Medical X-ray image detecting device

A medical X-ray image detecting device wherein the fluorescent surface of a narrow belt-shaped X-ray fluorescen plate which emits light at the time of irradiation of X-ray through a slit is divided to rectangular units, optical fiber bundles are distributed alternately right and left and arranged vertically, the one end surface of each optical fiber bundle is attached to one of the divided fluorescent surface unit, the other end surface of each optical fiber bundle is attached to the image pickup surface of a solid-state image pickup device to make image formation possible, and the solid-state image pickup device is disposed behind an X-ray shielding member by which the slit is formed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to improvements in an X-ray image detecting 
device for detecting X-ray penetration images using solid-state image 
pickup devices in a panoramic X-ray diagnosis apparatus for medical 
treatment, particularly for dental treatment. 
2. Prior Art 
Panoramic X-ray diagnosis apparatuses for medical treatment, particularly 
for dental treatment are widely used clinically to observe the arrangement 
of the teeth and the conditions of the dental roots in the mouth of a 
patient. As an example of such apparatuses, a panoramic photographing 
apparatus which performs panoramic radiographing by rotating an image 
detecting device and an X-ray source while maintaining a constant 
relationship between the image detecting device and the X-ray source, with 
the head of the patient positioned therebetween, is widely used for dental 
treatment. A conventional panoramic radiographic apparatus opto-chemically 
formed images of penetrated X-ray on X-ray sensitive films. This method 
took a long time for development and was not suited for immediate 
observation and diagnosis during treatment. 
To solve this problem, an art is used for a dental radiographing apparatus 
to reproduce X-ray penetration images on a monitor unit by receiving 
slit-passed X-ray on a fluorescent plate to first obtain a visible light 
image, by forming the image on the image pickup surface of a pickup tube 
or a CCD image pickup device via an optical lens system and by converting 
the image to an electric signal. In addition, another art which directly 
and optically combines a fluorescent surface and an image pickup surface 
by using optical fiber and transmits images, instead of forming images by 
using an optical lens system, has been developed. 
A prior art related to the above-mentioned technology has been disclosed, 
in the case of radiographing only one tooth and its surrounding area by 
using an apparatus (I) which receives X-ray beams from an X-ray source 
outside the mouth and picks up the beams as a still image by using an 
arrangement wherein a sensor comprising optical fiber which optically 
combines an X-ray fluorescent plate and the image pickup surface of an 
electronic chip, such as a CCD image pickup device, is disposed behind the 
tooth to be photographed in the mouth (Japanese Laid-open Patent 
Application No. 60-234645). 
Another panoramic radiographing apparatus (II) discloses an art which 
combines the fluorescent surface image extending in the longitudinal 
direction of the above-mentioned slit on a small image pickup surface by 
gradually reducing the diameter of each element of the optical fiber (used 
to connect a narrow belt-shaped fluorescent surface to a CCD image pickup 
device) in the direction from the fluorescent surface to the image pickup 
surface of the CCD image pickup device (FIG. 2 in Japanese Laid-open 
Utility Model Application No. 63-140907). A third apparatus (III) 
discloses an art wherein the one end of the optical fiber bundle connected 
to the fluorescent surface extending in the longitudinal direction of the 
slit is cut at the surface obliquely to the axis of each element of the 
fiber bundle and the other end of the fiber bundle is cut at the surface 
orthogonally to the axis and connected to the image pickup surface of the 
CCD image pickup device, thereby the image on the fluorescent surface in 
the longitudinal direction of the slit is reduced and formed on the CCD 
image pickup device (FIG. 3 in Japanese Laid-open Utility Model 
Application No. 63-140907 cited above). With these apparatuses (II) and 
(III), the narrow belt-shaped fluorescent surface is connected via a fiber 
bundle to the image pickup surfaces of a plurality of CCD image pickup 
devices and the image signals from the CCD image pickup devices are 
electrically combined to obtain an X-ray panoramic image on the display 
screen of a monitor unit. 
The above-mentioned solid-state image pickup device, such as a CCD image 
pickup device, wherein the image pickup surface of the solid-state image 
pickup device, is connected to an optical fiber bundle, X-ray transmits a 
visible light image to be formed on the fluorescent surface and the image 
is observed on the display screen on a monitor unit, has an image pickup 
surface size of about 5 mm square. This value is far smaller than the 
longitudinal length (about 150 mm) of the fluorescent surface. It is very 
difficult to increase the size of the image pickup surface. Even if 
possible, the cost is assumed to be excessive. 
