Cobalt compensator-based IMRT device: A treatment planning study of head and neck cases.

PURPOSE: Our goal is to develop a novel cobalt-compensator-based IMRT device for low- and middle-income countries that is reliable and cost-effective while delivering treatment plans of equal quality to those from linac-MLC devices. The present study examines the quality of treatment plans using this device. METHODS: A commercial treatment planning system (TPS; RayStation v.8B) was commissioned for this device using Monte Carlo simulations from the Geant4 toolkit. Patient-specific compensators were created as regions-of-interest. Thirty clinical head & neck cases were planned and compared to clinical plans with a 6MV linac using IMRT. The mock head and neck plan from TG-119 was used for further validation. RESULTS: PTV objectives were achieved in all 30 plans with PTV V95% >95 %. OAR sparing was similar to clinical plans. There were 14 cases where OAR dose limits exceeded the recommended QUANTEC limits in the clinical plan in order to achieve target coverage. OAR sparing was better in the cobalt compensator plan in 8 cases and worse in 3 cases, in the latter cases exceeding the clinical plan doses by an average of 8.22 % (0.0 %-13.5 %). Average field-by-field gamma pass-rate were 93.7 % (2 %/2mm). Estimated treatment times using the Co-60 compensator device were 1 min 27 s vs 1 min 2 s for the clinical system. CONCLUSION: This system is the first of its kind to allow for IMRT with a Co-60 device. Data here suggests that the delivery meets plan quality criteria while maintaining short treatment times which may offer a sustainable and cost-low option for IMRT on the global scale.

The Dancing Cord: Inherent Spinal Cord Motion and Its Effect on Cord Dose in Spine Stereotactic Body Radiation Therapy.

BACKGROUND: Spinal cord dose limits are critically important for the safe practice of spine stereotactic body radiotherapy (SBRT). However, the effect of inherent spinal cord motion on cord dose in SBRT is unknown. OBJECTIVE: To assess the effects of cord motion on spinal cord dose in SBRT. METHODS: Dynamic balanced fast field echo (BFFE) magnetic resonance imaging (MRI) was obtained in 21 spine metastasis patients treated with SBRT. Planning computed tomography (CT), conventional static T2-weighted MRI, BFFE MRI, and dose planning data were coregistered. Spinal cord from the dynamic BFFE images (corddyn) was compared with the T2-weighted MRI (cordstat) to analyze motion of corddyn beyond the cordstat (Dice coefficient, Jaccard index), and beyond cordstat with added planning organ at risk volume (PRV) margins. Cord dose was compared between cordstat, and corddyn (Wilcoxon signed-rank test). RESULTS: Dice coefficient (0.70-0.95, median 0.87) and Jaccard index (0.54-0.90, median 0.77) demonstrated motion of corddyn beyond cordstat. In 62% of the patients (13/21), the dose to corddyn exceeded that of cordstat by 0.6% to 13.8% (median 4.3%). The corddyn spatially excursed outside the 1-mm PRV margin of cordstat in 9 patients (43%); among these dose to corddyn exceeded dose to cordstat >+ 1-mm PRV margin in 78% of the patients (7/9). Corddyn did not excurse outside the 1.5-mm or 2-mm PRV cord cordstat margin. CONCLUSION: Spinal cord motion may contribute to increases in radiation dose to the cord from SBRT for spine metastasis. A PRV margin of at least 1.5 to 2 mm surrounding the cord should be strongly considered to account for inherent spinal cord motion.

Durable Improvement in Patient Safety Culture Over 5 Years With Use of High-volume Incident Learning System.

