FITTING THE BRAGG CURVE: INCREASING THE ACCURACY OF PROTON THERAPY WITH ON-SITE DATA ANALYSIS

Proton beam therapy is one of the most sophisticated methods for treating tumors. The high dose gradient allows for dose distributions that can tightly conform to a tumor volume, reducing damage to surrounding tissue. However, uncertainties exist regarding beam interactions within a given patient due to the heterogeneity of the human body. While this creates serious limitations on therapy, these uncertainties can be reduced with radiography. In radiography, a high energy proton beam is quickly shot through the patient’s tissue and then interacts with a detector further downstream. Comparing experimental data from the detector with expectations derived through simulation will give a more accurate insight on how the proton beam interacts within the patient. In order to analyze the proton beam with a sufficiently high resolution, the detector used needs to be capable of three-dimensional analysis. Since no such proton detector exists commercially, Dr. Dolney, a professor at the University of Pennsylvania, and his lab has created a quasi-three-dimensional detector by placing two-dimensional detector grids one after another within a single construct. While the quasi-three-dimensional design does not provide a continuum of data, a fitting algorithm set to model the Bragg Curve can trace out the missing data. It has been shown that the 1.5 cm longitudinal resolution, without any fitting algorithm, produces range errors up to 4 mm. However, if the fit is applied, the resolution increases to 0.5 mm, and range errors decrease to below 1 mm.

Additional Abstract Information

Student(s): Evan G. Meekins

Department: Physics

Faculty Advisor: Dr. Derek Dolney (Radiation Oncology, Hospital of the University of Pennsylvania)

Type: Oral

Year: 2016