What is the role of static interfractional assessment in image-guided radiotherapy (IGRT) 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

As radiotherapy for prostate cancer has become increasingly conformal, dose escalation has become a standard approach to the management of early-stage disease, [20] and accurate target and normal tissue localization has become increasingly important. Proper target identification becomes necessary in 3 distinct phases of treatment planning and treatment execution.

When patients are selected for primary radiotherapy treatment, simulation is performed. Computed tomography (CT)-based imaging is most commonly used; however, some centers prefer magnetic resonance imaging (MRI). [1]

Accurate delineation of normal tissues in relation to the prostatic target is equally important in this phase of patient care. Physician review of axial CT images allows delineation of the prostate. Because most radiation oncologists lack formal training in the interpretation of radiographic imaging, appropriate assessment requires either review with a diagnostic radiologist or extensive clinical experience.

After identification of the prostatic target (ie, the gross target volume [GTV]), the clinical target volume (CTV) and the planning target volume (PTV) are created. Although this phase of treatment planning allows accurate target localization on the basis of the gland’s location at the time of CT imaging, it does not address organ motion subsequent to that date.


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