We attempted to test the applicability of the polymethyl metacrylate (Acrylite) as a body phantom for the deep radiotherapy. We measured the attenuation curves of the Acrylite and the percentage depth dose curves in the Acrylite phantom for the X-rays of the half value layer 0.146 mm Cu, 0.26 mm Cu, 0.57 mm CU, 0.82 mm Cu and 2.07 mm Cu. The attenuation curves of the Acrylite for these X-ray qualities were compared with the zezo field percentage depth dose data of the Quimby's table, and also the effective mass absorption coefficients of the Acrylite for various X-ray qualities were determined from the attenuation curves. We found that the effective mass absorption coefficient of the Acrylite for the 0.1 Å X-rays was equal to that of water. On the other hand, it was found that the percentage depth dose. curves in the Acrylite phantom for these X-ray qualities coincided with those in water phantom, in spite of the difference of density between the Acrylite and water. Then we concluded that this circumstance was caused by the scattering in the Acrylite phantom.
Since physiological contrast has great influence on interpretation of radiographs, the authors made an experiment on the changes in border line between visible part and inbisble under various conditions, using the Phantom devised by G.C.E. Buger. The following results were obtained. 1. The thinner and wider an object is, the more visible is the image. 2. In high valtage radiography, the visible extent is wide but with Lysholm's diagram, it is narrow ; the irregular image make an image invisible of which size is the same as that of irregularity.
During physical examinations of studies of this university, the following points in regard to chest radiography were studied.1. The adult male's chest diameter and circumference.2. The suitability of the size of film.3. The interpretation of the radiographs.4. The proper conditions needed to obtain good radiographs. The following points were clear.1. The present size of the film is not sufficient, as the physique as improved.2. The radiogrphers' interpretation of the radiographs are in accord with the physicians'.3. The best conditions for obtaing good radiographs : Degree of Blackening : 1.4 (mean value) R. P diameter of the chest : 20 cm. Voltage : 64 kVp. Ampers : 200 mA. Time of exposure : 0.1 sec. Focus of skin distance : 200 cm.
In radiography of the renal Sugiuron has been used and pressure has been applied to the supine patient. In this procedure, however, the patient suffers pain and a natural image cannot be obtained. The authors studied contrast mediam and exposure time to obtain a natural image of the renal without pressure. A full distinct image of the renal was obtained without pressure, using 76% Urosectan B for 6 to 15 minutes. Then the patient stands erect and more pictures are taken. 70% of the images were satisfactory.
With a certain kind of planagraph apparatus there in an inevitable prolongation of the time of projection with changes in the transversal angle. The calculation has been difficult and has been apt to depend on experience and intuition. Therefore, the author with a stroboscope measured the time of projection and the exect incidence angle of each transversal angle and calculated energy of X-ray putting all the results together to make a simple and practical exposure chart for planagraphy.
To study the visalization ability of film-mark, we have investigated about X-ray tube voltage and milliampere-seconds, with following results.1) Visualization of the film-mark was difficult more or less, or impossible, when photography was done under the condition of over 45 kVp. 100 mAs. and more than 50 kVp.2) It was easy to see the marks by means of metal plate when tube voltage and milliampere-seconds exceeded the above mentioned values. For clinical utility, we made the followins table showing the optimal thicknees of metal plate under various tube voltages.
X-ray apparatus is generally operated from control panel with the various measurements. None of them, however, is completely accurate and the peculiarities of each apparatus cause an error when the voltage is changed. Therefore, the author measured radiant energy directly with a pocket chamber ; when compared with the results of indirect measuring, the difference was difinite ahd this direct method gave a more accurate count of radiant energy.
Dropping the voltage of the coil pole of the bias tube lower than that of the filament to reduce the dielectric flux, the authors with a pin hole camera took a photograph of the process reducing the aperture of the lens. The best condition of focusing was studied from all the results of observation and measurement of form and resolving power by test-chart and distribution curve of density. A good result was obtained clinically.
No Screen Film are used mostly for the Industrial examination of the penetration of X-rays. When the fluorescent intensifying screen is not used, an increase in sharpness is generally aequired ; high energy X-rays or gamma rays are used to increase the penetrability. There the image is apt to be flat ; the property of No Screen Film, i.e., high gamma rays and high density are needed to satify the conditions of this type of radiography. Its practical application in medicine to investigate a detailed image and its field of application was studied as well as the properties of the film.
Only a few reports on lateral radiography of the knee have been published. According to a recent text, However, the lateral image of the knee is taken with the angle of projection inclined to a certain degree, which several authors reported made a great difference. The degee of angle was examined and the necessary angle decided to improve the accuracy of radiographic examination.