fig. 4, of
a picture of a sample bone displayed on a display unit;
Figure 10 is a graph corresponding to the
inversion of the pattern shown in Fig. 5;
Figure 11 is a graph showing the left end
portion of the pattern shown in Fig. 10 in an enlarged
view;
Figures 12A, 12~ and 12C are flow charts of a
pattern smoothing process, a peak detecting process and
a baseline detecting process in accordance with the
present invention, respectively;
Figure 13 is a plan view showing an enlarged
mark formed by reversing a mark 82 shown in Fig. 4 as
displayed on a screen, in an embodiment employing means
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g
for both writing and erasing marks including a reference
point and a reference line;
Figur~s 14A and 14B are flow charts of a
process of correcting the quantity of illuminating light
to be executed by a microprocessor when automatically
reading the roentgenographic images of a sample bone and
an aluminum standard step wedge;
Figure 15 is a plan view of assistance in
explaining a process of setting an object measuring
region when reading the roentgenographic images of a
sample bone and an aluminum standard step wedge;
Figure 16 is a schematic view of X-ray film
conveying means, an image illuminating light source and
a transmitted light-quantity detecting unit;
Figure 17 is a typical plan view showing the
roentgenographic images of a sample bone and an aluminum
standard step wedge displayed on a display unit for
rough image reading;
Figure 18 is a typical plan view, similar to
Fig. 17, in which a narrow region is specified by region
specifying means;
Figure 19 is a typical plan view of a
roentgenogram having the roentgenographic images of a
sample bone and an aluminum standard step wedge, for the
detection of the end of the aluminum standard step
wedge;
Figures 20A and 20B are graphs typically
showing patterns for detecting a portion of a roentgeno-
graphic image corresponding to an end of an aluminum
standard step wedge;
Figure 21 is a block diagram of a morphometric
bone assay system in a preferred embodiment according to
the present invention, comprising a bone-morphometric
apparatus using an X-ray film, and a morphometric bone
assay apparatus connected to the bone-morphometric
apparatus.
BEST MODE OF CARRYING OUT THE INVENTION
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The bone morphometry in accordance with the present
invention uses a radiographic image obtained by exposing
a sample bone to radioactive rays, such as gamma rays or
X-rays, or a roentgenographic image of a sample bone
S obtained by an X-ray of the sample bone together with a
standard step block. The roentgenographic image formed
on an x-ray film, principally, represents the tone and
shape of the image of the sample bone formed on the
X-ray film. Usually, the standard step block is an
aluminum step wedge. A tapered aluminum rod or block
(aluminum slope) may be used instead of the aluminum
step wedge. A bone which forms a high-contrast
roentgenogram, such as a bone having a uniform, thin
layer of soft tissues, is desirable. Desirable bones
are bones of the hand, and long bones, such as humerus,
radius, ulna femur and tibias. The second metacarpal
bone is practically most desirable. Cancellous bones,
such as calcaneus, vertebra and epiphyses of long bones
may be used as sample bones. The calcaneus is practi-
cally most desirable.
Figure 2 shows an arrangement of sample bones,i.e., bones of the hand, and an aluminum step wedge on a
taking plane for an X-ray. In Fig. 2, the right
hand 12, the left hand 13 and an aluminum step wedge 11
are placed on an X-ray dry plate 10, and the second
metacarpal bone 14 of the right hand 12 is shown.
Referring now to Fig. 1, an X-ray bone-morphometric
apparatus 20 embodying the present invention has a
boxed-shaped case 21 provided in its upper wall with a
film feed table 28 for supporting an X-ray film 22
having an image 22a of the sample bone (the image of the
aluminum step wedge i5 omitted). Arranged in the front
portion of the case 21 are display unit 23 for dis-
playing a picture corresponding to the images formed on
the X-ray film, a point input unit 24 having, for
example, push-button switch means for moving and
locating a cursor, not shown, in the screen of the
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display unit 23 to give a point 27 indicating a refer-
ence position, an output unit 25 for printing out the
results of bone morphometry, for example, on a paper
sheet, and an input unit 26 provided wi~h means, for
example, a keyboard, for giving control commands for
controlling various operations.
Referring to Fig. 3, the bone-morphometric appa-
ratus 20 shown in Fig. 1 comprises morphometric func-
tional units including the foregoing units, an automatic
image read unit 31, and a bone-morphometric data
processing unit 32 for recording and analyzing an image
read by the automatic image read unit 31.
The automatic image read unit 31 comprises a light
source 41 for illuminating the X-ray film 22 having the
image 22a of the sample bones, i.e., the bones of the
right hand, an image detector 42 for detecting trans-
mitted light combined with a focusing lens 43 to detect
the quantity of light transmitted through the X-ray
film 22 when the X-ray film 22 is illuminated by the
light emitted by the light source 41, and an automatic
film feed means, which will be described afterward, for
feeding the X-ray film 22 in a predetermined
direction F.
The light source 41 may be a point light source
which emits a light beam which falls on a surface as a
spot. Since the point light source requires a scanning
mechanism to move the point light source along the
surface of the X-ray film 22 for scanning, preferably
the light source 41 is a linear light source, such as a
linear LED (light emitting diode), a high-frequency-
lighting tubular fluorescent lamp, a dc-lighting tubular
lamp, or a linear light source formed by bundling
optical fibers with their ends arranged in a line and
provided with a lamp for emitting light toward the other
ends of the optical fibers. The light source 41, such
as a linear LED, is extended widthwise of the X-ray
film 22. A light source control circuit 45 turns the
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light source 41 on and off and adjusts the quantity of
illuminating light emitted by the light source 41.
The image detector 42 may be of any type capable of
detecting transmitted light for the automatic reading of
the image 22a. When used in combination with the linear
light source 41, the image detector 42 is a linear image
detector. The practically preferable linear image
detector is a contact linear image detector formed by
linearly arranging, for example, CCDs (charge-coupled
devices). To enable a roentgenographic tone measurement
with a spatial resolution not lower than that of the
microdensitometer, namely, 40% MTF (modulation transfer
function) and 1.7 to 1.9 lines per millimeter, such a
contact, linear image detector is formed by linearly
arranging 4096 CCDs at a pitch of 65 ~m in a direction
substantially perpendicular to the X-ray film feed
direction F. Light emitted by the linear light source
(LED) 41 and transmitted through the X-ray film 22 is
focused by the focusing lens 43 on the image de-
tector 42. Then, the image detector 42 provides signals
representing the tone of the image formed on the X-ray
film 22. The X-ray film 22 may be fed stepwise at a
minute feed step of 65 ~m by a driving motor 51, such as
a stepping motor. The CCDs of the linear image de-
tector 42 are, preferably, capable of providing ananalog voltage signal proportional to the incident light
quantity, namely, the quantity of light corresponding to
the density of the image formed on the X-ray film 22. A
rod lens 43a as shown in Fig. 6 is used preferably as
the focusing lens 43. Preferably, the rod lers 43a is
constructed by placing two rows each of a linear
arrangement of about 250 refractive index profile lenses
formed by bundling and resin-bonding a plurality of
short optical fibers arranged along a direction perpen-
dicular to their axes in a case 43b. The detectingaction of the image detector 42 comprising CCDs is
controlled by a CCD driver 46 so that data accumulated
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in the CCDs can be read according to given timing.
Since the respective component elements of the linear
light source 41, the linear image detector 42, and the
focusing lens 43 comprising the rod lens 43a are
arranged linearly widthwise of the X-ray film 22, the
characteristics thereof vary with respect to the width
of the X-ray film 22. The automatic image read unit 31
is provided with a DSP (digital signal processor) 47, a
REF memory (reference data memory) 48 and an A/D
converter (analog-to-digital converter) 49 to correct
variations in the characteristics of the linear light
source 41, the linear image detector 42 and the focusing
lens 43. Preferably, the resolution of the A/D con-
verter 49 is eight bits (256) or higher so that the
resolution of the A/D converter 49 is not lower than
that of the microdensitometer. The time-dependent
variation in the performance of the automatic image read
unit 31 attributable to the deterioration of the linear
light source 41, dust accumulation on the rod lens 43a
and the change of the sensitivity of the linear image
detector 42 can be automatically compensated by the
DSP 47, the REF memory 48 and the A/D converter 49.
The automatic film feed means for feeding the X-ray
film 22 comprises a pair of feed rollers 44a and 44b, a
driving motor 51 for driving one of the feed rollers 44a
and 44b, for example, the feed roller 44b, and a motor
driver/controller 52. The X-ray film 22 may be fed
either continuously or intermittently, and thus the
driving motor 51 may be a stepping motor, a dc motor or
an ac motor. Since it is desirable to feed the X-ray
film 22 in the direction F perpendicular to the direc-
tion of extension of the linear image detector 42 for
the detection of the transmitted light by the linear
image detector 42, it is preferable to feed the X-ray
film 22 intermittently at a minute step in the range of
65 to 100 ~m for image detection in a higher accuracy by
the linear image detector 42 comprising CCDs.