PURPOSE: Incident learning systems (ILSs) require substantial time and effort to maintain, risking staff burnout and ILS disuse. Herein, we assess the durability of ILS-associated safety culture improvements and ILS engagement at 5 years. METHODS AND MATERIALS: A validated survey assessing safety culture was administered to all staff of an academic radiation oncology department before starting ILS and annually thereafter for 5 years. The survey consists of 70 questions assessing key cultural domains, overall patient safety grade, and barriers to incident reporting. A χ2 test was used to compare baseline scores before starting the ILS (pre-ILS) with the aggregate 5 years during which ILS was in use (with ILS). ILS engagement was measured by the self-reported number of ILS entries submitted in the previous 12 months. RESULTS: The survey response rate was ≥68% each year (range, 68%-80%). High-volume event reporting was sustained (4673 reports; average of 0.9 ILS entries per treatment course). ILS engagement increased, with 43% of respondents submitting reports during the 12 months pre-ILS compared with 64% with ILS in use (P < .001). Significant improvements (pre- vs. with-ILS) were observed in the cultural domains of patient safety perceptions (25% vs 39%; P < .03), and responsibility and self-efficacy (43% vs 60%; P < .01). The overall patient safety grade of very good or excellent significantly increased (69% vs 85%; P < .01). Significant reductions were seen in the following barriers to error reporting: embarrassment in front of colleagues, getting colleagues into trouble, and effect on department reputation. CONCLUSIONS: Comprehensive incident learning was sustained over 5 years and is associated with significant durable improvements in metrics of patient safety culture.

A ring-based compensator IMRT system optimized for low- and middle-income countries: Design and treatment planning study.

PURPOSE: We propose a novel compensator-based IMRT system designed to provide a simple, reliable, and cost-effective adjunct technology, with the goal of expanding global access to advanced radiotherapy techniques. The system would employ easily reusable tungsten bead compensators that operate independent of a gantry (e.g., mounted in a ring around the patient). Thereby the system can be retrofitted to existing linac and cobalt teletherapy units. This study explores the quality of treatment plans from the proposed system and the dependence on associated design parameters. METHODS: We considered 60 Co-based plans as the most challenging scenario for dosimetry and benchmarked them against clinical MLC-based plans delivered on a linac. Treatment planning was performed in the Pinnacle treatment planning system with commissioning based on Monte Carlo simulations of compensated beams. 60 Co-compensator IMRT plans were generated for five patients with head-and-neck cancer and five with gynecological cancer and compared to respective IMRT plans using a 6 MV linac beam with an MLC. The dependence of dosimetric endpoints on compensator resolution, thickness, position, and number of beams was assessed. Dosimetric accuracy was validated by Monte Carlo simulations of dose distribution in a water phantom from beams with the IMRT plan compensators. RESULTS: The 60 Co-compensator plans had on average equivalent PTV coverage and somewhat inferior OAR sparing compared to the 6 MV-MLC plans, but the differences in dosimetric endpoints were clinically acceptable. Calculated treatment times for head-and-neck plans were 7.6 ± 2.0 min vs 3.9 ± 0.8 min (6 MV-MLC vs 60 Co-compensator) and for gynecological plans were 8.7 ± 3.1 min vs 4.3 ± 0.4 min. Plan quality was insensitive to most design parameters over much of the ranges studied, with no degradation found when the compensator resolution was finer than 6 mm, maximum thickness at least 2 tenth-value-layers, and more than five beams were used. Source-to-compensator distances of 53 and 63 cm resulted in very similar plan quality. Monte Carlo simulations suggest no increase in surface dose for the geometries considered here. Simulated dosimetric validation tests had median gamma pass rates of 97.6% for criteria of 3% (global)/3 mm with a 10% threshold. CONCLUSIONS: The novel ring-compensator IMRT system can produce plans of comparable quality to standard 6 MV-MLC systems. Even when 60 Co beams are used the plan quality is acceptable and treatment times are substantially reduced. 60 Co-compensator IMRT plans are adequately modeled in an existing commercial treatment planning system. These results motivate further development of this low-cost adaptable technology with translation through clinical trials and deployment to expand the reach of IMRT in low- and middle-income countries.

State of dose prescription and compliance to international standard (ICRU-83) in intensity modulated radiation therapy among academic institutions.

