A structured FMEA approach to optimizing combinations of plan‐specific quality assurance techniques for IMRT and VMAT QA

Abstract

BackgroundMany commercial tools are available for plan‐specific quality assurance (QA) of radiotherapy plans, with their functionality assessed in isolation. However, multiple QA tools are required to review the full range of potential errors. It is important to assess their effectiveness in combination with each other to look for ways to both streamline the QA process and to make certain that errors of high impact and/or high occurrence are caught before reaching patient treatment.PurposeTo develop a structured method to assess the effective risk reduction of combinations of QA methods for IMRT/VMAT treatments.MethodsFirst, a structured prospective risk assessment was performed to establish the major failure modes (FMs) of IMRT/VMAT QA, and assign occurrence (O), severity (S), and baseline detectability (BD) rankings to them. The baseline assumed that chart checks and linear accelerator QA was performed, but no plan‐specific secondary dose calculation or measurement was done. Second, the detectability of each FM for two secondary dose calculation methods and four plan measurement methods (point‐based dose calculation, Monte‐Carlo‐based dose calculation, 2D fluence‐based measurement, 2.5D phantom‐based measurement, log file analysis with dose recalculation, and log file analysis combined with MLC QA) was determined. Third, we used a minimum detectability approach in addition to each FM's occurrence and severity to determine the optimal combination of QA methods. We analyzed the cumulative risk priority number of eight combinations of QA methods. The analysis was done on (1) all FMs, (2) FMs with high severity, (3) FMs with high‐risk priority numbers (RPN) of O*S*BD, and (4) on FMs with both high severity and high RPN.ResultsOur analysis resulted in 54 FMs, including commissioning, planning, data transfer, and linear accelerator failures. 1D secondary dose calculation plus measurement provided a 19%–22% risk reduction from baseline. 1D/3D secondary dose calculation plus log files created a 25%–32% reduction. 3D secondary dose calculation plus measurement resulted in a 27%–34% reduction. 3D secondary dose calculation plus log files with additional machine QA provided the greatest reduction of 31%–42%.ConclusionThis novel structured approach to comparing combinations of QA methods will allow us to optimize our procedures, with the goal of detecting all clinically significant FMs. Our results show that log‐file QA with 3D dose recalculation and supplemental machine QA provides better risk reduction than measurement‐based QA. This work builds evidence to justify reducing or eliminating measurement‐based PSQA with an independent 3D dose verification, log‐file measurement, and appropriate supplementation of machine QA. The process also highlights FMs that cannot be caught by pre‐treatment QA, prompting us to consider future directions for on‐treatment QA.

Dosimetric evaluation in Helical TomoTherapy for lung SBRT using Monte Carlo‐based independent dose verification software

“…Several present studies have been reported that combining various QA tools improves the sensitivity of error detection. 20,34,35 O'Daniel et al assessed the effective risk reduction of combinations of QA methods for IMRT/VMAT treatments. 34 They showed that the MC-based secondary dose calculation was available to reduce the overall risk.…”

“…20,34,35 O'Daniel et al assessed the effective risk reduction of combinations of QA methods for IMRT/VMAT treatments. 34 They showed that the MC-based secondary dose calculation was available to reduce the overall risk. The utilization of softwarebased QA facilitated the identification of dosimetric errors caused by small targets and heterogeneities that were not detected by conventional measurement-based QA approaches.Therefore,independent verification with DoseCHECK or other Monte Carlo codes should be an important role in lung SBRT with HT.…”

Guía para el control de calidad y seguridad en aceleradores lineales de uso clínico

“…En esta evaluación de variación del perfil de riesgo, debe tenerse en cuenta no solamente el CC del acelerador lineal sino la combinación de todos los métodos de aseguramiento de calidad empleados como por ejemplo las verificaciones de planes. 41 A título orientativo se incluyen unas tablas con recomendaciones de frecuencias y tolerancias, de aplica-ción a los aceleradores representativos del estado de la tecnología en estos momentos en nuestro país, queremos recalcar que se trata de unas recomendaciones de mínimos. Los modelos de acelerador que pueden considerarse representativos de sus marcas son el TrueBeam® (Varian Medical Systems, Palo Alto, CA) y el Versa HD™ (Elekta AB, Stockholm,Sweden) según los colaboradores de los fabricantes consultados por el GTCCAL.…”

Evaluation of Fused Deposition Modeling Materials for 3D-Printed Container of Dosimetric Polymer Gel

“…The transformative influence of 3D printing technology is especially conspicuous in the realm of radiotherapy, where its applications span various treatment modalities, including photon, electron, and proton therapies [4][5][6][7]. Accurate dose verification and patient-specific quality assurance (PSQA) are becoming more important, as the complexity of radiation therapy has continuously increased, such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) [8,9]. This importance extends to stereotactic radiotherapy techniques like stereotactic radiosurgery and stereotactic body radiotherapy (SBRT), where ensuring precise dose delivery prior to treatment is paramount [10,11].…”