. Elementary and dental radiography / by Howard Riley Raper . ness of the part be known, reference can be madeto a printed table and the exact time of exposure necessary commending such work as efforts along the right line, I considerthem failures so far as practical application in dental work is that in the calculation the density of the part and sensitiveness ofthe plate are not taken into account at all. MAKING RADIOGRAPHS 73 Each man must learn to properly time his exposure by personal ex-perimentation. This statement is likely to be contradicted by those who
. Elementary and dental radiography / by Howard Riley Raper . ness of the part be known, reference can be madeto a printed table and the exact time of exposure necessary commending such work as efforts along the right line, I considerthem failures so far as practical application in dental work is that in the calculation the density of the part and sensitiveness ofthe plate are not taken into account at all. MAKING RADIOGRAPHS 73 Each man must learn to properly time his exposure by personal ex-perimentation. This statement is likely to be contradicted by those whoconstrue it to mean that no idea at all of the time of the exposure canbe learned except by experiment. That is not what I am saying, idea I wish to convey is that these tables of calculation, on the timeof exposure, give only the approximate length of time necessary, and thata very little experience and the use of judgment render them are always useless except when a penetrometer is used and the coilis equipped with a Fig. 72. Trays for developing and fixing solution To make a negative (the picture on the glass of the plate) like theradiograph shown in Fig. 71, the factors may be as follows: 1. Machine used: A large induction coil, with a two-point elec-trolytic interrupter, operating on no-volt. circuit. Three-fourths ofthe resistance of rheostat cut out. 2. Strength of current: Machine not equipped with ammeter ormilliammeter. Approximate amperage of the primary current, 20. Sec-ondary current sufficiently powerful to obtain a fat. fuzzy spark 10 incheslong—an estimate, about 10 milliamperes. 3. Penetration of X-rays : Tube backs up 5 inches of parallel of tube regulating spark gap 5 inches. Therefore, the tube ismedium high and the rays from it rather penetrating when it is properlylighted. Benoist penetrometer 5. 4. Distance of target from plate: Twenty (20) inches. 5. Thickness of part: That of hand, about ilA
Size: 2441px × 1023px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookauthorraperhowardriley, bookcentury1900, bookdecade1910