When using the prior art applied to the apparatus (I) for a panoramic 
radiographing apparatus, its image pickup surface is too small, and all 
ranges including the upper and lower jaw sections cannot be photographed. 
When using the art applied to the apparatus (II), it is difficult to 
uniformly taper (gradually reduce the diameter) the end of each element of 
the fiber. Even if possible, production cost would be excessive. 
As a problem common to both the apparatuses (II) and (III), if the 
reduction ratio between the image on a divided fluorescent surface and the 
image formed by the fiber bundle on the image pickup surface of the CCD 
image pickup device is made larger, the resolution of the image signal 
from the CCD image pickup device is deteriorated. 
In the case of all above-mentioned prior arts, since the solid-state image 
pickup devices are disposed in the penetration range of the slit-passing 
X-ray, the electric charges by X-ray irradiation inside the devices 
accumulate, being in danger of causing the solid-state image pickup 
devices to break. 
The rim of the sealing material for the solid-state image pickup device is 
generally larger than the image pickup surface thereof and protrudes from 
the surface. If a plurality of image pickup devices are placed side by 
side, the rim of the sealing material for a solid-state image pickup 
device makes contact with the adjacent fiber bundles and the rims of the 
sealing materials for other adjacent solid-state image pickup devices, 
causing a problem when arranging the solid-state image pickup devices in 
an X-ray image detecting device. 
SUMMARY OF THE INVENTION 
In view of solving the above-mentioned problems, it is an object of the 
present invention to provide a medical X-ray image detecting device which 
uses solid-state image pickup devices to obtain a panoramic X-ray image of 
the entire jaw sections ranging from the upper to lower jaw bones without 
reducing the resolution of the image. 
Another object of the present invention is to prevent the solid-state image 
pickup devices from being damaged by irradiated X-ray during panoramic 
photographing and to ensure easy arrangement of the solid-state image 
pickup devices in the apparatus. 
For these purposes, the present invention uses fiber bundles which are not 
specially processed (tapered for example) to optically connect the 
fluorescent surface of the narrow belt-shaped fluorescent plate to the 
image pickup surfaces of a plurality of solid-state image pickup devices. 
By using the fiber bundles, the image on the fluorescent surface, at least 
the length of which in the longitudinal direction of the fluorescent 
surface is equal to the image pickup surface of the solid-state image 
pickup device, is projected to the image pickup surfaces of the 
solid-state image pickup devices. The image signals from a plurality of 
the solid-state image pickup devices are electrically combined to form 
images on the narrow belt-shaped fluorescent surfaces. Then in 
synchronization with the rotation of the fluorescent surfaces around the 
dental arch, the images on the fluorescent surfaces are electrically 
combined on the monitor screen to conduct curved tomographic photographing 
which provides an overall view of the entire dental arch as a panoramic 
image.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides a medical X-ray image detecting device 
comprising a narrow belt-shaped X-ray fluorescent plate disposed behind a 
slit formed by an X-ray shielding member, a plurality of optical fiber 
bundles, with the one end surface of each of the optical fiber bundles 
being attached to the fluorescent surface of the fluorescent plate, and 
solid-state image pickup devices, with the other end surface of each of 
the optical fiber bundles being attached to the image pickup surface of 
one of the image pickup devices. The X-ray image detecting device is 
characterized in that the fluorescent surface is divided in the 
longitudinal direction thereof into a plurality of rectangular units, the 
total length of which is the same as the vertical length of the image 
pickup surface of the image pickup device, the one end surface of each of 
the optical fiber bundles is attached to one of the divided fluorescent 
surface units to make individual image formation possible, and the bundles 
are distributed alternately right and left in the longitudinal direction, 
the other end surface of each of the fiber bundles is attached to the 
image pickup surface of one of the image pickup devices disposed on the 
right/left side at the backward position of the fluorescent surface unit 
and behind the X-ray shielding member to make individual image formation 
possible, whereby the X-ray image on the whole fluorescent surface is 
detected by combining individual image signals obtained from the 
solid-state image pickup devices. 
In the present invention, the narrow belt-shaped fluorescent surface is 
divided in its longitudinal direction into a plurality of rectangular 
units by using the vertical length of the image pickup surface of a single 
solid-state image pickup device as one unit to be divided, and each 
solid-state image pickup device corresponding to one of the divided 
fluorescent surface units is connected by the optical fiber bundle. The 
image projected on the image pickup surface of each solid-state image 
pickup device is thereby not reduced. Since it is easy to make the 
diameter of the optical fiber element sufficiently smaller than the 
diameter of the picture element of the solid-state image pickup device, 
the resolution of the image is not made lower than that of the solid-state 
image pickup device. 
