Risk factors for radiotherapy incidents: a single institutional experience.

We aimed to analyze risk factors for incidents occurring during the practice of external beam radiotherapy (EBRT) at a single Japanese center. Treatment data for EBRT from June 2014 to March 2017 were collected. Data from incident reports submitted during this period were reviewed. Near-miss cases were not included. Risk factors for incidents, including patient characteristics and treatment-related factors, were explored using uni- and multivariate analyses. Factors contributing to each incident were also retrospectively categorized according to the recommendations of the American Association of Physicists in Medicine (AAPM). A total of 2887 patients were treated during the study period, and 26 incidents occurred (0.90% per patient). Previous history of radiotherapy and large fraction size were identified as risk factors for incidents by univariate analysis. Only previous history of radiotherapy was detected as a risk factor in multivariate analysis. Identified categories of contributing factors were human behavior (50.0%), communication (40.6%), and technical (9.4%). The incident rate of EBRT was 0.90% per patient in our institution. Previous history of radiotherapy and large fraction size were detected as risk factors for incidents. Human behavior and communication errors were identified as contributing factors for most incidents.

Multi-institutional comparison of secondary check of treatment planning using computer-based independent dose calculation for non-C-arm linear accelerators.

PURPOSE: This report covers the first multi-institutional study of independent monitor unit (MU)/dose calculation verification for the CyberKnife, Vero4DRT, and TomoTherapy radiotherapy delivery systems. METHODS: A total of 973 clinical treatment plans were collected from 12 institutions. Commercial software employing the Clarkson algorithm was used for verification after a measurement validation study, and the doses from the treatment planning systems (TPSs) and verification programs were compared on the basis of the mean value ±â€¯two standard deviations. The impact of heterogeneous conditions was assessed in two types of sites: non-lung and lung. RESULTS: The dose difference for all locations was 0.5 ±â€¯7.2%. There was a statistically significant difference (P < 0.01) in dose difference between non-lung (-0.3 ±â€¯4.4%) and lung sites (3.5 ±â€¯6.7%). Inter-institutional comparisons showed that various systematic differences were associated with the proportion of different treatment sites and heterogeneity correction. CONCLUSIONS: This multi-institutional comparison should help to determine the departmental action levels for CyberKnife, Vero4DRT, and TomoTherapy, as patient populations and treatment sites may vary between the modalities. An action level of ±5% could be considered for intensity-modulated radiation therapy (IMRT), non-IMRT, and volumetric modulated arc radiotherapy using these modalities in homogenous and heterogeneous conditions with a large treatment field applied to a large region of homogeneous media. There were larger systematic differences in heterogeneous conditions with a small treatment field because of differences in heterogeneity correction with the different dose calculation algorithms of the primary TPS and verification program.