IMRT Delivery Techniques:

  1. Peacock - This system, now unused, utilized a bolt collimation system that effectively created an iris slit with leaves on either side of the slit that could either be in an open or closed position.  These leaves would open and close as the radiation source rotated around a treatment slice.  A new slice would then be translated into view (by couch translation), and then the source rotation would occur again. The slice thickness was determined by the opening on the iris with smaller openings yielding more conformal plans. This technique comprised the initial concept behind what would develop into tomotherapy.
  2. Step-and-shoot - we implement MLCs that move into a pattern and then the beam comes on.  The beam then turns off so that the MLCs can move into a new pattern.

 

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  1. Dynamic Step-and-Shoot - this is the same as step-and-shoot except that the beam doesn’t turn off as the new pattern is obtained.  This gets rid of complications due to the dose rate ramping up or down.

 

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