X-ray pelvimetric examinations are carried out for the purpose of diagnosing the cephalo pelvic disproportion at terminal pregnancy and they are still an excellent method, being performed more often than other examinations. However the invitable fetal exposure is considered to be a significant dose and makes an estimation of stochastic fetal risk related to X-ray exposure and to investigate the methods of dose reduction. As the methods judging the exposure dose actually made in the hospitals, a questionnarie regarding the main technical factors of an X-ray examination was given to 26 hospitals, including 5 university hospitals, in Kantou district, and the answeres were analyzed. The estimated risks involving genetics, leukemia and malignant diseases were dependent on the exposure dose which could be calculated on the basis of the technical factors obtained. Total risks on the foetus ranged widely from 1.27×10 rad^<-1> to 1.19×10 rad^<-1>. So for as we have investigated, if all the hospitala used a grid ratio of 5 : 1,a tube voltage of 120 kV, intensitying screens with rare earth phosphors and green-sensitive orthomatic medical X-ray films for the X-ray pelvimetric examinations, it would be possible to reduce the present exposure dose by one-fourth. The ratio of the X-ray pelvimetry taken on pregnant patients ranged from 2% to 33%, having a mean value of 15%.
The diagnosis of the instability of the carpal bones (carpal instability) remained difficult problem. Recently, roentgenographic and anatomical investigations performed by Linscheid et al. and Taleinsnick made advance in the diagnosis. We have also interested in this problem for several years and in this article, describe the outline of carpal instability, method of roentgraphic diagnosis, and the support of motion study designed by us. Necessary projections for the diagnosis are as follows and called motion study of the wrist. Anteroposterior views with the wrist neutral Posteroanterior views with the wrist in radial flexion, neutral, and ulnar flexion. Lateral views with the wrist in dorsiflexion, neutral, and volar flexion. Additional anterior projection making fist may be useful. In the posteroanterior and anteroposterior views, the space between carpal bones are significant to diagnosis and in the lateral views, the relationships of the carpal bones to each other and radius are important to investigate the motion study. On these projections, the positioning of the wrist becomes unstable without any supports. To reduce this difficulty, we designed the suppor for the motion study. This suppor is composed of projection table, forearm support, rail and adaptors for posteroanterior and lateral projections. Absorption rates are increased 34% on anteroposterior projection and 27% on lateral projection by using this support. Magnification rates lies between 1.087 and 1.010. We examined 21 normal wrists and 23 deformed wrists including scapho-lunate dissociation, scaphoid-trapezium-trapezoid dissociation, central carpal instability, non-union of the scaphoid, proximal carpal instability and Kienbock disease. Reviewed results suggested the usefulness of this support.
Characteristics of NERO (Non-invasive Evaluation of Radiation Output), an X-ray analysing device are compared with the conventional direct measuring methods. They are X-ray tube voltage evaluation, relative mA, exposure time and tube voltage and radiation waveforms. NERO has accurate characteristics for tube peak voltage of 12 peak and 2 peak X-ray generators and exposure time of 12 peak generators. Regarding the characteristics of tube current (relative mA), waveforms and exposure time for 2 peak generators, further studies are necessary both for the users as well as the manufacturer.
CRT film sensitometry is very difficult compared with the method with direct photographing film. The authors created a light source simulating the wavelength of the imaging camera's emitting light by means of glass and gelatin filters. Then, using commercial exposure meter, we measured CRT film sensitometry. Problems raised in advance included the matter of antimetrical irregularity due to the difference between exposing time of the imaging camera and that of exposure meter. However, no actual problem was found as long as the experiment was concerned. Conclusively, good result was obtained in measuring CRT film sensitometry with a light source simulating the image camera's light emitting wavelength by means of filters.
First, under accepted Gaussian distribution of noise, and additional signal to noise, the signal detection theory using the ideal detector is discussed in the spatial area by means of the deploying probability matrix theory. Second, the signal detectivity in the spatial frequency area which is able to be deal with the integration value of square of the spectral signal-to-noise ratio is explained. The ideal detector of the spatial area, having the same movements of the matched filter of spatial frequency area is discovered. As stated above, since the signal detection theory can be explained by the filter theory, it is easy to apply the signal detection theory to not only the evaluating radiographic imaging system but also the real detector, generating noise can be analyzed. Finally, the reason that the detectivity is increased by emphasizing the gradient and spectra of images is proven.
Sensitometric techniques are used for determining the characteristic curve in medical imaging. In this study intensity-scale (inverse square law, simulated light) methods are used in the determination of radiographic screen-film system characteristic curve. Films which were exposed to simulated light and X-ray were processed in the same automatic processor simultaneously. These curves were overlapped at Net density of 1.0 to compare the curve shapes. The results show there is a good correlation between the density of X-ray sensitometry and that of simulated light sensitometry. The differences of density are within ±0.12 (±10% log exposure). This applies to both blue sensitive and green sensitive systems.
The study of radiological technology should always benefit men's life, especially people in pain. In order to make this contribution three things are necessary ability, time, and material, with ability being the prime factor of the three. I sometimes come across people who misinterpret the meaning of study. Such people associate measuring data, making mathematical calculating with study. But study is not just of matter of measuring and calculating, it must include some originality. The study of radiological technology is to contribute to the field of radiology including diagnosis and therapy how to reduce the expose dose when taking X-ray or imaging and how to improve radio treatment. We therefore must study not only in the field of medicine but other fields as well.
It is not easy to answer correctly to the question ; "How the research on radiologic technology should be done?"Let us consider the types and fields of researches carried out by the members of Japanese Society of Radiological Technology. The members of the Society are mainly consisted of technolologists working at the clinics. The results of the research should be applicable to clinical practice. The fields of the research are quite wide because the radiologic technology is based on many branches of science. The speaker's procedure of developing an easy method to determine the precise attenuation curves by exposing three ionization chambers to the X-ray simultaneously, is described as an example of such researches.
The theme of radiographic granularity is now found in a lot of literature, among which are famous three papers written by R. E. Sturm and R.H. Morgan, K. Rossmann and K. Doi, respectively. We obtained many results regarding wiener spectrum using FFT algorithm through the past ten years of researches on the radiographic granularity. In this symposium, the transition of ways of thinking about researches on the radiographic granularity, their points in issue and the process of their improvements are introduced, and this, we strongly expect to be useful for how to make researches into the discipline of radiological technology in future. Good ideas for the researches originate from such an attitude as making questions and careful observations and finding out what is concealed behind. It is so called hypothesis that poses concrete problems to such good ideas, and its verification is made through a series of processes including establishment of theory and method for measurements, planning, execution, arrangement of results, observations, discussion and conclusion. In the present report, three cases of measurements of radiographic granularity are presented as actual examples indicative of the process of such researches.
In the studies of radiological technology, it is very important that we should research for imporved functions of conventional equipment. The experimental study has been performed as to the possibility for the application of X-TV system for the synthesis of plane or sxial transverse tomographic images. By this method, it is possible to obtain any of multi-section images which are constructed from the video-images recorded during one linear, circular or one rotary motion of the X-ray tube. On the plane tomographic method, each recorded images are displaced following to exposure angle and height-ratio of the plane, therefore, multi-tomographic images can be obtained on the storage tube surface when recorded images are synthesized reversely to cancel displacement. On the transverse tomographic method, selected slit-signals from each of the recorded frames are back projected on the storage tube surface and are reconstructed as tomographic images. Therefore, other slit-signals from the samevideo images reconstruct another tomographic section. We have shown the synthesized images obtained with chest, lead wire and dried lumbar bone.