- Email: [email protected]
Experimental study of photoroentgenographic pantomography
Experimental study of photoroentgenographic pantomography Hitoshi Kntayamn, M.D., Ph.D.,” Tnkeshi Ohba, D.D.S.,*# Votohisa Tsudn, R.Sc.++** and Soichi Hirakawa, B.Sc.,*** Fzdxoka, Kitakydw, and Kyoto, Japan An experimental study of a new technique of photoroentgenographic pantomography is reported. The photoroentgenographic pantomogram of a head phantom was obtained by means of an x-ray image amplifier and a fluorographic camera while the head phantom and photographic film rotated synchronously. Pictures obtained were not totally satisfactory with regard to sharpness of the images. This study, however, indicated that photoroentgenographic pantomography could be made available and put to practical use if certain problems were overcome.
T
he orthopantomograph has been widely used not only in dentistry but also in otolaryngology for radiologic examination of the maxillofacial region. In our previous investigation, we pointed out that, orthopantomography may be useful for dental mass surveys with some changes in the technic.] At present, orthopantomography is not practical for mass surveys where it is necrssary to perform a large number of examinations in a limited time. In this scrics of experiments we have tried to introduce the photoroentgenographic technique into pantomography. Photoroentgenographic pantomography has never been reported in the literature. This report is concerned only with the experimental study of photoroentgenographic pantomography. METHOD
AND
MATERIALS
Current pantomographic techniques have been carried out by rotating the x-ray tube and the cassette, with the rotational axis located at a static object (the patient). This study was designed to take photoroentgenographic pantomographs with an x-ray tube, a g-inch image amplifier, and a fluorographic camera while rotating the head phantom and photographic film synchronously. A female head phantom and the film were rotated manually. Each was set *Radiology Department, Faculty of Medicine, Kyushu University, Fukuoka, **Dental Radiology Department, Kyushu Dental College, Kitakyushu, Japan. ***Radiation Apparatus Division, Shimadzu Seisakusho, Ltd., Kyoto, Japan.
428
Japan
Volume 35 Number 3
Photoroedgeno,graphic
Ii II
0
pantomography
429
L '
710
A
6
I
6
Fig. 2. Diagrams depicting the experimental equipment. 1, X-ray tube. .8, Head phantom. 8, Image amplifier (g-inch). 4, Slit. 5, Dark box. 6, Belt. 7, Wheel. 8, Wheel. 9, Lens system. 20, Handle.
on its respective wheel, which was connected to the other by a belt. A diagram of this model is shown in Fig. 1. The speed of rotation was controlled by changing the diameters of each wheel. The x-ray unit was operated at 75 KVP and 2 Ma. Details of the experimental equipment are as follows: The rating of the x-ray tube was 90 KVP and 15 Ma. The experimental model was equipped with a g-inch image amplifier, of which the diameter of effective input field was 230 mm. and that of output image was 23 mm. The resolution of the amplifier was 14 lp/cm. A tandem lens system was employed to project an image on the photographic film.
Oral Surg. March. 1973
Fig. t. A photoroentgenographic pantomogrnm equipment. -F Maxillary sinus. + Lower cavity.
of the phantom dental arch. .+
taken with the experimental Nasal septum. + Nasal
The exposure time was 20 seconds. The image was demagnified on film by a factor of 1.6 and projectecl on 7 by 7 cm. photoroentgenographic film. The slits in front of the film and the image amplifier were used to minimize scattered radiation and to prevent superimposition of off-center anatomic structures. RESULTS
Fig. 2 shows a photoroentgenographic pantomogram of the female head phantom made with the experimental equipment described. Sharpness of the image WilS quite unsatisfactory, but gross anatomy of the maxillomandibular region was demonstrated. Ilongitudinal striations ma’rkedly obscured the anatomic details. DISCUSSION
Immobilization of the experimental equipment was not perfect, and the rotation of the moving parts was not smooth. This created a situation wherein evenness of density of the film could not be achieved. The longitudinal striations were due to uneven rotation of phantom and film. Poor image sharpness of the dental arch was due in part to lack of synchronous rotation of the dental arch of the phantom and the film and in part to poor fixation of the equipment. In addition, the shape of the dental arch and the circular movement of the phantom
Volume 35 Number 3
Photoroentgenographic
pantomography
431
----
5
8 6 Fig. 3. A schematic illustration of another possibility for photoroentgenographic pantomography. The x-ray tube and image amplifier are rotated. 1, X-ray tube. b, Head phantom. 8, Image amplifier. 4, Slit. 5, Camera. 6, Slit. 7, Film. 8, Film Spur.
