GB1302141A - - Google Patents

Abstract

1302141 X-ray apparatus DENTAL CORP OF AMERICA 25 May 1971 16794/71 Heading H5R Panoramic radiographs of the dental arches are produced by directing a beam of X-rays successively at different angles towards the open end of the dental arches to obtain adjacent and slightly overlapping exposures, on a single film, of the posterior left (PL), anterior left (AL), anterior right (AR), and posterior right (PR) portions of the arches while the patient remains stationary, using apparatus which includes a frame incorporating a positioning plate 18 for insertion into the patients mouth; a support for an X-ray source U pivotally mounted to perform incremental movements along an arcuate path behind the patient's head to direct the X-rays along paths PR, AR, AL, and PL; and an arch-shaped cassette holder 51 mounted for incremental lateral movement in a horizontal direction, and arranged to permit successive portions of the X-ray film to be exposed to the X-rays directed along the paths PR to PL. As shown, a vertical member 11, vertically adjustable to suit the patients' height, supports at its lower end the detachable positioning plate 18, and rails 16 and 17 permitting horizontal movement of a support member 52 for the cassette holder 51. At its upper end, member 11 has a horizontal bracket 12 having a pin 21 about which the X-ray source assembly 20, 25, 32, and 30 pivots. Slide 26 permits adjustment towards and away from the patient, while slide 34 and fastening screw 35 permit the X-ray source to be lowered by an inch and tilted upwards by about 5 degrees, by reason of the inclination of the lower portion of the bar 36, when the AL and AR exposures are made, whereby interference by the bone structure of the upper palate is avoided, interference by the spinal column being similarly avoided by the angle-preferably 14 degrees-which axes AL and AR make to the longitudinal axis of the dental arches. The cassette holder 51 is provided with four X-ray impermeable shield plates 63, 65, 67, and 69 (Fig. 9, not shown), which are successively removed as the PL, AL, AR, and PR exposures are made, the end plates 63 and 69 having lips 63e and 69e to shield the ends of the cassette, which is provided with a flexible leadcoated plastics lining (Fig. 10, not shown). The indexing of the cassette holder and the X-ray source to the positions appropriate for the successive PL, AL, AR, and PR exposures is effected by the engagement of spring-urged ball detents in part-spherical depressions formed at appropriate points on the movable members, e.g. in Fig. 8, the cassette holder is indexed to the AR exposure position by the engagement of sphere 56 in recess 57; subsequent movement of member 52 to the position in which the sphere engages in recess 57<SP>1</SP> is appropriate to the AL exposure; while for the PL and PR exposures the holder is moved until it abuts the left and right side, respectively, of the patients' face.