3D dosimetry for brachytherapy and heterogeneities

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

“…Accurate and comprehensive measurement of dose distributions about brachytherapy sources remains a challenging yet relevant problem. Varying dose rates and complex distributions about these sources require a measurement system capable of high spatial accuracy and resolution, and large dynamic range [ 1 ]. Due to these challenges, most published characterizations of brachytherapy sources rely heavily on Monte Carlo simulations with experimental verification at select points [ 2 ].…”

“…3D dosimetry has potential to provide a more comprehensive verification. A number of studies have investigated gel dosimetry for brachytherapy [ 3 , 4 ]; sensitivity of the polymerization process to oxygen, energy dependence (for low energy sources), and diffusion of monomers across steep dose gradients close to the source are challenges to achieving accurate results [ 1 ]. Another 3D dosimeter, PRESAGE® (Heuris Inc, NJ) [ 3 , 5 ], is a polyurethane based dosimeter that is solid and transparent.…”

Mathematical Modeling of the Response of Polymer Gel Dosimeters to HDR and LDR Brachytherapy Radiation

“…Brachytherapy involves implanting multiple radioactive seeds in the human body 2, 3. Because bones and soft tissues have heterogeneous structures, it is difficult for medical physicists to predict the exact 3D dose distribution that will be delivered within and near the tumor 9, 30–32. As a result, they need 3D dosimetry tools to help them plan and achieve better brachytherapy treatments 33–36.…”

“…As a result, they need 3D dosimetry tools to help them plan and achieve better brachytherapy treatments 33–36. Also PAG dosimeters may be useful in characterizing the basic radiation dose properties of new brachytherapy seeds,22, 32, 37–39 [e.g., to determine the seed anisotropy factor for nonspherical seeds,40 which is included in Equation 1 below].…”

“…As shown in Figure 4(a) and (b), radiation doses tend to be highest near the radioactive seeds (also called sources) and become lower as the distance from the seeds increases. Steep changes in radiation dose (dose gradients) occur near the seeds, and a large part of the dose is delivered within a few millimeters or centimeters from the source 32…”