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Therefore, the driving motor Sl is preferably a stepping
motor, the stepping operation of which can be easily
controlled by a pulse signal.
The accuracy of detection of the image detector 42
and the film feed speed can be enhanced by synchronously
controlling the light source 4l and ~he automatic film
feed means so that the light source 41 is turned on only
while the X-ray film 22 is stopped through the coopera-
tive operation of the light source controller 45 and the
motor driver/controller 52. The light source
controller 45 is also capable of adjusting the quantity
of illuminating light emitted by the light source 41
according to the density level of the image formed on
the X-ray film 22. That is, when a low-contrast image
is formed on the X-ray film 22 and the difference
between the output signals of the image detector 42
respectively representing the densities at different
positions in the image is small, the measuring sensi-
tivity is not sufficiently high. Accordingly, the
quantity of light emitted by the light source 41 is
adjusted so that the quantities of light transmitted
through portions of the image of the aluminum step
wedge ll (Fig. 2) corresponding to the stepped sections
of the aluminum step wedge ll meet predetermined
conditions.
It is also possible to specify a narrow region
containing an object part in the image 22a, to automati-
cally read only a portion of the image 22a corresponding
to the object part.
The operation of the correcting means of the
automatic image read unit 31, comprising the DSP 47, the
REF memory 48 and the A/D converter 49 will be described
hereinafter. Prior to mounting the X-ray film 22 on the
automatic image read unit 31, light is projected by the
linear light source 4l directly on the linear image
detector 42 through the focusing lens 43, i.e., the rod
lens 43a, and the quantity of light emitted by the
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linear light source 41 is adjusted so that the respec-
tive maximum analog outputs of the components of the
linear image detector 42 are not saturated and are
nearly equal to the upper limit of the scale. Then, the
light-quantity detection pattern of the image de-
tector 42 is converted into digital data by the AD
converter 49 and the digital data is stored in the REF
memory 48 as reference data for the components of the
linear image detector 41. Subsequently, the X-ray
film 22 is subject to bone morphometry on the automatic
image read unit 31. A light-quantity detection pattern
obtained by detecting the quantities of transmitted
light transmitted through parts of the X-ray film 22
corresponding to the elements of the linear image
detector 41 (data obtained by the elements of the linear
image detector 41 will be designated as "MES data") is
corrected by the DSP 47 by a procedure expressed by
Expression (1),
{(MES data)/REF data)} x (~aximum REF data) =
Corrected data ......................... (I)
and then the DSP 47 provides the corrected data as the
image data of the image 22a formed on the X--ray film 22.
Figures 7A and 7B are the results of experiment
conducted to confirm the effect of correction. Fig-
ure 7A shows the light-quantity detection pattern
obtained by directly illuminating the linear light
source 41 without placing the X-ray film between the
linear light source 41 and the linear image detector 42,
and Fig. 7b shows the corrected light-quantity detection
pattern, which proves the effective correction of
variations in the light-quantity detection pattern of
Fig. 7A.
It is preferable to perform the correcting opera-
tion every time the transmitted light is detected after
feeding the X-ray film 22 by the minute distance to
eliminate the need for a special time for correction.
When an object measuring region on the X-ray
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film 22 is set previously for a bone-morphometric data
processing unit 32, which will be described afterward,
it is possible to shorten the measurement time by
rapid-feed portions of the X-ray film other than a
portion having the object measuring region, namely, a
portion including the second metacarpal bones and the
aluminum step wedge, to store only digital data repre-
senting the measured densities of the object measuring
region.
The transmitted light-quantity data of the image of
the sample bone read by the automatic image read unit 31
is converted into digital signals by the A/D con-
verter 49, the digital signals axe corrected and
processed by the DSP 47, and then the corrected and
processed data is sent out as bone-morphometric data
representing different positions in the image from the
DSP 47. Naturally, the bone-morphometric data may be
analog data of the respective images of the sample bone
and the aluminum step wedge.
The configuration and operation of the bone-morpho-
metric data processing unit 32 will be described
hereinafter.
The bone-morphometric data of the respective images
of the sample bone and the aluminum step wedge read by
the automatic image read unit 31 is applied to the
bone-morphometric data processing unit 32 for storage
and processing.
The bone-morphometric data processing unit 32
comprises an image I/O unit 55, an image memory 56 for
storing the bone-morphometric data received through the
image I/O unit 55, an interface PIO 57 interconnecting
the automatic image read unit 31 and the bone-morpho-
metric data processing unit 32, a microprocessor (a MPU
or a CPU) 60, a ROM 61, a RAM 62, a bus 58 connecting
the ROM 61 and the RAM 62 to the MPU 60, a keyboard
interface (KBI/F) 63, a keyboard 26 connected through
the keyboard interface 63 to the bus 58, display means
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comprising of a CRT 23 and a display controller (CRTC)
64, output means comprising a printer 25 and a printer
interface (PR I/F) 65, a RS-232C 66 and a MODEM 67. The
RS-232C 66 and the MODEM 67 are provided, when neces-
sary, for communication between the bone-morphometric
data processing unit 32 and a morphometric bone assay
system, which will be described afterward.
It is known from experiments that the roentgeno-
graphic image of the sample bone can be formed in a
142 mm x 57 mm area and the required capacity of the
image memory 56 is 1.9 MB when the sample bone is the
second metacarpal bone, and the required capacity of the
image memory 56% for storing the data of the aluminum
step wedge is 0.1 MB. Accordingly, a sufficient
capacity for the image memory 56 is on the order of
2 MB. The MPU 60 may be a commercial 16-bit MPU to
address the image memory 56.
The operation of the bone-morphometric data pro-
cessing unit 32 will be described hereinafter. The
bone-morphometric data of the image formed on the X-ray
film 22, read by the automatic image read unit 31 and
received by the image I/O unit 55 is stored in the image
memory 56. The bone-morphometric data stored in the
image memory 56 is applied through the bus 58 and the
display controller 64 to the CRT 23 to display the
picture of the sample bone on the screen 23a of the
CRT 23, preferably, in an enlarged size, as shown in
Fig. 4.
Referring to Fig. 4, a picture 81 of the second
metacarpal bone is displayed on the screen 23a of the
CRT 23. Three reference points 82, 83 and 84 are set at
the caput and epiphyses of the second metacarpal bone by
moving the cursor in the screen by the picture display
means including the CRT 23 (for example, a 7 in.,
640-dot, 400-line CRT) and the point input unit 24
(Fig. 1) to specify measuring regions in the picture 81
of the second metacarpal bone.
203~561
- 18 -
As stated above, the point input unit 24 is means
for applying signals to specify a position on the
screen, such as cursor-locating control means, light-pen
input means, touch-panel input means, push-button input
means or mouse input means. The point input unit 24 is
connected to the bus 58.
When carrying out a bone-morphometric operation, a
region to be measured is determined in the image 22a of
the sample bone stored in the image memory 56 with
reference to the reference point specified by the point
input unit 24, the bone-morphometric data relating to
the region in the image of the sample bone is read out,
and then the MPU 60 manipulates the bone-morphometric
data according to an operation program stored in the
ROM 61 for bone-morphometric operation, which will be
described afterward. The RAM 62 stores the data that
will be utilized by the MPU 60 during the execution of
the operation program.
Figure 5 shows a concrete operation process for
bone-morphometric operation. Other generally Xnown
bone-morphometric techniques employing the MD method,
such as those disclosed in Japanese Unexamined (Kokai)
Patent Publication Nos. 59-8935, 59-49743, 60-83646,
61-109557 and 62-183748, may be used. When analog image
data representing both the respective images of the
sample bone and the aluminum step wedge are stored in
the image memory 56, the analog image data of the sample
bone may be converted into data expressed by the thick-
ness of the aluminum step wedge.
Figure 5 shows a pattern representing the image
data of the image 81 of the second metacarpal bone on a
transverse line crossing the middle point of the longi-
tudinal axis of the image 81. In Fig. 5, D is the width
of the bone, a hatched area expresses bone density, d1
and d2 are the widths of bone cortices, d is the width
of the bone marrow, GSmin corresponds to the minimum
value of a valley 87 between peaks 85 and 86 and is the
203~561
-- 19 --
index of the density of (the bone cortex) + (the bone
marrow), GSmaXl and GSmaX2 are the respective maximum
values of peak portions, and ~ GS is the total area of
the hatched area with respect to the width D. (Kotsu
Taisha, Vol. 4, pp. 319-325 (1981)) That is, the
operating means 60, 61 and 62 compute the caput 82 and
the perpendicular bisector of a line connecting the
epiphyses 83 and 84 to detect the intersection point and
use the results of computation for the operation of the
stored data to determine the values of D, D1 , d2 ~ d,
GSmin r GSmaxl, GSmax2 and ~ GS. Then, the operating
means 60, 61 and 62 compute, for example, bone cortex
width index MC1 (= (d1 + d2)/2), bone marrow width d, an
index GSmin indicating the quantity of bone ~ineral of
(the bone cortex) + (the bone marrow), an index GSmaX
(= (GSmaxl + GSmax2)/2) indicating the quantity of bone
mineral of the bone cortex, and an index E ~S/D indi-
cating the mean ~uantity of bone mineral per bone width
by using the data obtained by the operation shown in
Fig. 5. The results of the computation may be applied
through the printer interface 65 to the printer 25 or
may be stored in storage means similar to the RAM 62.
