United States. Surgeon-General's Office, American Roentgen Ray Society · New York : Middleditch · leaf 214
factory 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… … 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…
