The application of digital image processing in cineradiography was attempted. The advantage of digital image processing is flexibility of display and electronic transmission of image. After the 35mm cineradiographic film was digitized using TV camera and A/D converter, greyscale conversion and edge enhancement were tried by digital image processing technique. They involved high contrast by linear conversion, soft tissue image by logarithmic conversion and edge enhancement by unsharp masking technique or differential operator. In addition, the construction of the animation was also made.
Although the processed image suffered from background noise and quantization error, they proved to be effective on the analysis of the mechanism of speech production and deglutition.
These processings might be quite useful to improve the diagnostic capability in cineradiography.

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The authors have carried out various experiments in order to diagnose diseases within the maxillary bone by analysis of a wave of percussion sound, produced by tooth percussion. These percussion sounds were collected from the microphone held in the left and the right external acoustic meatus.
Okumura elucidated the mechanism for the occurrence of percussion sound, which is produced by percussion of the maxillary teeth. Stimulated by this finding, the authors conducted experiments as described below to conjecture the resonance site of the percussion sound.
1) Ratio of the intensity of impulse and the amplitude of maximum resonance frequency.
2) Amplitude ratio of maximum resonance frequency of percussion sound obtained from the left and the right microphone.
3) Analysis of Fourier spectrum of percussion sound of person having normal teeth.
4) Synthesis of the wave of a percussion sound by a computer and measurements of its attenuation constant.
5) Measurements of attenuation constant of the percussion sound from a person having a low level of the floor of maxillary sinus group and non-low level group.
6) Measurements of attenuation constant of the percussion sound in patient with maxillary sinusitis. From experiments on the above described items, the following conclusions could be obtained.
1) When the maxillary tooth was tapped and percussion sound was collected from the external acoustic meatus, the resonance site of the percussion sound was found to be in the maxillary sinus and the area around the nasal cavity.
2) It was found that the resonance site may shift to either left or right according to individual cases.
3) Relative values of the attenuation constant for percussion sounds were distributed in the range of 0.5 to 4.0.
4) From the fact that the resonance site is in the area around the maxillary sinus, it is possible to diagnose diseases with the maxillary sinus. This fact indicates that the attenuation constant may be useful as a diagnostic parameter.

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One of the latent somatic risks to low level radiation dose is leukemia. Radiation induced leukemia is apparently produced by irradiation of active bone marrow. The average radiation dose to the active bone marrow is an important index of the somatic risks. This index is known as the mean bone marrow dose.
The purpose of this study was to estimate the individual mean bone marrow dose to Western and Japanese adult and child in order to obtain the basic data for risk calculations of panoramic radiography using Monte Carlo method. In this study, the mathematical phantom of five years child designed by Hwang and of adult designed by Snyder were used.
The phantom consists of three parts (head, trunk, leg) and three regions (skeletal, lung and soft tissue). The density assigned to the skeletal region (bone plus marrow), lung and the remainder of the phantom are 1.5, 0.3 and 1.0gcm^-3 respectively. In the skelton, bone and marrow are assumed to be mixed homogeneously.
The interaction between photon and phantom took into consideration photoelectric absorption, coherent and incoherent scattering. The atomic form factor and the scattering function for electron binding corrections to coherent and incoherent scattering were considered. The photon histories of 500, 000 according to the x-ray photon spectrum were pursued. The spectrum according to single phase, tube voltage, target angle of x-ray tube and total filtration were generated by computer simulation. The x-ray photon data used here are for the target angle of 16 degrees and for the total filtrations of 1, 2, 3 and 4mm Al eq., at an increment of 10kV steps of tube voltage between 60 and 90kV.
The mean bone marrow dose is determined considering the energy deposited in the skelton, the weighting factor for the active marrow in the skeleton, the ratio of the mass energy absorption coefficient for the active marrow to the skelton, the excess dose factor due to photo-electrons and the total mass of the active marrow.
Following conclusions were obtained.
1) Examples of the mean bone marrow dose are ranged about 30 to 100μGy according to the race, adult or child and radiographic factors.
2) Concerning mean bone marrow dose in panoramic radiography, more than 90% of whole absorbed energy in bone marrow are absorbed in the head and neck parts and remainder is very small.
3) The mean bone marrow dose increases as an increase of tube voltage when other radigraphic factors remains constant.
4) The complicated problems related to the dosimetry of low energy and dose of x-rays could be avoided. In the case of Japanese child, special care must be taken about justification and optimisation, because the mean bone marrow dose was suggested grater than that of Japanese adult.

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Radiological representation of internal derangement of the temporomandibular joint arthrosis by Fuji Computed Radiography were studied. We found that best results of articular soft tissue image were obtained using a tomographic movement with spiral and angle 16° and from narrowing the field to 5cm diameter of the IP's surface. Further articular soft tissue image was clearer in the spatial frequency enhanced image which emphasized edge effect than the gradient enhanced image. In the series of 103 cases (147 joints) of the temporomandibular joint arthrosis, there were found of abnormal Type A (56 joints), abnormal Type B (14 joints) and no abnormality detected (77 joints). In the correlation of FCR images of articular soft tissue and clinical symptoms, Type A was definitely associated with clicking and Type B with jaw locking.

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An angle of horizontal long axis in condylar head determined by the axial image is a prerequisite for individualized technique of lateral transcranial projection and sagittal tomography. The measurement of this angle is influenced by several factors including projection angles to the condyle examined and base lines to the long axis of condyle. The objective of this study was to determine the significance of these two factors and to measure the variaton of this angle in Japanese individuals. Five human dry skulls were radiographed using projection angles which were perpendiculary to the planes ranged between orbitomeatal and acanthiomeatal lines. Images obtained were served to measure the angle of long axis to three different base lines including a line connected both sides of ear rod, and two lines refered by the anatomical landmarks situated in the median sagittal plane. Results showed that the projection angles and base lines used in this experiment did not have significant effects to the measurement of angle. The most variances of angles came from the individual difference of shape in the condylar head, which indicates that the individualized positioning is necessary in the lateral projection and sagittal tomography. The horizontal long axis of condylar head measured in the 150 patients suffered from temporomandibular joint arthritis, was 13-15 degree and ranged between-6 degree and 37 degree. This value corresponds equally to the one previously reported in Japanese normal population.

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