X-ray radiographic apparatus, method of measuring head tilt in taking radiograph, stand for X-ray radiographic apparatus, chair for X-ray radiographic apparatus, and head tilt setting device

Provided is an X-ray radiographic apparatus that can take a lateral cephalometric radiograph, a posteroanterior cephalometric radiograph, etc. under the same state of the tilt in the front-rear direction of the head of a subject easily and with high reproducibility, and is free of risks associated with the use of an infraorbital point pointing bar. The X-ray radiographic apparatus includes: a pair of arms provided facing each other with a reference line therebetween; ear rods provided to mutually facing inside surfaces of the pair of arms; a head tilt setting device for setting the tilt in the front-rear direction of the head of the subject provided on one arm, and a horizontal plane verification mechanism provided on the head tilt setting device or outside of the head tilt setting device.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a national stage of International Application No. PCT/JP2013/069464 filed on Jul. 18, 2013, which claims priority to Japanese Patent Application No. 2012-165495 filed on Jul. 26, 2012, Japanese Patent Application No. 2012-274275 filed on Dec. 17, 2012, and Japanese Patent Application No. 2013-108647 filed on May 23, 2013, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present invention relates to an X-ray radiographic apparatus, a method of measuring head tilt in taking a radiograph, a stand for X-ray radiographic apparatus, a chair for X-ray radiographic apparatus and a head tilt setting device which are suitable, for example, for applying in taking a cephalometric radiograph by a cephalometric X-ray radiographic apparatus.

In an orthodontic treatment, etc., when deciding a treatment plan, generally, taking a cephalometric radiograph (cephalogram) of a patient, and based on the cephalometric radiograph, the cephalometric analysis is performed (for example, see Non-Patent Literatures 1 and 2). Conventionally, as a cephalometric radiograph, a lateral (side surface) cephalometric radiograph is solely taken. As necessary, there is a case where a posteroanterior (PA) cephalometric radiograph is taken, but it is quite rare, even more, the fact is that it is hard to say that effective information useful for the treatment can be obtained from the posteroanterior cephalometric radiograph. The main reason is that setting the tilt in the front-rear direction of the head when taking a posteroanterior cephalometric radiograph is quite difficult, and therefore, every time taking a posteroanterior cephalometric radiograph, the head tilt becomes different. When taking a cephalometric radiograph under the different head tilt, the posteroanterior cephalometric radiograph to be obtained gives completely different impression. For this, under the present conditions, in the first place, the posteroanterior cephalometric radiograph is considered not to be reliable materials in judging the head skeleton, etc. of a patient.

Conventionally, a lateral cephalometric radiograph is said to be taken at the position that the Frankfort plane of the head of a patient becomes parallel to the floor surface (see Non-Patent Literatures 1 and 2). Here, the Frankfort plane is a plane connecting an orbitale with a porion. In order to make the Frankfort plane of the head parallel to the floor surface when taking a lateral cephalometric radiograph, it is known that an infraorbital point pointing bar with a needle-like sharp tip is provided in the horizontal plane in a cephalometric X-ray radiographic apparatus so as to face the face of a patient (see Non-Patent Literature 2). And it is also known that a posteroanterior cephalometric radiograph is similarly taken at the position that the Frankfort plane becomes parallel to the floor surface (see Non-Patent Literature 2).

Also, in the text of Proffit with highest standing in the world as a text of orthodontics (see Non-Patent Literature 3), it is indicated that with regard to the cephalometric analysis, “A cephalometric radiograph is to be taken at the natural head position (NFP), from which the physiologically real horizontal plane can be obtained”.

PRIOR ART LITERATURE

SUMMARY

Subjects to be Solved by Invention

However, in the Non-Patent Literature 2, it is only described that when taking a posteroanterior cephalometric radiograph, “The image remarkably tends to vary by variation of the head, therefore it is better to take a lateral cephalometric radiograph first, by which a patient learns the body position, then, to take a posteroanterior cephalometric radiograph.” (see the literature, p. 147, lines 11-13), and no specific method of making the Frankfort plane of the head of a patient parallel to the floor surface, when taking a posteroanterior cephalometric radiograph is not described. For this, it is considered to be absolutely difficult that a posteroanterior cephalometric radiograph and a lateral cephalometric radiograph are taken under the same head tilt of a patient. Also, the method has a risk which the face, etc. of a patient would contact with the infraorbital point pointing bar.

Also, according to the method of the Non-Patent Literature 3, when taking a lateral cephalometric radiograph, not to mention a posteroanterior cephalometric radiograph, it is inevitable that the head tilt varies every time taking a cephalometric radiograph, and it is considered that taking a posteroanterior cephalometric radiograph and a lateral cephalometric radiograph under the same head tilt of a patient is very difficult.

Further, as far as the inventor of the present invention knows, a method of taking a posteroanterior cephalometric radiograph and a lateral cephalometric radiograph under the same head tilt of a patient easily is not known.

Also, in order to investigate the growth and development of the maxilla and mandible, it is important to take lateral cephalometric radiographs or posteroanterior cephalometric radiographs at different time, and investigate aging by superposing those lateral cephalometric radiographs or posteroanterior cephalometric radiographs. However, as mentioned above, it was very difficult to take a posteroanterior cephalometric radiograph and a lateral cephalometric radiograph under the same head tilt of a patient, and therefore the investigation of aging was practically difficult.

Therefore, a subject to be solved by the present invention is to provide an X-ray radiographic apparatus wherein a lateral cephalometric radiograph, a posteroanterior cephalometric radiograph, an anteroposterior cephalometric radiograph, and a cephalometric radiograph in any direction between the posteroanterior direction and anteroposterior direction, etc. can be taken under the same tilt in the front-rear direction of the head of a subject easily and with high reproducibility, furthermore there is no risk associated with the use of an infraorbital point pointing bar, and a method of measuring head tilt when taking a radiograph.

Another subject to be solved by the present invention is to provide a stand for X-ray radiographic apparatus, a chair for X-ray radiographic apparatus, and a head tilt setting device wherein a lateral cephalometric radiograph, a posteroanterior cephalometric radiograph, an anteroposterior cephalometric radiograph, a cephalometric radiograph in any direction between the posteroanterior direction and anteroposterior direction, etc. can be taken easily and with high reproducibility under the same tilt in the front-rear direction of the head of a subject, and furthermore, there is no risk associated with the use of an infraorbital point pointing bar.

The above subjects and the other subjects will be apparent from the following description referring to the attached drawings.

Means for Solving the Subjects

In order to solve the above subject, according to the present invention, there is provided an X-ray radiographic apparatus, comprising:a pair of arms provided facing each other,ear rods respectively provided on inside surfaces facing each other of the pair of arms,a head tilt setting device for setting the tilt in the front-rear direction of the head of a subject which is provided at at least one of the pair of arms, having a transparent plate provided vertically to the central axis of the ear rods integrally with the arm, or provided vertically to the central axis of the ear rods on the exterior surface of the arm; anda horizontal plane verification mechanism.

The pair of arms is typically provided facing each other with a reference line therebetween, and is constituted to be able to rotate around the reference line. The head tilt setting device typically sets the head tilt of a subject under the state inserting the ear rods of the pair of arms in the external acoustic openings of both ears of the subject. The head tilt setting device typically sets the head tilt so that when looking at the head from the lateral side (side surface), a straight line connecting the first reference point on the arms or the ear rods with the second reference point of the face of the subject becomes the horizontal line, or a straight line tilted at a predetermined angle to the horizontal line. The head tilt setting device has preferably the function of a protractor for measuring the inclination angle to the horizontal line centered on the first reference point. By using the function of a protractor, the tilt in the front-rear direction of the head can be set accurately. The inclination angle to the horizontal line centered on the first reference point may be a positive angle (when the straight line connecting the first reference point with the second reference point tilts upward to the horizontal line), or a negative angle (when the straight line connecting the first reference point with the second reference point tilts downward to the horizontal line).

