Title: The Demonstration of the Standardization of the Roentgen Ray Dosage
Abstract: For the purpose of demonstrating the standardization of the X-ray dosage by showing certain methods which are in use at the present time, we have prepared an exhibit by which the various methods may be explained so that they can be readily understood. Since the problem of the standardization of the X-ray dosage may be divided into four parts, we have also made four divisions of the demonstration. A.—The Theoretical Definition of the Roentgen Dose Unit The roentgen dose unit as variously defined is shown in Figure 1. It is found that the absolute unit of the roentgen ray dose, the R- or the e-unit as defined by Villard in 1908, by Friedrich and Duane in 1918, and by Behnken in 1924, is the same unit as that of Fricke and Glasser as well as that of Solomon, if the latter's definition is slightly modified. These definitions, therefore, may be used in formulating a definition for an international standard unit of roentgen ray dosage. B.—The Experimental Determination of the Roentgen Dose Unit in the Standardization Laboratory This process is illustrated in Figure 2. The unit is determined experimentally according to the text, as follows: I. By the compressed-air chamber. II. By the large air-ionization chamber. (This instrument is used only to determine the standard R-unit and to calibrate and to standardize all types of dosimeters.) The roentgen ray beam from the focus F (see Fig. 3), passing through the lead diaphragm D1, D2, D3, and D4 ionizes the air inside the large chamber. The measuring electrode E1 is connected to an electrometer system M. This electrode carries a potential of −200 volts which are supplied by the battery system B1, B2, and B3. E3 has a potential of +1,500 volts, which are furnished by a D.C. generator (H). The effective air volume is that included between E1 and E3. The electrodes designated as E2 are guard electrodes. For the given electrical factors the number of ions formed in the effective air volume is measured by observing the discharge time of the electrometer. The measured dose in roentgen units per minute is given by this formula:??
Publication Year: 1928
Publication Date: 1928-04-01
Language: en
Type: article
Indexed In: ['crossref']
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