SINGLE INSTITUTION VARIABILITY IN INTENSITY MODULATED RADIATION TARGET DELINEATION FOR CANINE NASAL NEOPLASIA.

Area of Science:

• Veterinary Radiation Oncology
• Medical Imaging and Radiation Therapy

Background:

• Contouring variability presents a significant challenge to accurate radiation therapy delivery and reporting.
• Standardizing the delineation of radiation targets and organs at risk is crucial for consistent treatment outcomes.

Purpose of the Study:

• To quantify the variation in contouring radiation targets and organs at risk among participants within an institution.
• To assess whether all participants contoured the same normal tissues in canine nasal tumor datasets.

Main Methods:

• A descriptive study involving two canine nasal tumor datasets.
• Contouring performed by two ACVR-certified radiation oncologists and two radiation oncology residents.
• Analysis of contouring consistency for defined targets (gross tumor volume, clinical target volume, planning target volume) and organs at risk.

Main Results:

• Significant contouring variation was observed for both targets and normal tissues, particularly for the gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV).
• Mean metric scores and Dice Similarity Coefficients indicated substantial contouring variation, falling below threshold criteria for multiple structures.
• Not all normal tissues were contoured consistently across all datasets.

Conclusions:

• The study refutes the hypothesis of minimal variation in target and normal tissue delineation.
• Contouring variability can influence tumor response and toxicity, affecting patient outcomes.
• Results underscore the difficulty in replicating radiation protocols due to individual contouring influences.