Recommendations for Quality Assurance Guidelines for Gamma Knife Radiosurgery in Republic of Korea : A Multi-institutional Survey.

Objective: The Leksell Gamma Knife (LGK) is one of the most precise radiosurgical tools available. However, the quality assurance (QA) practices for LGK vary considerably across institutions in Korea. In this study, we aim to identify and standardize key QA items, categorized into daily, monthly, biannual, and annual protocols, based on a nationwide survey conducted at 16 medical centers. Additionally, the tolerance values for each QA items were reviewed, comparing them with the American Association of Physicists in Medicine Task Group (TG-178), and tailored to establish distinct Korean Gamma Knife Radiosurgery (GKRS) tolerances reflecting local standards and regulatory requirements.

Methods: The survey focused on QA practices for the LGK Icon™/Esprit™ and Perfexion™ systems. The QA items were categorized into daily, monthly, biannual, and annual tasks in accordance with the guidelines set by TG-178. Sixteen participating institutions were asked to rate the importance of each QA item on a scale of 0 (not important) to 5 (extremely important). Items rated 4 or 5 were selected to create a national priority list.

Results: Eleven daily, six monthly, and three annual QA items were identified as high priority. Daily QA tasks primarily focused on radiation and patient safety, whereas the monthly tasks were largely related to dosimetric validation. Annual QA emphasizes mechanical and dosimetric checks. Biannual evaluations were not prioritized as they were routinely performed by the manufacturer's maintenance service (Elekta AB, Stockholm, Sweden).

Conclusion: We succeeded in making recommendations for Gamma Knife QA standardization in Korea. Continuous QA updates are essential to ensure treatment safety, particularly with the introduction of new LGK models. These findings may contribute to the development of unified national QA guidelines for GKRS.