Project Summary
Ionizing radiation (IR) is a critical component of modern medicine. When IR penetrates through the organism, it
could depart its energy to the medium mainly through ionization and excitation. The energy departure of IR is
medium composition dependent, and hence it is used to ‘see’ the inner structure of the human beings, enabling
the application of IR in the medical imaging of mammography, chest x-rays, computational tomography, positron
emission tomography, etc. IR can also damage the structure and/or affect the function of the organism and hence
it is applied to treat cancer in the form of radiosurgery and radiotherapy. Meanwhile, IR is found to be genotoxic
and carcinogenic, calling the non-ending effort to understand the fundamental effects.
Advanced cellular radiobiological study exhibited that the damage of deoxyribonucleic acid (DNA) plays a pivotal
role towards the determination of the final biological or even clinical outcome after exposure to IR. It is
hypothesized that when IR interacts with DNA, it could damage DNA in picoseconds by the primary and
secondary IR particles and in microseconds by subsequently generated radiation radicals. It is then essential to
understand how IR produces this initial damage under various radiation conditions. Microscopic Monte Carlo
(MC) simulation such as Geant4-DNA, capable of computing this damaging process, has been playing an
important role in the quantitative hypothesis-test. However, there are several issues in the state-of-the-art MC
tools, making it hard to meet the increasing demanding for advanced applications. These include the low
efficiency in dealing with the ‘many-body’ problem, the relatively large uncertainty in the final computing results,
the lack of support for the entire cell cycle and the limited-access/user-unfriendly designs, etc.
In this project, we propose to solve the above issues by developing a next-generation MC simulation tool for IR
induced DNA damage computation through the novel implementations of graphical processing units (GPUs)
parallel computing, the molecular dynamics/first principles based computation, the new DNA model development
based on the extrusion model and polymer physics, and the open-source release with user-friendly interface.
Upon success, the developed system is expected to serve as a next-generation simulation platform for the
calculation of the initial DNA damage caused by IR, which can become a profound first-step towards a successful
accomplishment of the “bottom-up” multi-scale modeling for the entire radiobiological process, making a
significant impact in radiation medicine.
