Speaker
Description
The clinical introduction of magnetic resonance-guided linear accelerators (MR-Linacs) in 2017 represents, to date, one of the most promising techniques for cancer treatment. By combining the high soft-tissue contrast provided by MRI with a linear accelerator, these systems allow for precise radiation delivery, real-time target visualization and tracking, and the potential reduction of treatment margins. However, the presence of a strong transverse magnetic field significantly changes the behavior of dose-depositing secondary electrons due to the Lorentz force. This phenomenon complicates dose distribution and makes standard dosimetry more challenging than in conventional accelerators. Therefore, precise quality assurance (QA) is an essential step to ensure that the radiation dose is delivered accurately to the tumor while preserving the surrounding healthy organs.
Despite numerous investigations aimed at identifying the most suitable detector for relative dosimetry in MR-Linacs, none of the currently available options fully fulfill all the clinical requirements. An ideal detector for these systems should offer a real-time response, tissue equivalence, and high spatial resolution, while being MR-compatible and suitable for both small and large radiation fields. Furthermore, improving QA protocols is vital for clinical workflow; reducing equipment verification time is necessary to manage the ever-increasing number of cancer patients while maintaining high treatment standards.
In this work, we review the current commercial and non-commercial solutions used for quality assurance in MR-Linac systems. By highlighting the advantages and disadvantages of these technologies, we identify the existing gaps that must be addressed for future QA solutions. Additionally, we present a potential detector for MR-Linac dosimetry consisting of a plastic scintillator screen coupled with a complementary metal-oxide-semiconductor (CMOS) camera. This proposed system aims to provide a practical, high-resolution solution tailored to the specific physical and clinical requirements of modern MR-guided radiation therapy.