State of Radiography
In many ways, radiography has changed little from
the early days of its use. We still capture a shadow image on
film using similar procedures and processes technicians were using
in the late 1800's. Today, however, we are able to generate images
of higher quality and greater sensitivity through the use of
higher quality films with a larger variety of film grain sizes.
Film processing has evolved to an automated state, producing more
consistent film quality by removing manual processing variables.
Electronics and computers allow technicians to now capture images
digitally. The use of "filmless radiography" provides
a means of capturing an image, digitally enhancing, sending the
image anywhere in the world, and archiving an image that will
not deteriorate with time. Technological advances have provided
industry with smaller, lighter, and very portable equipment that
produce high quality X-rays. The use of linear accelerators provide
a means of generating extremely short wavelength, highly penetrating
radiation, a concept dreamed of only a few short years ago.
the process has changed little, technology has evolved allowing
radiography to be widely used in numerous areas of inspection. Radiography has seen expanded usage in industry to inspect not
only welds and castings, but to radiographically inspect items
such as airbags and canned food products. Radiography has found
use in metallurgical material identification and security systems
at airports and other facilities.
Gamma ray inspection has also changed considerably since the
Curies' discovery of radium. Man-made isotopes of today are far
stronger and offer the technician a wide range of energy levels
and half-lives. The technician can select Co-60 which will effectively
penetrate very thick materials, or select a lower energy isotope,
such as Tm-170, which can be used to inspect plastics and very
thin or low density materials. Today gamma rays find wide application
in industries such as petrochemical, casting, welding, and aerospace.
Addressing Health Concerns
It was in the Manhattan District of US Army Corps of Engineers that
the name "health physics" was born, and great advances
were made in radiation safety. From the onset, the leaders of
the Manhattan District recognized that a new and intense source
of radiation and radioactivity would be created. In the summer
of 1942, the leaders asked Ernest O. Wollan, a cosmic ray physicist
at the University of Chicago, to form a group to study and control
radiation hazards. Thus, Wollan was the first to bear the title
of health physicist. He was soon joined by Carl G. Gamertsfelder,
recently graduated physics baccalaureate, and Herbert M. Parker,
the noted British-American medical physicist. By mid 1943, six
others had been added. These six include Karl Z. Morgan, James
C. Hart, Robert R. Coveyou, O.G. Landsverk, L.A. Pardue, and John
Within the Manhattan District, the name "health physicist"
seems to have been derived in part from the need for secrecy (and
hence a code name for radiation protection activities) and the
fact that it was a group of mostly physicists working on health
related problems. Activities included developing appropriate
monitoring instruments, physical controls, administrative
procedures, monitoring radiation areas, personnel monitoring,
and radioactive waste disposal. It was in the Manhattan
District that many of the modern concepts of protection were born,
including the rem unit, which took into account the biological
effectiveness of the radiation. It was in the Manhattan District
that radiation protection concepts realized maturity and enforceability.