were not identical. If better orthoradial projections are technically feasible, a fluorogram of better quality may be obtained. This experiment demonstrated the possibility of photoroentgenographic pantomography for mass survey use. Sharpness of the image can be improved by overcoming the problems mentioned and by using a ‘I-inch image amplifier. Fig. 3 shows a schematic illustration of another possibility for photoroentgenographic pantomography. The x-ray tube and the image amplifier are rotated. The rotational axis is located at the center of the dental arch. A new type of camera should be developed that would rotate the film synchronously. In Japan, Koseki and his associates2 have recently assembled a dental mass survey car. They have placed an ordinary pantomograph (Asahi AX-3) into a car with minor changes. They used a Toshiba D-1801 type x-ray tube which allows thirty successive exposures. They have reported that scattered radiation is negligible. CONCLUSION
Indirect photoroentgenographic pantomography is possible, but there remain some problems which must be overcome in the future. REFERENCES
Comparison of Orthopantomography 1. Ohba, Takeshi, and Katayama, Hitoshi: ventional Periapical Dental Radiography, ORAL SURG. 34: 524, 1972. 2. Koseki, Yonoshin: Dental Mass Survey, Proceedings of 12th annual meeting Dental Radiology, Yokosuka, Japan, 1971. Reprint requests to: Dr. Hitoshi Katayama Radiology Department Faculty of Medicine Kyushu University Fukuoka, Japan
With
Con-
of Japanese
T
he orthopantomograph has been widely used not only in dentistry but also in otolaryngology for radiologic examination of the maxillofacial region. In our previous investigation, we pointed out that, orthopantomography may be useful for dental mass surveys with some changes in the technic.] At present, orthopantomography is not practical for mass surveys where it is necrssary to perform a large number of examinations in a limited time. In this scrics of experiments we have tried to introduce the photoroentgenographic technique into pantomography. Photoroentgenographic pantomography has never been reported in the literature. This report is concerned only with the experimental study of photoroentgenographic pantomography. METHOD
AND
MATERIALS
Current pantomographic techniques have been carried out by rotating the x-ray tube and the cassette, with the rotational axis located at a static object (the patient). This study was designed to take photoroentgenographic pantomographs with an x-ray tube, a g-inch image amplifier, and a fluorographic camera while rotating the head phantom and photographic film synchronously. A female head phantom and the film were rotated manually. Each was set *Radiology Department, Faculty of Medicine, Kyushu University, Fukuoka, **Dental Radiology Department, Kyushu Dental College, Kitakyushu, Japan. ***Radiation Apparatus Division, Shimadzu Seisakusho, Ltd., Kyoto, Japan.
428
Japan
Volume 35 Number 3
Photoroedgeno,graphic
Ii II
0
pantomography
429
L '
710
A
6
I
6
Fig. 2. Diagrams depicting the experimental equipment. 1, X-ray tube. .8, Head phantom. 8, Image amplifier (g-inch). 4, Slit. 5, Dark box. 6, Belt. 7, Wheel. 8, Wheel. 9, Lens system. 20, Handle.
on its respective wheel, which was connected to the other by a belt. A diagram of this model is shown in Fig. 1. The speed of rotation was controlled by changing the diameters of each wheel. The x-ray unit was operated at 75 KVP and 2 Ma. Details of the experimental equipment are as follows: The rating of the x-ray tube was 90 KVP and 15 Ma. The experimental model was equipped with a g-inch image amplifier, of which the diameter of effective input field was 230 mm. and that of output image was 23 mm. The resolution of the amplifier was 14 lp/cm. A tandem lens system was employed to project an image on the photographic film.
Oral Surg. March. 1973
Fig. t. A photoroentgenographic pantomogrnm equipment. -F Maxillary sinus. + Lower cavity.
of the phantom dental arch. .+
taken with the experimental Nasal septum. + Nasal
The exposure time was 20 seconds. The image was demagnified on film by a factor of 1.6 and projectecl on 7 by 7 cm. photoroentgenographic film. The slits in front of the film and the image amplifier were used to minimize scattered radiation and to prevent superimposition of off-center anatomic structures. RESULTS
Fig. 2 shows a photoroentgenographic pantomogram of the female head phantom made with the experimental equipment described. Sharpness of the image WilS quite unsatisfactory, but gross anatomy of the maxillomandibular region was demonstrated. Ilongitudinal striations ma’rkedly obscured the anatomic details. DISCUSSION
Immobilization of the experimental equipment was not perfect, and the rotation of the moving parts was not smooth. This created a situation wherein evenness of density of the film could not be achieved. The longitudinal striations were due to uneven rotation of phantom and film. Poor image sharpness of the dental arch was due in part to lack of synchronous rotation of the dental arch of the phantom and the film and in part to poor fixation of the equipment. In addition, the shape of the dental arch and the circular movement of the phantom
Volume 35 Number 3
Photoroentgenographic
pantomography
431
----
5
8 6 Fig. 3. A schematic illustration of another possibility for photoroentgenographic pantomography. The x-ray tube and image amplifier are rotated. 1, X-ray tube. b, Head phantom. 8, Image amplifier. 4, Slit. 5, Camera. 6, Slit. 7, Film. 8, Film Spur.
were not identical. If better orthoradial projections are technically feasible, a fluorogram of better quality may be obtained. This experiment demonstrated the possibility of photoroentgenographic pantomography for mass survey use. Sharpness of the image can be improved by overcoming the problems mentioned and by using a ‘I-inch image amplifier. Fig. 3 shows a schematic illustration of another possibility for photoroentgenographic pantomography. The x-ray tube and the image amplifier are rotated. The rotational axis is located at the center of the dental arch. A new type of camera should be developed that would rotate the film synchronously. In Japan, Koseki and his associates2 have recently assembled a dental mass survey car. They have placed an ordinary pantomograph (Asahi AX-3) into a car with minor changes. They used a Toshiba D-1801 type x-ray tube which allows thirty successive exposures. They have reported that scattered radiation is negligible. CONCLUSION
Indirect photoroentgenographic pantomography is possible, but there remain some problems which must be overcome in the future. REFERENCES
Comparison of Orthopantomography 1. Ohba, Takeshi, and Katayama, Hitoshi: ventional Periapical Dental Radiography, ORAL SURG. 34: 524, 1972. 2. Koseki, Yonoshin: Dental Mass Survey, Proceedings of 12th annual meeting Dental Radiology, Yokosuka, Japan, 1971. Reprint requests to: Dr. Hitoshi Katayama Radiology Department Faculty of Medicine Kyushu University Fukuoka, Japan
With
Con-
of Japanese