Methodical Notes on the Term “Intensity” in Medicine and Physics

Abstract

In the article, as a discussion of the publication [1] published earlier in the journal on terminology in medical physics, the application of the term intensity in medicine and physics is considered. It is shown, contrary to the statement of the original article, that the term intensity is very widely used in various branches of physics, from optics and photometry to electrodynamics and radiophysics. At the same time, its ambiguity and non-identity of the use in different branches of physics, including the different dimensions of these quantities used, which often introduces a confusion and leads to errors in results, is also shown and discussed. For optics and photometry, according to the recommendations of the international SI system, the term intensity should be unambiguously understood as a quantity with the dimension W·sr–1. This is the main physical quantity of the SI system that characterizes radiation, but in Russian-language publications it is also called as a force of radiation, which can be misleading.