The printer 25 is an example of the output means
and may be a dot printer, a thermal printer, a laser
printer or a video printer to provide the results of the
computation in hard copies. Practically, preferable
output means are CRTs, particularly, display means
capable of displaying the bone density distribution in
colors.
In the foregoing example, the bone-morphometric
indices are calculated by using only the stored data
representing the image data on the transverse line
crossing the middle point of the longitudinal axis of
the image. The bone-morphometric indices may be deter-
mined by averaging bone-morphometric indices for image
data on transverse lines extending parallel to and on
the opposite sides of the transverse line crossing the
203056 ~
- 20 -
middle point of the longitudinal axis. The operating
means 60, 61 and 62 may be such as disclosed in U.S.
Pat. No. 4,721,112 which performs the bone morphometry
of regions of a long bone and determines the bone
density distribution of the long bone on the basis of
the measured results.
This bone-morphometric apparatus embodying the
present invention is capable of automatically carrying
out the bone-morphometric operation using a roentgeno-
gram at a high efficiency, scarcely requiring manualoperation. The employment of the automatic image read
means including the linear light source for illuminating
the X-ray film, and the linear image detector for
detecting the quantity of transmitted light, in parti-
cular, improve~ the efficiency of bone-morphometric
operation significantly. The adjustable linear light
source enables accurate bone morphometry regardless of
the variation in the contrast level of the
roentgenogram.
Figure 8 is a block diagram of a bone-morphometric
apparatus in another embodiment according to the present
invention, which uses a radiographic image produced by
irradiating a sample bone with radioactive rays instead
of a roentgenographic image for bone morphometry.
Referring to Fig. 8, a radiographic image forming
apparatus 90 comprises a radiation source 91 which
radiates radioactive rays, such as gamma rays, in a
predetermined direction, a movable table 92 for sup-
porting a sample 93, for example, the human hand, a
radiation detector 94 for detecting the quantity of
radioactive rays transmitted through the sample 93, a
scanner controller 95 for controlling the movement of
the movable table 92 so that the sample 93 may be
scanned entirely by the radioactive rays, and an A/D
converter 96 which converts, similarly to the
afore-mentioned A/D converter 49, analog detection
signals provided by the radiation detector 94 into
- 21~30561
- 21 -
corresponding digital detection signals to be delivered.
The A/D converter 96 of the radiographic image forming
apparatus 90 sends out digital data representing the
radiographic image of the sample 93. A
bone-morphometric data processing unit 32 for processing
the ouiput digital data of the radiographic image
forming apparatus 90 for bone morphometry is the same as
that of the foregoing embodiment, and hence the compo-
nent parts of the bone-morphometric data processing
unit 32 corresponding to those of the bone-morphometric
data processing unit 32 of the foregoing embodiment
shown in Fig. 3 are denoted by the same reference
characters.
A further improved bone-morphometric method and a
further improved bone-morphometric apparatus will be
described hereinafter with reference to those of the
foregoing embodiment of the present invention.
First, a method of accurately carrying out bone
morphometry by combining the smoothing of the density
pattern of the image of a sample bone and the conversion
of the density pattern into density data expressed by
the thickness of a standard block, and an apparatus for
carrying out the method will be described.
The inventors of the present invention found,
through intensive studies of ways to perform bone
morphometry accurately and rapidly, that smoothing in a
direction perpendicular to the direction of a scanning
line for bone morphometry and, if necessary, the combi-
nation of such smoothing and smoothing in the direction
of the scanning line are effective.
In the following description, a roentgenogram is
used and reference is made with Figs. 2, 3, 5 and 9
to ll.
Digital signals corresponding to the quantity of
transmitted light transmitted through the roentgeno-
graphic image of a sample bone formed on a X-ray film
are stored as bone-morphometric data in the image
203~6~
- 22 -
memory 56 of the bone-morphometric data processing
unit 32 in relation with positions on the X-ray film.
The bone-morphometric method in this embodiment
obtains a first smoothed pattern of the image of the
sample bone by obtaining density patterns along substan-
tially parallel scanning lines around an object mea-
suring region and smoothing the density patterns
respectively at the corresponding positions. The
bone-morphometric apparatus has smoothing means. The
density pattern is a representation of quantities of
transmitted light or transmitted radiation at points on
the measuring line or a digital representation of
quantities of transmitted light or transmitted radia-
tion. Smoothing is obtaining the arithmetic mean or the
weighted mean of quantities of transmitted ligh~ or
transmitted radiation.
Figure 9 shows a picture 81 of a second metacarpal
bone displayed on the screen 23a of the CRT 23 (display
means) as a concrete example of a first smoothed pat-
tern. Reference points 82 to 84 specified by means ofthe point input unit 24 are shown on the picture 81.
When the object measuring region is the middle
portion of the second metacarpal bone with respect to
the reference points 82, 83 and 84 in Fig. 3, the first
smoothed pattern is obtained by scanning the picture
along a plurality of scanning lines 98 extending at
equal intervals of 65 ~m in a very narrow range of
0.1 mm or less about the object measuring region to
obtain patterns of quantities of transmitted light on
the scanning lines and subjecting the patterns to a
smoothing process, such as the calculation of the
weighted mean. Such a smoothing process eliminates
random noise in the pattern of the quantity of trans-
mitted light effectively without reducing the spatial
resolution.
The number of the scanning lines 98 for smoothing
may be determined in view of the following conditions.
- 23 - 203~5~
A quantity of transmitted light measured by an automatic
image read means having a resolution on the order of
65 ~m includes random noise on the order of 1~4 to 1/5
of the thickness step (1 mm) of an aluminum wedge, i.e.,
0.2 to 0.25 mm. Although the greater number of the
scanning lines 98 is desirable, it is simple and pref-
erable to average the data of quantities of transmitted
light on about twenty-one scanning lines in the same
weighting, because an excessively large number of
scanning lines 98 makes the object measuring region
ambiguous and the noise must be reduced to a value below
0.05 mm.
A first smoothed pattern of the quantity of trans-
mitted light for the sample bone thus obtained is
converted on the basis of the thickness of the standard
block and the quantity of transmitted light to obtain a
converted pattern represented by the thickness of the
standard block. The effect of the difference in
roentgenographic conditions on the bone-morphometric
data can effectively be eliminated by converting the
pattern of the quantity of transmitted light into a
pattern represented by the thickness of the standard
block prior to arithmetic processing.
The apparatus of Fig. 8 uses an image formed by
detecting transmitted radiation. In such a case, it is
practically desirable to store the relation between the
thickness of a standard sample, i.e., a phantom, and the
quantity of transmitted radiation in advance and to
obtain a converted pattern on the basis of the relation.
According to the present invention, if necessary, a
second smoothed pattern may be produced by subjecting
such a converted pattern or the first smoothed pattern
of the transmitted light to a smoothing process, such as
the calculation of the moving average of data at a
plurality of points on the scanning lines. The combina-
tion of the f irst and second smoothing processes enables
the ef f icient elimination of high-f requency noise in a
2~3~5fi~
- 24 -
plane and accurate operation for bone morphometry. In
practical bone-morphometric operation, it is preferable
to employ a digital filter capable of filtering spatial
frequencies exceeding a frequency corresponding to a
period of 0.5 mm, because variations of periods not
greater than 0.5 mm are unnecessary. When the second
smoothed pattern is obtained from the first smoothed
pattern, the second smoothed pattern must be converted
into a converted pattern. Practically, it is preferable
to obtain converted patterns respectively corresponding
to the first and second smoothed patterns.
The bone-morphometric apparatus in accordance with
the present invention comprises first smoothing means,
converting means and, if need be, second smoothing
means. Concretely, those means comprises the MPU 60,
the ROM 61 and the RAM 62 of the aforesaid bone-morpho-
metric data processing unit 32.
The aforesaid bone-morphometric operation (Fig. 5)
is performed on the basis of the thus obtained smoothed
pattern or the converted pattern. Shown in Figs. 12
(Fi.gs. 12A-12C) is a flow chart of the foregoing
smoothing process to be performed by the MPU 60, the
ROM 61 and the RAM 62 of the bone-morphometric data
processing unit 32. In carrying out the smoothing
process, the MPU 60 executes operation according to a
predetermined program stored in the ROM 61, and the
RAM 62 stores the data that will be utilized by the
MPU 60 during the execution of the program.
The bone-morphometric apparatus in this embodiment
detects peaks, such as peaks 85 and B6 shown in Fig. 5,
automatically through the following procedure. The
gradients of tangents to the profile of the image in a
global region is examined so that small peaks attribut-
able to noise or the like may not erroneously be
detected as peaks, and then a peak point is set at a
position where the gradient is zero, namely, where the
sign of the gradient changes from positive to negative
- 25 - - ~ 3 0 5 ~ 1
or from negative to positive.