The horizontal plane verification mechanism can be used for an inspector to recognize the horizontal plane when setting the head tilt using the head tilt setting device. The horizontal plane verification mechanism may be provided to the transparent plate or may be provided outside of the transparent plate. When providing the horizontal plane verification mechanism to the transparent plate, as the horizontal plane verification mechanism, for example, a horizontal plate provided on the transparent plate protruding inside vertically to the transparent plate is used, and further, a colored horizontal line provided at the position of both sides of the transparent plate facing each other can be used. The horizontal plate may be a simple plate, and further, for example, the one having a foldable scale-like constitution which is able to open and close in the horizontal plane. Further, the horizontal plane verification mechanism may be, for example, an optical device (including a light source and a scanning mechanism) which is able to irradiate a visible light beam or scan it in the horizontal plane, or a horizontal colored line. The visible light beam is a laser beam or a beam-like light which is made from the light emitted from a light-emitting diode. The colored line is, for example, a thin linear wire made of metal, carbon fiber, plastics, etc. of which surface is colored, or a linear transparent fiber colored by making a visible light such as a red light or a green light, etc. wave guide from the end face. Further, the colored line may be the visible light beam itself. When providing the horizontal plane verification mechanism outside of the transparent plate, as the horizontal plane verification mechanism, for example, a horizontal plate which is able to move up and down or move in the horizontal plane, and further, the various kinds mentioned as examples of the horizontal plane verification mechanism when providing the horizontal plane verification mechanism to the transparent plate can be used. On the transparent plate constituting the head tilt setting device, as necessary, a scale showing a length made of X-ray shielding materials is provided. Preferably, the transparent plate is provided on one of the pair of arms, and another transparent plate provided with a scale showing a length made of X-ray shielding materials is provided on the other arm of the pair of arms. These scales can serve as a reference of the length in radiographs or images obtained by cephalometric radiography.

In order to make the straight line connecting the first reference point with the second reference point become the Frankfort plane of the head or a plane near to it, the first reference point is selected to be, for example, the uppermost point of the ear rods (which coincides with the porions of both ears of a subject at the time of taking a radiograph), and the second reference point is selected to be, for example, the orbitale, the orbital margin just under the center of the pupil, or the center of the palpebral fissure, etc. In case the straight line connecting the first reference point with the second reference point does not need to be the Frankfort plane or a plane near to it, the first reference point and the second reference point can be selected arbitrarily.

The X-ray radiographic apparatus is, for example, a cephalometric X-ray radiographic apparatus, but may be the other X-ray radiographic apparatus for medical and dental use, or may be a computed tomography (CT) apparatus, etc. The region to be taken a radiograph of a subject is typically a head, but may include the cervical region in addition to the head or may be only the cervical region.

Further, according to the present invention, there is also provided a method of measuring head tilt in taking a radiograph, comprising:

when taking a radiograph of the head of a subject, measuring the tilt in the front-rear direction of the head of a subject under the state that the ear rods respectively provided on inside surfaces facing each other of a pair of arms provided to mutually facing each other are inserted in the external acoustic openings of both ears of the subject, using a head tilt setting device provided at at least one of the pair of arms for setting a straight line connecting the first reference point on the arm or the ear rods with the second reference point of the face of the subject becomes the horizontal line or a straight line tilted at a predetermined angle to the horizontal line when looking at the head from the lateral direction, having a transparent plate provided vertically to the central axis of the ear rods integrally with the arm, or provided vertically to the central axis of the ear rods on the exterior surface of the arm; and a horizontal plane verification mechanism.

In the present invention of a method of measuring head tilt in taking a radiograph, unless otherwise violating the character, the explanation concerning the invention of the X-ray radiographic apparatus comes into effect.

Further, according to the present invention, there is also provided a stand for X-ray radiographic apparatus used when taking a radiograph of the head of a subject by an X-ray radiographic apparatus having a pair of arms provided facing each other and ear rods respectively provided on inside surfaces facing each other of the pair of arms, comprising:a head tilt setting device for setting the tilt in the front-rear direction of the head of the subject under the state that the ear rods of the pair of arms are inserted in the external acoustic openings of both ears of the subject so that a straight line connecting the first reference point on the arm or the ear rods with the second reference point of the face of the subject becomes the horizontal line or a straight line tilted at a predetermined angle to the horizontal line when looking at the head from the lateral direction, having a transparent plate provided vertically to the central axis of the ear rods integrally with the arm, or provided vertically to the central axis of the ear rods on the exterior surface of the arm; anda horizontal plane verification mechanism.

Here, the stand for X-ray radiographic apparatus is typically set so that the head tilt setting device comes to the same position as the head tilt setting device in the X-ray radiographic apparatus at the time of taking a radiograph.

Further, according to the present invention, there is also provided a chair for X-ray radiographic apparatus used when taking a radiograph of the head of a subject by an X-ray radiographic apparatus having a pair of arms provided facing each other and ear rods respectively provided on inside surfaces facing each other of the pair of arms, comprising:a head tilt setting device for setting the tilt in the front-rear direction of the head of the subject under the state that the ear rods of the pair of arms are inserted in the external acoustic openings of both ears of the subject so that a straight line connecting the first reference point on the arm or the ear rods with the second reference point of the face of the subject becomes the horizontal line or a straight line tilted at a predetermined angle to the horizontal line when looking at the head from the lateral direction, having a transparent plate provided vertically to the central axis of the ear rods integrally with the arm, or provided vertically to the central axis of the ear rods on the exterior surface of the arm; anda horizontal plane verification mechanism.

Here, the head tilt setting device of the chair for X-ray radiographic apparatus is typically set at the same position as the head tilt setting device in the X-ray radiographic apparatus at the time of taking a radiograph.

Further, according to the present invention, there is also provided a head tilt setting device to be provided at at least one of a pair of arms of an X-ray radiographic apparatus having the pair of arms provided facing each other, and ear rods respectively provided on inside surfaces facing each other of the pair of arms,

used, when taking a radiograph of the head of a subject, to set the tilt in the front-rear direction of the head of the subject under the state that the ear rods of the pair of arms are inserted in the external acoustic openings of both ears of the subject so that a straight line connecting the first reference point on the arm or the ear rods with the second reference point of the face of the subject becomes the horizontal line or a straight line tilted at a predetermined angle to the horizontal line when looking at the head from the lateral direction, comprising:a transparent plate provided vertically to the central axis of the ear rods on the exterior surface of the arm, the transparent plate having a horizontal plane verification mechanism,the head tilt setting device having the function of a protractor for measuring the inclination angle to the horizontal line centered on the first reference point.

In the present invention of the stand for X-ray radiographic apparatus, the chair for X-ray radiographic apparatus, and the head tilt setting device, regarding other than those of mentioned above, the explanation concerning the invention of the X-ray radiographic apparatus comes into effect unless it is contrary to its character.

Effect of the Invention

According to the present invention, a lateral cephalometric radiograph, a posteroanterior cephalometric radiograph, an anteroposterior cephalometric radiograph, and a cephalometric radiograph in any direction between the posteroanterior direction and the anteroposterior direction, etc. can be taken under the same tilt in the front-rear direction of the head of a subject easily and with high reproducibility, moreover there is no risk associated with the use of an infraorbital point pointing bar.

DETAILED DESCRIPTION

Modes for carrying out the invention (hereafter referred as “embodiments”) will now be explained below.

1. The First Embodiment

FIG. 1shows the cephalometric X-ray radiographic apparatus according to the first embodiment. As shown inFIG. 1, the cephalometric X-ray radiographic apparatus has an X-ray generator11, arms12and13, an arm control device14, and an X-ray detector15. The X-ray generator11has an X-ray tube11a, and from the X-ray tube11a, the X-ray is generated. The arm control device14is supported for the floor surface by a support part of which drawing is omitted.

The X-ray generated from the X-ray tube11ais irradiated to the head of a subject, the X-ray transmitted through the head enters into the X-ray detector15, and the transmission X-ray image is obtained. The X-ray detector15is not specifically limited, but, for example, an X-ray film, an imaging plate, a semiconductor detector, etc. are used. The transmission X-ray image is, as necessary, converted to a digital image signal, for example.

