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Pion in vivo dosimetry using aluminum activation
Author(s) -
Hogstrom Kenneth R.,
Amols Howard I.
Publication year - 1980
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.594659
Subject(s) - physics , dosimeter , nuclear physics , dosimetry , pion , nuclear medicine , neutron , aluminium , irradiation , radiochemistry , materials science , radiation , chemistry , medicine , metallurgy
The method of aluminum activation to 24 Na has been shown feasible as a high‐LET, in vivo dosimeter for clinical pion beams at the Clinton P. Anderson Meson Physics Facility in Los Alamos. A 3×3 in. φ NaI (Tl) well detector measures the 24 Na activity following exposure by windowing the 2.75 MeV photopeak. Calculations of the 24 Na activity agree well with experiment if one assumes a production ratio of 0.075 24 Na/stopped π − in aluminum, and an in‐flight cross section of 26 mb. The activity is produced primarily by stopping pions although 15–25% of the activity is the result of neutrons. Thus, the induced activation is a good measure of high‐LET dose. By comparison with high‐LET dose measured by a 7.6 μ silicon detector and a Rossi chamber, the amount of high‐LET dose per activation is found to be 1.35×10 −6 rad/( 24 Na/gm Al). A clinical setup has been installed and a sample patient measurement is compared with high‐LET dose calculated by treatment planning programs.