In order to assure safety of both patient and operator, and to provide uniform quality radiographs, it is necessary to perform periodic calibration of diagnostic X-ray equipment. A basic parameter of diagnostic equipments and its image sharpness is the size (and shape the energy distribution) of the focal spot as viewed along the central X-ray beam. This size determines the resolution possible with the equipment and also determines the heat characteristics of an anode. A fine focus tube gives

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... gh resolution but causes high local heating of target. In past, the pin-hole and star pattern image measurement for evaluation of resolution have been widely used, but it produced blurring and inaccuracy of irnage. So newly inverted Ug-meter has advantage in more convenient measurement method and less out-put bias than other image measurement. The authors intended to compare measured focal size between Ug-meter and focal spot test tool, changed state from setting to now of units. 2, Abstract Tomography standard lay height be measured by several times exposure in the past. The scale you got it is somewhat higher or lower, also take you long time to calibrate it exactly. The new tomography lay height tester that we designed can tell you the accuracy height of standard lay scale by one exposure. Then put the indicator to mach the scale, all the calibration jop is be finished, The principle of new tester is that make several marks in a certain range and each mark indicate a certain height. Every mark can be distinguished from each other. After one exposure on the film, accerding the best sharpness one of mark image, decide actual standard lay height scale indicator. The capability of resolution of tester can up to O.1 mm. Since the accuracy height resolution capability, we can use tester to find out the factors which reffer to the standard lay height, After a quantity of test, we find that different cassette can being 2tv3 mm difference in lay height even same manufacture. Same cassette, the positioning direction is different, lay height may be also different. Dividing use same cassette may get different lay height in different exposured film. For accuracy tomtography, the best way is use same cassette with same direction for each Iay, not be divided to use. 3, MicroselectroR HDR at SLMC, Philippines Abstract In March, 1991, the first high dose rate remote afterloading brachytherapy machine in the PHILIPPINES was installed at St. Luke's Medical Center in Quezon City. This microselectron system (Ir-192) from Nucletron, Holland requires extensive acceptance testings specific to (438) NII-Electronic