Recentry, the problems of X-ray dosimetry in diagnostic regions have become important, because the dose measurements on the irradiated patients are necessary and the diagnostic x-ray units are required to be controlled in accordance with the above objects. However, the properties of diagnostic x-rays are very complicated. They are commonly high dose rate pulsating and soft, largely absorbed by the irradiated matters. And the contribution of characteristic x-rays can not be neglected. On account of these complicated matters, we do not have suitable dosemeters to be used on the diagnostic field and the directions to the accuracies of their measurements. From these points of view, auther discussed the following points. 1) The out put doses from the diagnostic x-ray units were measured by Victoreen Condenser R-meter under the radiographic condition.; 150kVp, 300mA, focus chamber distance 100cm. Comparing thg obtained results and the calculations based on the recombination theory, it was concluded that the 0.25 and 1R chamber can not be used for such radiographic exposure, because the general recombinations in the chamber are too large to be neglected. 2) A ionization chamber indicating the exposure-area product was used to estimate the volume dose absorbed. The estimation of the volume dose from the measured exposure-area product was carried out by the following two methods.; One is Mayneord's method and the other energy fluence method. The results of the calculation showed good agreements. 3) The accurate determinations of x-ray qualities are necessarilly required to obtain the accurate value of dose. This fact is especially important in the diagnostic field, because the quality ranges of diagnostic x-ray cover the large quality dependency regions of the chamber. The specifications by HVL to express the quality of continuous x-rays are inadequate. It was concluded that the most adequate method to specify the quality of x-rays is the Greening's method, which contains three parameters ; kVp, 1st HVL and 2nd HVL. 4) The determination of kVp value of the under-constant-filtration diagnostic x-ray is directry connected to the determination of the x-ray quality. Then a method, which enables to more accurately estimate the x-ray tube voltage through measurement of the excitation voltage characteristic X-ray, was discussed. 5) The X-ray quality problems in the field of scattered radiation dosimetry by film badge method are more fully to be discussed, because of the oblique irradiation to the badge filter. Author believes that the scattered radiation quality determination using the energy dependency of TLD dosimeters will open a new application in this field, as Dixon showed. 5) The author concerned futher the problems of the anguler quality variation caused by x-ray self absorption in the target itself, and then the utilization of K-absorption effect of contrast medium to the field of the radiographic technique.

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