In addition, since the optical fiber bundles are distributed alternately 
right and left in the longitudinal direction behind the fluorescent 
surface unit divided as mentioned above, the solid-state image pickup 
devices connected to the individual optical fiber bundles are vertically 
aligned at the distributed right-side and left-side fiber bundle positions 
behind the fluorescent plate (in one line on each side) of the fluorescent 
plate. A space is thus provided between adjacent optical fiber bundles. 
Therefore, even if the rims of the sealing material for the solid-state 
image pickup device protrude the image pickup surface of the solid-state 
image pickup device around the circumference of the device, the protruded 
sections of the solid-state image pickup devices connected to the optical 
fiber bundles do not contact each other, thereby allowing the solid-state 
image pickup devices to be disposed and arranged easily in the X-ray image 
detecting device. 
EXAMPLES 
Examples of the present invention are described below referring to the 
accompanying drawings. 
FIG. 1 (A) is an overall view of a dental panoramic X-ray diagnosis 
apparatus which incorporates the X-ray image detecting device of the 
present invention. This diagnosis apparatus is structured so that an X-ray 
source 9 incorporating an X-ray tube and a photographing box 8 
incorporating the X-ray image detecting device of the present invention 
rotate around the jaw section 7 of a patient while an opposed positional 
relationship is maintained between the X-ray source 9 and the 
photographing box 8. The X-ray beam X irradiated from the slit 91 of the 
X-ray source 9 penetrates the jaw section 7 and reaches the slit 83 of the 
photographing box 8. 
FIG. 1 (B) is a partially cutaway perspective view of an example of the 
X-ray image detecting device of the present invention incorporated in the 
photographing box 8. This example is detailed referring to FIGS. 2 (A), 2 
(B) and 2 (C). 
FIG. 2 (A) is a traverse plan view of the photographing box 8. Numeral 82 
in the figure represents a steel plate used to form the photographing box 
8. Numeral 81 represents a lead plate provided with a slit 83 (about 
7.times.150 mm) and is used to shield the X-ray. Numeral 84 represents a 
black opaque plate disposed in front of the slit 83 to shield visible 
light. Behind the slit 83, a rectangular narrow belt-shaped fluorescent 
plate 1 is secured. A fluorescent material layer 10 which emits visible 
light when stimulated by X-ray is coated on the surface of the transparent 
glass substrate 11 of the fluorescent plate 1, thereby forming a 
fluorescent surface 10. The back side of the glass substrate 11 is 
attached to the end surface 21 of an optical fiber bundle 2 to make 
optical connection to the fluorescent surface 10. 
The other end surface 22 of the fiber bundle 2 is connected to the image 
pickup surface 30 of a CCD image pickup device 3 via a protection glass 
plate 32 in the case of this example to make image formation possible. The 
optical fiber bundle 2 is bent nearly orthogonally almost in the middle of 
its route. The CCD image pickup device 3 is disposed outside the incident 
X-ray range at the backward position of the glass substrate 11 of the 
fluorescent plate 1 and behind the X-ray shielding plate 81 so that the 
device 3 is not adversely effected or damaged by the X-ray which passes 
the slit 83. Numeral 5 represents a lead plate used to shield the 
penetrated X-ray. 
FIG. 2 (B) is a partially perspective view of the X-ray image detecting 
device and illustrates a mutual arrangement relationship among the 
fluorescent plate, the optical fiber bundles and the CCD image pickup 
device in the photographing box 8. In this figure, the fluorescent plate 1 
is divided to ten sections in the longitudinal direction. The end surfaces 
21, 21a, 21b, 21c, . . . of the ten optical fiber bundles 2, 2a, 2b, 2c, . 
. . corresponding to the ten sections are optically connected to the 
divided fluorescent surface units of the glass substrate 11. The optical 
fiber bundles 2, 2a, 2b, 2c, . . . are bent nearly orthogonally almost in 
the middle of their routes so that they are alternately distributed right 
and left with respect to the incident direction of the incident X-ray. 
The image pickup surfaces 30 of the CCD image pickup devices 3, 3a, 3b, . . 