PURPOSE: The purpose of this study was to evaluate dose prescription and recording compliance to international standard (International Commission on Radiation Units & Measurements [ICRU]-83) in patients treated with intensity modulated radiation therapy (IMRT) among academic institutions. METHODS AND MATERIALS: Ten institutions participated in this study to collect IMRT data to evaluate compliance to ICRU-83. Under institutional review board clearance, data from 5094 patients-including treatment site, technique, planner, physician, prescribed dose, target volume, monitor units, planning system, and dose calculation algorithm-were collected anonymously. The dose-volume histogram of each patient, as well as dose points, doses delivered to 100% (D100), 98% (D98), 95% (D95), 50% (D50), and 2% (D2), of sites was collected and sent to a central location for analysis. Homogeneity index (HI) as a measure of the steepness of target and is a measure of the shape of the dose-volume histogram was calculated for every patient and analyzed. RESULTS: In general, ICRU recommendations for naming the target, reporting dose prescription, and achieving desired levels of dose to target were relatively poor. The nomenclature for the target in the dose prescription had large variations, having every permutation of name and number contrary to ICRU recommendations. There was statistically significant variability in D95, D50, and HI among institutions, tumor site, and technique with P values < .01. Nearly 95% of patients had D50 higher than 100% (103.5 ± 6.9) of prescribed dose and varied among institutions. On the other hand, D95 was close to 100% (97.1 ± 9.4) of prescribed dose. Liver and lung sites had a higher D50 compared with other sites. Pelvic sites had a lower variability indicated by HI (0.13 ± 1.21). Variability in D50 is 101.2 ± 8.5, 103.4 ± 6.8, 103.4 ± 8.2, and 109.5 ± 11.5 for IMRT, tomotherapy, volume modulated arc therapy, and stereotactic body radiation therapy with IMRT, respectively. CONCLUSIONS: Nearly 95% of patient treatments deviated from the ICRU-83 recommended D50 prescription dose delivery. This variability is significant (P < .01) in terms of treatment site, technique, and institution. To reduce dosimetric and associated radiation outcome variability, dose prescription in every clinical trial should be unified with international guidelines.

Interrater reliability of a near-miss risk index for incident learning systems in radiation oncology.

PURPOSE: Tools for assessing the severity and risk of near-miss events in radiation oncology are few and needed. Recent work has described guidelines for the use of a 5-tier near-miss risk index (NMRI) for the classification of near-miss events. The purpose of this study was to assess the reliability of the NMRI among users in a radiation oncology department. METHODS AND MATERIALS: Reliability of the NMRI was assessed using an online survey distributed to members of a radiation oncology department. The survey contained 70 events extracted from the department's incident learning system (ILS). Survey participants rated each event using the NMRI guidelines, reported their attendance to weekly ILS meetings (used as a surrogate for familiarity with the ILS), and indicated their familiarity with the radiation oncology workflow. Interrater reliability was determined using Krippendorff's alpha. Use of the NMRI to rate actual events during 5 weekly ILS meetings was also assessed and interrater reliability determined. RESULTS: Twenty-eight survey respondents represented a wide variety of care providers. Krippendorff's alpha was calculated for the whole respondent cohort to be 0.376, indicating fair agreement among raters. Respondents who had the most participation at ILS meetings (n = 4) had moderate agreement with an alpha of 0.501. Interestingly, there were significant differences in reliability and median NMRI scores between professions. NMRI use during weekly NMRI meetings (80 events rated), participants showed moderate reliability (alpha = 0.607). CONCLUSIONS: Using the NMRI guidelines, raters from a wide variety of professions were able to assess the severity of near-miss incidents with fair agreement. Those experienced with the ILS showed better agreement, and higher agreement was seen during multidisciplinary ILS meetings. These data support the use the indices such as the NMRI for near-miss risk assessment in patient safety and prioritization of process improvements in radiation oncology.

Targeting safety improvements through identification of incident origination and detection in a near-miss incident learning system.

