# In Situ Dose Measurements in Brachytherapy Using Scintillation Detectors Based on the Al2O3:C, Al2O3:C,Mg, and GAGG:Ce Crystals

## TL;DR

This study tests scintillation crystals for real-time radiation dose measurements during brachytherapy, showing promising linear responses for accurate in situ monitoring.

## Contribution

The study introduces and evaluates Al2O3:C, Al2O3:C,Mg, and GAGG:Ce crystals for in situ brachytherapy dosimetry using fiber-optic detection.

## Key findings

- GAGG:Ce crystals showed excellent linearity in dose-response measurements.
- Al2O3:C and Al2O3:C,Mg crystals demonstrated nearly linear dose–response relationships.
- Measurements were conducted in a clinical phantom using a 192Ir source under realistic conditions.

## Abstract

Currently, the use of scintillation crystals connected via optical fiber to a luminescence spectrometer (so-called fiber-optic dosimeters) offers a promising approach for real-time dosimetric measurements during brachytherapy treatments with γ-ray sources. This study aims to evaluate the applicability of fiber-optic dosimeters for in situ dose measurements during brachytherapy procedures, using Al2O3:C and Al2O3:C,Mg crystals, which have near-tissue density and effective atomic number (ρ = 3.99 g/cm3, Zeff = 10.8), as well as heavy GAGG:Ce scintillation crystals (ρ = 6.63 g/cm3, Zeff = 54.4). Radiation dose delivery was assessed through measurements of the resulting radioluminescence of the aforementioned scintillation crystals, connected via long optical fibers and recorded with highly sensitive, compact luminescence spectrometers. Measurements were performed in a dedicated phantom under clinical conditions at the Oncology Center in Bydgoszcz, Poland. The dosimeters were evaluated for in situ dose monitoring within the 0.5–8 Gy range during brachytherapy procedures using a 192Ir (392 keV) source. The results showed a clear linear relationship between the delivered radiation dose and the scintillation output measured by the fiber-optic detector. The Gd3Al2.5Ga2.5O12:Ce crystal detector exhibited excellent linearity, while the Al2O3:C and Al2O3:C,Mg crystal detectors also showed a nearly linear dose–response relationship.