RADIOGRAPHIC INTERPRETATION (RT): The identification of subsurface discontinuities indicated on the
radiograph. The evaluation as to the acceptability or rejectability of the material is based upon the judicious application
of the radiographic specifications and standards governing the material.
RADIOGRAPHIC TECHNIQUE (RT): The selection of those radiographic factors such as kilovoltage, milliamperage,
type of film and screen, distance, and exposure time as to render the best possible radiographic sensitivity.
RADIOGRAPHY (RT): A nondestructive testing method wherein a source of X-rays or gamma rays, is utilized to
indicate the subsurface condition of opaque materials. A permanent record of the soundness characteristics is generally
made on a specially prepared film called the radiograph.
RADIOISOTOPE: An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation.
More than 1300 natural and artificial radioisotopes have been identified.
RADIOLOGY: That branch of medicine that uses ionizing radiation for diagnosis and therapy.
RADIONUCLIDE (RT): A nuclide that is radioactive.
RADIUM: A radioactive element with the atomic number 88 and an atomic weight of 226. In nature, radium is found
associated with uranium, which decays to radium, by a series of alpha and beta emissions. Radium is used as a
RANGE (UT): The maximum ultrasonic path length that can be displayed; see SWEEP.
RANGE MARKERS: See MARKERS.
RAREFACTION: The thinning out, or moving apart of the particles in a material as an ultrasonic wave is propagated.
Opposite in its effect to compression. The sound wave is composed of alternate compressions and rarefactions of the
RATE METER (RT): A device designed to measure radiation per unit time, as in milliroentgens per hour. It is used
for detecting radiation fields and measuring the exposure rate.
RAY: A beam of energy of small cross section.
RAYLEIGH WAVE (UT): See SURFACE WAVE.
RBE DOSE: RBE stands for relative biological effectiveness. An RBE dose is the dose measured in rems. (This is
discussed in the report of the International Commission on Radiological Units and Measurements, 1956, NBS
Handbook 62, p. 7).
READOUT (ET): The method by which eddy current information is presented or displayed. Readout includes meters,
recorders and CRTs (cathode ray tubes).
REAL-TIME RADIOGRAPHY (RT): A type of radiography in which an image is not produced photographically, but
is instead produced on a fluorescent screen viewed by a video camera. The image may be intensified or enhanced
before display on a television monitor. This enables radiographic interpretation concurrent with irradiation of a
specimen, and lends itself to remote rapid inspection of items on an assembly line. A video recorder may be used to
record the image.
To increase the carbon content of molten cast iron or steel by adding carbonaceous material, high-carbon
pig iron or a high-carbon alloy. (2) To carburize a metal part to return surface carbon lost in processing.