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Published on: July 29, 2013
Physical considerations on discrepancies in target volume delineation
Raphaël Moeckli1, Wendy Jeanneret Sozzi, René-Olivier Mirimanoff
1University Institute for Radiation Physics, Grand-Pré 1, 1007 Lausanne, Switzerland. Raphael.Moeckli@chuv.ch
Zeitschrift Fur Medizinische Physik
|December 8, 2009
Summary
Physicians showed significant variability in outlining radiation therapy target volumes, impacting treatment consistency. Delineating in multiple planes may improve accuracy and reduce discrepancies in oncology centers.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Cancer Treatment Planning
Background:
- Variability in target volume delineation across different radio-oncology centers.
- Inconsistent interpretations can affect treatment efficacy and patient outcomes.
Purpose of the Study:
- To compare target volume delineations and interpretations among physicians in various radio-oncology centers.
- To assess the consistency of Gross Tumor Volume (GTV), Clinical Target Volume (CTV), and Planning Target Volume (PTV) delineations.
Main Methods:
- Eleven Swiss radio-oncology centers participated, delineating volumes for prostate and head and neck cancer cases.
- Evaluated consistency using target volume dimensions and the proximity index (intersection over union ratio).
Main Results:
- Significant discrepancies observed in delineated target volumes across centers for both prostate and head and neck cases.
- Prostate CTV: 105±55 cm³, PTV: 218±44 cm³; Head and Neck GTV: 46±15 cm³, CTV: 327±154 cm³, PTV: 528±106 cm³.
- Mean proximity index for CTV ranged from 0.42-0.50, and for PTV ranged from 0.57-0.59, indicating substantial variation.
Conclusions:
- Large discrepancies in target volume delineations highlight a need for improved standardization in radio-oncology.
- An inverse relationship between CTV volume and CTV-PTV margin suggests a compensatory mechanism.
- Delineation in sagittal and frontal planes, in addition to the transverse plane, is recommended to enhance consistency and accuracy.
