Head Clamps for a Fenestrated Shield for Roentgenography of the Nasal Accessory Sinuses

Abstract

An improvement has been made on the fenestrated shield described in Radiology, February, 1928, X, 163. The shield presented here consists 0 f a lead plate 1.15 mm. thick, faced on each side with a sheet of brass 0.4 mm. thick, making a composite plate with a total thickness of 1.95 millimeters. The mask is large enough to cover an 8 by 10 cassette exactly, and has a flanged edge to prevent any displacement. Two disks have been cut out of the mask, leaving two circular apertures, spaced 12 cm. center to center. These disks fit the openings in the mask exactly, one being kept in place while an exposure is being made through the opposite side. Each disk has a rivet soldered in the center to facilitate handling. The improvement comprises two metal wings adjustable on a common sleeve, which, in turn, is mortised and movable on a square bar. The ends of the square bar are secured in the upper ends of two brackets permanently fastened to the shield. The metal wings extend 15.2 cm. from their supporting hubs, broadening from a width of 3.17 cm. at the hub to 6.03 cm. at the outer ends. They are 1.58 cm. thick, with edges and corners rounded. The hubs are fitted to slide easily for adjustment over the sleeve and are anchored in position by thumb screws. The cylindrical shape of the sleeve permits the wings to be moved vertically and fastened in position as desired. The sleeve slides easily for lateral adjustment and is held in position by a thumb screw fitted into one end. The fact that the square bar is stationary and is permanently secured to the two brackets, permits the sleeve and wings to be easily located and fastened in proper position. The brackets extend at 45· outward 6.98 cm. from, and 8.89 cm. above, the top of the shield and are 38.1 cm. apart. The sleeve is of 1.74 cm. outside diameter and is 22.86 cm. long. The wing hubs are 2.54 cm. long and 2.22 cm. in diameter. The bar is 0.952 cm. square in cross-section and 40.64 cm. long. The upper ends of the brackets are 1.40 cm. in diameter and 1.27 cm. long, each haying a 0.952 cm. square mortise to receive the ends of the bar which are held by a No. 8-32 machine screw in each. Although this instrument was devised previously for roentgenography of the nasal sinuses, it has been found of equal utility in the making of roentgenograms of the mastoid regions.