The arms12and13are provided facing each other with a reference line16parallel to the vertical line and perpendicular to the central X-ray therebetween. The upper parts of the arms12and13are fixed to an arm control device14. And by the arm control device14, the arms12and13are able to rotate around the reference line16, move up and down in a parallel direction to the reference line16, and move translatory in an opposite direction each other in the horizontal direction. The width of the lower parts of the arms12and13becomes gradually narrowing towards the bottom edge, and the bottom edge becomes a circular shape (seeFIG. 2). Also, the bottom edges of the arms12and13, after folded back at a predetermined angle inward to the vertical line respectively, again becomes parallel to the vertical line. However, the arms12and13may be parallel to the vertical line on the whole. At least the parts of the arms12and13irradiated by the X-ray at the time of taking a radiograph are constituted of transparent materials. Generally, almost all the parts of the arms12and13are constituted of the transparent materials. The inside surfaces facing each other of the bottom edges of the arms12and13are respectively provided concentrically with column-shaped ear rods17and18with pointed tips. As the ear rods17and18, publicly known ear rods can be used. The outlines of the ear rods17and18come out at the time of taking a radiograph.

At least on one of the exterior surfaces of the arms12and13, a head tilt setting device19for setting the tilt in the front-rear direction of the head of a subject is fixed. In FIG.1, an example that the head tilt setting device19is fixed to the exterior surface of the arm13is shown. In this case, the head tilt setting device19is constituted of a rectangular transparent plate vertically to the central axis of the ear rod18. As the transparent plate, a transparent plastic plate such as an acrylic plate, a PET (polyethylene terephthalate) plate, etc. or a glass plate, etc. can be used. The transparent plate may be that a necessary mechanical strength can be obtained, and is thick enough not to fold easily. Thickness of the transparent plate may be, for example, 2 mm or more and 10 mm or less. The method of fixing the head tilt setting device19is not specifically limited, but may be adhesion, clip-on, screwed down, etc.

The details of the head tilt setting device19are shown inFIG. 2.FIG. 2is a drawing looking at the head tilt setting device19from the vertical direction to the surface. As shown inFIG. 2, the bottom edge surface (the base) of the head tilt setting device19is parallel to the horizontal plane. The bottom edge surface of the head tilt setting device19coincides with the tangential direction drawn to the vertical direction to the central axis of the ear rod18at the uppermost point of the ear rod18. At the head tilt setting device19, an angle scale19acentered on the uppermost point of the ear rod18is formed, and has the function of a protractor. InFIG. 2, the angle scale19ais formed from 0° to 90° marked every 10°, but a method of marking the angle scale19ais not limited to this. For example, the angle scale19amay be formed, marked every 5° or 1°. Or the angle scale19amay be formed only within a specific angle range, for example, from 0° to 30°. The line at a 0° of the angle scale19acoincides with the bottom edge surface of the head tilt setting device19. The angle scale19ais typically formed with a black colored line as the same as a general protractor, for example, but is not limited to this. The angle scale19aexcept for the 0° may be provided on one surface of the head tilt setting device19and is preferably provided respectively on the corresponding position each other to both surfaces. Like this, by providing the angle scale19aat the corresponding position each other to the both surfaces of the head tilt setting device19, when looking at the angle scale19afrom the horizontal direction, the direction that the angle scales19aof the both surfaces coincide is the horizontal direction, and in case not coinciding, it can be judged to go off from the horizontal direction. As shown inFIG. 3, at the bottom edge surface of the head tilt setting device19, a horizontal plate20protruding inward vertically to the head tilt setting device19is provided.FIG. 3shows a plan view of the head tilt setting device19and the horizontal plate20. As shown inFIG. 3, the horizontal plate20has a wide part at the part distant from the ear rod18. In order to make the visual confirmation easy when confirming the horizontal plane, the horizontal plate20is preferably colored, specifically, for example, is colored in black. Materials, thickness, width in the horizontal direction, etc. of the horizontal plate20are selected, preferably so as to come out to the X-ray transmission images. The materials of the horizontal plate20are, for example, transparent plastics such as acryl, etc., opaque plastics, metal, etc. The thickness of the horizontal plate20is, for example, 0.2 mm or more and 2 mm or less, but is not limited to this. The width in the horizontal direction of the horizontal plate20is, for example, 1 mm or more and 30 mm or less, but not limited to this.

Next, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus will be explained.

(1) A Method of Taking a Lateral Cephalometric Radiograph

InFIG. 1, the arms12and13are made to move translatory to the outside in the horizontal direction, well away from each other, and to move to a high enough position. Under the state, as shown inFIG. 4, the head21of a subject is positioned between the arms12and13so that its median sagittal plane becomes vertical to the central X-ray from the X-ray tube11a. The subject may be in a sitting position, sitting on a chair or in a standing position, standing up. Next, by descending the arms12and13, the ear rods17and18are made to come to the position of the height of the right and left external acoustic openings of the head21of the subject. Next, the arms12and13are made to move translatory inward in the horizontal direction, and the ear rods17and18are inserted in the right and left external acoustic openings of the head21of the subject. And by making the uppermost points of the ear rods17and18contact with the porions, the head21is fixed so that the irradiation direction of the central X-ray coincides with the central axis of the ear rods17and18. Next, an inspector searches for a predetermined reference point (the second reference point) of the face of the head21, for example, the orbitale (Or), the orbital margin just under the center of the pupil, the center of the palpebral fissure, etc. For example, when making the orbitale as a reference point, the inspector can search by touching the vicinity of the infraorbital margin with a fingertip. And as shown inFIG. 5, a circular small colored seal22is put on the reference point that is searched for like this. The color of the seal22may be basically any color, but, for example, may be red, yellow, green, blue, white, black, etc. In case that it is difficult to look the seal22put on the reference point from the lateral direction of the head21, another seal22is also put on the outside of the horizontal direction from the seal22on the face, for example, at the position apart from 5 to 20 mm. Next, as shown inFIG. 6, the inspector looks at the head tilt setting device19in the horizontal direction from the outside. At this time, the seal22can be seen through the head tilt setting device19made of the transparent plate. And, using the angle scale19aof the head tilt setting device19, a straight line connecting the porion (that coincides with the uppermost point of the ear rod18) with the orbitale is set at an intended angle. InFIG. 6, as an example, a case where a plane connecting the porion with the orbitale, that is, the Frankfort plane is set horizontally. In case the Frankfort plane is set horizontally like this, the horizontal plate20that coincides with a 0° of the angle scale19ais observed from the outside. In case the horizontal plate20is seen like a line, the observation is made from the horizontal direction, and the tilt in the front-rear direction of the head21is set so that a straight line connecting the porion with the orbitale coincides with the horizontal plate20. Thus, the Frankfort plane of the head21is set to parallel to the horizontal plane (floor surface).

By taking a radiograph under the state that the tilt of the head21is set at an intended tilt as mentioned above, a lateral cephalometric radiograph is taken.

As an example of taking a lateral cephalometric radiograph at the position that the Frankfort plane of the head21is tilted at positive or negative angle to the horizontal plane, a case of taking a lateral cephalometric radiograph under the state that the Frankfort plane of the head21is tilted at a 10° (the face faces upward) to the horizontal plane is shown inFIG. 7. As shown inFIG. 7, in this case, using the angle scale19aof the head tilt setting device19, adjusting the tilt in the front-rear direction of the head21, the straight line connecting the porion with the orbitale is set at an angle of 10°.

(2) A Method of Taking a Posteroanterior Cephalometric Radiograph

As shown inFIG. 8, the arms12and13are rotated 90° around the reference line16from the position shown inFIG. 1. And as shown inFIG. 9, as the same as the case of taking a lateral cephalometric radiograph, inserting the ear rods17and18in the right and left external acoustic openings of the head21of a subject, and by contacting the uppermost point of the ear rods17and18with the porion, the head21is fixed. In this case, the face of the head21faces the X-ray detector15. Also, the irradiation direction of the central X-ray intersects at right angles with the central axis of the ear rods17and18. On the predetermined reference point of the face of the head21, specifically, for example, on the orbitale, the seal22is kept putting. Next, the inspector looks at the head tilt setting device19from the outside in the horizontal direction. At this time, the seal22can be seen through the head tilt setting device19. And, as the same as the case of taking a lateral cephalometric radiograph, using the angle scale19aof the head tilt setting device19, the straight line connecting the porion with the orbitale is set at the same angle as in the case of taking the lateral cephalometric radiograph. And, by taking a radiograph at the position, the posteroanterior cephalometric radiograph can be taken under the state that the tilt in the front-rear direction of the head21is the same as when taking the lateral cephalometric radiograph. For example, a lateral cephalometric radiograph and also a posteroanterior cephalometric radiograph can be taken at the position that the Frankfort plane of the head21becomes parallel to the horizontal plane (floor surface).

