Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.21/4379
Título: Dosimetric effect of tissue heterogeneity for 125I prostate implants
Autor: Oliveira, Susana Maria
Teixeira, Nuno
Fernandes, Lisete
Teles, Pedro
Vaz, Pedro
Palavras-chave: Brachytherapy
Prostate cancer
Monte Carlo
Tissue heterogeneity
Model-based calculation algorithms
Computerized tomography
Dose–volume histogram
External beam radiotherapy
Equivalent uniform dose
Normal tissue complication probability
Tumor control probability
Differential dose–volume histogram
Data: Abr-2014
Editora: Elsevier
Citação: Oliveira SM, Teixeira NJ, Fernandes L, Teles P, Vaz P. Dosimetric effect of tissue heterogeneity for (125)I prostate implants. Rep Pract Oncol Radiother. 2014;19(6):392-8.
Resumo: Aim - To use Monte Carlo (MC) together with voxel phantoms to analyze the tissue heterogeneity effect in the dose distributions and equivalent uniform dose (EUD) for (125)I prostate implants. Background - Dose distribution calculations in low dose-rate brachytherapy are based on the dose deposition around a single source in a water phantom. This formalism does not take into account tissue heterogeneities, interseed attenuation, or finite patient dimensions effects. Tissue composition is especially important due to the photoelectric effect. Materials and Methods - The computed tomographies (CT) of two patients with prostate cancer were used to create voxel phantoms for the MC simulations. An elemental composition and density were assigned to each structure. Densities of the prostate, vesicles, rectum and bladder were determined through the CT electronic densities of 100 patients. The same simulations were performed considering the same phantom as pure water. Results were compared via dose-volume histograms and EUD for the prostate and rectum. Results - The mean absorbed doses presented deviations of 3.3-4.0% for the prostate and of 2.3-4.9% for the rectum, when comparing calculations in water with calculations in the heterogeneous phantom. In the calculations in water, the prostate D 90 was overestimated by 2.8-3.9% and the rectum D 0.1cc resulted in dose differences of 6-8%. The EUD resulted in an overestimation of 3.5-3.7% for the prostate and of 7.7-8.3% for the rectum. Conclusions - The deposited dose was consistently overestimated for the simulation in water. In order to increase the accuracy in the determination of dose distributions, especially around the rectum, the introduction of the model-based algorithms is recommended.
Peer review: yes
URI: http://hdl.handle.net/10400.21/4379
DOI: 10.1016/j.rpor.2014.03.004
Versão do Editor: http://www.sciencedirect.com/science/article/pii/S1507136714000376#
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