Identifier: practicalpointsi00judd (find matches)
Title: Practical points in the use of X-ray and high-frequency currents
Year: 1909 (1900s)
Authors: Judd, Aspinwall
Subjects: X-rays Electrotherapeutics Radiography X-Rays Radiography
Publisher: New York : Rebman Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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Fig. 43.—Shows the best position to place the plate in relation to theX-ray tube. E represents the X-ray plate, D the part to beradiographed, A represents a cork having a thread passed downthrough the center of it B and a pointer attached to the lower endC. This pointer should come over the central portion of theX-ray plate. General Laws Governing the Use of X-rayTubes. For our purpose the principal ray froman X-ray tube is midway between the cathodeand a point opposite the anode, but it must beremembered that rays are given off with less X-Ray Tubes 85 intensity from all parts of the tube. (See Fig.43.) The patient should be placed opposite theprincipal ray, which should be as carefully ad-justed as in aiming with a gun. This is a pointmore generally neglected by the beginner inradiotherapeutic work than any other point wehave noticed. (See Figs. 44 and 45.) The action of the soft X-ray produced by thecathode stream is only upon the surface of the
Text Appearing After Image:
Fig. 44.—Illustrating the Necessity of a Diaphragm for UseWhen Making a Radiograph. Above figure shows the wild rays from the entire front of the tube fallingon the object to be radiographed and then on to the X-ray plate itself,tending to cause an indistinct plate. skin, and is escharotic to a marked degree if thetube is placed too close. The action of the X-ray is not only upon the surface, but upon alltissues, and is effectual at greater distances thanthe cathode ray. The strength of the rays is inversely propor- 86 X-Ray and High-Frequency Currents tional to the square of the distance of the tubefrom the patient. Example: Let twelve inchesdistance from the patient represent one. At sixinches distance we have four times the effect;at three inches5 distance four times four or six-teen times; at one and one-half inches distancesixteen times sixteen or 256 times. This is apoint often lost sight of and is of extreme im-

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