(3) A Method of Taking an Anteroposterior Cephalometric Radiograph

A method of taking an anteroposterior cephalometric radiograph is the same as the method of taking a posteroanterior cephalometric radiograph, except that the head21is positioned so that the face of the head21faces to the X-ray generator11.

(4) A Method of Taking a Cephalometric Radiograph from any Direction Between the Posteroanterior Direction and the Anteroposterior Direction

The arms12and13are rotated by an angle β (0°<β<360°) around the reference line16from the position shown inFIG. 1. The plan view of the cephalometric X-ray radiographic apparatus and the head in this state is shown inFIG. 10. And, as the same as the case of taking a lateral cephalometric radiograph, inserting the ear rods17and18in the right and left external acoustic openings of the head21of a subject, by making the uppermost point of the ear rods17and18contact with the porion, the head21is fixed. In this case, the irradiation direction of the central X-ray is tilted at an angle β to the central axis of the ear rods17and18. On the predetermined reference point of the face of the head21, specifically, for example, on the orbitale, the seal22is kept putting. Next, the inspector looks at the head tilt setting device19from the outside in the horizontal direction. At this time, the seal22can be seen through the head tilt setting device19. And, as the same as the case of taking a lateral cephalometric radiograph, using the angle scale19aof the head tilt setting device19, the straight line connecting the porion with the orbitale is set at the same angle as the case of taking a lateral cephalometric radiograph. And by taking a radiograph at this position, a cephalometric radiograph can be taken under the state that the tilt in the front-rear direction of the head21is the same as the case of taking a lateral cephalometric radiograph. For example, the radiograph can be taken at the position that the Frankfort plane of the head21becomes parallel to the horizontal plane (floor surface) as the same as a lateral cephalometric radiograph and a posteroanterior cephalometric radiograph.

By the cephalometric X-ray radiographic apparatus according to the first embodiment, the following various advantages can be obtained. That is, using the head tilt setting device19, the tilt in the front-rear direction of the head21at the time of taking a radiograph can be set at the intended tilt. By this, a lateral cephalometric radiograph, a posteroanterior cephalometric radiograph, an anteroposterior cephalometric radiograph, a cephalometric radiograph in any direction between the posteroanterior direction and anteroposterior direction, etc. can be taken easily and with high reproducibility under the same state of the tilt in the front-rear direction of the head21of a subject. For this, for example, when taking a lateral cephalometric radiograph or a posteroanterior cephalometric radiograph at different time, for example, when taking a radiograph one year after from a certain time taking a radiograph, a radiograph can be taken under the same state of the tilt in the front-rear direction of the head21. Like this, because of being able to take a radiograph any time under the same tilt in the front-rear direction of the head21, the superposition of a lateral cephalometric radiograph or an anteroposterior cephalometric radiograph can be made easily. By this, the aging of the maxilla and mandible of the head21can be investigated correctly, and the growth and development of the maxilla and mandible can be investigated correctly. In addition, in the first embodiment, as the infraorbital point pointing bar is not used, there is no risk with regards to the use of the infraorbital point pointing bar.

2. The Second Embodiment

In the cephalometric X-ray radiographic apparatus according to the second embodiment, unlike the cephalometric X-ray radiographic apparatus according to the first embodiment, the head tilt setting device19is not provided to the arm13, but the head tilt setting device19is provided to a stand for X-ray radiographic apparatus attached to the cephalometric X-ray radiographic apparatus.

FIG. 11shows the stand for X-ray radiographic apparatus. As shown inFIG. 11, the stand for X-ray radiographic apparatus has a support platform51to be placed on the floor surface, a support bar52being stood vertically to the support platform51, and the head tilt setting device19fixed to the upper edge of the support bar52. The support bar52is constituted telescopically, and its length can be adjusted within a predetermined range. For this, by adjusting the length of the support bar52, the height of the head tilt setting device19can be adjusted, and by this, the positional relation between the head tilt setting device19and the head21can be set as the same as the first embodiment. With regards to the head tilt setting device19, it is the same as the first embodiment.

Next, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus will be explained.

(1) A Method of Taking a Lateral Cephalometric Radiograph

In the cephalometric X-ray radiographic apparatus shown inFIG. 1which is not provided with the head tilt setting device19to the arm12, the arms12and13are made to move translatory towards the outside in the horizontal direction, set apart enough distance from each other, and to move to a high enough position. Under the state, as shown inFIG. 4, the head21of a subject is positioned between the arms12and13so that the median sagittal plane becomes vertically to the central X-ray from the X-ray tube11a. The subject may be in a sitting position, sitting on a chair or a standing position, standing up. Next, by descending the arms12and13, the ear rods17and18are made to come to the height position of the right and left external acoustic openings of the head21of the subject. Next, the arms12and13are made to move translatory inside in the horizontal direction, inserting the ear rods17and18in the right and left external acoustic openings of the head21of the subject, fixing the head by making the uppermost point of the ear rods17and18contact with the porion, so that the irradiation direction of the central X-ray coincides with the central axis of the ear rods17and18. Next, the inspector searches for the predetermined reference point of the face of the head21, specifically, for example, the orbitale. And, as shown inFIG. 5, the seal21is put on the reference point. Next, the stand for X-ray radiographic apparatus shown inFIG. 11is made to move on the floor surface, and the head tilt setting device19provided on the upper edge of the support bar52is made to come to the same position as the position shown inFIG. 4for the head21of the subject. That is, the head tilt setting device19is made to contact with the exterior surface of the arm13. And, under the state, as the same as the first embodiment, the inspector, using the angle scale19aof the head tilt setting device19, sets the straight line connecting the porion with the orbitale at an intended angle. And, by taking a radiograph at the position, a lateral cephalometric radiograph is taken.

(2) A Method of Taking a Posteroanterior Cephalometric Radiograph

When taking a posteroanterior cephalometric radiograph, using the head tilt setting device19provided on the upper edge of the support bar52, as the same as the first embodiment, a posteroanterior cephalometric radiograph can be taken.

(3) A Method of Taking an Anteroposterior Cephalometric Radiograph

When taking an anteroposterior cephalometric radiograph, using the head tilt setting device19provided on the upper edge of the support bar52, as the same as the first embodiment, an anteroposterior cephalometric radiograph can be taken.

(4) A Method of Taking a Cephalometric Radiograph from any Direction Between the Posteroanterior Direction and the Anteroposterior Direction

When taking a cephalometric radiograph from any direction between the posteroanterior direction and the anteroposterior direction, using the head tilt setting device19provided on the upper edge of the support bar52, as the same as the first embodiment, a cephalometric radiograph can be taken.

According to the second embodiment, the same advantages as the first embodiment can be obtained.

3. The Third Embodiment

In the cephalometric X-ray radiographic apparatus according to the third embodiment, unlike the cephalometric X-ray radiographic apparatus according to the first embodiment, the head tilt setting device19is not provided to the arm13, but the head tilt setting device19is provided to a chair for X-ray radiographic apparatus attached to the cephalometric X-ray radiographic apparatus.

FIG. 12shows the chair for X-ray radiographic apparatus. As shown inFIG. 12, the chair for X-ray radiographic apparatus has a support platform61to be placed on the floor surface, a support bar62being stood vertically to the support platform61, a main part63provided to the upper edge of the support bar62, a support member64provided to the main part63, and the head tilt setting device19provided to the upper edge of the support member64. The main part63is comprised of a seating face63aand a backrest63b. The support bar62is constituted telescopically, and the height of the seating face63acan be adjusted. The support member64is provided to the back of the backrest63bof the main part63. The support member64is comprised of a horizontal part and a vertical part, and the horizontal part is constituted telescopically in the horizontal direction for the backrest63b, and the vertical part is constituted telescopically in the direction of the vertical line. For this, by adjusting the position on the floor surface of the chair for X-ray radiographic apparatus, the height of the seating face63a, the length of the horizontal part and vertical part of the support member64, etc., the positional relation between the head tilt setting device19and the head21can be set as the same as the first embodiment. With regards to the head tilt setting device19, it is the same as the first embodiment.

