A national survey on technology and quality assurance for stereotactic body radiation therapy

Stereotactic body radiation therapy (SBRT) for early stage solid tumors and metastases is increasing worldwide. In 2013, the Italian Association of Medical Physicists (AIFM) created a working group in order to standardize the SBRT dosimetric aspects (AIFM/SBRT-WG). The aim of this study was to investigate the current status of technology and quality assurance (QA) as regards SBRT in Italy. Clinical evaluation of SBRT was beyond the scope of the present study.

A pre-questionnaire was designed by three medical physicists expert in SBRT. It contained questions on 4 main aspects: technology, image-guidance solutions (IGRT), treatment planning system commissioning and QA. In early 2018, all the centers involved in the AIFM/SBRT-WG were invited to complete the online questionnaire.

The survey was undertaken by 45 centres (83% of them involved in the AIFM/SBRT-WG). The most available delivery system was conventional linacs with VMAT modality; 6MV and 6MV-FFF were the most common energies; robotic couch was available in 56% of centers; CBCT/MVCT was the most used IGRT technique (58% of centers) and 40% of centers adopted respiratory management during treatment delivery. The smallest measured field size for lateral beam profiles was ≤1 × 1 cm² in 79% of linac-based centers. Great heterogeneity in terms of protocols and guidelines for QA were found. A large number of centers (51%) felt the need to upgrade their dosimetric QA devices dedicated to SBRT.

This survey on SBRT is a starting point in standardizing the dosimetry of SBRT verification and to improve the QA procedure.