Patterns of quality assurance and treatment planning for stereotactic body radiation therapy in India - A survey

The use of stereotactic body radiation therapy (SBRT) is an increasing trend in the country. The aim of this study is to gain knowledge on patterns of quality assurance (QA) and treatment planning (TP) aspects with respect to SBRT. A questionnaire with multiple choice was designed to determine practices of SBRT covering areas such as years of experience, type of linear accelerator, tumor-motion strategies, calculation algorithm used in the TP system (TPS), the protocol used for small field dosimetry, the detector used for small field dosimetry and QA, respiratory management during delivery. The survey was sent to all radiotherapy institutes in the country having a minimum of one linear accelerator, and responses were analyzed. From June 2022 to December 2022, 265 responses to the SBRT survey were received with response rate as 60.4%. The most common reason for not adopting SBRT was reported as a lack of capability of treatment machines to deliver SBRT (61.6%). Lung (81.1%) was the most practiced site. The most common delivery unit was a conventional linear accelerator (83%); 6 MV FFF (85.7%) was mostly used energy; volumetric-modulated arc radiotherapy (VMAT) (91.5%) was mostly used delivery technique; most of the equipment (more than 91.5%) used multileaf collimator (MLC) leaf width ≤5 mm. The most popular methods used for motion strategies during computed tomography (CT) were motion-encompassing and breath-hold techniques used by 65 (62.5%) and 62 (59.6%) respondents, respectively. The most popular method used for respiratory management during delivery was breath-hold by 55 (52.4%) respondents. Most TPS are equipped with either Type-C or Type-B algorithms. Heterogeneity was observed in the QA protocol and acceptance criteria for analysis of patient-specific QA. The survey resulted in heterogeneity in QA and TP aspects among users of SBRT and demands for harmonizing the dosimetric aspects of SBRT in the country.