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Title: SU-E-T-58: Calculation of Dose Distribution of Accuboost Brachytherapy in Deformable Polyvinil Alcohol Breast Phantom Using Biomechanical Modeling and Monte Carlo Simulation

Purpose: the accuboost is the most modern method of breast brachytherapy that is a boost method in compressed tissue by a mammography unit. the dose distribution in uncompressed tissue, as compressed tissue is important that should be characterized. Methods: In this study, the mechanical behavior of breast in mammography loading, the displacement of breast tissue and the dose distribution in compressed and uncompressed tissue, are investigated. Dosimetry was performed by two dosimeter methods of Monte Carlo simulations using MCNP5 code and thermoluminescence dosimeters. For Monte Carlo simulations, the dose values in cubical lattice were calculated using tally F6. The displacement of the breast elements was simulated by Finite element model and calculated using ABAQUS software, from which the 3D dose distribution in uncompressed tissue was determined. The geometry of the model is constructed from MR images of 6 volunteers. Experimental dosimetery was performed by placing the thermoluminescence dosimeters into the polyvinyl alcohol breast equivalent phantom and on the proximal edge of compression plates to the chest. Results: The results indicate that using the cone applicators would deliver more than 95% of dose to the depth of 5 to 17mm, while round applicator will increase the skin dose. Nodal displacement, inmore » presence of gravity and 60N forces, i.e. in mammography compression, was determined with 43% contraction in the loading direction and 37% expansion in orthogonal orientation. Finally, in comparison of the acquired from thermoluminescence dosimeters with MCNP5, they are consistent with each other in breast phantom and in chest's skin with average different percentage of 13.7±5.7 and 7.7±2.3, respectively. Conclusion: The major advantage of this kind of dosimetry is the ability of 3D dose calculation by FE Modeling. Finally, polyvinyl alcohol is a reliable material as a breast tissue equivalent dosimetric phantom that provides the ability of TLD dosimetry for validation.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Nuclear Engineering Department, School of Mechanical Engineering, Shiraz Un, Ilam (Iran, Islamic Republic of)
  2. Nuclear Engineering Department, Shiraz University, Shiraz (Iran, Islamic Republic of)
  3. Radiotherapy and Oncology Department, Namazi Hospital, Shiraz University of M, Shiraz (Iran, Islamic Republic of)
  4. Shiraz University of Medical Sciences, Medical Imaging Research Center, Shiraz (Iran, Islamic Republic of)
  5. Comprehensive cancer center of Nevada - University of Nevada Las Vegas UNL, Las Vegas, NV (United States)
Publication Date:
OSTI Identifier:
22339826
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 41; Journal Issue: 6; Other Information: (c) 2014 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ANIMAL TISSUES; BIOMEDICAL RADIOGRAPHY; BRACHYTHERAPY; CHEST; COMPUTERIZED SIMULATION; FINITE ELEMENT METHOD; MAMMARY GLANDS; MONTE CARLO METHOD; PHANTOMS; PVA; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; SKIN; THERMOLUMINESCENT DOSEMETERS; THERMOLUMINESCENT DOSIMETRY