Dosimetric effect of nanoparticles in the breast cancer treatment using INTRABEAM^® system with spherical applicators in the presence of tissue heterogeneities: A Monte Carlo study

Abstract

Using the 50 kV INTRABEAM® IORT system after breast-conserving surgery: tumor recurrence and organs at risk (OARs), such as the lung and heart, long-term complications remain the challenging problems for breast cancer patients. So, the objective of this study was to address these two problems with the help of high atomic number nanoparticles (NPs). A Monte Carlo (MC) Simulation type EGSnrc C++ class library (egspp) with its Easy particle propagation (Epp) user code was used. The simulation was validated against the measured depth dose data found in our previous study (Tegaw, et al 2020 Dosimetric characteristics of the INTRABEAM ® system with spherical applicators in the presence of air gaps and tissue heterogeneities, Radiat. Environ. Biophys. (10.1007/s00411-020-00835-0)) using the gamma index and passed 2%/2 mm acceptance criteria in the gamma analysis. Gold (Au) NPs were selected after comparing Dose Enhancement Ratios (DERs) of bismuth (Bi), Au, and platinum (Pt) NPs which were calculated from the simulated results. As a result, 0.02, 0.2, 2, 10, and 20 mg-Au/g-breast tissue were used throughout this study. These particles were not distributed in discrete but in a uniform concentration. For 20 mg-Au/g-breast tissue, the DERs were 3.6, 0.420, and 0.323 for breast tissue, lung, heart, respectively, using the 1.5 cm-diameter applicator (AP) and 3.61, 0.428, and 0.335 forbreast tissue, lung, and heart using the 5 cm-diameter applicator, respectively. DER increased with the decrease in the depth of tissues and increase in the effective atomic number (Zeff) and concentration of Au NPs, however, there was no significant change as AP sizes increased. Therefore, Au NPs showed dual advantages such as dose enhancement within the tumor bed and reduction in the OARs (heart and lung).

Gold-nanoparticle-enriched breast tissue in breast cancer treatment using the INTRABEAM® system: a Monte Carlo study

“…The reduced breast skin dose is due to a shielding effect of the breast tissue, including AU NPs, which in turn is due to an increased Z eff and the low photon energy produced in the 50-kV system used in the present study. As a result, long-term complications of the surrounding neighboring healthy tissue of the breast cancer patients will be reduced (Ngwa et al 2014;Tegaw et al 2021).…”

“…Previously, Au NPs were also used for skin therapy (Chow 2018a;Paro et al 2016;Zheng and Chow 2017) and prostate therapy (Khoo et al 2017;Martelli and Chow 2020;Martinov and Thomson 2017). In INTRABEAM ® IORT the use of NPs could lead to higher patient comfort (Sedlmayer et al 2007) and to a reduction of the dose to neighboring healthy cells (Tegaw et al 2021) by decreasing the prescribed dose and treatment time, especially when large AP sizes are used. As already mentioned above, treatment time required for the INTRABEAM ® IORT system depends on the size of the lumpectomy cavity, the size of the selected AP, and the prescribed dose (Njeh et al 2010).…”