Imaging of HDR brachytherapy dose distributions using NMR Fricke-gelatin dosimetry

The application of NMR Fricke-gelatin dosimetry to the imaging of dose distributions around high dose rate (HDR) radioactive Ir-192 seeds in brachytherapy is presented. The duration of the irradiations required to give changes of the Fricke-gelatin NMR characteristics, which were readily detected by the magnetic resonance imager, typically ranged from 4 to 25 min for single source and multiple source (33 source positions distributed among three catheters) geometries, respectively. A fast approach for determining radiation dose from MR image intensity using a calibration curve is described. NMR Fricke-gel dosimetry is shown to be a viable means of verifying the dose distributions from brachytherapy sources.