Radionuclide dosimetry with radiochromic gels: a feasibility study

Radiochromic gel dosimeters were studied with respect to their potential as tools to validate Monte Carlo models and procedures used in molecular radiotherapy (MRT). The Fricke xylenol orange gel (FX gel) and the Turnbull Blue dye gel (TB gel) containing typical carriers of selected radionuclides used in MRT were examined. ¹⁷⁷Lu was the only radionuclide that did not impair the optical, chemical or dosimetric properties of the FX gel. The TB gel was found unusable altogether because all of the carriers tested either brought about a significant increase in the gel's spontaneous background or caused gel precipitation. The difference between the absorbed dose-to-water observed by using the FX gel with ¹⁷⁷Lu and the results of the Monte Carlo simulation using the MCNPX™ code was about 10%. However, the measurement uncertainty was so high that it precluded the use of the gel for validation of the Monte Carlo results.