A peak point on an image formed on an X-ray film is
detected by the following method.
First, when detecting the first peak 85, a smooth
ness differential is calculated by using
j-d j+~+dDATA(j) = s DATA(i) - ~ DATA(i) .... (II)
i= j-~-~ i= j+~
A position where DAT~(j) meeting the following condi-
tions is maximum is in the vicinity of the peak.
dDATA(j-l) _ 0 and dDATA(j+l) > 0 --- (III)
In Expressions (II) and (III), DATA(j) is the
quantity of transmitted light transmitted through a
portion of the image corresponding to a position j, and
~ and ~ are constants determined preferably with refer-
ence to the resolution of the apparatus, the magnitude
of the noise component or the size of the region.
Practically, with an apparatus having a spatial
resolution on the order of 65 ~m, ~ = 4 and ~ = 17. The
peak 85 can be further accurately detected by detecting
the maximum value in the data of a region around the
peak 85 again. Once the peak is detected, it is prefer-
able to recognize the detected peak as a peak if any
peak is not detected in a region 7 after the former peak
has been detected in order that the peak 86 is not
recognized as the first peak. The size of the region 7
is dependent on the distance between the adjacent peaks.
Practically, the value of the region 7 is on the order
of 20. The peak 86 is detected likewise. The peak 87
corresponds to the minimum in a region between the
peaks 85 and 86.
A bone-morphometric method or apparatus in a
preferred embodiment according to the present invention
determines the base line Bs (Fig. 5) by the following
procedure. Referring to Figs. l0 and ll, an inflection
point 99 is determined on the basis of a fact that the
second order difference is maximum in one of the rising
2~3~5~1
_ 26 -
portions of the curve, and then a line 100 for the left
soft part is determined by linear regression analysis
using y pieces of data after x pieces data outward from
the inflection point 99. A line 101 for the right soft
part is determined likewise. Then, contact lines 102
and 103 each having a maximum gradient are determined by
linear regression analysis using z pieces of data inward
from the inflection point 99 for each line. The inter-
section point 104 of the lines 100 and 102 and the
intersection point 105 of the lines 101 and 103 are
connected to determine the base line Bs (Fig. 5~.
Practically, x = 8, y = 10 and z = 16 are
desirable.
The bone-morphometric method and the bone-morpho-
metric apparatus embodying the present invention elimi-
nates effectively the effect of differences in the
conditions of radiographic photographing operation and
noise attributable to the X-ray film to enable accurate
bone morphometry.
A bone-morphometric apparatus employing picture
display means, such as the CRT 23 (Fig. 3) for dis
playing the picture of the image of a sample bone,
provided with mark display means capable of displaying
and erasing marks, such as a reference point for indi-
cating a reference position, and lines, in the monochro-
matic picture will be described hereinafter. The
indication and erasing of marks will be described
hereinafter with reference to Figs. 3, 4 and 13 on an
assumption that the bone-morphometric apparatus and the
bone-morphometric method embodying the present invention
are applied to the bone morphometry of the roentgeno-
grams of a sample bone and a standard block.
In this embodiment, the bone-morphometric apparatus
is provided with mark display means capable of reversing
the density of a monochromatic picture. Preferably, a
picture display means capable of displaying binary
pictures, such as characters and diagrams, as well as a
2030~
- 27 -
toned picture. The CRT 23 meets such a requirement.
In Fig. 13, a reference point formed by reversing
the reference point 82 shown in Fig. 4 is displayed on
the screen 23a.
The image storage means (image memory 56) of the
bone-morphometric apparatus in this embodiment stores
image data for displaying a picture of 400 (vertical~
x 600 (horizontal) picture elements. The density of
each picture element is expressed by 8-bit gradation.
The capacity of the image storage means is dependent on
the accuracy of the screen, and the number of picture
elements and the expression of the density of each
picture element need not be limited to the foregoing
values.
A specific position on the monochromatic picture is
marked with a point by the following procedure.
Picture elements showing the position to be marked
are specified, and then the densities of the picture
elements are obtained. The densities of the picture
elements are subjected, in combination with 255, to an
exclusive OR operation for density reversal. Then
picture elements respectively having reversed densities
are displayed instead of the original picture elements,
respectively, to indicate the point. When the density
of the original picture element is, for example, 196,
the density of the corresponding reversed picture
element is 59.
Likewise, the mark can be erased by reversing the
reversed picture elements again by the same reversing
procedure.
The picture element can be reversed by deriving the
one's complement of the density value, however, in view
of processing rapidness, the procedure of the present
invention is more advantageous.
Marks which can be foxmed by dots, such as lines,
circles and symbols, may be used as well as points.
As is obvious from the foregoing description, the
2030~61
- 28 -
bone-morphometric apparatus in this embodiment is
capable of readily indicating marks on the monochromatic
picture and readily erasing the marks to restore the
original monochromatic picture. Particularly, the
employment of the density reversing means simplifies the
hardware of the apparatus and enables the use of a
memory having a comparatively small capacity.
A liquid crystal display (LCD) or a plasma display
may be used instead of the CRT employed as picture
display means by this embodiment, however, to obtain a
high resolution picture display, the CRT is most
appropriate.
A bone-morphometric method and a bone-morphometric
apparatus in a preferred embodiment capable of adjusting
the quantity of light emitted by the light source
according to the condition of a roentgenogram will be
described hereinafter with reference to Figs. 2, 3, 5,
14A and 14B.
The bone-morphometric apparatus in this embodiment
illuminates an X-ray film carrying the images of a
sample bone and an aluminum step wedge, and measures the
quantity of transmitted light transmitted through the
images for bone morphometry. The basic features of this
bone-morphometric apparatus are to determine a region in
the image of the aluminum step wedge that transmits a
quantity of light meeting a predetermined condition, to
make a first decision on whether the range of quantity
of transmitted light transmitted through an object
measuring region in the image of the sample bone is
included in the range of quantity of transmitted light
transmitted through the aluminum step wedge, to make a
second decision on whether the quantity of transmitted
light transmitted through the object measuring region
and the corresponding quantity of transmitted light
transmitted through the aluminum step wedge are detected
in a predetermined resolution, and to adjust the
quantity of illuminating light for illuminating the
203~5~1
- 29 -
X-ray film on the basis of the results of the second
decision.
When the quantity of illuminating light must be
increased for light-quantity adjustment, the quantity I
of transmitted light transmitted through the aluminum
step wedge greater than and approximately equal to the
maximum quantity of transmitted light transmitted
through the object measuring region is determined, and
the quantity of illuminating light is adjusted so that
the quantity I of transmitted light is not greater than
and nearly equal to a predetermined value ImaX.
When the quantity of illuminating light needs to be
reduced, a portion of the object measuring region
through which a quantity of light exceeding the prede-
termined value ImaX is transmitted is detected, an
appropriate quantity of illuminating light is estimated
on the basis of the size of the portion of the object
measuring region and the quantity of illuminating light
is adjusted to the appropriate quantity.
The above-mentioned decisions and the adjustment of
the quantity of illuminating light are achieved by the
following method. The X-ray film is illuminated by a
quantity of illuminating light determined previously
according to the examinee~s sex and age and the quantity
of transmitted light transmitted through the image of
the aluminum step wedge is measured with the X-ray film
positioned at a predetermined position.
Effective regions in the images of the steps of the
aluminum step wedge, namely, regions which can effec-
tively be discriminated from each other, are determined
on the basis of the relation between the measured
quantity of transmitted light and the respective thick-
nesses of the steps of the aluminum step wedge. In view
of bit errors in A/D conversion, the difference in the
quantity of transmitted light as expressed by digital
signals provided by the A/D converter 49 between the
adjacent regions in the image of the aluminum step wedge
20~0~1
- 30 -
corresponding to the adjacent steps of the aluminum step
wedge must be not less than two digits and the quantity
of transmitted light must not saturate the image, when
the measured quantity of transmitted light is converted
into digital signals by the A/D converter 49. The
maximum quantity Il of transmitted light transmitted
through the image of the aluminum step wedge and the
minimum quantity I2 of transmitted through the aluminum
step wedge are determined. The maximum quantity Sl of
transmitted light and the minimum quantity S2 of trans-
mitted light among those of transmitted through the
image OI the object measuring region of the sample bone
are determined.
A query is made for the first decision to see if
Sl < Il. When the quantity of illuminating light is
excessively large, the response to the query is nega
tive, and thus the quantity of illuminating light must
be reduced. When the response is affirmative, a query
is made to see if S2 > I2. When the quantity of illumi-
nating light is excessively small, the response to thequery is negative, and thus the quantity of illuminating
light must be increased. When Sl > Il and S2 < I2 '
bone morphometry is impossible regardless of the
quantity of illuminating light. When bone morphometry
is impossible, information is displayed on the display
to that effect and the X-ray film is ejected.
