Section I. INTRODUCTION
The purpose of this subcourse is to discuss the hazards of ionizing and
nonionizing radiation and the Department of Army radiation protection programs for
control of these hazards so that the preventive medicine specialist will gain the
knowledge necessary to aid him in implementing such programs.
The scope of this subcourse includes a brief history of the discovery of radiation
and a discussion of basic radiation physics, to include radiation units and
the Department of Army radiation protection programs.
a. Man has always lived in a radiation environment. We are continuously
bombarded each day by cosmic rays from space, terrestrial radiation from the crust of
the earth, and even radiation from radioactive materials within our own bodies. It has
only been during this century, however, that we have come to recognize and
characterize these radiations and to artificially produce radioactive materials and
manufacture radiation-producing devices for the benefit of mankind.
b. In 1895, x-rays were discovered by Wilhelm Conrad Roentgen, a German
physicist, but many scientists before him paved the way for his discovery. Many major
discoveries relating to electricity had been made during the three centuries that
preceded the discovery of x-rays, but it was the study of electrical discharges under
high voltage in vacuum tubes that led to the actual discovery of these rays. Scores of
scientists had experimented with electrical discharges through different types of vacuum
tubes and, no doubt, many of them had produced x-rays but had not recognized them
as a new type of ray.
c. Roentgen himself was experimenting with cathode rays when he observed
the presence of this new radiation. He was working with a certain vacuum tube
(Crookes-Hittorf) through which a current, under high voltage, was being passed. The
tube was entirely enclosed in black paper so as to exclude all the light emanating from
it. During the experiment, Roentgen observed a fluorescence of some barium platino-
cyanide crystals coating a piece of cardboard lying nearby. It had been known for some