The Collaborative International Dictionary of English v.0.48:

dosimetry \do*sim"e*try\, n. [NL. dosis dose + -metry.] (Med.)
   Measurement of doses; specif., a system of therapeutics which
   uses but few remedies, mostly alkaloids, and gives them in
   doses fixed by certain rules. -- Do`si*met"ric, a. --
   Do*sim"e*trist, n.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

dosimetry
    n 1: measuring the dose of radiation emitted by a radioactive
         source