When both the conditions Sl < Il and S2 ~ I2 are
satisfied, the second decision is made. That is, a
quantity Il' of transmitted light transmitted through
the aluminum step wedge greater than and nearest to the
quantity Sl of transmitted light, and a quantity I2' of
transmitted light transmitted through the aluminum step
wedge smaller than and nearest to the quantity S2 of
transmitted light are selected. Then, digital values
corresponding to the respective thickness of the steps
of the aluminum step wedge corresponding to the range of
Il' to I2' are determined and the minimum value ~I among
203~6 1
- 31 -
the digital values is selected. For example, when the
difference in thickness between the adjacent steps of
the aluminum step wedge is 1 mm and the required resolu-
tion is 0.2 mm or less, ~I must be five digits or
greater, preferably, seven digits or greater. When ~I
must be, for example, seven digits or greater, a query
is made to see if QI > 7. When the response is affirma-
tive, it is considered that the X-ray film 22 is illumi-
nated by an appropriate quantity of illuminating light,
and the subsequent steps of bone morphometry are
performed. If the response is negative, the quantity of
illuminating light must be increased.
The adjustment of the quantity of illuminating
light will be described hereinafter. When it is decided
that the quantity of illuminating light is insufficient,
the quantity of illuminating light is adjusted so that
the quantity Il' of transmitted light is not greater
than and nearest to the predetermined value ImaX , and
then the measurement is performed again. Preferably, a
value corresponding to the predetermined value ImaX is
in the range of 95 to 98~ of the saturation level of the
image detector 42 or the A/D converter 49.
When the quantity of illuminating light is exces-
sively large, the length of a measured portion where the
quantity of transmitted light is greater than the
predetermined value ImaX is measured, namely, the number
of dots on the CCD detector or the like corresponding to
the length of the portion is counted. The relationship
between the count of dots and (quantity of illuminating
light) - (appropriate quantity of illuminating light)
for the second metacarpal bone is shown in Table 1.
- 32 - 2030~61
Table 1
_
Dot Count 5 12 20 50 80 100 130 150
Quantity of Illuminating Light
- Quantity of Transmitted Light 2 3 4 5 6 7 ~ 9
The appropriate quantity of illuminating light is
estimated from the dot count on the basis of the rela-
tionship shown in Table 1. When the dot count of aportion where the quantity of transmitted light exceeds
the predetermined value ImaX is zero, the quantity I
of transmitted light corresponding to a step of the
aluminum step wedge thicker by one common thicknass
difference than the step corresponding to the quan-
tity I1 of transmitted light is estimated by using a
formula
Ill = Il - 2.5(I12 + I13)
where I12 is the quantity of transmitted light corre-
sponding to a step of aluminum step wedge thinner by onecommon thickness difference than the step corresponding
to the quantity Il of transmitted light, and I13 is the
quantity of transmitted light corresponding to a step of
aluminum step wedge thinner by two common thickness
differences than the step corresponding to the quan-
tity Il of transmitted light. The quantity of illumi-
nating light is adjusted so that the quantity Ill of
transmitted light is smaller than and approximately
equal to, preferably, nearest to the predetermined
value ImaX.
If the condition is not improved by the adjustment
of the quantity of illuminating light, it is decided
that the bone morphometry of the images is impossible,
to avoid wasting time for useless measurement. In such
a case, it is preferable to display information to that
effect and to automatically eject the X~ray film.
When necessary, gamma value 7 defined by 7 = (OD
2 ~ 6 ~
- 33
(absorbance) variation)/(relative exposure variation)
may be used for a third decision. Accurate measurement
is possible only when the minimum gamma value 7 among
those for the steps of the aluminum step wedge in the
S range of I1' to I2' is greater than a predetermined
gamma value 70. Therefore, it is preferable to use a
gamma value in combination with the resolution decision.
Preferable gamma value 7 is in the range of 1 to 4, and
preferable predetermined gamma value 70 is in the range
of 1 to 2.
A variation of the illuminating time is one method
of adjusting the quantity of illuminating light. When
the linear light source 41 comprising LEDs is employed
as light emitting means, and the linear image de-
tector 42 is employed as transmitted light detectingmeans, illuminating time can be adjusted by controlling
the lighting frequency of the LEDs by a pulse signal
generated by a pulse generator. Practically, it is
desirable to adjust the quantity of illuminating light
by varying illuminating time without changing the
intensity of illuminating light for the effective
correction to eliminate the influence of the secular
change in the characteristics of the linear light
source 41 and the linear image detector 42, such as
ununiformity of the LEDs in luminance and/or the
ununiformity of the CCDs in sensitivity, when the
automatic image read means employs the LEDs and CCDs for
reading the image.
To improve the measuring efficiency, it is practi-
cally advantageous to change a set value representing anilluminating time on the basis of the relation between
set va].ue and illuminating time as shown in Table 2
stored in storage means.
2030~61
- 34 -
Table 2
Set value 1 2 3 4 5 6 7
-
Illuminating time128 256 384 512 640 768 896
-
Set value 8 9 10 11 12 13 14
Illuminating time102411521280 153617922048 2304
Set value 15 16 17 18 19 20 21
Illuminating time256030723584 454455686592 7615
Set value 22 23 24 25 26
-
Illuminating time 9088 11136 13632 15680 1~176
The adjustment of the quantity of illuminating
light in accordance with the present invention can be
achieved by a bone-morphometric apparatus comprising the
automatic image read unit 31 and the bone-morphometric
data processing shown in Fig. 3. The MPU 60, ROM 61 and
RAM 62 of the bone-morphometric data processing unit 32,
and the light source control circuit 45 of the automatic
image read unit 31 carries out the functions of the
region detecting means, the first decision means, the
second decision means and the illuminating light
quantity adjusting means. The MPU 60 has the function
of the region detecting means and serves also as means
for storing given conditions such that the A/D converted
value representing the quantity of light corresponding
to one common thickness difference of the aluminum step
wedge is two digits or greater. The MPU 60 further has
the function of the first decision means and serves as
storage means îor storing I1 , I2 r Sl and S2 and as
comparing means for comparing quantities. The MPU 60
serves also as the second decision means for entering
and storing a criterion on which the decision of ~I is
based. As regards the illuminating light quantity
adjusting means, which is one of the features of the
203~5~
- 35 -
bone-morphometric apparatus in this embodiment, the
MPU 60 decides a set value for an adjusted quantity of
illuminating light, and the light source control cir-
cuit 45 sets the luminous intensity of the light
source 41. The MPU 60 must have functions for entering
and storing ImaX , calculating Ill , and comparing
quantities. The ROM 61 storing the contents of Tables 1
and 2 facilitates the efficient automatic adjustment.
The bone-morphometric apparatus stores the position
of the reference point on the picture display means
(CRT 23, CRTC 64) entered by the point input means in
the storage means, i.e., the RAM 62 before the adjust-
ment of the quantity of illuminating light, reads again
the same region in the image formed on the X-ray film by
using the adjusted quantity of illuminating light
determined on the basis of the result of decision, and
then specifies a point in the picture displayed on the
CRT 23 with reference to the reference point previously
stored in the RAM 62. A series of these operations are
carried out by the automatic image read unit 31 con-
trolled by the MPU 60 (Fig. 3). After a new quantity of
illuminating light has been set, the X-ray film is fad
automatically to locate the respective images of the
aluminum step wedge and the object portion of the sample
bone at the read position and, when the object portion
needs to be indicated by a point, the point previously
stored and stored is displayed automatically, which
reduces load on the operator.
Figures 14A and 14B show flow charts of procedures
for carrying out the correction of the quantity of
illuminating light by the MPU 60, the ROM 61, the RAM 62
and the light source control circuit 45.
A bone-morphometric arithmetic routine 1 shown in
Figs. 14A and 14B is executed by the bone-morphometric
data processing unit including the MPU 60, the ROM 61
(arithmetic program storage) and the RAM 62 which stores
the data that will be utilized by the MPU 60 during the
2~3~61
- 36 -
execution of the arithmetic routine.
The results of the bone morphometry are provided by
the SIO 66 and the printer 25, i.e., the output means
(Fig. 3).
The bone-morphometric method in this embodiment
corrects the quantity of illuminating light by a practi-
cally simple operation to enable the bone morphometry of
images of tones varying in a wide tone range formed on
X-ray films, which has been difficult to carry out by
the conventional method. The bone-morphometric appa-
ratus in this embodiment employs the illuminating light
quantity correcting means to enable the bone morphometry
of images of tones varying in a wide tone range formed
on X-ray films through a simple operation.
A bone-morphometric apparatus embodying the present
invention including an automatic image read unit 31
capable of reading a roentgenographic image formed on an
X-ray film at an improved efficiency will be described
hereinafter.
