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Involved Site Radiotherapy
(ISRT)
o
ISRT accomomodates cases in which optimal prechemotherapy
imaging is not available to the radiation oncologist
o
In these situations, it is not possible to reduce the CTV to the same
extent as with INRT, because the prechemotherapy GTV
information may not be optimal
o
In ISRT, clinical judgment in conjunction with the best available
imaging is used to contour a larger CTV that will be accommodate
the uncertainties in defining the prechemotherapy GTV