PURPOSE: Radiation treatment planning involves a complex workflow that has multiple potential points of vulnerability. This study utilizes an incident reporting system to identify the origination and detection points of near-miss errors, in order to guide their departmental safety improvement efforts. Previous studies have examined where errors arise, but not where they are detected or applied a near-miss risk index (NMRI) to gauge severity. METHODS: From 3/2012 to 3/2014, 1897 incidents were analyzed from a departmental incident learning system. All incidents were prospectively reviewed weekly by a multidisciplinary team and assigned a NMRI score ranging from 0 to 4 reflecting potential harm to the patient (no potential harm to potential critical harm). Incidents were classified by point of incident origination and detection based on a 103-step workflow. The individual steps were divided among nine broad workflow categories (patient assessment, imaging for radiation therapy (RT) planning, treatment planning, pretreatment plan review, treatment delivery, on-treatment quality management, post-treatment completion, equipment/software quality management, and other). The average NMRI scores of incidents originating or detected within each broad workflow area were calculated. Additionally, out of 103 individual process steps, 35 were classified as safety barriers, the process steps whose primary function is to catch errors. The safety barriers which most frequently detected incidents were identified and analyzed. Finally, the distance between event origination and detection was explored by grouping events by the number of broad workflow area events passed through before detection, and average NMRI scores were compared. RESULTS: Near-miss incidents most commonly originated within treatment planning (33%). However, the incidents with the highest average NMRI scores originated during imaging for RT planning (NMRI = 2.0, average NMRI of all events = 1.5), specifically during the documentation of patient positioning and localization of the patient. Incidents were most frequently detected during treatment delivery (30%), and incidents identified at this point also had higher severity scores than other workflow areas (NMRI = 1.6). Incidents identified during on-treatment quality management were also more severe (NMRI = 1.7), and the specific process steps of reviewing portal and CBCT images tended to catch highest-severity incidents. On average, safety barriers caught 46% of all incidents, most frequently at physics chart review, therapist's chart check, and the review of portal images; however, most of the incidents that pass through a particular safety barrier are not designed to be capable of being captured at that barrier. CONCLUSIONS: Incident learning systems can be used to assess the most common points of error origination and detection in radiation oncology. This can help tailor safety improvement efforts and target the highest impact portions of the workflow. The most severe near-miss events tend to originate during simulation, with the most severe near-miss events detected at the time of patient treatment. Safety barriers can be improved to allow earlier detection of near-miss events.

Can emergent treatments result in more severe errors?: An analysis of a large institutional near-miss incident reporting database.

PURPOSE: Emergent radiation treatments may be subject to more errors because of the compressed time frame. Few data exist on the magnitude of this problem or how to guide safety improvement interventions. The purpose of this study is to examine patterns of near-miss events in emergent treatments using a large institutional incident reporting system. METHODS AND MATERIALS: Events in the incident reporting database from February 2012 to October 2013 were reviewed prospectively by a multidisciplinary team to identify emergent treatments. Reports were scored for potential near-miss risk index (NMRI) on a 0 to 4 scale. Workflow steps of where events originated and were detected were analyzed. Events were categorized by use of the causal factor system from the Radiation Oncology Incident Learning System. Mann-Whitney U tests were used to compare mean NMRI score, and Fisher exact tests were performed to compare the proportion of high-risk events between emergent and nonemergent treatments and between emergent treatments on weekdays and weekends or holidays. RESULTS: Over the study period, approximately 1600 patients were treated, 190 of them emergently. Seventy-one incident reports were submitted for 55 unique patients. Fewer events were reported for emergent treatments than for nonemergent treatments (0.37 events per new treatment vs 0.86; P < .01). Mean risk index for emergent reports was 1.90 versus 1.48 for nonemergent reports (P < .01). Rate of NMRI 4 was 10% for emergent treatments versus 4% for nonemergent treatments (P < .01). Emergent treatments started on a weekend or holiday had a higher proportion of critical near-miss events than emergent treatments started during the week (37% vs 7.9%, P = .034). CONCLUSIONS: In this study, fewer near-miss incidents were reported per treatment course for emergent treatments. This may be attributable to reporting bias. More importantly, when emergent near misses occur, they are of greater severity.

Metrics of success: Measuring impact of a departmental near-miss incident learning system.

