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The lens coupling efficiency in megavoltage imaging
Author(s) -
Swindell William
Publication year - 1991
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 - 10.1118/1.596624
Subject(s) - lens (geology) , magnification , optics , physics , scintillator , refractive index , detector
In TV‐based megavoltage imaging systems it is useful to be able to estimate the geometrical efficiency g 2 of the camera lens. It is shown that the appropriate expression is g 2 =(16 n 2 ) −1 ×[ F (1+1/ m )] −2 , where n is the refractive index of the scintillator, F is the F ‐number of the lens and m is the optical magnification. This expression yields estimates for g 2 that are 5 to 10 times smaller than the estimates that have appeared previously in the literature.