background: verification of radiation therapy treatment using electronic portal images (epi) involves the correlation between a reference image and a treatment epi. this paper investigates the accuracy and confidence in reference anatomy outlining and anatomy matching components of epi review, when performed by radiation therapists with varying experience in epi analysis.

methods: thirty radiation therapists performed reference anatomy contouring and anatomy matching of seven pairs of reference and treatment images belonging to five previous patients. accuracy was determined by the discrepancy (mm) between the anatomy contouring and matching of the subjects and the original parameters completed by an experienced senior radiation therapist, with formal training in epi analysis. confidence was recorded on a 10cm visual-analogue scale (vas).

results: no significant differences were found in the accuracy of anatomy contouring or anatomy matching between subjects with and without formal epi training nor between subjects with less than or greater than five or more years of radiation therapy experience (p > 0.18). significantly different confidence scores were found in subjects with formal training in epi (p < 0.00006)

conclusions: accuracy of anatomy contouring and matching was not significantly influenced by the years of radiation therapy experience and formal epi training, although these factors did affect subjects' confidence in performing epi review tasks. frequent exposure to portal image analysis may be as or more important to the technical skills required in epi review, than formal training or years of experience.