SOD (RT): Source to object distance. The distance between x-ray tube or radioisotope and the object being
SOFT RADIATION (RT): A qualitative term used to describe the relatively less penetrating types of ionizing radiation.
SOFT X-RAYS: A term used to express the quality or penetrating power of X radiation; their penetrating power is
SOLARIZATION (RT): The instances decreased (photographic) density produced by exposure additional to that
required to give maximum density. This may result in reversal.
SOLDER EMBRITTLEMENT: Reduction in mechanical properties of a metal as a result of local penetration of solder
along grain boundaries.
SOLDERING: Sticking or adhering of metal to portions of the die.
SOLENOID: A solenoid is a coil consisting of a number of loops of wire or cable to carry electric current. It may be
used for both magnetizing and demagnetizing purposes.
SOLIDIFICATION SHRINKAGE: The decrease in volume of a metal during solidification.
SOLUBLE (PT): The amount of a substance that will dissolve in a given amount of another substance and is typically
expressed as the number of parts by weight dissolved by 100 parts of solvent at a specified temperature and pressure or
as a percent by weight or by volume.
SOLUTION HEAT TREATMENT: A heat treatment in which an alloy is heated to a sufficiently high temperature to
permit many or all of the alloying elements to become randomly dispersed throughout the metal.
SOLVENT ACTION: The dissolution of a fluid or solid by another material.
SOLVENT CLEANING (PT): The process of removing the excess penetrant from the surface of a part by washing or
wiping with a solvent for the penetrant.
SOLVENT DEVELOPER (PT): A developer in which the developing powder is applied as a suspension in a quick-
SOURCE (RT): The origin of radiation; an X-ray tube or radioisotope.
SOURCE ASSEMBLY (RT): A component of a gamma radiography exposure device to which the sealed source is
affixed or in which the sealed source is contained. The source assembly includes the sealed source.
SOURCE CAPSULE (RT): The immediate container that, along with the contained radioactive material, constitutes a
sealed source of ionizing radiation.
SOURCE-FILM DISTANCE (SFD) (RT): The distance between the focal spot of an X-ray tube or radiation source and
the film generally expressed in inches.
SOURCE GUIDE TUBE (CONDUIT) (RT): A flexible or rigid tube for guiding the sealed source from the exposure
device to the exposure head.
SOURCE HOUSING (RT): An enclosure for a sealed source that provides attenuation for the radiation emitted by the
source. The enclosure may have an aperture through which the useful beam is emitted or through which the source is