. The American journal of roentgenology, radium therapy and nuclear medicine . e useof parallel plates set on edge without the aidof cross members. The clean-up effect forthe same spacing intervals was found to beless than with the cross-membered grid; butthe opportunity of placing the strips muchcloser together by the parallel plan was muchgreater. It was obvious from the beginningthat with parallel strips and a single uniformmotion, there would result no shadows fromthe strips. After numerous experiments itwas found that with ^ inch strips of type-metal spaced five to the inch, there was pro
. The American journal of roentgenology, radium therapy and nuclear medicine . e useof parallel plates set on edge without the aidof cross members. The clean-up effect forthe same spacing intervals was found to beless than with the cross-membered grid; butthe opportunity of placing the strips muchcloser together by the parallel plan was muchgreater. It was obvious from the beginningthat with parallel strips and a single uniformmotion, there would result no shadows fromthe strips. After numerous experiments itwas found that with ^ inch strips of type-metal spaced five to the inch, there was pro-duced all the absorption of scattered raysthat could be desired for practical work. Working models were made and tested,the latest one of which is herewith of type metal ^ inch wide, 1/50 inchthick and 2 feet long are mounted on a 292 The Bucky Diaphragm Principle AppHed to Roentgenography 293 form which is shaped so as to resemble asection of the shell of a cylinder. All metalstrips are parallel and spaced by guttedwooden strips about 1/6 inch thick. This. Fig. I. Schematic representation of primary rajs (P)and scattered rays (S) which are cut off by thefaces of grid (B) before arriving at plate (C). makes the strips with the spacers run aboutive to the inch. The curve put into the com-plex is such that the rays from a tube target25 inches above, pass through the spaceswithout impinging on the sides of the strips,just the edges. (Fig. i.) This complex is mounted on roller bear-ings made to run on a curved track, so thatmotion is across the length of the strips, andthe distance of movement about five inches.(Fig. 2.) The power used for movement isthe weight of a mass of lead. This weight ishung from an equalizing rod, each of whoseends is attached by cable over pulley to aside of the movable grid. The movement isregulated in speed and made uniform in rateby an oil drag placed on the opposite side ofthe grid and attached thereto by a pair of:ables and equalizer
Size: 1460px × 1711px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidamericanjour, bookyear1906
