ESTRO 2024 - Abstract Book

S4929

Physics - Quality assurance and auditing

ESTRO 2024

3022

Digital Poster

Automation of the Rotation Period quality control test of a Tomotherapy linear accelerator

Jorge Alonso Muriedas 1 , Rodrigo Astudillo Olalla 2 , Noelia Suárez Álvarez 2 , Fernando Gómez Enríquez 3 , Guillermo Camacho de la Vega 2 , Ana Reguilón Martín 2 , Javier Uzquita López 2 , Marina Gutiérrez Ruiz 2 , María Teresa Pacheco Baldor 2 , José Andrés Vázquez Rodríguez 2 , Samuel Ruiz Arrebola 2 , Juan Ignacio Raba Diez 2 , Rosa Fabregat Borrás 2 , Paula Delgado Tapia 2 1 Hospital Universitario de Cruces, Unidad de Radiofísica y Protección Radiológica, Baracaldo, Spain. 2 Hospital Universitario Marqués de Valdecilla, Servicio de Oncología Radioterápica, Santander, Spain. 3 Complejo Asistencial de Zamora, Servicio de Radiofísica, Zamora, Spain

Purpose/Objective:

Tomotherapy enables the delivery of helical treatments in radiotherapy, resulting in high conformity of the tumor and sparing dose at the surrounding organs at risk. The treatment planning system calculates the rotation period for each treatment based on the dose per session, overlap, and jaw aperture. An incorrect rotation period would lead to a dose distribution different from the calculated one due to a miscoordination between the multileaf collimator system (MLC), the position of the gantry and patient position. Therefore, assessing the accuracy and reproducibility of the system's rotation period is a crucial aspect to control The objective of this work is to automate the analysis of data collected from this test to streamline the quality control process for this equipment and provide an independent verification, independent from that proposed by the manufacturer.

Material/Methods:

The rotation period of an Accuray Radixact Tomotherapy linear accelerator was verified using two A1SL ion chambers from Standard Imaging and the Tomo HE from SunNuclear. This phantom includes various inserts along a transversal plane where the chambers can be inserted. The phantom was irradiated with treatment plans while the table was fixed, and for rotation periods of 12s, 20s, 30s, and 40s, during which the chambers continuously recorded measurements. The experimental setup is illustrated in Figure 1 [1]. Measurement data from the chambers were acquired using TEMS software with a sampling time of 100ms.

The chambers show peaks in their measurements each time the head passes closest to them. By measuring the time intervals between these peaks, the rotation period of the equipment can be determined.

Automated analysis was carried out using an in-house Python program. This program visualizes the data, identifies the peaks and calculates the mean of the differences between peaks. Consequently, the equipment's rotation period is automatically obtained by inputting the data file into the program.