Next, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus will be explained.

(1) A Method of Taking a Lateral Cephalometric Radiograph

In the cephalometric X-ray radiographic apparatus shown inFIG. 1which is not provided with the head tilt setting device19to the arm13, the arms12and13are made to move translatory outside in the horizontal direction, set apart enough distance from each other, and to move to high enough position. Under the state, as shown inFIG. 4, the head21of a subject is positioned between the arms12and13so that the median sagittal plane becomes vertically to the central X-ray from the X-ray tube11a. The subject sits on the chair for X-ray radiographic apparatus shown inFIG. 12. Next, by descending the arms12and13, the ear rods17and18are made to come to the height position of the right and left external acoustic openings of the head21of the subject. Next, the arms12and13are made to move translatory inside in the horizontal direction, the ear rods17and18are inserted in the right and left external acoustic openings of the head21of the subject, and the head is fixed by making the uppermost point of the ear rods17and18contact with the porion, so that the irradiation direction of the central X-ray coincides with the central axis of the ear rods17and18. Next, the inspector searches for the predetermined reference point of the face of the head21, specifically, for example, the orbitale. And as shown inFIG. 5, the seal21is put on the reference point. Next, by adjusting the position on the floor surface of the chair for X-ray radiographic apparatus, the height of the sitting face63a, and the length of the horizontal part and the vertical part of the support member64, etc., the head tilt setting device19is made to come to the same position with the position shown inFIG. 4for the head21of the subject. That is, the head tilt setting device19is made to contact with the exterior surface of the arm13. And, under the state, as the same as the first embodiment, the inspector sets the straight line connecting the porion with the orbitale at the intended angle by using the angle scale19aof the head tilt setting device19. And, by taking a radiograph at the position, a lateral cephalometric radiograph is taken.

(2) A Method of Taking a Posteroanterior Cephalometric Radiograph

When taking a posteroanterior cephalometric radiograph, using the head tilt setting device19provided to the chair for X-ray radiographic apparatus shown inFIG. 12, as the same as the first embodiment, a posteroanterior cephalometric radiograph can be taken.

(3) A Method of Taking an Anteroposterior Cephalometric Radiograph

When taking an anteroposterior cephalometric radiograph, using the head tilt setting device19provided to the chair for X-ray radiographic apparatus shown inFIG. 12, as the same as the first embodiment, an anteroposterior cephalometric radiograph can be taken.

(4) A Method of Taking a Cephalometric Radiograph from any Direction Between the Posteroanterior Direction and the Anteroposterior Direction

When taking a cephalometric radiograph from any direction between the posteroanterior direction and the anteroposterior direction, using the head tilt setting device19provided to the chair for X-ray radiographic apparatus shown inFIG. 12, as the same as the first embodiment, a cephalometric radiograph can be taken.

According to the third embodiment, the same advantages as the first embodiment can be obtained.

4. The Fourth Embodiment

FIG. 13shows the cephalometric X-ray radiographic apparatus according to the fourth embodiment. As shown inFIG. 13, in the cephalometric X-ray radiographic apparatus, the lower parts12aand13aof the arms12and13can be folded at an angle in the predetermined range relative to the upper parts12band13b, and can be fixed at the angle. Here, the lower part12aof the arm12can rotate around the point C1ofFIG. 13, and the lower part13aof the arm13can rotate around the point C2ofFIG. 13. Also, by the arm control device14, the arms12and13can move up and down in the direction parallel to the reference line16independently from each other. In other words, the lower parts12aand13aof the arms12and13can be positioned at the different height each other.

At one of the edges of the upper parts12band13bof the arms12and13, a lower part of the arm tilt setting device71composed of a rectangular transparent plate parallel to the vertical line for setting the inclination angle (angle γ relative to the vertical line, in case the upper parts12band13bare parallel to the vertical line) relative to the upper parts12band13bof the lower parts12aand13aof the arms12and13is provided. A method of fixing the lower part of the arm tilt setting device71is not specifically limited, may be adhesion, clip-on, screwed, etc.

The details of the lower part of the arm tilt setting device71are shown inFIG. 14.FIG. 14is a drawing looking at the lower part of the arm tilt setting device71provided to the edge of the upper part13bof the arm13from the direction vertical to the plane of the lower part of the arm tilt setting device71. As shown inFIG. 14, at the lower part of the arm tilt setting device71, the angle scale71acentered on the points C1and C2of the lower parts12aand13aof the arms12and13is formed, and has the function of a protractor. InFIG. 14, the angle scale71ais formed from 0° to 90° marked every 10°, but the marking of the angle scale71ais not limited to this, for example, may be marked every 5° or 1°, or only the angle in a specific range, for example, may be formed with an angle scale from 0° to 30°, for example. The line of a 0° of the angle scale71ais a vertical line. The angle scale71ais typically formed by a black colored line, for example, as the same as a general protractor, but is not limited to this. The angle scale71amay be formed on one surface of the lower part of the arm tilt setting device71, but is preferably formed respectively at the corresponding position on both surfaces each other. Like this, by forming the angle scale71aat the corresponding position on the both surfaces of the lower part of the arm tilt setting device71each other, when looking at the angle scale71afrom the horizontal direction, the direction coinciding with the angle scale71aof both surfaces is the horizontal direction, and if not coinciding, it can be judged to be different from the horizontal direction.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment.

Next, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus will be explained.

InFIG. 13, the arms12and13are made to move translatory outside in the horizontal direction, set apart at an enough distance each other, and move to a high enough position. Also, the arms12and13are made to rotate around the reference line16so that the inclination angle β (seeFIG. 10) relative to the central X-ray of the central axis of the ear rods17and18becomes an intended angle. Under the state, as shown inFIG. 13, the head21of a subject is made to be positioned between the arms12and13so that the median sagittal plane is inclined at an angle γ (0°≦γ≦90°) relative to the central X-ray from the X-ray tube11a. In this case, the median sagittal plane of the subject inclines relative to the floor surface. For this, in order to enable the head21to hold at the position, for example, the subject sits on a chair which is able to adjust the inclination angle of the sitting face relative to the floor surface, and the body is fixed by fastening a belt under the tilted state relative to the vertical line. In order to tilt the median sagittal plane of the head21of the subject to an angle γ relative to the central X-ray, a lower part of the arm tilt setting device71is used. That is, as shown inFIG. 14, using the angle scale71aof the lower part of the arm tilt setting device71, the lower parts12aand13aof the arms12and13are folded at an intended angle γ relative to the upper parts12band13b. InFIG. 14, a case of γ=20° is shown. Under the state, by descending the arms12and13independently each other, the ear rods17and18are made to come to the height position of the right and left external acoustic openings of the head21of the subject. Next, the arms12and13are made to move translatory inside in the horizontal direction, the arms12and13are descended independently each other, the ear rods17and18are inserted in the right and left external acoustic openings of the head21of the subject, and by making the uppermost point of the ear rods17and18contact with the porion, the head21is fixed. The seal21is put on the predetermined reference point of the face of the head21in advance. Next, the inspector looks at the head tilt setting device19from the outside in the direction vertical to the head tilt setting device19. At this time, the seal21also can be seen through the head tilt setting device19. And, using the angle scale19aof the head tilt setting device19, the straight line connecting the porion with the orbitale is set at the intended angle α. And, by taking the radiograph at the position, a cephalometric radiograph can be taken.

According to the fourth embodiment, in addition to the inclination angle α in the front-rear direction of the head21, by setting the angles β and γ respectively, a cephalometric radiograph can be taken from any direction, and by taking the cephalometric radiograph from plural directions different from each other, the cephalometric analysis can be performed three-dimensionally. Also, the cephalometric radiograph is taken from plural directions, and from the plural two-dimensional images taken like this, the three-dimensional image can be composed.

