Medical applications extensively use ionizing radiation of various energies for therapeutic and diagnostic purposes. Minimizing radiation doses to healthy tissue is imperative, leading to the implementation of crucial quality assurance (QA) procedures. Luminescent materials, especially lanthanide-activated NaREF4 radioluminescent nanoparticles (RLNPs), are promising for QA procedures. These RLNPs exhibit charge carrier trapping upon exposure to ionizing radiation, resulting in a dose-dependent luminescence signal. However, the RLNP sensitivity is currently insufficient, and the charge trapping is unstable at room temperature which causes information loss over time. This project aims to stabilize charge trapping and enhance sensitivity of the RLNPs to reduce QA-procedure time in low-dose-rate applications. Secondly we strive to obtain a self-referenced, dose-dependent luminescence signal capable of distinguishing between various ionizing radiation energies to ensure a proper correction can be applied in applications with a varying radiation energy. This will be achieved through a systematic spectroscopic investigation to uncover the RLNP charge trapping mechanism, facilitating the synthesis of customized RLNPs for QA-procedures. Testing the resulting dosimeters in different clinical setups, including mammography, X-ray diagnostics, cobalt and cesium sources, ensures a thorough evaluation of RLNP-loaded films under clinically relevant conditions.