5590 cares of non malignant diseases were treated with superficial X-rays from 1959 to 1969 at Department of Dermatology, Chiba Unirersity Hospital. 8 per cent of all the new out patients at Department of Dermatology have been treated with Superficial X-rays. But its number has been decreasing every year. Male patients were almost equal to female. Age distribution showed peak in the group less than five year old and second peak was in the group from 16 to 25 year old. Ninety per cent of the patients were irradiated with Dermopan 29KV. From the results of phantom experiments, the dose of the testes is 30 per cent of surface air dose of the scrotum and that of the ovary is 0.9 per cent of surface air dose of the hypogastrium.
It is said that the gonadal dose of patients at the time of superficial x-ray treatment is less than other radiation. But as the diseases are nonmaligant, gonadal dose is not always negligible. I tried to determine the gonadal dose by the measurement of the phantom experiment. Dose measurement were performed by using of the Philips Universal Dosimeter, GM Survey Meter and Film Density Method. The majority of lesions with superficial x-ray were head and neck areas. The average treatment dose was 900R. The gonadal dose of female patients treated hypogastric area was found 6.5R from the results of phantom experiment. But gonadal doses of other regions of female patients were found less than 10mR. The gonadal dose of the male patient irradiated scrotum was 55.6R. But it was between the 1.5R and 130mR at the regions other than head, neek. feet and fingers.
In recent years, medical x-ray examinations are on the increase therefore we are imposed the task of decreasing of genetically significant dose. In our country, the X-ray examination of digestive organs contribute genetically significant dose. We tried to standardization of method for gastric x-ray examination and measured the detector (thermoluminescence dosimeter) into the bladder of Machlett-radiography phantom and testis dose was measured by attaching same detector to the scrotum phantom of Mix-Dp. When patients are examined our standard method, the majority are not exposed to direct x-ray beam. therefore gonad dose of the examination of stomach will decrease on a large scale.
The purpose of the present investigation is minimizing radiation exposure of diagnostic X-ray examination on lateral lumbar spine. Restricted radiation field without shielding body parts that need to be demonstrated on the roentgenogram was limited by using lead collimator. Exposure to the reproductive organs was reduced by one-half on male and one-third on femal.
Uneven density of x-ray photographs may be raised causing by the factors of either the absorbing difference or the thickness of the object to be photographed. To equalize such uneveness by other solid materials (AL. Cu.), however, extinction of edge lines of the materials may come into question. For photographing the front cervical vertebrae, the side thoracic vertebrae (1-3) and (10-12), the metatarsal bones and phalanxes evenly, which is considered difficult to photograph, set the compensation objects either the wedge-type or the shaped-type (a shape to suit the position to be photographed) onto the side of x-ray tubes so as to apply the x-rays freely by reiterating in arc and automatically so to extinct the the edge lines of the materials and obtain the x-ray pictures of wider diagnostic range by soft x-rays. As I obrained a favorable result on the above development, I therefore. make a report named as "Arc Type Automatac Compensation system."
In order to improve to diagnostic Potency of bone radiograph, Carbon graphite compensating filters were made for better film density distribution. 1) The general feature and thickness of each filter were determined by simulating the film density of the object to that of the Carbon graphite step phantom radiographed on the same Voltage. 2) The mass of Carbon graphite was cut down to each component, which was pasted together on the thin plate to construct the filter for appropriate sharpe and thickness propotional to the focus-film distance and X-ray absorption. 3) This kind of filter is more useful to compensate the X-ray absorption in the case of complex shaped objects, especially uneven in the direction perpendicular to the X-ray beams. 4) Remarkable improvement of diagnostic potency was obtained using these filter in spite of the slight depression of clearness and contrast.
Recently, mammography with soft X-rays has been practically utilized as one of routine diagnostic procedures for the breast tumors. Some foundamental experimentes on the soft X-rays tomography was performed with the soft X-rays tomograph device built as a trial. Providing finer details of tumor tissue, the conbination of the conventional plain mammography and our the soft X-rays tomography is bilieved to improve the accuracy of diagnosis in variolus diseases of breasts. For the protection of the patient from the radiation damage, the resuts of measure how much are also discussed.
In case of rotation therapy, the first step for the estimation of central axis dose is to obtain the tumor skin distance every 10-20 degrees around the patient contour. Then tissue-air ratio corresponding to each distance can be read from the ready-made T.A.R. table. These are summed and averaged. In practice, however, the method is somewhat tedious and timeconsuming, which is a disadvantage in busy department. In this paper, a rapid and simple method to obtain the average tumor-skin distance in case of rotation therapy of the patient with carcinoma of uterine cervix was described. 50 samples were randomly drawn from the group of carcinoma of uterine cervix that has been recieving radiation therapy in our department. Their contour, antero-posterior and lateral dimensions were statisfying analysed. From this analysis the following conclusion was obtained. If the anteroposterior and lateral dimensions of the patient were measured, the average skin-tumor distance could be calculated from the graph (Fig. 4) based on the equation that was statisfying obtained from 50 patients. The differences of dosage calculation between the method of averaged T.A.R. and this simple method were 2% at the most.
In spite of the fact that many gamma-emitting nuclides have more than one useful gamma energy. it is impossible in imaging with the conventional scintiscanner system to include more than one photopeak within the window, unless the two peaks are very close together. The dual-spectrometer system. we describe here. requires the addition of a second summing network and pulse-height analyzer to the standard Toshiba scintiscannner. In the case of ^<67>Ga, detection efficiency has been increased 30%-50% without degrading resolution by using the dual-spectrometer system.
Recent advances in medicine have brought about increases in the frequency in both the diagnostic and therapeutic usage of radiation. There have been reports from both Japan and abroad that short-time period exposures using portable self-rectifying X-ray machines are not possible because they operate on one half of the electrical cycle and the mA value is small. However, as described in Reports 1 and 2 and in Fuji X-ray Research (Kenkyu), No. 95,1972,the authors have been successful in per-forming short-time period X-rays of the chest. and in 1969 were able to produce cerebral vascular X-rays of diagnostic value. On the basis of this, the authors devised an animal shaped X-ray machine for taking X-rays of small children and infants. This effort has proved to be worthwhile as the appearance of fth machine captures the interest of the child and thus has been highly efficacious in that it has reduced body movement during exposure which in turn has reduced the need for re-takes resulting in lower risk from exposure.
The 1969 population mean marrow dose and leukaemia significant dose from diagnostic medical x-ray examinations in Japan were estimated. The estimation was made based on a nation wide survey reported elsewhere. The bone marrow dose was measured using thermoluminescent dosimeters embedded in none marrow sites in phantoms. The leukaemia significant dose was calculated according to a weighting factor, the use of which takes into account the shape of the time-incidence curve of radiation induced leukaemia, and the survival statistics for the various age groups in the population. The population mean marrow dose was 36.6,26.8 and 126 m rad per person per year for radiography, photofluorography and fluoroscopy, respectively, with a total of 189 m rad. The leukaemia significant dose was 32.7,24.6,and 112 m rad, with a total of 169 m rad.