File:Radiography, x-ray therapeutics and radium therapy (1915) (14570836440).jpg

Identifier: radiographyxrayt00knoxuoft (find matches)
Title: Radiography, x-ray therapeutics and radium therapy
Year: 1915 (1910s)
Authors: Knox, Robert, 1868-1928
Subjects: Radiography Radiotherapy X-rays
Publisher: London : A. & C. Black
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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of the X-ray bulb. The spintermeter may be attached to the coil, or more conveniently mounted on a separate base, and placed at some distance from the coil. The Bauer Qualimeter is an instrument for determining the degree of hardness of the X-ray tube. It is useful, but not always to be relied upon. This instrument is connected by a wire to the negative terminal of the coil or the cathode of the tube. It is a static electrometer and condenser which indicates automatically the potential of the cathode, and hence the quality of the X-rays. The apparatus consists of two wings, which swing between two fixed plates. Both wings and plates are equally charged, so that a repulsion takes place between them. fig. 55.—Bauer qualimeter. (FavTe. The intensity of this repulsion is in exact proportion to the electrical tension in the secondary circuit, and is indicated by the deviation of a pointer over a suitably divided scale. As is well known, the penetration of the X-rays is a function of the
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BAUER QUALIMETER 57 electrical potential iu the secondary circuit, so that a simple measurementof this potential between the anode and cathode mil give us an indicationof the hardness of the tube. The scale is gauged according to the absorptionof the X-rays by sheets of lead of different thickness, increasing regularfrom one-tenth of a milHmetre to one millimetre. No. 1 on the scale denotes X-rays of such a hardness as to be totallyabsorbed by y^ millimetre of lead. When the index is at No. 10 we knowthat the tube is gi\ing out rays which will penetrate 0-9 milhmetre of lead,but will be totally absorbed by 1 milhmetre of lead. As already explained, the instrument is unipolar, being joined up by asingle ^vire to some point in electrical connection with the cathode. Theinstrument is contained in an ebonite case, which swings freely from a bracketon the wall or a stand, so as to be always in a vertical position. The following experiment will demonstrate the use of the instrument.The tube

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