Towards comprehensive characterization of Cs-137 Seeds using PRESAGE? dosimetry with optical tomography

7th International Conference on 3D Radiation Dosimetry

Adamson, J.^1 ; Yang, Y.^1 ; Rankine, L.^1 ; Newton, J.^1 ; Adamovics, J.^2 ; Craciunescu, O.^1 ; Oldham, M.^1

Dept. of Radiation Oncology, Duke University Medical Center, Box 3295, Durham, NC 27710, United States^1

Dept. of Chemistry, Rider University, Lawrenceville, NJ 08648, United States^2

关键词: Brachytherapy;    Comprehensive measurement;    High dynamic range;    Large field of views;    Measurement accuracy;    Postirradiation;    Radial dose;    Source orientations;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/444/1/012100/pdf
DOI  :  10.1088/1742-6596/444/1/012100

来源: IOP

【 摘 要 】

We describe a method to directly measure the radial dose and anisotropy functions of brachytherapy sources using polyurethane based dosimeters read out with optical CT. We measured the radial dose and anisotropy functions for a Cs-137 source using a PRESAGE® dosimeter (9.5cm diameter, 9.2cm height) with a 0.35cm channel drilled for source placement. The dosimeter was immersed in water and irradiated to 5.3Gy at 1cm. Pre- and post-irradiation optical CT scans were acquired with the Duke Large field of view Optical CT Scanner (DLOS) and dose was reconstructed with 0.5mm isotropic voxel size. The measured radial dose factor matched the published fit to within 3% for radii between 0.5-3.0cm, and the anisotropy function matched to within 4% except for θ near 0° and 180° and radii >3cm. Further improvements in measurement accuracy may be achieved by optimizing dose, using the high dynamic range scanning capability of DLOS, and irradiating multiple dosimeters. Initial simulations indicate an 8 fold increase in dose is possible while still allowing sufficient light transmission during optical CT. A more comprehensive measurement may be achieved by increasing dosimeter size and flipping the source orientation between irradiations.