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An original questionnaire was used to investigate the available types of reference and treatment image verification equipment and specific practices related to image analysis. A section on treatment site-specific imaging was included. The questionnaire was distributed to all radiation oncology facilities in Australia and New Zealand. A response rate of 87% (40/46) was achieved. Most facilities (90%) in Australia and New Zealand reported the availability of electronic portal imaging devices. Use of computer software to assist with image interpretation was indicated by 92% of centres. Frequency of image acquisition and tolerance levels used for radical treatment sites were variable, but palliative treatment site protocols were more consistent between treatment facilities. In conclusion, departments should strive to use evidence-based protocols and guidelines to ensure acceptable accuracy in treatment delivery.

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 10 cm 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 Ͼ 0.18). Significantly different confidence scores were found in subjects with formal training in EPI (p Ͻ 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.

Radiation therapy treatment verification can be performed using hard copy portal films or digital Electronic Portal Images (EPI) of the treatment field, acquired at the time of treatment. This paper describes a practical method of assessing the accuracy of reference anatomy outlining, for treatment sites involving the pelvis, breast and lumbar spine. Seven original bone anatomy outlines contoured onto verification images of five patients, were printed on transparency sheets and reference points were marked at equal distances along the anatomy curves. Two sample anatomy contour sets were created by two independent radiation therapists who outlined visible bone anatomy on the same seven digitally reconstructed radiographs (DRR) and hard copy outlines were obtained. Three independent observers with differing levels of experience, assessed the discrepancies between the original anatomy contours and the sample sets on two occasions one week apart, by measuring the distances between the original and sample set contours (absolute values in mm). The degree of agreement between the same assessor on two occasions (intra-rater reliability) and between assessors (inter-rater reliability) was analysed using parametric analysis for levels of relationship and significant differences. This simple method of reference anatomy outline measurement was shown to be highly reliable within assessors and between assessors (r > 0.87 and r 2 > 0.75 for both intra-and inter-rater comparisons). This measurement process may be a suitable method, for undertaking quality assurance activities in image verification within radiation therapy departments.