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Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion
Author(s) -
Kissick Michael W.,
Boswell Sarah A.,
Jeraj Robert,
Mackie T. Rockwell
Publication year - 2005
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 - 10.1118/1.1935774
Subject(s) - motion (physics) , extension (predicate logic) , orthodontics , computer science , medicine , computer vision , programming language
The interplay between a constant scan speed and intrafraction oscillatory motion produces interesting fluence intensity modulations along the axis of motion that are sensitive to the motion function, as originally shown in a classic paper by Yu et al. [Phys. Med. Biol. 43, 91–104 (1998)]. The fluence intensity profiles are explored in this note for an intuitive understanding, then compared with Yu et al. , and finally further explored for the effects of low scan speed and random components of both intrafraction and interfraction motion. At slow scan speeds typical of helical tomotherapy, these fluence intensity modulations are only a few percent. With the addition of only a small amount of cycle‐to‐cycle randomness in frequency and amplitude, the fluence intensity profiles change dramatically. It is further shown that after a typical 30‐fraction treatment, the sensitivities displayed in the single fraction fluence intensity profiles greatly diminish.