. Elementary and dental radiography / by Howard Riley Raper . Fig. 333. Another view of the film holder in position. 3o6 DENTAL RADIOGRAPHY tippingthe tube. It is not necessary to tip the tube, as it is shifted,in order to have the X-rays strike the object andplate at the proper angles—at the angles at which theeyes of an observer would see the object, because theX-rays emanate from the focal point on the target in diverging lines in alldirections. So the same X-rays are not used to make the second picturethat are used to make the first. If they were, it would be necessary totip the tube to ma
. Elementary and dental radiography / by Howard Riley Raper . Fig. 333. Another view of the film holder in position. 3o6 DENTAL RADIOGRAPHY tippingthe tube. It is not necessary to tip the tube, as it is shifted,in order to have the X-rays strike the object andplate at the proper angles—at the angles at which theeyes of an observer would see the object, because theX-rays emanate from the focal point on the target in diverging lines in alldirections. So the same X-rays are not used to make the second picturethat are used to make the first. If they were, it would be necessary totip the tube to make them strike the object and the plate at the properangles. (Observe lines G and H of Fig. 327.) When using a compres-. Fig. 334 Fig. 335 Fig. 330 Fig. 334. The photographic print from which this halftone was taken was made from the original negative, or first 335. The same as Fig. 334, except made from pictures one and two, held together with binding 330. 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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