The bone-morphometric apparatus in this embodiment
is featured by an automatic image read unit for automat-
ically reading roentgenographic images formed on an
X-ray film, which comprises: a film loading unit, film
feed means, linear image detecting means extended in a
direction perpendicular to the film feed direction,
image read region setting means for setting a skipping
feed distance a along the film feed direction, an
effectivs feed distance b through which the X-ray film
is fed for image reading, a distance c from a reference
position to an image read region with respect to the
direction perpendicular to the film feed direction and
an image scanning distance d, and image storage means
for storing image data read by the linear image de-
tecting means in the image read region set by the image
read region setting means.
The film feed means, linear image detecting means,
light source means which emits light for illuminating
~030~1
- 37 -
the film and image read region setting means of the
bone-morphometric apparatus in this embodiment may be
those respectively corresponding to the means shown in
Fig. 3-
Referring to Fig. 15 showing an illustration of
assistance in explaining an example of an image read
region setting operation for setting an object measuring
region in an X-ray film 22, the X-ray film carrying the
respective images ll', llO and lll of an aluminum step
wedge, i.e., a standard block, the bones of the right
hand of the examinee and the bones of the left hand of
the same is fed to the right. The second metacarpal
bone of the right hand, i.e., the object measuring
region, is located in the central portion of an image
read region 112 defined by distances a, b, c and d.
With a 253 mm wide and 302 mm long X-ray film, for
example, a = 46 mm, k= 65 mm (1024 lines), c = 1 mm (16
picture elements) and d = 130 mm (2048 picture ele-
ments).
Referring to Fig. 16 showing the automatic image
read unit 31 shown in Fig. 3 in a further simplified
view, while being fed in the direction of the arrow by a
pair of feed rollers 44c and 44d and a pair of feed
rollers 44a and 44b, the X-ray film 22 is illuminated by
the light emitted by a linear light source 41. The
quantity of transmitted light transmitted through the
X-ray film 22 is detected by a linear image detector 42.
In this embodiment, the bone-morphometric apparatus is
provided with proper film edge detectors 120 and 122 for
detecting the edge of the X-ray film 22.
In this embodiment, the skipping feed distance a
through which the X-ray film 22 is fed without being
scanned may be a distance al from the leading edge of
the X-ray film 22 to the front boundary of an object
measuring region ~Fig. 15) or may be the sum of the
distance a1 and a distance a2 equal to the effective
distance between the film edge detector 122 and the
2~3~5~
- 3~ -
linear image detector 42 (Fig. 16). When the skipping
feed distance a is the sum of the distances a1 and a2 '
the film edge detector 122 is able to ascertain readily
if the X-ray film is fed normally, which is practically
advantageous. The leading edge of the X-ray film 22 may
be detected by the film edge sensor 120 and the linear
image detector 42 as shown in Fig. 16 through the
detection of change in the output of the linear image
detector 42 comprising CCDs. A quick-feed pulse signal
is applied to a stepping motor 51 for driving the feed
rollers to feed the X-ray film 22 at a high feed speed,
the pulses applied to the driving motor 51 are counted
by a pulse counter, and the quick-feed pulse signal is
stopped upon the coincidence of the pulse count with a
number corresponding to the skipping feed distance a.
Subsequently, a slow-feed pulse signal is applied
to the stepping motor 51 to feed the X-ray film 22
intermittently by a distance correspondLng to the pitch
of scanning lines at a time for image reading. The
image data of only the picture elements within a given
range along the extension of the linear image de-
tector 42 is stored in an image memory 56. A picture
element counter counts the number of picture elements
detected by the linear image detector 42.
Upon the coincidence of the picture element count
of the picture element counter with a given total count,
the image read operation is stopped, the stepping
motor 51 is set in a reverse mode, and a quick-feed
pulse signal is applied to the stepping motor 51 to
eject the X-ray film from the bone-morphometric
apparatus. Upon the detection of the leading edge,
i.e., the trailing edge when the X-ray ~ilm 22 is
reversed, by the film edge detector 120, the stepping
motor 51 is stopped.
It is preferable, for the accurate setting of the
object measuring region on the X-ray film, to use one of
the side edges of the X-ray film 22 parallel to the film
~0~6~
- 39 - -
feed direction as a reference position for setting the
distance c, but in practice the use of one side line of
a region secured for the film to be fed as the reference
position is advantageous, because such a reference
position facilitates setting the distance c.
The bone-morphometric apparatus in this embodiment
is provided with input means for entering values of the
distances a, b, c and d for defining the object mea-
suring region, and storage means for storing the input
values of the distances a to d.
It is practically advantageous to use previously
determined standard values for the distances a to d
entered by input means (keyboard 26) and stored previ-
ously in the storage means for the normal bone-morpho-
metric measuring operation and to enter special valuesgreatly differing from the standard values only for a
special bone-morphometric measuring operation.
In a modification, the automatic image read unit of
the bone-morphometric apparatus may be provided with
object measuring region setting means for setting the
distances a, b, c and d for defining each of an object
measuring region and a calibration image region in an
X-ray film, and image storage means for storing images
read respectively from the object measuring region and
the calibration image region.
Thus, the automatic image read unit is capable of
entering values for distances a', b', c~ and d' for
definins an object measuring region including the
image ll' (Fig. 15) of a standard block for calibration,
such as an aluminum step wedge, and values for the
distances a, b, c and d for defining the object mea-
suring region including the image of the second
metacarpal bone of the right hand.
Furthermore, if necessary, the automatic image read
unit may be such as capable of entering values for the
distances a, b, c and d for defining one object mea-
suring region or each of a plurality of object measuring
203~56:L
- 40 -
regions, capable of sequentially reading images formed
in the plurality of object measuring regions, and
capable of storing the data of the images respectively
in combination with the positions of the corresponding
object measuring regions.
The bone-morphometric apparatus in this embodiment
requires image storage means comprising a very small
number of image memories, is capable of reading images
in a very short image read time and, if necessary, is
able to read selectively the images formed in a plura-
lity of object measuring regions.
Requiring only a small number of image memories,
the bone-morphometric apparatus in this embodiment can
be easily formed in a compact construction suitable for
carrying and is capable of rapid bone morphometry.
A bone-morphometric apparatus in a further embodi-
ment according to the present invention will be
described hereinafter. This bone-morphometric apparatus
is capable of surely and efficiently reading roentgeno-
graphic images including that of a sample bone formed onan X-ray film regardless of the positional variation of
those roentgenographic images.
The bone-morphometric apparatus in this embodiment
has the configuration shown in Figs. l and 3 as the
basic configuration and comprises coarse image-read
means for coarsely reading images including those of the
standard matter and a sample bone formed in a wide
object measuring region while the film is being fed by
the film feed means of the automatic image read unit, to
obtain data of picture elements in a thin distribution,
picture display means for displaying a coarse picture
represented by the data obtained by the coarse image-
read means, object measuring region specifying means for
specifying narrow object measuring regions respectively
including the respective small portions of the images of
the standard matter and the sample bone in the coarse
picture displayed by the picture display means, and
21~3~5~
- 41 -
minute image-read means for minutely reading the respec-
tive small portions of the images included respectively
in the narrow object measuring regions specified by the
object measuring region specifying means while the film
is being fed by the film feed means, to obtain data of
picture elements in a dense distribution.
The coarse image-read means in this embodiment
reads the picture elements distributed in a thin distri-
bution in the entire area of the film including the
respective images of the standard matter and the sample
bone by the linear image read unit while the film is fed
at a coarse-feed speed higher than a minute-feed speed
for feeding the film for minute reading. Preferably,
the coarse feed speed for coarse reading is two to
sixteen times the minute-feed speed for minute reading.
When the coarse-feed speed is eight times the minute-
feed speed, the number of data obtained by the coarse
reading is as small as 1/8 that of data obtained by the
minute reading. Thus, the images in the entire wide
region can be represented by a small number of image
data, so that only a small storage area may be assigned
to those image data.
As shown in Fig. 17, the picture display means
displays the picture of the entire wide region repre-
sented by the image data obtained by the coarse image-
read means. The CRT 23 shown in Fig. 3 is a preferable
picture display means. In Fig. 17 r the coarse pic-
ture 211~ of an aluminum step wedge, i.e., the standard
matter, the coarse picture of 210 of the bones of the
right hand and the coarse picture 211 of the bones of
the left hand obtained through coarse image-reading and
displayed on the screen 23a of the CRT 23.
Preferably, the display means is able to display
the images in a degree of coarseness with respect to a
direction perpendicular to the film feed direction
substantially the same as the degree of coarseness with
respect to the film feed direction to display the images
- 42 - 2~3~61
without distortion. Preferably, the distribution of the
image data with respect to a direction perpendicular to
the image feed direction is thinned by software which
regularly omits part of the coarse image data stored in
the image storage means in displaying the coarse image
data.
The enhancement of the film feed speed for coarse
image-reading can simply be achieved by adding software
to or modifying the software of the motor control means.
The enhancement of the film feed speed reduced image
read time.
