What terminology is specific to 3-dimensional conformal radiotherapy (3D-CRT) for the treatment of prostate cancer?

Updated: Nov 29, 2018
  • Author: Isamettin Andrew Aral, MD, MS; Chief Editor: Edward David Kim, MD, FACS  more...
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Answer

Answer

Essential to the discussion of 3D-CRT is a working knowledge of the following terms:

  • Gross tumor volume (GTV) – This is the delineation of the visible target using common imaging modalities (eg, CT or MRI)

  • Clinical target volume (CTV) – This describes the structures that may be beyond the easily visible anatomic structures delineated by CT or MRI; specifically, the CTV encompasses the anticipated microscopic extent of tumor, as well as anticipated subclinical areas that may be at risk for disease involvement

  • Planning target volume (PTV) – The PTV acknowledges that daily patient positioning and setup vary and should be addressed in creating radiation portals

Although each of these terms is readily applied to single-organ structures (eg, prostate or seminal vesicles), it remains unclear how well the structures can be defined in the delineation of regional pelvic adenopathy.


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