Computer Science ETDs


Zhe Chen

Publication Date



Photon-based radiosurgery is widely used for treating local and regional tumors. The key to improving the quality of radiosurgery is to increase the dose falloff rate from high dose regions inside the tumor to low dose regions of nearby healthy tissues and structures. Currently, most radiosurgeries rely on focusing a number of external radiation beams to create a sharp dose falloff. As the number of focused beams increases, the contributions from each beam will inevitably decrease, and hence an improved dose falloff will be obtained. However, with most radiosurgeries being delivered in a step-and-shoot manner, the number of external beams is limited to a few hundred. For example, Gamma Knife radiosurgery, which has long been a gold standard for radiosurgery, uses about two hundred beams. In this research, we investigated the use of Dynamic Photon Painting (DPP) to further increase dose falloff rate. The key idea of DPP is to treat a target by moving a beam source along a dynamic trajectory, where the speed, directions and even dose rate of the beam source change constantly during irradiation. A number of studies regarding DPP were carried out in this research. We found that DPP can create a dose gradient that rivals proton Bragg Peak and outperforms Gamma Knife radiosurgery. These promising results indicate that DPP has the potential to significantly improve current photon-based radiosurgery.




Dynamic Photon Painting, Radiosurgery, Dose falloff rate, isodose distribution

Document Type


Degree Name

Computer Science

Level of Degree


Department Name

Department of Computer Science

First Advisor

Luan, Shuang

First Committee Member (Chair)

Luan, Shuang

Second Committee Member

Cao, Daliang

Third Committee Member

Hecht, Adam

Project Sponsors

National Science Foundation and National Cancer Institute