A given particle, however, does not travel in a straight line as it slows down, so the range by its nature is an average value given by where E is the incident electron energy. Experimental Radiation Dosimetry Most of the experimental techniques in use for intravascular radiation therapy were originally developed for use in brachytherapy for radiation oncology. These are described in the references. The major difference, from an experimental point of view, is that reference distances in oncology are measured in centimeters while for intravascular therapy they are measured in millimeters. This puts a greater requirement on the spatial resolution of the detector.
Absorbed dose is the quantity of main interest to the clinician for both and gamma sources.
It is the quotient of d E by dm, that is the differential energy absorbed in the differential mass in the medium. The unit of absorbed dose is the gray , which is 1 joule per kilogram. Depth dose defines the relationship between the absorbed dose and depth in tissue. Thus, one can define a reference depth in terms of the absorbed dose at 2 mm from the center of the center line of the source. Air kerma strength is the quantity used to specify the strength of a gamma-ray emitting radionuclide.