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November 3, 1917


Author Affiliations

St. Louis Instructor in Clinical Medicine, Washington University Medical School

JAMA. 1917;LXIX(18):1520-1521. doi:10.1001/jama.1917.25910450001014

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A roentgen-ray machine is no better than its plate when viewed in an illuminator; consequently, the better the illuminator, the better the value of the roentgen-ray machine.

Figure 1 is the top view of the ordinary illuminating box, with the lights directly back of a ground glass plate. This plate then becomes a source of light, emitting light rays of equal intensity through the roentgen plate. It will be necessary here to call attention to the fact that a roentgen plate represents in black and white the obstruction to the roentgen rays as they penetrate the body; therefore, the plate represents an uneven distribution of rays caused by the varying densities through which the roentgen rays must travel; in other words, the plate has been produced by uneven light.

Figure 2 is the top view of my box, in which a light is hidden on each side, the rays being

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