Example

By using the head tilt setting device19, the lateral cephalometric radiographs and the posteroanterior cephalometric radiographs of the subjects 1 to 18 were taken at the position that the Frankfort plane of the head21is parallel to the floor surface. The radiographs were taken at the centric occlusal position or a position near to it.FIG. 15,FIG. 17,FIG. 19,FIG. 21,FIG. 23,FIG. 25,FIG. 27,FIG. 29,FIG. 31,FIG. 33,FIG. 35,FIG. 37,FIG. 39,FIG. 41,FIG. 43,FIG. 45,FIG. 47andFIG. 49show the lateral cephalometric radiograph of the subjects 1 to 18, respectively. Here, the lateral white lines seen inFIG. 15,FIG. 17,FIG. 19,FIG. 21,FIG. 23,FIG. 25,FIG. 27,FIG. 29,FIG. 31,FIG. 33,FIG. 35,FIG. 37,FIG. 39,FIG. 41,FIG. 43,FIG. 45,FIG. 47andFIG. 49are the images of the horizontal plate20provided at the bottom edge of the head tilt setting device19, and show the Frankfort plane. Also,FIG. 16,FIG. 18,FIG. 20,FIG. 22,FIG. 24,FIG. 26,FIG. 28,FIG. 30,FIG. 32,FIG. 34,FIG. 36,FIG. 38,FIG. 40,FIG. 42,FIG. 44,FIG. 46,FIG. 48andFIG. 50show the posteroanterior cephalometric radiographs of the subjects 1 to 18, respectively.

FIG. 51shows a posteroanterior cephalometric radiograph taken at the position that the Frankfort plane of the head21of a subject 19 is parallel to the floor surface. Also,FIG. 52shows a posteroanterior cephalometric radiograph of the subject 19 taken, facing the face upward. Also,FIG. 53shows a posteroanterior cephalometric radiograph of the subject 19 taken, facing the face downward.

FromFIG. 15toFIG. 50, of all of these subjects 1 to 18, it is known that the lateral cephalometric radiographs and the anteroposterior cephalometric radiographs can be taken at the position that the Frankfort plane of the head is parallel to the floor surface. Also, fromFIG. 51toFIG. 53, the posteroanterior cephalometric radiographs taken, facing the face upward and downward are quite different from the posteroanterior cephalometric radiograph taken at the position that the Frankfort plane of the head21is parallel to the floor surface in their impression.

5. The Fifth Embodiment

FIG. 54shows the cephalometric X-ray radiographic apparatus according to the fifth embodiment. As shown inFIG. 54, in the cephalometric X-ray radiographic apparatus, the horizontal plate20contacts with the bottom edge surface of the head tilt setting device19, under the state of protruding toward the inside, vertically to the head tilt setting device19. The plan view of the present state head tilt setting device19and horizontal plate20are the same asFIG. 3. The horizontal plate20is constituted so as to be able to move up and down, or move in the horizontal plane, or carryout the both of them by a moving mechanism of which drawing is omitted. The moving mechanism can be set up at the arm13, or on the floor surface, etc. The horizontal plate20is, for example, risen by the moving mechanism from the position just under the head tilt setting device19shown in a dot and dash line inFIG. 54, stopped at the time of contacting with the bottom edge surface of the head tilt setting device19, and the state is kept held. For example, the horizontal plate20and the head tilt setting device19may be constituted so that the horizontal plate20engages to the bottom edge surface of the head tilt setting device19detachably at the time when the horizontal plate20contacts with the bottom edge surface. In this case, the moving mechanism can be descended after the horizontal plate20engages to the bottom edge surface of the head tilt setting device19. Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the first embodiment.

A method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is the same as the first embodiment.

According to the fifth embodiment, the same advantages as the first embodiment can be obtained.

6. The Sixth Embodiment

FIG. 55AandFIG. 55Bshow a foldable scale-like horizontal plate81to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the sixth embodiment. Here,FIG. 55Ashows the closed state of the foldable scale-like horizontal plate81, andFIG. 55Bshows the open state of the foldable scale-like horizontal plate81. As shown inFIG. 55AandFIG. 55B, the foldable scale-like horizontal plate81has two long and thin strip parts81aand81brotatable around the common shaft provided at one edge. As the same as the fifth embodiment, the foldable scale-like horizontal plate81is constituted so as to be able to move up and down or move in the horizontal plane, or carry out the both of them by a moving mechanism of which drawing is omitted. The foldable scale-like horizontal plate81is made to contact with the bottom edge surface of the head tilt setting device19. In this time, for example, the longitudinal direction of the foldable scale-like horizontal plate81is set to be parallel to the head tilt setting device19. The foldable scale-like horizontal plate81may be used to confirm the horizontal plane under the closed state as shown inFIG. 55A, or may be used to confirm the horizontal plane under the open state as shown inFIG. 55B. Also, for example, by rotating the strip part81boutside relative to the strip part81aunder the state that the strip part81aof the foldable scale-like horizontal plate81is made to contact with the bottom edge surface of the head tilt setting device19, the front edge of the strip part81bcan be made approach to the face of the head21of the subject. By selecting the installation position of the foldable scale-like horizontal plate81relative to the head tilt setting device19, the length of the foldable scale-like horizontal plate81, the open angle of the foldable scale-like horizontal plate81, etc., the front edge of the strip part81bcan be approached to the position near to the orbitale of the face of the head21of the subject, for example. By doing so, the tilt in the front-rear direction of the head21of the subject can be set correctly.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the sixth embodiment, the same advantages as the first embodiment can be obtained.

7. The Seventh Embodiment

FIG. 56shows a horizontal colored line82to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the seventh embodiment. The colored line82is typically provided parallel to the head tilt setting device19, but may be provided diagonally relative to the head tilt setting device19. The colored line82may be a thin linear wire having a diameter of its cross section of 0.5 mm and more and 2 mm and less, for example, made of metal such as steel, etc., carbon fiber, plastics, etc. of which surface is colored, or a linear transparent fiber made of glass or plastics, etc., colored by making a visible light such as a red light, a green light, etc. (a laser beam or a light from a light-emitting diode) wave guide from the edge surface. A visible light beam itself may be used. In this case, by using the colored line82instead of the horizontal plate20, the horizontal plane can be confirmed.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the seventh embodiment, the same advantages as the first embodiment can be obtained.

8. The Eighth Embodiment

FIG. 57shows an optical device83to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the eighth embodiment. The optical device83includes alight source and a scanning mechanism which are able to irradiate or scan a visible light beam85in the horizontal plane. The visible light beam85is a laser beam or a beam-like light which is made from the light emitted from a light-emitting diode. As the visible light beam85, for example, a red light beam, a green light beam, etc. is used. Around the optical device83, an X-ray shielding cover84made of X-ray shielding materials such as lead, etc. to protect the optical device83from the incident X-ray is provided. The X-ray shielding cover84is appropriately designed so that the optical device83can be shielded from the incident X-ray in consideration of the X-ray incident direction. In this case, by using the visible light beam85instead of the horizontal plate20, the horizontal plane can be confirmed. For example, when looking at the head tilt setting device19from the outside in the horizontal direction, the horizontal line corresponding to the angle 0° of the head tilt setting device19and the visible light beam85coincide with each other. At this time, the visible light beam85is irradiated or scanned on the face side of the head21of the subject. And if it is possible to confirm visually that the front edge of the visible light beam85coincides with the orbitale, the Frankfort plane of the head21can be judged as parallel to the floor surface. In this case, the seal22is not necessarily put on the face.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the eighth embodiment, the same advantages as the first embodiment can be obtained.

