In radiation therapy for the cancer of the maxillary sinus, it is important point clinically to reduce the dosis for the eye balls, even if the conformation technique were applied. In selective protection technique of the eye balls combined with the 6 MV X-ray conformation radiotherapy for maxillary sinus cancer, the effect of various sized absorber on dose distribution were studied. Cylinders of Tungsten alloy were used for absorber, and dose distribution were measured with film method. It was revealed that the larger the size of absorber, the greater the difference between interested target volume and high dose region. In regard to dose homogeneity of traget volume and to protection of eye balls, it became quite apparent that the absorber of 20mmφ to the healthy side, and 17.5mmφ to the tumor side were agreeable size.
In conformation radiotherapy combined with the hollow-out technique, it is essential to select the suitable material of the absorber, as the material of the absorber influences on the dose distribution. Practically, it is necessary to shield both-sided eyes, in the treatment of carcinoma of the maxillary sinus. The distortion of the dose distribution caused with the absorption of tungsten, copper and zinc were measured. In order to shield the healthy-sided eye completely, it was suitable to use tungsten rod (2cm. in diameter) as the absorber. With the use of tungsten rod to shield the ill-sided eye, its shielding effect was excellent, while the distortion of the dose distribution could not be ignored. By using the zinc rod, the distortion of the dose distribution deviated from the expected beam focus was neglisible, on the other hand the shielding to the ill-sided eye was considerably good.
The present status of technical factors for radiation dose of the patients in X-ray examination was studied in hospitals and clinics in the Niigata prefecture. The following four points are mainly treated. 1) Exposure factors in the chest and digestive organ examinations. 2) Exposure factors in roentgengraphy of the organs or neighboring to the gonads. 3) Difference between light and X-ray field size in usual X-ray machines. 4) Excess of radiation field size in automatically beam limiting X-ray TV machines.
In general, conventional high voltage roentgenography is performed at maximum voltage of 150kVp. On roentgenography at 200kVp, several investigations already reported were performed by roentgen therapy apparatus. At presents, diagnostic apparatus as 200kVp is available. The apparatus used here is Hitachi X-ray geneator (DR-205) and Philips's rotating anode tube (Super Rotalix 200) with focal spot size of 1.2mm and 0.6mm. The purpose of this paper is to investigate the property of focal spot size and capacity of phototimer (Hitachi Hi-Auto), and to test a new intensifying screen (KYOKKO LT-2) highly sensitive films (Fuji RXS and Sakura QS) at 200kVp roentgenography. 1) The focal spot size of the tube is not changed within the range of 100,150 and 200kVp. 2) Film density of chest roentgenograms taken with the phototimer are sufficiently controled at 200kVp. 3) The quality of images with new screen is compared with those screens HV, FS and VP. Sharpness of VP is superior than that of LT-2 but is difference is small, and less sensitive. HV is more sensitive at 200kVp than LT-2 but image quality is inferior. Quality of FS is almost same as LT-2 but less sensitive. So, it is concluded that the LT-2 is the best at 200kVp roentgenography. 4) Surface dose with sensitive films is reduced to 60 per cent of that with conventional films and image quality is almost same. 5) When filter of 1.0mm Cu+0.5mm Al is added, it is possible to reduce the surface dose less than one third.
It may be said that cerebral angiography is now one of the most important examination in neuroradiology. The purpose of this paper is to review certain technical aspects of various methods applied in cerebral angiography, with special reference to the image quality. The main points are as follows. 1) In routine radiography, it is emphasized that the object must be in as close approximation to the film as posible. However, in conventional serial cerebral angiography we referred to permissible maximum object-film distance in correlation with such the other factors influencing image quality as focus-film distance or effective size of focal spot. 2) The value of direct magnification angiography using a small focus tube is now being recognized. However, it has not yet been utilized widely for the the clinical work in neuroradiology. Therefore, actual procedures of direct magnification serial cerebral angiography in our department was presented and its technical problems were briefly discussed. 3) Angiotomography is useful for separation if opacified vascular structures which are superimposed on each other. Some technical problems in angiotomography using the Princeps (C.G.R.) were described.
Among the examination techniques in the neuroradiological field, we discussed about photographic subtraction, brain scanning and RI cisternography. 1) About photographic subtraction, we summarized those which we have reported. 2) Brain scanning was performed by using 1/2 miniscan. By using this method, it is possible to do a high speed scanning, and to gain more information. 3) We tried to use a short half life nuclide, ^<111>In-DTPA in RI cisternography, as a substitute for ^<169>Yb-DTPA, which is ordinarily used, because it gives problems when we discard excreted ^<169>Yb-DTPA in the excretion, By using short half life nuclide in RI cisternography, its clinical application will be widened in the future.
The increasing demand for neuroradiological examination increases the need for reliable ancillary radiological techniques. Tomography is one of these, which is used to separate anatomical structures. Recentry the multidirectional tomographic unit, the Diagnost-N and the macrotomographic apparatus have been development, We have used the technique prinicipally in the various parts of the skull with those apparatus. The purpose of this paper is to investigate the situation as follow, 1) Axial and lateral tomography of the optic canal utilizing the hypocyclidal tomography. 2) In cases of intracranial aneurysms is clarified by angiotomography with the Diagnost-N. 3) The technique and application of the macrotomogram in 3.5 times magnification of the labyrinthine windows and stapes are described, using a method comparable to that employ with the aid of dried skull.
Sn-Colloid made by means of "AUTOVIAL" developed by DINABOT CO. was compared is several ways with S-Colloid which has been used routinely in many centers. The results revealed the Sn-Colloid is at least no worse than S-Colloid from diagnostic point of view and is much better for safety of medical stuffs.