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Seniwal B, Freitas LF, Mendes BM, Lugão AB, Katti KV, Fonseca TCF. In silico dosimetry of low-dose rate brachytherapy using radioactive nanoparticles. Phys Med Biol 2021; 66:045016. [PMID: 33561008 DOI: 10.1088/1361-6560/abd671] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PURPOSE Nanoparticles (NPs) with radioactive atoms incorporated within the structure of the NP or bound to its surface, functionalized with biomolecules are reported as an alternative to low-dose-rate seed-based brachytherapy. In this study, authors report a mathematical dosimetric study on low-dose rate brachytherapy using radioactive NPs. METHOD Single-cell dosimetry was performed by calculating cellular S-values for spherical cell model using Au-198, Pd-103 and Sm-153 NPs. The cell survival and tumor volume versus time curves were calculated and compared to the experimental studies on radiotherapeutic efficiency of radioactive NPs published in the literature. Finally, the radiotherapeutic efficiency of Au-198, Pd-103 and Sm-153 NPs was tested for variable: administered radioactivity, tumor volume and tumor cell type. RESULT At the cellular level Sm-153 presented the highest S-value, followed by Pd-103 and Au-198. The calculated cell survival and tumor volume curves match very well with the published experimental results. It was found that Au-198 and Sm-153 can effectively treat highly aggressive, large tumor volumes with low radioactivity. CONCLUSION The accurate knowledge of uptake rate, washout rate of NPs, radio-sensitivity and tumor repopulation rate is important for the calculation of cell survival curves. Self-absorption of emitted radiation and dose enhancement due to AuNPs must be considered in the calculations. Selection of radionuclide for radioactive NP must consider size of tumor, repopulation rate and radiosensitivity of tumor cells. Au-198 NPs functionalized with Mangiferin are a suitable choice for treating large, radioresistant and rapidly growing tumors.
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Affiliation(s)
- Baljeet Seniwal
- Departamento de Engenharia Nuclear-Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270-901, Belo Horizonte, MG, Brasil
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Guebert A, Roumeliotis M, Watt E, Meyer T, Quirk S. Dosimetric consequences of seed placement accuracy in permanent breast seed implant brachytherapy. Brachytherapy 2021; 20:664-672. [PMID: 33358141 DOI: 10.1016/j.brachy.2020.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/18/2020] [Accepted: 11/24/2020] [Indexed: 10/22/2022]
Abstract
PURPOSE This study quantifies the dosimetric impact of implant accuracy and derives a quantitative relationship relating implant accuracy to target dosimetry. METHODS AND MATERIALS A framework was developed to simulate multiple implants for error combinations. Spherical clinical target volumes (CTVs) were modeled with volumes 1.4 cm3, 9.2 cm3, and 20.6 cm3, representing the range seen clinically. Each CTV was expanded 10 mm isotropically to create a planning target volume (PTV).. Random and systematic seed placement errors were simulated by shifting needles from their planned positions. Implant errors were simulated over the range of clinically practical errors in permanent breast seed implant. The relative effect on target coverage was evaluated. Regression analysis was performed to derive relationships between CTV dosimetry and the magnitude of implant accuracy. The validity of the clinically used 10 mm PTV margin for each of the CTVs was assessed. RESULTS Introducing practical implant errors resulted in CTV V90% median (10th and 90th percentile) of 97.7% (85.9% and 100%), 96.2% (86.8% and 99.7%), and 100% (77.8% and 100%) for the typical, large, and small CTV, respectively. All CTVs show similar trends in target coverage. Polynomials were derived relating seed placement accuracy to median (R2 = 0.82) and 10th percentile (R2 = 0.78) CTV V90%.. CONCLUSIONS: This work quantitatively describes the relationship between implant accuracy and CTV coverage. Based on simulations, the 10 mm PTV margin is adequate to maintain target coverage. These equations can be used with institutional seed placement accuracy to estimate coverage.
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Affiliation(s)
- Alexandra Guebert
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Division of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada.
| | - Michael Roumeliotis
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Division of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada; Department of Oncology, University of Calgary, Calgary, AB, Canada; Okolo Health, Calgary, AB, Canada
| | - Elizabeth Watt
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Division of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada; Okolo Health, Calgary, AB, Canada
| | - Tyler Meyer
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Division of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada; Department of Oncology, University of Calgary, Calgary, AB, Canada; Okolo Health, Calgary, AB, Canada
| | - Sarah Quirk
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Division of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada; Department of Oncology, University of Calgary, Calgary, AB, Canada
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