. Elementary and dental radiography . Fig. 333. Another view of the film holder in position. STIiRliOSCOriC 305 It is not necessary to tip the tube, as it is shifted. tipping in order to have the X-rays strike the object and the tube. plate at the proper angles—at the angles at which the eyes of an observer would see the object, because the X-rays emanate from the focal point on the target in diverging lines in all directions. So the same X-rays are not used to make the seconrl picture that are used to make the first. If they were, it would be necessary to tip the tube to make th
. Elementary and dental radiography . Fig. 333. Another view of the film holder in position. STIiRliOSCOriC 305 It is not necessary to tip the tube, as it is shifted. tipping in order to have the X-rays strike the object and the tube. plate at the proper angles—at the angles at which the eyes of an observer would see the object, because the X-rays emanate from the focal point on the target in diverging lines in all directions. So the same X-rays are not used to make the seconrl picture that are used to make the first. If they were, it would be necessary to tip the tube to make them strike the object and the plate at the proper angles. (Observe lines G and H of Fig. 327.) When using a compres-. Fig. 335 Fig. 336 Fig. Fig. 334 334. The photographic print from which this halftone was taken was made from theoriginal negative, or first picture. Fig. 335. The same as Fig. 334, except made from pictures one and two, held together with binding 336. The same field as Fig. 334, but made from the third picture. sion cone or cylinder we do use the same rays to make both radiographs,and hence it becomes necessary to tip the tube as it is shifted. This canbe accomplished with accuracy only by the use of the centering rod (seeFig. 329). Thus, if a cone or cylinder is to be used, the tube stand mustbe set not only to shift the tube but to tip it also as it is shifted. With the tube stand set, the tube in position I of Fig. 327, and theplate in the position shown in Fig. 327, the first exposure is made. Thetube is then shifted to position J. the plate carrier pushed in until theunexposed half of the plate comes under the window B, and the secondexposure is made. Since the two ra
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