The object measuring region specifying means in
this embodiment specifies narrow object measuring
regions respectively including specified portions of the
coarse images in the coarse picture displayed on the
coarse picture display means. Although the narrow
object measuring regions may be specified by any suit-
able method, a method using the cursor on a CRT i5
desirable. For example, a narrow object measuring
region 213 including part of the image of the aluminum
step wedge, i.e., the standard block, and a narrow
object measuring region 212 including part of the
image 214 of the second metacarpal bone of the right
hand are specified as shown in Fig. 18.
Concretely, as shown in Fig. 18, the object mea-
suring region 212 is specified by distances el and
respectively from the right-hand edge and lower side
edge of the screen and lengths f1 and h1 , and the
object measuring region 213 is specified by distances e2
and q2 respectively from the right-hand edge and lower
side edge of the screen and lengths f2 and h2 by
shifting the cursor. The length f2 for specifying the
object measuriny region 213 in the image 211' of the
aluminum step wedge may be very small to specify an
object measuring region like a single thin line. The
minute image-read means in this embodiment reads the
portions of the images in the narrow object measuring
203~
- 43 -
regions specified by the object measuring region speci-
fying means for minute image-reading in a high accuracy
by the automatic image read unit while the film is being
fed. It is desirable to feed the film at a film feed
speed lower than a film feed speed for coarse image-
reading to obtain image data of dense picture element
distribution with respect to the film feed direction.
Furthermore, the minute image-read means is provided
desirably with conversion means for converting the
specified object measuring region into a film feed
distance and a read range with respect to a direction
perpendicular to the film feed direction for efficient,
minute image-reading. For example, the distances el ,
g , e2 and q2 and the lengths fl , hl r f2 and -2
in Fig. 18 are converted by the conversion means; the
distance e1 and the length f1 of the object measuring
region 212 are converted into corresponding film feed
distances, the distance q1 and the length h1 of the
object measuring region 212 are converted into corre-
sponding ranges with respect to a direction perpen-
dicular to the film feed dir~ction, the distance e2 and
the length f2 of the object measuring region 213 are
converted into corresponding film feed distances and the
distance q2 and h2 of the object measuring region 213
are converted into corresponding ranges with respect to
a direction perpendicular to the film feed direction.
Preferably, the film is moved for minute image-reading
in a direction reverse to the film feed direction for
coarse image-reading, the film is moved at the lower
film feed speed only while the minute image-read means
travels relative to the film through the lengths fl and
f2 t and the image read means functions only in the
specified object measuring regions for minute image-
reading. That is, the image read means functions for
minute image-reading only for the range h1 while the
same travels relative to the film through the distance
fl and only for the range h2 while the same travels
_ 44 _ 2~3~61
through the distance f2.
Such an image reading mode of the minute image-read
means ensures and facilitates the accurate reading of
portions of the respective images of the standard block
and the sample bone which are essential to bone
morphometry.
During the minute image-reading operation, the
stepping motor of the film feed means is controlled so
as to feed the film at the highex film feed speed while
the automatic image read unit travels relative to the
film through regions other than those corresponding to
the lengths f1 and f2 to carry out the minute image-
reading operation efficiently.
Thus, the stepping frequency of the stepping motor
is reduced for minute image-reading operation to read
the images formed on the X-ray film by controlling the
pulse signal applied to the stepping motor so that the
X-ray film is fed intermittently by a distance corre-
sponding to the pitch of the scanning lines at a time.
When reading the portion of the image included in the
object measuring region 212, the number of the picture
elements in a range with respect to the direction of
extension of the linear image detector 42 corresponding
to the length hl is counted by a picture element counter
and the data of only the picture elements in the range
is read and stored in, for example, an image memory.
The portion of the image in the object measuring
region 213 is read likewise.
The bone~morphometric apparatus in this embodiment
is featured by the employment of the means having such
image reading functions as the automatic image read
means.
The image data obtained through the minute image-
reading operation, representing the quantities of
transmitted light transmitted through the detected
positions on the image of the sample bone, is converted
into digital signals representing the respective
~3~61
- 45 -
thicknesses of the steps of the aluminum step wedge
corresponding to the respective densities at detected
positions on the image to obtain digital data. The data
representing the quantities of transmitted light trans-
mitted through the respective images of the sample bone
and the aluminum step wedge may be used without con-
verting the same into digital signals. The digital data
is stored in suitable storage means, such as the image
memory 56 shown in Fig. 3. The bone-morphometric data
processing unit 32 processes the stored digital data in
the foregoing manner for bone morphometry. The results
of the bone-morphometric data processing operation are
provided by the output means, such as the printer 2~.
The bone-morphometric apparatus in this embodiment
is capable of surely and rapidly carrying out the image
reading operation and capable of achieving accurate bone
morphometry without increasing the storage area with
X-ray films having the images of sample bones at dif-
ferent positions.
A bone-morphometric method and a bone-morphometric
apparatus having the configuration shown in Figs. 1 and
3 in further preferred embodiments according to the
present invention will be described hereinafter. This
bone-morphometric method and this bone-morphometric
apparatus incorporates improvements for solving problems
that a dark portion of a roentgenographic image cannot
be measured precisely and the accurate data of the same
cannot be obtained due to leakage in the linear image
detector comprising CCDs, when an electric signal
representing the quantity of transmitted light trans-
mitted through a light portion contiguous with the dark
portion is large.
Prior to the bone morphometry of a sample bone
using the quantity of light transmitted through an X-ray
film carrying the respective images of the sample bone
and a standard matter having varying thickness, a
predetermined small quantity Lo of light is applied to a
2~30~1
- 46 -
portion of the image of the standard matter corre-
sponding to the vicinity of the edge of the thickest end
of the standard matter and the quantity of transmitted
light transmitted through the same portion is measured
to detect a portion of the image of the standard matter
corresponding to the edge of the thickest end of the
standard matter, a predetermined quantity L of light
greater than the quantity Lo is applied to the image of
the standard matter to determine the relation between
the thickness of the standard matter and the gradation
of the image on the basis of the relation between the
quantity of transmitted light and the distance from the
edge of the thickest end of the standard matter.
When detecting the portion of the image corre-
sponding to the edge of the thickest end of the standardmatter, such as an aluminum step wedge or an aluminum
slope, by the morphometric method in this embodiment,
the quantity Lo of light smaller than the quantity L of
light to be applied to the film in reading the respec-
tive images of the standard matter and the sample boneis applied to the vicinity of the portion of the image
of the standard matter corresponding to the vicinity of
the edge of the thickest end of the standard matter to
read the image of the edge of the thickest end of the
standard matter.
The quantity Lo of light is set, for example, by
directly illuminating the linear image detector 42
comprising CCDs by the light emitted by the linear light
source 41 and adjusting the duration of on-state of the
linear light source 41 so that the quantity of light
received by the linear image detector 42 is in the range
of 90 to 95~ of the saturation level of the CCDs.
The quantity L of light may be set by the foregoing
illuminating light quantity adjusting means capable of
adjusting the quantity of illuminating light according
to the condition of the images formed on the X-ray film
so that accurate bone morphometry can be achieved.
203~5~
- 47 -
Preferably, a portion of the image of the standard
block, i.e., the aluminum step wedge, corresponding to
the edge of the thickest end of the standard block is
detected, because a portion of the image of the standard
block corresponding to the edge of the thinnest end of
the standard block, in many cases, is not clear and
hence the latter portion is difficult to detect accu-
rately. For example, in the image 311' of the aluminum
step wedge sho~l in Fig. 19, the lower end corresponds
to the thickest end of the aluminum step wedge and is
the lightest when illuminated.
For example, in the image 311' of the aluminum step
wedge shown in Fig. 19, suppose that the x-axis is the
longitudinal center line of the image 311', the x-axis
intersects the lower side edge of the film 22 at a
point O, and positive values for x, i.e., distance from
the point O, are measured upward on the x-axis. Then,
the relationship between the quantity I of transmitted
light and the distance x from the point O can typically
be represented by the stepped curve as shown in
Fig. 20A. The unit for x corresponds to one 63.5 ~m
wide picture element. The relation between I and x is
stored in a storage means, such as the RAM 62, and the
mean transmitted light quantity I(x) per ~ is calculated
for each value of x by the MPU 60. Preferably, ~ is
five to ten picture elements; for example, seven picture
elements. Then, the difference D = I(x + ~) - I(x) is
calculated for each x. Desirably, ~ is in the range of
ten to twenty picture elements, for example, fourteen
picture elements, to reduce the influence of noise.
Figure 20B shows a typical relationship between D and x.
A position on the image 311' corresponding to a value of
x for the maximum value of D corresponds to the edge of
the thickest end of the aluminum step wedge. A usual
aluminum step wedge has twenty steps 10 mm in width and
a 1 mm common thickness difference including the thin-
nest step 1 mm thick and the thickest step 20 mm thick,
- 48 - 203~61
and a length of 200 mm.