9. The Ninth Embodiment

FIG. 58AandFIG. 58Bshow drawings looking at a foldable scale-like horizontal plate81to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the ninth embodiment from the bottom surface of the head tilt setting device19. Here,FIG. 58Ashows the closed state of the foldable scale-like horizontal plate81, andFIG. 58Bshows the open state of the foldable scale-like horizontal plate81. As shown inFIG. 58AandFIG. 58B, the foldable scale-like horizontal plate81has two thin and long strip parts81aand81brotatable around the common shaft provided on the one edge. The strip part81aof the foldable scale-like horizontal plate81is fixed on the bottom edge surface of the head tilt setting device19, parallel to the head tilt setting device19by a method of adhesion, etc. The foldable scale-like horizontal plate81may be used to confirm the horizontal plane under the closed state shown inFIG. 58Aor may be used to confirm the horizontal plane under the open state shown inFIG. 58B. Also, for example, by rotating the strip part81bof the foldable scale-like horizontal plate81outside relative to the strip part81a, the front edge of the strip part81bcan be approached to the face of the head21of the subject. By selecting the installation position of the foldable scale-like horizontal plate81for the head tilt setting device19, the length of the foldable scale-like horizontal plate81, and the open angle of the foldable scale-like horizontal plate81, etc., the front edge of the strip part81bcan be approached to a position near to the orbitale, for example, of the face of the head21of the subject. By doing this, the tilt in the front-rear direction of the head21of the subject can be set correctly.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the ninth embodiment, the same advantages as the first embodiment can be obtained.

10. The Tenth Embodiment

FIG. 59shows a horizontal colored line82to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the tenth embodiment. The colored line82is held by the supports86and87to one side surface of the head tilt setting device19. The colored line82is typically provided parallel to the head tilt setting device19, but may be provided diagonally for the head tilt setting device19. As the colored line82, for example, a thin linear wire having a diameter of its cross section of 0.5 mm and more and 2 mm or less, made of, for example, metal such as steel, etc., carbon fiber, plastics, etc. of which surface is colored, or a linear transparent fiber made of glass, plastics, etc. which is colored by making a visible light such as a red light, a green light, etc. (a laser beam or a light emitted from a light-emitting diode) wave guide from the edge surface is used. In this case, by using the colored line82instead of the horizontal plate20, the horizontal plane can be confirmed.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the tenth embodiment, the same advantages as the first embodiment can be obtained.

11. The Eleventh Embodiment

FIG. 60shows an optical device83to be used as the horizontal plane verification mechanism in the cephalometric X-ray radiographic apparatus according to the eleventh embodiment. The optical device83includes a light source and a scanning mechanism which are able to irradiate or scan a visible light beam85in the horizontal plane. The visible light beam85is a laser beam or a beam-like light which is made from the light emitted from a light-emitting diode. As the visible light beam85, for example, a red light beam, a green light beam, etc. is used. Around the optical device83, an X-ray shielding cover84made of X-ray shielding materials such as lead, etc. to protect the optical device83from the incident X-ray is provided. The X-ray shielding cover84is fixed on the side surface of the head tilt setting device19by the support88. The X-ray shielding cover84is appropriately designed so as to be able to shield the optical device83from the incident X-ray in consideration of the X-ray incident direction. In this case, by using the visible light beam85instead of the horizontal plate20, the horizontal plane can be confirmed. For example, when looking at the head tilt setting device19from the outside in the horizontal direction, the horizontal line corresponding to the angle 0° of the head tilt setting device19and the visible light beam85coincide with each other. At this time, the visible light beam85is irradiated or scanned on the face side of the head21of a subject. And if it is possible to confirm visually that the front edge of the visible light beam85coincides with the orbitale, it can be judged that the Frankfort plane of the head21is parallel to the floor surface. In this case, the seal22is not necessary put on the face.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the eleventh embodiment, the same advantages as the first embodiment can be obtained.

12. The Twelfth Embodiment

FIG. 61shows the head tilt setting device19to be used in the cephalometric X-ray radiographic apparatus according to the twelfth embodiment. As shown inFIG. 61, the marks91and92made of X-ray shielding materials such as lead, steel, etc. are provided on the side surface of the head tilt setting device19. The position of the marks91and92is basically arbitrarily. In order to enhance the contrast of the marks91and92on the image obtained by X-ray radiography, preferably, the images of the marks91and92are made to come to the outside region of the head21of a subject, but is not limit to this. InFIG. 61, the marks91and92are provided on the side surface of the bottom edge part of the head tilt setting device19, in this case, the straight line connecting the center of the mark91with the center of the mark92is parallel to the bottom edge surface of the head tilt setting device19. The scale showing the distance between the center of the mark91and the center of the mark92, that is, the length is properly selected, but, for example, is 5 cm or 10 cm. When detecting the marks91and92by computer processing on the image obtained by X-ray radiography, preferably the marks91and92are formed so as to be detected the images of the marks91and92with a double lined outline. The marks91and92may be provided on the transparent plate constituting the head tilt setting device19, may be buried in the transparent plate, or may be provided passing through the transparent plate. The shapes of the marks91and92, when looking at the head tilt setting device19from the side surface, may be basically any shape, and is selected as necessary, specifically, for example, circle, triangle, square, hexagon, etc.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the twelfth embodiment, the same advantages as the first embodiment can be obtained. In addition, the following advantages can be obtained. That is, the marks91and92made of X-ray shielding materials are provided on the head tilt setting device19, and a scale showing the length by these marks91and92is provided. For this, when taking a radiograph of the head21, in the transmission X-ray image to be detected by the X-ray detector15, in addition to the image of the head21, the images of the marks91and9221are taken, therefore the scale showing the length is displayed on the image. In this case, the center-to-center distance of the images of the marks91and92on the transmission X-ray image is enlarged compared with the center-to-center distance of the marks91and92on the head tilt setting device19. The enlargement factor M is M=(the distance between the X-ray tube11aand the detection plane of the X-ray detector15on the central X-ray)/(the distance between the X-ray tube11aand the marks91and92of the head tilt setting device19on the central X-ray). The enlargement factor m on the median sagittal plane of the head21is m=M×[(the distance between the X-ray tube11aand the detection plane of the X-ray detector15on the central X-ray)/(the distance between the X-ray tube11aand the median sagittal plane of the head21on the central X-ray)]. By using the equation, from the enlargement factor on the transmission X-ray image, the actual distance on the median sagittal plane of the head21can be obtained.

13. The Thirteenth Embodiment

FIG. 62shows the cephalometric X-ray radiographic apparatus according to the thirteenth embodiment. As shown inFIG. 62, in the cephalometric X-ray radiographic apparatus, in addition to the constitution of the cephalometric X-ray radiographic apparatus according to the first embodiment, a transparent plate93is provided on the outside surface of the arm12of which drawing is omitted. The transparent plate93is shown inFIG. 63. As shown inFIG. 63, as the same as the head tilt setting device19according to the twelfth embodiment, the marks94and95are provided at the transparent plate93. These marks94and95can be provided at the same position and with the same constitution as the marks91and92.

An example of providing with the marks91and92piercing through in the thickness direction of the head tilt setting device19is shown inFIG. 64. As shown inFIG. 64, the mark91has a shape of a nail or a rivet, and is pierced through in the thickness direction of the head tilt setting device19.

Other than those of the above constitution of the cephalometric X-ray radiographic apparatus is the same as the cephalometric X-ray radiographic apparatus according to the first embodiment. Also, a method of taking a cephalometric radiograph of a subject using the cephalometric X-ray radiographic apparatus is basically the same as the first embodiment.

According to the thirteen embodiment, the same advantages as the first embodiment can be obtained. In addition, the following advantages can be obtained. That is, the marks91and92made of X-ray shielding materials are provided on the head tilt setting device19provided on the outside surface of the arm13, and a scale showing the length by these marks91and92is provided. Also, the marks94and95made of X-ray shielding materials are provided on the transparent plate93provided on the outside surface of the arm12, and a scale showing the length by these marks94and95is provided. For this, when taking the cephalometric radiograph of the head21, in the transmission X-ray image to be detected by the X-ray detector15, in addition to the image of the head21, the images of the marks91and92and the marks94and95are also taken. In this case, the center-to-center distance of the marks91and92on the transmission X-ray image is enlarged compared with the center-to-center distance of the marks91and92on the head tilt setting device19. The enlargement factor M1is M1=(the distance between the X-ray tube11aand the detection plane of the X-ray detector15on the central X-ray)/(the distance between the X-ray tube11aand the marks91and92of the head tilt setting device19on the central X-ray). Also, the center-to-center distance of the images of the marks94and95on the transmission X-ray image is enlarged compared with the center-to-center distance of the marks94and95on the transparent plate93. The enlargement factor M2is M2=(the distance between the X-ray tube11aand the detection plane of the X-ray detector15on the central X-ray)/(the distance between the X-ray tube11aand the marks94and95of the transparent plate93on the central X-ray). The enlargement factor m on the median sagittal plane of the head21is m=(M1+M2)/2. Using the equation, from the enlargement factor on the transmission X-ray image, the actual distance on the median sagittal plane of the head21can be obtained.

