Safe High Dose Rate Brachytherapy (HDR-BT) requires quality assurance/quality control (QA/QC) according to IPEM and ESTRO recommendations. Recent advances in real-time dosimetry and related developments of QA, QC and in vivo dosimetry (IVD) systems have offered new possibilities for effective independent treatment verification, and thus for improving the patient safety.

This paper briefly reports the state of the art of different QA and QC approaches and systems. It also presents our related studies, carried out within the framework of DoRGaN research project, which have led to two proposed instruments: a QA pretreatment instrumented phantom and a QC gynecological applicator. Both systems implement a real-time dwell-source distance-measuring approach using multiple Gallium Nitride (GaN) dosimetry probes. First prototypes have been designed and tested. Their characteristics (including those of the employed GaN probes) are evaluated in comparison with the state of the art.

For developing systems for HDR-BT, the GaN probe has been shown to meet requirements for high sensitivity, high measurement rate, small response anisotropy and large dose measurement range. The proposed QA instrumented phantom has comparable or better characteristics when compared with diode-based and Al₂O₃:C-based systems. The other QC gynecological applicator has higher time and spatial resolutions than the state-of-the-art IVD systems, which proves that it is suitable for real-time monitoring of HDR-BT physical parameters.