224 Background: The purpose of this study was to elucidate the factors associated with radiation therapy (RT) treatment events and near misses at a large academic institution. Methods: All RT patient events and near misses/good catches were prospectively collected using an electronic incident reporting system from April 1, 2011-April 30, 2013. The event origin was categorized according to the step in the treatment process (simulation, physician prescription, dosimetry/physics, treatment delivery and other). The incident database was linked to the RT delivery (record and verify) database which contains date of treatment, radiation beam duration, number of fractions, and type of treatment. A treatment record was defined as a unique site description and date/time. Results: There were 224 reported RT events or near misses/good catches analyzed, of which there were 59 RT treatment delivery events associated with 105 treatment records, including 0 level I (most severe), 18 level II, 35 level III (least severe), and 6 level IV (near misses/good catches) among the 13,899 patients and 468,489 treatments. The remaining 165 RT events occurred at the other steps of the treatment process. The overall rate of RT events and near misses was 161.2 per 10,000 patients. The rate of RT treatment delivery events and near misses was 42.4 per 10,000 patients and 2.2 per 10,000 treatment records. Logistical multivariate analysis showed that treatment on Tuesday (Odds Ratio = 2.50, 95% CI 1.67-3.73, p<0.001), first day of treatment (5.16, 95% CI 3.32-8.02, p<0.001), number of fractions (continuous) (0.98, 95% CI 0.96-0.997, p<0.03), intensity modulated radiation therapy (IMRT) (2.87, 95% CI 1.44-5.74, p=0.003), electron only fields (2.00, 95% CI 1.27-3.14, p=0.003), and radiation beam duration (continuous minutes) (1.03, 95% CI 1.02-1.04, p<0.001), were associated with RT treatment events and near misses, while age, proton treatment, number of fields and after hours treatment were not. Conclusions: Treatments delivered on Tuesdays, on the first day of treatment, with fewer fractions, with IMRT, with electron only fields, and with longer radiation beam duration were associated with an increased risk of RT treatment events.