Thus, this embodiment is able to detect the edge of
a portion of the image of the aluminum step wedge
corresponding to the edge of the thickest step. Fur-
thermore, the bone-morphometric method is capable of
accurately determining the relationship between the
thickness of the aluminum step wedge and the quantity of
transmitted light transmitted through the aluminum step
wedge through the measurement of the quantity of trans-
mitted light along the x-axis by applying the quantity L
of illuminating light greater than the quantity Lo of
illuminating light to the image of the aluminum step
wedge. The quantity L of illuminating light is applied
to the image of the sample bone and the quantity of
transmitted light transmitted through the image of the
sample bone is measured, and then the quantity of
transmitted light is converted into the corresponding
thicknesses of the steps of the aluminum step wedge with
reference to the known relation between the quantity of
transmitted light and the thickness of the steps of the
aluminum step wedge for further accurate bone
morphometry.
The bone-morphometric apparatus in this embodiment
is capable of carrying out the foregoing bone-morpho-
metric method and is featured by image read meanscomprising means for detecting the edge of the image of
a standard matter corresponding to the edge of the
standard matter while the smaller quantity Lo of illumi-
nating light is applied to the image of the standard
matter, and means for reading the respective images of
the standard matter and the sample bone while the larger
quantity L of illuminating light is applied to the
images. The quantity of illuminating light may be
controlled, for example, by a lighting frequency control
circuit for controlling the lighting frequency, hence
the lighting duration, of the light source, such as a
LED.
_ 49 _ 2030~
The image storage means of the bone-morphometric
apparatus embodying the present invention may be any
storage means capable of storing digital signals
obtained by converting the quantity of transmitted light
transmitted through the roentgenographic image of the
sample bone in combination with corresponding positions
on the x-ray film. The image memory 56 shown in Fig. 3
is an exemplary image storage means.
The functions of the means for detecting the edge
by using the quantity Lo of illuminating light and the
means for reading the image by using the quantity L of
illuminating light may be executed by the linear light
source 41 and linear image detector 42 of the automatic
image read unit 31 shown in Fig. 3. The functions of
the lighting frequency control circuit may be executed
by the light source control circuit 45.
After storing the data of the roentgenographic
image of the sample bone in the image memory 56, the
stored data can be readily processed by the bone-morpho-
metric data processing unit 32. The bone-morphometric
method or bone-morphometric apparatus in this embodiment
is capable of surely and accurately reading the image of
the standard block, i.e., the aluminum step wedge, for
further accurate bone morphometry.
A morphometric bone assay system in a preferred
embodiment according to the present invention will be
described hereinafter. The morphometric bone assay
system comprises the aforesaid bone-morphometric appa-
ratus for the bone morphometry of a sample bone, first
transmission means for transmitting bone-morphometric
data obtained by the bone-morphometric apparatus, a
morphometric bone assay apparatus which stores the
bone-morphometric data transmitted by the transmission
means and assays the sample bone by using the stored
bone-morphometric data, bone-morphometric data obtained
in the past and, if necessary, other data, and second
transmission means for transmitting the results of the
~3~561
- 50 -
morphometric bone assay of the sample bone to the
bone-morphometric apparatus.
The bone-morphometric apparatus is such an appa-
ratus as shown in Fig. 3 which processes images formed
by transmitted light transmitted through the respective
roentgenographic images of a standard block and a sample
bone formed on an X-ray film or an apparatus as shown in
Fig. 8 which processes the respective radiographic
images of a standard block and a sample bone obtained by
irradiating the standard block and the sample bone with
radioactive rays, such as X-rays or gamma rays.
The morphometric bone assay apparatus comprises
storage means for storing bone-morphometric data trans-
mitted thereto by the communication means, and assay
means for assaying the data of the sample bone including
the quantity of bone mineral through the analysis of the
bone-morphometric data given thereto in combination with
bone-morphometric data previously stored therein.
If possible, various bone-morphometric information
may be included in the assay. Concretely, the assay of
the time-dependent variation of the sample bone based on
the examination of the previous bone-morphometric data,
and the analysis of the difference between the present
bone-morphometric data and the last bone-morphometric
data. The morphometric bone assay system may be pro-
vided with functions for storing morphometric indices of
bones of healthy persons of the same sex and the same
age as reference indices and for comparing the morpho-
metric indices of the sample bone with those reference
indices. Records of medication for therapy may be
stored for use in combination with the morphometric data
for morphometric bone assay.
Figure 21 is a block diagram of a morphometric bone
assay system including a bone-morphometric apparatus
which uses roentgenograms. Naturally, the bone-morpho-
metric apparatus may be substituted by the radiographic
bone-morphometric apparatus shown in Fig. 8.
2030~61
- 51 -
Referring to Fig. 21, the morphometric bone assay
system comprises a morphometric bone assay appa-
ratus 351, and one or a plurality of bone-morphometric
apparatus 20 connected by communication means 350
including first and second transmission means, such as
telephone circuits. The morphometric bone assay appa-
ratus 351 comprises storage means 353 and 354, and assay
means 352. Preferably, the morphometric bone assay
apparatus 351 is provided with self-diagnostic means to
check the operating condition of the bone-morphometric
apparatus 20.
The self-diagnostic means checks the condition of
inputs, such as the condition of the received image data
of a sample bone, in order to ascertain that the condi-
tion is satisfactory, and maintains the normal functionsof the morphometric bone assay apparatus by inquiring
and eliminating the causes of malfunction to ensure the
correct bone morphometry of the sample bone.
In the case of the practical self-diagnosis o~ the
bone-morphometric apparatus 20 which uses an X-ray
film 22 carrying the roentgenogram of a sample bone, a
central equipment compares periodically the respective
output levels of the light source and the linear image
detector 42 with reference levels, respectively, to
determine the secular degradation of the light source
and the linear image detector 42. It is desirable to
readjust the associated apparatus when the degradation
has proceeded beyond a given limit.
The morphometric bone assay apparatus 351 may be
provided with generally known means for inquiring the
causes of malfunction including (1) means for checking
the contents of the data memory (RAM 62) and image
memory (image memory 56) of the computer by using check
sums, (2) means for testing the functions of the
printer, the CRT controller 64 and the keyboard 26, (3)
means for testing the operation of the motor controller
by using a standard test film for testing film feed and
2~30~6~
- 52 -
(4) means for luminance regulation test for checking the
functions of the image read unit 31 and correcting
function.
It is desirable to realize the self-diagnostic
functions on the assumption that variation in the
quantity of light with respect to the direction of the
width of the linear image detector is corrected for
every measurement of the roentgenogram, the basic
functions of the computer and communication functions
are checked through self-tests without using the commu-
nication means and the basic functions of the computer
and the communication functions are normal.
When telephone circuits are employed as the commu-
nication means 350, practically, MODEM communication
using public telephone circuits or use of a leased
circuit is preferable. Accordingly, the bone-morpho-
metric data processing unit 32 of the bone-morphometric
apparatus 20 is provided with a MODEM 67.
Thus, the present invention enables the use of
practically and economically advantageous telephone
circuits by transmitting a small amount of simplified
data, such as the results of morphometric bone assay
performed by the morphometric bone assay apparatus and
the results of bone morphometry performed by the bone-
morphometric apparatus, even if a large amount ofbone-morphometric data of sample bones is produced.
The bone-morphometric apparatus 20 of the morpho-
metric bone assay system of the present invention are
installed respectively at the sites of roentgenographic
operaticn for the quick bone morphometry immediately
after X-raying sample bones, transmits the simplified
results of bone morphometry to the morphometric bone
assay apparatus 351, performs collectively the compli-
cated assay of sample bones including the comparison of
the simplified results with stored bone-morphometric
data by the morphometric bone assay apparatus 351, and
feeds back the results of morphometric bone assay
2~305~
- 53 -
immediately.
The contents of communication between each bone-
morphometric apparatus 20 and the morphometric bone
assay apparatus 351 are, for example, (1) information
about the examinee including an ID number identifying
the examinee, name, data of birth, date of initial
registration, the diagnosis, the newest bone-morpho-
metric data and data storage location, (2) the bone-
morphometric data of the examinee including data number,
date of X-raying, measuring illuminance and ~ GS, and
(3) system data including the number of all the regis-
tered examinee, the number of the bone-morphometric
apparatus, the title of the installation and the results
of the self-diagnosis of the apparatus.
The morphometric bone assay system thus constructed
carries out morphometric bone assay at a location far
apart from the bone-morphometric apparatus 20 and feeds
back the results of morphometric bone assay to enable
quick bone morphometry and bone morphometry. Further-
more the morphometric bone assay system enables the use
of the bone-morphometric apparatus at remote places and
ensures accurate bone morphometry.
~ urthermore, the morphometric bone assay system in
accordance with the present invention is able to use
existing telephone circuits as communication means
realizes collective and efficient bone morphometry by
the plurality of bone-morphometric apparatus distributed
as terminal equipments in different regions and the
single morphometric bone assay apparatus as the central
equipment. The morphometric bone assay system carries
out automatic morphometric bone assay quickly and
efficiently through the automatic bone morphometry
including the automatic reading of the roentgenograms or
radiograms of sample bones.