Example

By using the head tilt setting device19, the lateral cephalometric radiographs of subjects 20 to 22 were taken at the position that the Frankfort plane of the head21is parallel to the floor surface. Here, as the head tilt setting device19, the head tilt setting device19provided with the marks91and92and with a scale showing the length which was used in the twelfth embodiment was used. As the marks91and92, commercially available nails made of steel of which front edge was cut off were used, which were buried in the transparent plate made of acrylic. The radiographs were taken at the centric occlusal position or a position near to it.FIG. 65toFIG. 67show the lateral cephalometric radiographs of the subjects 20 to 22, respectively. Here, the lateral white lines seen inFIG. 65toFIG. 67are the images of the transparent plate20provided at the bottom edge of the head tilt setting device19, and show the Frankfort plane. Also, inFIG. 65toFIG. 67, the images of the marks91and92are observed as a double circle. Only using the commercially available nail made of steel of which front edge is cut off as the marks91and92like this, the double circle image can be obtained easily.

14. The Fourteenth Embodiment

In the first embodiment, as shown inFIG. 5, when the inspector has difficulty in looking at the seal22put on the predetermined reference point (the second reference point) of the face of the head21, for example, on the orbitale from the lateral side of the head21, it is explained that there is a case where the seal22is also put on the position apart from, for example, 5 to 20 mm outside in the horizontal direction from the seal22on the face. In the fourteenth embodiment, a method of putting the seal22at the position in the horizontal direction from the seal22put on the orbitale with high dimensional accuracy will be explained.

First, as shown inFIG. 68, as the seal22, the circular seal22composed of a small circular area22ain the center and a ring-like area22bsurrounding the area22ais used. The diameter d of the area22aand the diameter of the outer shape (the diameter of the outer shape of the seal22) D are selected so that the inspector can make visual confirmation of the seal22and the center area22aeasily. Specifically, for example, d is selected to be 1 mm and more and 2 mm and less (for example, 1.5 mm), and D is selected to be 5 mm and more and 9 mm and less (for example, 6.5 mm), but is not limited to them. Also, the colors of the area22aand the area22bare selected so that the inspector can make visual confirmation of the seal22and the center area22aeasily. Specifically, for example, white is selected for the area22a, black for the area22b, or black for the area22a, red for the area22b, but are not limited to them.

A method of putting the seal22at the position in the horizontal direction from the seal22put on the orbitale with high dimensional accuracy using the seal22shown inFIG. 68will be explained.

First, as shown inFIG. 69, by the method explained in the first embodiment, the seal22is put on the orbitale so that the center of the seal22coincides with the orbitale.

On the other hand, as shown inFIG. 70, the seal22is put on the position apart a small distance (for example, the position of 3 mm and more and 10 mm and less apart) in the horizontal direction of the face side from the porion.

Next, using a Frankfort plane indicator gauge100shown inFIG. 71A,FIG. 71BandFIG. 71C, the plane connecting the center of the seal22put on the orbitale with the center of the seal22put on a position a little apart from the porion is decided as follows. Here,FIG. 71Ais the plan view,FIG. 71Bis the front view, andFIG. 71Cis the perspective view of the Frankfort plane indicator gauge100. As shown inFIG. 71A,FIG. 71BandFIG. 71C, the Frankfort plane indicator gauge100has a curved shape so that a long and thin rectangular plate as a whole fits to the part from the part under the eyes of the face of the head21to ears, and consists of the nearly planar first part100a, the curved second part100b, and the nearly tabular third part100c. The first part100ais the part applying to the part of the face of the head21under the eyes, and the third part100cis the part applying to the side surface of the head21. The length of the first part100ais shorter than the length of the third part100c. According to the Frankfort plane indicator gauge100, by applying force on the first part100aand the third part100c, making the first part100aand the third part100crotate centered on the curved part100b, the angle between the first part100aand the third part100ccan be changed. The Frankfort plane indicator gauge100is formed by, for example, transparent plastic materials such as acrylic, PET, etc., but is not limited to them, and the materials to be used, and whether it is made transparent or opaque are selected as necessary. The upper edge surface100dof the Frankfort plane indicator gauge100is, for example, colored in black. Also, on the upper side surface of the Frankfort plane indicator gauge100, a scale (for example, a scale marked every mm) is marked, and the distance in the length direction of the Frankfort plane indicator gauge100can be measured. Giving a concrete example of the Frankfort plane indicator gauge100, the material is acrylic, the length of the first part100ais about 3 cm, the length of the third part100cis about 7 cm, the length of the second part100bis about 3 cm, the height is about 3 cm, and the thickness is about 1 mm. The size of the head21differs from adult or child, male or female, etc. Therefore, it is effective to prepare the plural kinds of Frankfort plane indicator gauge100with different sizes, select and use the size fit to the head21of a patient from them.

As shown inFIG. 72andFIG. 73, the Frankfort plane indicator gauge100is lightly pushed to the face of the head21so that the first part100aapplies to the part under the eye of the face of the head21, and the third part100capplies to the side surface of the head21. And the Frankfort plane indicator gauge100is positioned so that the upper edge surface100dof the first part100acoincides with the center of the area22aof the seal22put on the orbitale, and the upper edge surface100dof the third part100ccoincides with the center of the area22aof the seal22put on near the porion.

As shown inFIG. 74, with a care that the Frankfort plane indicator gauge100positioned as the above is not out of position, the third part100cof the Frankfort plane indicator gauge100is slightly risen from the side surface of the head21, so that a clearance is formed between the third part100cand the face of the head21. Then the seal22is inserted in the clearance and is put on the side surface of the head21so that the center of the area22aof the seal22coincides with the upper edge surface100dof the Frankfort plane indicator gauge100. In this case, the seal22showing the position of putting the seal22may be put in advance at the side surface of the Frankfort plane indicator gauge100(FIG. 71BandFIG. 71C). By this, the seal22can be put on the position in the horizontal direction from the seal22put on the orbitale with high dimensional accuracy.

Or, as shown inFIG. 74by a dot and dash line, it may be possible to position the Frankfort plane indicator gauge100so that the top edge surface100dof the first part100acoincides with the bottom edge of the seal22put on the orbitale and the top edge surface100dof the third part100ccoincides with the bottom edge of the seal22put on near the porion, and to put the seal22on the side surface of the head21at the upper of the seal22put on the side surface of the Frankfort plane indicator gauge100in advance so that its bottom edge coincides with the upper edge surface100dof the Frankfort plane indicator gauge100. By this, the seal22can be put at the position in the horizontal direction from the seal22put on the orbitale with high dimensional accuracy.

According to the fourteenth embodiment, by using the seal22shown inFIG. 68and the Frankfort plane indicator gauge100shown inFIG. 71A,FIG. 71BandFIG. 71C, the seal22can be put at the position in the horizontal direction from the seal22put on the orbitale with high dimensional accuracy.

Heretofore, embodiments and examples of the present invention have been explained specifically. However, the present invention is not limited to these embodiments and examples, but contemplates various changes and modifications based on the technical idea of the present invention.

For example, numerical numbers, configurations, materials, constitutions, procedures, etc. presented in the embodiments and examples are only examples, and the different numerical numbers, configurations, materials, constitutions, procedures, etc. may be used as necessary.

Moreover, the head tilt setting device may be, for example, a video camera taking the head of a subject from the lateral direction and a display (a liquid crystal display or an organic EL display) displaying the images taken by the video camera, and a protractor measuring the inclination angle to the horizontal line centered on the first reference point may be displayed on the display. In this case, the combination of the head tilt setting device with the horizontal plane verification mechanism can be used, and by doing so, the head tilt of a subject can be set.

EXPLANATION OF REFERENCE NUMERALS