Page 298 - 2014 Printable Abstract Book
P. 298
ions at relatively low linear energy transfer (LET) values have been focused to submitcrometer scales to
mimic single high-LET ion tracks and their biological efficiency. These experiments provide data for an
advanced testing of the assumptions in Monte Carlo track structure based biological models, as they
differentiate the damage complexity on nanometer scale from lesion clustering on micrometer scale,
which are closely interwoven in conventional radiobiological studies. Simulation results on yields of DSB,
DNA fragmentation patterns and dicentrics in comparison to corresponding experimental data are
presented and the needs for refinements of the models discussed.
Acknowledgement: This work was supported by the project ‘LET-Verbund’ (funding no. 02NUK031C) of
the German Federal Ministry of Education and Research.
(PS5-20) In silico growth of a hypoxic head and neck tumour including angiogenic processes. David
1
1;2
1
Marcu, MSc and Loredana G. Marcu, PhD ; University of Oradea, Oradea, Romania and University of
2
Adelaide, Adelaide, Australia
Tumour hypoxia in head and neck cancers is a well-known reason for treatment failure despite
the multidisciplinary approach used in managing the disease. The aim of the current project is to simulate
the growth and treatment of a head and neck tumour considering its spatial distribution (each cell being
represented by its x, y, z coordinates) and cellular oxygenation level. The tumour growth is started from
a single (seed) stem cell and all the branching decisions are made based purely on statistical probabilities
researched in the literature. Four types of cells are considered: a) stem cells, which divide indefinitely
preserving themselves and generating a daughter cell that can be either stem, finitely proliferating
(differentiated) or quiescent; b) finitely proliferating cells, which divide a finite number of times
generating a daughter cell that can be either another finitely proliferating or quiescent; c) quiescent cells,
that are potentially viable cells but they enter the resting phase, outside the cell cycle; d) endothelial cells,
which are the building blocks of the tumour's vascular network. The tumour dynamics is evaluated every
hour, each cell being advanced along its own cell cycle. A cell diameter of 0.01mm has been considered.
Given an average size for an avascular tumour of 1mm, the model allows oxygen to be distributed by a
blood vessel at a depth of 100 cells. Cell oxygenation varies along this depth over a gradient, creating
chronically hypoxic cells at the end of the scale. Because of the stochastic nature of the model, the
angiogenesis process encounters blockages and interruptions that are responsible for acute hypoxia,
which in turn influences the tumour dynamics. With a mean cell cycle time of 33 hours for stem and finitely
proliferating cells and a cell loss factor of 85%, the tumour volume doubling time has an average value of
50 days. This virtual tumour serves as an in silico model for radiotherapy, chemotherapy and anti-
angiogenic therapy for unresectable head and neck cancers.
(PS5-21) Monte Carlo simulation of secondary electron spectra from copper-water targets after fast
proton impact. Anderson Travia; Michael Dingfelder, East Carolina University, Greenville, NC
Monte Carlo simulations of charged particles in condensed matter is an essential computational
method for progress in the field of radiation biology. The extreme difficulties in performing experimental
work with biologically relevant targets makes the data scarce or unavailable for many important materials
such as biological tissues. The accuracy of these simulations depend mostly on the quality of the cross-
sections for each type of interaction that the charged particles undergo as they travel through the
296 | P a g e
mimic single high-LET ion tracks and their biological efficiency. These experiments provide data for an
advanced testing of the assumptions in Monte Carlo track structure based biological models, as they
differentiate the damage complexity on nanometer scale from lesion clustering on micrometer scale,
which are closely interwoven in conventional radiobiological studies. Simulation results on yields of DSB,
DNA fragmentation patterns and dicentrics in comparison to corresponding experimental data are
presented and the needs for refinements of the models discussed.
Acknowledgement: This work was supported by the project ‘LET-Verbund’ (funding no. 02NUK031C) of
the German Federal Ministry of Education and Research.
(PS5-20) In silico growth of a hypoxic head and neck tumour including angiogenic processes. David
1
1;2
1
Marcu, MSc and Loredana G. Marcu, PhD ; University of Oradea, Oradea, Romania and University of
2
Adelaide, Adelaide, Australia
Tumour hypoxia in head and neck cancers is a well-known reason for treatment failure despite
the multidisciplinary approach used in managing the disease. The aim of the current project is to simulate
the growth and treatment of a head and neck tumour considering its spatial distribution (each cell being
represented by its x, y, z coordinates) and cellular oxygenation level. The tumour growth is started from
a single (seed) stem cell and all the branching decisions are made based purely on statistical probabilities
researched in the literature. Four types of cells are considered: a) stem cells, which divide indefinitely
preserving themselves and generating a daughter cell that can be either stem, finitely proliferating
(differentiated) or quiescent; b) finitely proliferating cells, which divide a finite number of times
generating a daughter cell that can be either another finitely proliferating or quiescent; c) quiescent cells,
that are potentially viable cells but they enter the resting phase, outside the cell cycle; d) endothelial cells,
which are the building blocks of the tumour's vascular network. The tumour dynamics is evaluated every
hour, each cell being advanced along its own cell cycle. A cell diameter of 0.01mm has been considered.
Given an average size for an avascular tumour of 1mm, the model allows oxygen to be distributed by a
blood vessel at a depth of 100 cells. Cell oxygenation varies along this depth over a gradient, creating
chronically hypoxic cells at the end of the scale. Because of the stochastic nature of the model, the
angiogenesis process encounters blockages and interruptions that are responsible for acute hypoxia,
which in turn influences the tumour dynamics. With a mean cell cycle time of 33 hours for stem and finitely
proliferating cells and a cell loss factor of 85%, the tumour volume doubling time has an average value of
50 days. This virtual tumour serves as an in silico model for radiotherapy, chemotherapy and anti-
angiogenic therapy for unresectable head and neck cancers.
(PS5-21) Monte Carlo simulation of secondary electron spectra from copper-water targets after fast
proton impact. Anderson Travia; Michael Dingfelder, East Carolina University, Greenville, NC
Monte Carlo simulations of charged particles in condensed matter is an essential computational
method for progress in the field of radiation biology. The extreme difficulties in performing experimental
work with biologically relevant targets makes the data scarce or unavailable for many important materials
such as biological tissues. The accuracy of these simulations depend mostly on the quality of the cross-
sections for each type of interaction that the charged particles undergo as they travel through the
296 | P a g e
