Evaluation of the 3D Dosimetry of the Nucletron MHDR-V2 Source Using PRESAGETM Dosimeters
O Huang1*, J Adamovics2, G Ibbott3, (1) UT MD Anderson Cancer Center, Houston, TX, (2) Heuris Pharma LLC, Skillman, NJ, (3) UT MD Anderson Cancer Center, Houston, TXSU-E-T-67 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To characterize PRESAGE™ dosimeters for interstitial sources through comparison of direct measurements of the 3D dose parameters of Nucletron mHDR-v2 sources to published dose parameters in AAPM Report No. 229. This project aims to establish PRESAGE™ as an accurate brachytherapy dosimeter and investigates an effective technique in 3D dosimetry.
Methods:PRESAGE™ dosimeters are solid, polyurethane-based dosimeters doped with radiochromic leuco-dyes that produce a linear optical-density response to dose. Dosimeters were scanned prior to irradiation to measure background signal. To eliminate potential imaging artifacts due to oversaturated responses in the immediate range of the source, channels 0.4cm and 1.4cm in diameter and 6cm depth were cast in the center of PRESAGE™ dosimeters 9.5cm in height and 11.6cm in diameter. Polyurethane plugs of the same dimensions as the channels were inserted into the dosimeters during irradiation and the HDR catheter positioned in the center of the plug. The irradiation times of 10 and 35 seconds for the 0.4 cm-channel and 1.4 cm-channel dosimeters resulted in doses of 3 Gy at y=0.5cm and y=1cm respectively. After irradiation, the plugs were removed and the dosimeters were scanned with an optical-CT scanner. The reconstructed pre- and post-irradiation images were subtracted and exported to CERR for dose measurements. The calculated dose rates were normalized to the dose rate values at y=1cm and y=1.5cm for the 0.4 cm-channel and 1.4 cm-channel dosimeters.
Results:Comparing measured to published dose rates, the average absolute percent differences were approximately 25.8% (stdev. 6.4%) and 12.8% (stdev. 2.8%) for the 0.4cm and 1.4 cm-channel dosimeters respectively.
Conclusion:Initial results suggest PRESAGE™ with optical-CT has high potential in measuring accurate 3D dosimetry of Nucletron mHDR-v2 sources. The 1.4 cm-channel dosimeters measured more accurate results, perhaps due to the increased dwell time and dose delivered. Characterization of PRESAGE™ with a low-dose-rate source will follow.