Shika Hoshasen
Online ISSN : 2185-6311
Print ISSN : 0389-9705
ISSN-L : 0389-9705
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Volume 31, Issue 3
Displaying 1-6 of 6 articles from this issue
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  • THE STANDARD HEAD PHANTOM FOR DOSIMETRY AND THE STUDY OF DOSE DISTRIBUTION ANALYSIS
    -PART 1 DEVELOPMENT OF A STANDARD HEAD PHANTOM FOR ORGAN DOSIMETRY-
    Masaaki OGAWA, Keiji TANIMOTO, Minoru FUJITA, Yoshikazu SUEI, Akira TA ...
    1991 Volume 31 Issue 3 Pages 233-243
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.233
    JOURNAL FREE ACCESS
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    To obtain accurate estimation of radiation doses within the head, a new phantom was constructed. The osseous structures were represented by a human skull. The soft tissue of the phantom was composed of polyurethane whose x-ray absorption and scattering properties are nearly equal to human soft tissue. Soft tissue thickness and facial contours were measured by CT-images of 20 volunteers. Contours, sizes, and positions of salivary glands were also measured and located in the phantom exactly.
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  • EFFECTIVE DOSE EQUIVALENT FOR DENTAL RADIOGRAPHIC EXAMINATION
    -BASED ON THE SURVEY OF DENTAL X-RAY UNITS BY MAIL-
    Naomichi MASE
    1991 Volume 31 Issue 3 Pages 244-254
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.244
    JOURNAL FREE ACCESS
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    To evaluate output and effective energy of dental X-ray unit, a simple and inexpensive test device was developed and used in a field survey under routine cunditions in 70 dental offices in Japan. The test device consists of aluminum filters with different thicknesses (0, 1, 2, 3mm) and BeO micro-rods (2mmφ×12mm) of thermoluminescence dosimeter (TLD) wihch were placed behind the filters. The X-ray outputs were determined with the TLDs in the no-filterpart. The attenuation curves of dental X-ray beams by the aluminum filter were determined with the TLD rods placed behind the filter elements. The effects of X-ray quality on the effective dose equivalent from dental X-ray examinations were investigated with a questionnaire and a phantom experiment.
    The results of field survey showed that the mean output was 2.39×10-4C/kg (926mR) for the upper molar radiographic examination and averaged half-value layer was 1.67mmAl (effective energy: 26.5keV). It was found that the effective dose equivalent per unit entrance dose was increased with increasing the effective energy. Recentry, dental X-ray beams have a tendency to become hard with an added filter. From present survey, it is noted that the hardenning can increase the effective dose equivalent in dental examination.
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  • ACCURACY OF TOMOGRAPHIC LAYER DETERMINATION AND REPRODUCIBILITY OF BONY CONTOUR IN CORRECTED LATERAL TOMOGRAPHY OF TEMPOROMANDIBULAR JOINT
    Hideki KITAMORI, Hironobu SATO, Kazunori YOSHIURA, Miho YAMADA, Kazuyu ...
    1991 Volume 31 Issue 3 Pages 255-262
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.255
    JOURNAL FREE ACCESS
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    Corrected lateral tomography of the temporomandibular joint (TMJ) in lateral recumbent position was performed. Tomographic layer was predetermined on an axial radiogram and the distance between rotation center of head positioner and the tip of ear-rod was taken into consideration in positioning of tomography. The accuracy of the location of the tomographic layer predetermined, and the reproducibility of the bony contour of the TMJ on the tomogram were examined.
    Six TMJs from three human dried skulls and 100 TMJs of 54 patients were used for this study. The accuracy of tomographic layer was estimated by differences between the predetermined layer and the actually projected layer on the tomogram. The reproducibility was evaluated from measurements of joint space on replicated block slices of dried skulls and on corresponded tomograms of them.
    The results are summarized as follows:
    1) The mean differences between the predetermined layer and the actually projected layer on the tomogram were 1.2±0.9mm in the dried skulls and 2.0±1.5mm in the patients.
    2) There was a significant correlation between bony contours of TMJ of dried skulls and on tomograms.
    3) The tomographic layer of the condylar midpoint could be determined accurately on corrected lateral tomograms by measurement on an axial radiogram.
    In conclusion, the radiograms obtained from corrected lateral tomography showed high accuracy of predetermined tomographic layer and provided good reproducibility of the bony contour of the TMJ. Corrected lateral tomography is considered to be clinically useful in diagnosis and monitoring longitudinal change of TMJ.
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  • MORPHOLOGICAL MEASUREMENTS OF LATERAL PTERYGOID MUSCLE USING X-RAY CT IMAGES
    Hideo OKUDA, Kazunori YOSHIURA, Masafumi OHKI, Naoyuki YAMADA, Tomohir ...
    1991 Volume 31 Issue 3 Pages 263-269
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.263
    JOURNAL FREE ACCESS
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    Although the lateral pterygoid muscle has been considered to be important in the analysis of jaw movement and temporomandibular joint disorders, its morphology still remains unknown.
    The purpose of this study was to determine the normative morphological measurements of this muscle using X-ray CT images.
    X-ray CT images of transverse views of the lateral pterygoid muscle were obtained from 54 patients who had no clinical findings for TMJ or abnormality of the masticatory muscles.
    Volume, length, transverse and longitudinal cross-sectional areas of the lateral pterygoid muscle were measured using CT imaging.
    The results were as follows:
    1) In many cases the upper and lower caput of lateral pterygoid muscle could not be separately observed on reconstructed X-ray CT images.
    2) Mean volume, transverse and longitudinal cross-sectionl areas, length were 7.18cm3, 3.49cm2, 5.34cm2, 3.58cm, respectively.
    3) There was a significant correlation between measurement values for the right and left sides and a significant difference between genders in measurement values, but no correlation with age was found for any measurement.
    4) Cross-sectional area of the muscle was significantly related to its volume.
    By thus establishing the normal ranges of the various measurement values described above, We can represent quantiatively the rriorphological abnormalities of the lateral pterygoid muscle caused by TMJ disorders and facial deformities. In addition, the functional status of the lateral pterygoid muscle may be more precisely evaluated.
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  • [title in Japanese]
    1991 Volume 31 Issue 3 Pages 270-271
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.270
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    1991 Volume 31 Issue 3 Pages 272-276
    Published: September 15, 1991
    Released on J-STAGE: September 05, 2011
    DOIhttps://doi.org/10.11242/dentalradiology1960.31.272
    JOURNAL FREE ACCESS
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