. , shown in FIG. 2 (C) are optically connected and attached to the other 
end surfaces 22, 22a, 22b, 22c, . . . of the optical fiber bundles 2, 2a, 
2b, 2c, . . . respectively via the protection glass plates 32 to make 
image formation possible. Both end surfaces 21 and 22 of the optical fiber 
bundle 2 are cut orthogonally to the axis of the fiber and attached to the 
glass substrate 11 of the fluorescent plate 1 and the glass protection 
plate 32 of the CCD image pickup device 3 respectively so that images to 
be obtained are not magnified or reduced and are free from image 
distortion when the optical fiber bundle 2 transmits the image on the 
fluorescent surface 10 to the image pickup surface 30 of the CCD image 
pickup device 3. 
In addition, since the CCD image pickup devices 3, 3a, 3b, . . . are 
alternately distributed right and left, they do not cause any problem in 
their disposition, even when rims 31 made by the protruded sealing 
material of the CCD image pickup device 3 protrude and extend from the 
circumferences of the image pickup surfaces. 
With this example, the X-ray image detecting device of the present 
invention is applied to a dental panoramic X-ray diagnosis apparatus. In 
this case, the longitudinal direction of the fluorescent surface 10 of the 
image pickup device incorporated in the photographing box 8 is vertical. A 
plurality of fluorescent surface units are disposed in the vertical 
direction, and the fiber bundles 2 corresponding to the fluorescent 
surface units are arranged in the vertical direction and alternately 
distributed right and left in the middle of their routes. The outgoing end 
surfaces of the fiber bundles 2 are respectively attached to the image 
pickup surfaces of the individual solid-state image pickup devices located 
in the same ranges corresponding to the vertically divided fluorescent 
surface units. 
When applying the present invention to general medical panoramic 
radiographing apparatuses, the X-ray image detecting device of the present 
invention is moved laterally or rotationally with respect to the slit 83 
to tomographically photograph planes or tomographically photograph curved 
surfaces other than dental arches. In this way, the X-ray image detecting 
device of the present invention can be used for general medical panoramic 
radiographing apparatuses by simply changing the relative positions and 
the movement direction of the X-ray source and the X-ray image detecting 
device, without changing the structure of the X-ray image detecting 
device. 
FIGS. 3 (A), 3 (B) and 3 (C) are plan views of arrangements of other 
examples of the present invention and illustrate the positional 
relationship among the fluorescent plate 1, the optical fiber bundles 2 
and the CCD image pickup device 3. In the case of the arrangement shown in 
FIG. 3 (A), the bending angle of the optical fiber bundles 2 alternately 
distributed right and left is smaller than a right angle to make the fiber 
bundles 2 formed easily. The bundles 2 are preferably bent circularly. 
In the case of the arrangement shown in FIG. 3 (B), the optical fiber 
bundles 2 are not bent but made straight so that their end surfaces are 
oblique to the axis of the fiber. As shown in the figure, the CCD image 
pickup devices 3 and 3a can be disposed on the same plane. This allows the 
CCD image pickup devices 3 distributed right and left to be secured and 
wired on the same wiring board for higher convenience. In the case of the 
arrangement shown in FIG. 3 (C), the axes of the optical fiber bundles are 
orthogonal to the image pickup surface of the CCD image pickup devices 3, 
but are oblique to the fluorescent surface 10. An inclination angle 
between the image pickup surface and the fluorescent surface 10 can be set 
to an appropriate value to the extent that the resolution in the lateral 
direction of the fluorescent surfaces 10 is not deteriorated. 
To reproduce an image signal from each CCD image pickup device on the 
monitor screen, a sync signal from an oscillator (not shown) common to the 
CCD image pickup devices is used. The image signals of the individual CCD 
image pickup devices are combined in a monitor unit (not shown) and 
reproduced on a display (not shown) as images. At this time, the images of 
the individual CCD image pickup devices 3 are assigned to the vertical 
sections on the display. In addition, the images of the individual CCD 
image pickup devices are continuously developed horizontally on the 
display in synchronization with the radiographing apparatus's rotation 
angle around the jaw section, thus obtaining an entire X-ray panoramic 
image of the jaw section on the display. 
Since the X-ray sensitivity of solid-state image pickup devices, such as 
CCD image pickup devices, is made generally high by properly selecting 
fluorescent material to be coated on the fluorescent plate, the intensity 
of the X-ray source can be made far smaller, 1/100 or less, than the 
intensity of the X-ray source for the film sensitivity method. As a 
result, the X-ray dose exposed to the patient can be reduced 
significantly.