ESTRO 2025 - Abstract Book

S3630

Physics - Quality assurance and auditing

ESTRO 2025

Purpose/Objective: Statistical Process Control (SPC) is a widely used methodology to enhance the efficacy of quality assurance methods in healthcare industry. We report the results of the adoption of SPC for routine quality assurance on two Elekta medical linear accelerators in radiotherapy in a eight-years period. Material/Methods: We present the analysis of the application of SPC to the daily beam dose output, symmetries and flatness for the photon beam energies of two different Elekta linacs (Precise and VersaHD) from 2016 to 2023. Shewhart-type control charts and capability indices (C p , C pk and C pm ) were applied to these processes. Customized action limits were determined using the process capability index C pm . A Gage R&R analysis was performed to assess the capability of the ion-camber measuring devices. Results: The spread of data distribution of all items for the Precise linac were about twice of those of the VersaHD. At a 2% specification level, the process capability ratios ranged from 0.8 to 3.3 for the Precise linac and from 1.1 to 3.9 for the VersaHD linac. For the dose output items, mean C pm were 1.35 and 1.01 for the two linacs, indicating that the processes operate at a sigma level equal to 4 and 3, respectively. Using the C pm index, the action limits were found to be of the order of ±1.0% for both linacs. The transverse symmetry process was found out of control at 1% specification for both linacs.

Conclusion: SPC quantitatively assessed the inherent variability of the linac output, indicating the ability to maintain photon beam parameters under control with regard to clinical specifications. This approach can be used to customize the optimal QA tolerance levels, able to improve the standard of therapy delivery and ultimately patient safety and outcomes.

Keywords: Statistical control process, linac QA

2010

Digital Poster Implementation of the Quality Assurance Protocol for a Magnetic Resonance Imaging (MRI) Simulator System Miguel Torres López, Pedro Matías Liñán Rodríguez, Ruth Rodríguez Romero, Patricia Sánchez Rubio, Carmen Escalada Pastor, Alfredo Montes Uruén, Luis Alejo Luque, Julia Orive Escalada Servicio de Radiofísica Hospitalaria y Protección Radiológica, Hospital Universitario Puerta de Hierro de Majadahonda, Majadahonda, Spain Purpose/Objective: The increasing use of magnetic resonance (MR) images for volume delineation and absorbed dose calculation in radiotherapy has led to the development of MRI systems adapted for treatment conditions, known as MR