Computerized System for Safety Verification of External Beam Radiation Therapy Planning.

PURPOSE: To report an assessment of in-house software, Verifier, developed to improve efficacy and efficiency of the radiation therapy (RT) treatment planning process and quality control review (QCR). METHODS AND MATERIALS: Radiation therapy plan parameters retrieved from our treatment planning database are used by automated tests to give 75 types of warnings, such as prescription and plan discrepancies. The software is continuously updated on the basis of new issues, ideas, and planning policies. Verifier was retrospectively assessed (2007-2015) by examining impact on treatment plan revisions, frequency of quality improvement incident reports of avoidable RT plan-related safety events, unaddressed issues, and staff efficiency. RESULTS: Plan revisions for specific issues declined dramatically in response to implementation of corresponding Verifier tests. Between 2012 and 2015 our institution's total rate of plan revisions dropped from 18.0% to 11.2%. Between 2008 and 2015 specific tests were added to Verifier while the rate of corresponding avoidable safety events was reduced from 0.34% to 0.00% over the same period. Simulations suggest Verifier saves approximately 2 to 5 minutes per QCR. CONCLUSIONS: The decrease in quantifiable metrics of plan revisions and incident reports suggests automatic RT plan-checking software enhances patient safety and clinical efficiency. Although only modest time savings may be gained using Verifier for the QCR itself, the greater impact on efficiency is through avoiding late-stage plan modifications and improving documentation via automation. We encourage other institutions to consider working toward adding similar technologies to enhance their RT quality assurance programs.

Independent brachytherapy plan verification software: improving efficacy and efficiency.

BACKGROUND AND PURPOSE: To compare the pre-treatment brachytherapy plan verification by a physicist assisted by custom plan verification software (SAV) with those performed manually (MV). MATERIALS AND METHODS: All HDR brachytherapy plans used for treatment in 2013, verified using either SAV or MV, were retrospectively reviewed. Error rate (number of errors/number of plans) was measured and verification time calculated. All HDR brachytherapy safety events recorded between 2010 and 2013 were identified. The rate of patient-related safety events (number of events/number of fractions treated) and the impact of SAV on the underlying errors were assessed. RESULTS: Three/106 errors (2.8%) were found in the SAV group and 24/273 (8.8%) in the MV group (p=0.046). The mean ±1 standard deviation plan verification time was 8.4±4.0min for SAV and 11.6±5.3 for MV (p=0.006). Seven safety events out of 4729 fractions delivered (0.15%) were identified. Four events (57%) were associated with plan verification and could have been detected by SAV. CONCLUSIONS: We found a safety event rate in HDR brachytherapy of 0.15%. SAV significantly reduced the number of undetected errors in HDR treatment plans compared to MV, and reduced the time required for plan verification.

Low incidence of chest wall pain with a risk-adapted lung stereotactic body radiation therapy approach using three or five fractions based on chest wall dosimetry.

PURPOSE: To examine the frequency and potential of dose-volume predictors for chest wall (CW) toxicity (pain and/or rib fracture) for patients receiving lung stereotactic body radiotherapy (SBRT) using treatment planning methods to minimize CW dose and a risk-adapted fractionation scheme. METHODS: We reviewed data from 72 treatment plans, from 69 lung SBRT patients with at least one year of follow-up or CW toxicity, who were treated at our center between 2010 and 2013. Treatment plans were optimized to reduce CW dose and patients received a risk-adapted fractionation of 18 Gy×3 fractions (54 Gy total) if the CW V30 was less than 30 mL or 10-12 Gy×5 fractions (50-60 Gy total) otherwise. The association between CW toxicity and patient characteristics, treatment parameters and dose metrics, including biologically equivalent dose, were analyzed using logistic regression. RESULTS: With a median follow-up of 20 months, 6 (8.3%) patients developed CW pain including three (4.2%) grade 1, two (2.8%) grade 2 and one (1.4%) grade 3. Five (6.9%) patients developed rib fractures, one of which was symptomatic. No significant associations between CW toxicity and patient and dosimetric variables were identified on univariate nor multivariate analysis. CONCLUSIONS: Optimization of treatment plans to reduce CW dose and a risk-adapted fractionation strategy of three or five fractions based on the CW V30 resulted in a low incidence of CW toxicity. Under these conditions, none of the patient characteristics or dose metrics we examined appeared to be predictive of CW pain.

Systemic RNAi in C. elegans requires the putative transmembrane protein SID-1.

Double-stranded RNA-mediated gene interference (RNAi) in Caenorhabditis elegans systemically inhibits gene expression throughout the organism. To investigate how gene-specific silencing information is transmitted between cells, we constructed a strain that permits visualization of systemic RNAi. We used this strain to identify systemic RNA interference-deficient (sid) loci required to spread gene-silencing information between tissues but not to initiate or maintain an RNAi response. One of these loci, sid-1, encodes a conserved protein with predicted transmembrane domains. SID-1 is expressed in cells sensitive to RNAi, is localized to the cell periphery, and is required cell-autonomously for systemic RNAi.