File:Röntgen rays and electro-therapeutics - with chapters on radium and phototherapy (1910) (14571770527).jpg

Identifier: rntgenrayselectr00kass (find matches)
Title: Röntgen rays and electro-therapeutics : with chapters on radium and phototherapy
Year: 1910 (1910s)
Authors: Kassabian, Mihran Krikor, 1870-1910
Subjects: Electrotherapeutics X-rays Phototherapy Radiology Radiotherapy
Publisher: Philadelphia & London : J.B. Lippincott Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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icators, the shadows of thetwo rods are formed on the surface D, and the shadow of the foreignbody in the eye assumes a new position. If the distance of one of theindicating rods from the centre of the cornea is known, and the distance 286 ELECTEO-THEEAPEUTICS. between the two indicators is measured, the position of the metal in theeye may be determined, since the shadow of the foreign body preservesat all times a fixed relation to the shadows of the indicating balls, inwhatever position the light is placed. ^ Accurate localization requires that the axis of the eyeball shall beparallel with the two indicators and with the photographic plate, thatone of the ir.dicating balls be opposite to the centre of the cornea and ata known distance from it, and that both indicators are at a measureddistance from each other. The plate-holder and indicators have beencombined into a special apparatus which firmly holds the head of thepatient, as shown in Fig. 166. The arrangement of the parts of this
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Fig. 166.—Indicating apparatus secured to the side of the head. (Courtesy of Dr. Wm. M. Sweet.) apparatus is such that the indicators, while freely adjustable, are alwaysparallel to each other and to the plate, and the two balls are perpen-dicular to the plate and 15 cm. distance between their centres when theapparatus is in place. It is necessary that the patient rotate the eyeballto bring the ocular axis parallel with the plane of the photographicplate, and that the operator adjust the indicators so that the centre ballis opposite the centre of the cornea. To determine the position of the foreign body in the eye, twocircles are drawn, representing the horizontal and vertical sections of thenormal adult eyeball, and upon these are marked the situations of theindicating balls at the time the radiographs are made. THE CLINICAL APPLICATIONS. 287

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