File:X-ray manual - U.S. Army (1917) (14570635290).jpg

Identifier: xraymanualusarmy00unit (find matches)
Title: X-ray manual : U.S. Army
Year: 1917 (1910s)
Authors: United States. Surgeon-General's Office American Roentgen Ray Society
Subjects: X-rays Fractures Teeth Chest Heart Radiography
Publisher: New York : Middleditch
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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plate, the angle of the tubemust be altered to accommodate. The central ray shouldenter the head about 3 inches above and 3 inches behindthe external auditory canal, and exit at the externalauditory meatus next to the plate. The tube stand should be supplied with a small coneand this brought down with firm pressure on the head.Stereoscopic plates may be made by shifting and tiltingthe proper distance on each side of the angle. Fig. 8. Technique for Accessory Sinuses. In order to obtain a satisfactory postero-anterior im-age of all the accessory sinuses at one exposure, it isnecessary that the rays pass through the head at acertain angle. If this angle is not observed, the petrousportion of the temporal bone obstructs the view of theethmoids or antrum or the sinuses are so distorted thatthe information given is not correct. The proper angle is one which will cause the shadowof the petrous portion to cut across the lower one-thirdof the orbit, leaving the lower two-thirds of the antrum
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Fig. 8. Adjustment for exposure of mastoid. 207 208 X-RAY MANUAL—U. S. ARMY free and also the upper two-thirds of the orbit clear.The superior portion of the antrum is not so important,as any condition affecting the antrum to the extent of anX-ray diagnosis will involve the inferior portion as well.The possible exception to this is in the case of a fractureinvolving the lower orbital margin. In this case thepetrous must be thrown down into the antrum. The position described shows clearly all that is re-quired of the frontals, ethmoids, and antra on a singleplate, and the sinuses in their proper relation and size. To obtain this position the principal ray must be di-rected through the head at an angle of 23 degrees from aline extending from the external auditory meatus to theglabella. This angle may be obtained by a pair of dividers or apermanent triangle set at an angle of 23 degrees. Fig. 9. The patient is seated before an adjustable stand or maylie prone on a table. The head rests

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