PURPOSE: There is a growing interest in the application of incident learning systems (ILS) to radiation oncology. The purpose of the present study is to define statistical metrics that may serve as benchmarks for successful operation of an incident learning system. METHODS AND MATERIALS: A departmental safety and quality ILS was developed to monitor errors, near-miss events, and process improvement suggestions. Event reports were reviewed by a multiprofessional quality improvement committee. Events were scored by a near-miss risk index (NMRI) and categorized by event point of origination and discovery. Reporting trends were analyzed over a 2-year period, including total number and rates of events reported, users reporting, NMRI, and event origination and discovery. RESULTS: A total of 1897 reports were evaluated (1.0 reports/patient, 0.9 reports/unique treatment course). Participation in the ILS increased as demonstrated by total events (2.1 additional reports/month) and unique users (0.5 new users/month). Sixteen percent of reports had an NMRI of 0 (none), 42% had an NMRI of 1 (mild), 25% had an NMRI of 2 (moderate), 12% had an NMRI of 3 (severe), and 5% had an NMRI of 4 (critical). Event NMRI showed a significant decrease in the first 6 months (1.68-1.42, P < .001). Trends in origination and discovery of reports were broadly distributed between radiation therapy process steps and staff groups. The highest risk events originated in imaging for treatment planning (NMRI = 2.0 ± 1.1; P < .0001) and were detected in on-treatment quality management (NMRI = 1.7 ± 1.1; P = .003). CONCLUSIONS: Over the initial 2-year period of ILS operation, rates of reporting increased, staff participation increased, and NMRI of reported events declined. These data mirror previously reported findings of improvement in safety culture endpoints. These metrics may be useful for other institutions seeking to create or evaluate their own ILS.

Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique.

Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course.

Measurable improvement in patient safety culture: A departmental experience with incident learning.

PURPOSE: Rigorous use of departmental incident learning is integral to improving patient safety and quality of care. The goal of this study was to quantify the impact of a high-volume, departmental incident learning system on patient safety culture. METHODS AND MATERIALS: A prospective, voluntary, electronic incident learning system was implemented in February 2012 with the intent of tracking near-miss/no-harm incidents. All incident reports were reviewed weekly by a multiprofessional team with regular department-wide feedback. Patient safety culture was measured at baseline with validated patient safety culture survey questions. A repeat survey was conducted after 1 and 2 years of departmental incident learning. Proportional changes were compared by χ(2) or Fisher exact test, where appropriate. RESULTS: Between 2012 and 2014, a total of 1897 error/near-miss incidents were reported, representing an average of 1 near-miss report per patient treated. Reports were filed by a cross section of staff, with the majority of incidents reported by therapists, dosimetrists, and physicists. Survey response rates at baseline and 1 and 2 years were 78%, 80%, and 80%, respectively. Statistically significant and sustained improvements were noted in several safety metrics, including belief that the department was openly discussing ways to improve safety, the sense that reports were being used for safety improvement, and the sense that changes were being evaluated for effectiveness. None of the surveyed dimensions of patient safety culture worsened. Fewer punitive concerns were noted, with statistically significant decreases in the worry of embarrassment in front of colleagues and fear of getting colleagues in trouble. CONCLUSIONS: A comprehensive incident learning system can identify many areas for improvement and is associated with significant and sustained improvements in patient safety culture. These data provide valuable guidance as incident learning systems become more widely used in radiation oncology.

Radiation treatment for newly diagnosed esophageal cancer with prior radiation to the thoracic cavity.

The purpose of this report is to communicate the use of single-positron emission computed tomography scan in planning radiation treatments for patients with a history of radiation to the thoracic cavity. A patient presented with obstructive esophageal cancer, having previously received chemotherapy and radiation therapy to the mediastinum for non-Hodgkin lymphoma 11 years earlier. Owing to a number of comorbidities, the patient was not a surgical candidate and was referred to the University of Washington Medical Center for radiation therapy. Prior dose to the spinal cord and lung were taken into account before designing the radiation treatment plan.

A case study of radiotherapy planning for Intensity Modulation Radiation Therapy for the whole scalp with matching electron treatment.

The purpose of this report is to communicate a technique to match an electron field to the dose distribution of an Intensity-Modulated Radiation Therapy (IMRT) plan. A patient with multiple areas of squamous cell carcinoma over the scalp was treated using 60 Gy in 2.0-Gy fractions to the entire scalp and first echelon nodes with multiple 6-MV photon fields. To deliver an adequate dose to the scalp, a custom 1.0-cm bolus helmet was fashioned using a solid piece of aquaplast. Along with the IMRT scalp treatment, a left zygoma area was treated with electrons matching the anterior border of the IMRT dose distribution. The border was matched by creating a left lateral field with the multileaf collimator shaped to the IMRT dose distribution. The result indicated an adequate dose to the skin match between the IMRT plan and the electron field. Results were confirmed using optically stimulated luminescence placed at the skin match area, so that the dose matched the prescription within 10%.