. I principi e la pratica della tecnica roentgenologica. Equenza delle interupzioni, ecc., che devono essere considerati nella produzione attuale. 2. Dal calore prodotto mediante assorbimento completo. Questo, tuttavia, non è indice pratico del MISURATORE di IONIZZAZIONE 104 l'energia effettiva dei raggi X per la produzione di calore è in realtà molto piccola. 3. Fluorescenza. L'effetto fluorescente di un fascio è compartealla fluorescenza eccitata da una sorgente standard, come radium, ma la maggiore potenza fluorescentea dei raggi morbidi e la disuniformità delfluorescenza delle parti diiTerenti della schermata samesea e, fatica, ma
1570 x 1591 px | 26,6 x 26,9 cm | 10,5 x 10,6 inches | 150dpi
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. The principles and practice of roentgenological technique . equency of in-terruptions, etc., which are to be considered inthe current production. 2. By the heat produced by complete ab-sorption. This, however, is no practical index of the 104 IONIZATION METER actual energy of the x-ray for the heat pro-duction is actually very small. 3. Fluorescence. The fluorescent effect of a beam is comparedto the fluorescence excited by a standardsource, as radium, but the greater fluorescentpower of soft rays and the unevenness of thefluorescence of the diiTerent parts of the samescreen and, fatigue, make this method unreli-able. 4. Ionizing action. The total ionization is a reliable measureof the energy. An ionization meter has been constructedwhich is called the iontoquantimeter. It con-sists of an ionization chamber which is placedon the receiving surface. Thoroughly insu-lated leads extend to sensitive electrometer.The circuit in which the chamber is placed ischarged and the needle of the meter is adjustedin such a wav that it indicates O. Bv ionizing. Fig. 145.—Radiograph of the penetrometer. Thelead 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 1.2centimeters. 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
