. The principles and practice of roentgenological technique . helead disc has been in motion for five secondsand the tube, backing up a two-inch gap, wasenergized by five milliamperes. The compari-son of the densities of the ring to the bakehteshadows shows that this density correspondsto that sector numbered .6. This means thatthe rays from this tube will be reduced to fiftyper cent at a depth of .6 centimeters under theskin, and reduced to twenty-five per cent at the air in this chamber the x-ray diminishesthe resistance of this circuit and the intensity of the ionization is
. The principles and practice of roentgenological technique . helead disc has been in motion for five secondsand the tube, backing up a two-inch gap, wasenergized by five milliamperes. The compari-son of the densities of the ring to the bakehteshadows shows that this density correspondsto that sector numbered .6. This means thatthe rays from this tube will be reduced to fiftyper cent at a depth of .6 centimeters under theskin, and reduced to twenty-five per cent at the air in this chamber the x-ray diminishesthe resistance of this circuit and the intensity of the ionization is indicated by the deviationof the needle over a scale which is graduatedin Kienbock units. Various scales have beenconstructed for rays of various penetratingpower. The greater the intensity of the x-rays, thestronger the ionization, the greater the flowof electricity in one unit of time through themeter circuit. The iontoquantimeter measuresthe product of intensity and radiation time, inother words, surface energy. This is independent of the degree of pene-. FiG. 146.—A test similarly made with five milliam-peres in a tube backing up three inches of that under these conditions, an .8 ray wasused. This indicates that 50% of the ray willbe absorbed at the depth of .8 centimeter. trability of the ray or its hardness. The con-sideration of penetration is necessary in the es-timation of dosage. But the meter permits thecomparison of the surface energy of rays ofvarying penetration. There are sources of error which arise fromthe tendency of the ionized gas to regain itsnon-conducting state, because of reunionof the disrupted parts (the electron and thepositive remainder) of the atom. To preventthis, the ions must be removed at high speedby a voltage large enough to secure saturatingcurrent. Though theoretically it appears im-possible to obtain a complete absorption bythe gas in the chambers of all the x-rays enter-ing it, the method of measurement still has PHOTOGRAPHIC ME
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectradiogr, bookyear1920
