The planning of interstitial radium needle implants is usually based upon standard geometric forms. Anatomical limitations, tumor extension requiring supplemental needles, and technical imperfections result in implants somewhat at variance with standard geometry. Accurate delivery of planned dosage requires calculation from the completed implant rather than from the initial plan. With standard radium distributions, or limited deviations therefrom, measurements from radiographs taken in perpendicular planes with the use of the Pythagorean theorem (1) are generally adequate for calculation purposes. For more marked deviations and for multiple or curved planes, the perpendicular projection technic (2) allows an accurate and more complete survey of needle distribution. This method requires identification of all needles on the radiographs. In multiple plane and large volume implants, identification of needles is difficult and in some cases impossible. In these cases, reconstructions from stereoradiographs (3) usually can be made, but at the expense of considerable time. A“Siemens' Transversal PlanigraphA“ (Fig. 1) was available in our department. It was conceived that the rotational feature would lend itself to the study of linear opaque objects such as radium needles which would not be as well demonstrated by conventional tomography using linear tube travel (Fig. 6). The areas of major clinical concern were the tongue, floor of the mouth, buccal mucosa, and neck. In these areas dosage levels were critical, accurate identification of large numbers of needles was difficult, and the axis of implants frequently paralleled the axis of the body. These factors suggested a trial of transverse tomography. The basic equipment and technic of axial transverse tomography has recently been reviewed by Wilk (4). In our department, effort had been directed toward improvement in diagnostic detail. We had been unable to achieve film detail comparable to that of conventional tomography, but gross anatomy was well demonstrated. Various modifications (Fig. 2) facilitated clinical application and improved results. The tube stand-patient distance was increased and fixed to provide a constant low magnification factor and allow better beam alignment by eliminating one axis of motion, the horizontal tube travel. Limitation in a second axis of motion, vertical tube travel, also improved beam alignment. Variation for special clinical situations could be obtained by altering the angle of declination of the beam and by raising or lowering the patient in the rotating chair. Air compression bags originally furnished with the equipment allowed some shift of the patient during rotation. These were replaced by foam rubber pads, which reduced motion while providing adequate comfort. Motion of the head was minimized by addition of a radiolucent plastic extension head rest to which the head could be fixed.