Table of Contents
Physics Research International
Volume 2012, Article ID 714782, 11 pages
Research Article

A New Technology for Fast Two-Dimensional Detection of Proton Therapy Beams

1Department of Physics, University of Pennsylvania, Philadelphia, PA 19104, USA
2Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA

Received 20 July 2012; Accepted 20 November 2012

Academic Editor: Flavio P. Marchetto

Copyright © 2012 Robert Hollebeek et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The Micromesh Gaseous Structure, or Micromegas, is a technology developed for high count-rate applications in high-energy physics experiments. Tests using a Micromegas chamber and specially designed amplifiers and readout electronics adapted to the requirements of the proton therapy environment and providing both excellent time and high spatial resolution are presented here. The device was irradiated at the Roberts Proton Therapy Center at the University of Pennsylvania. The system was operated with ionization gains between 10 and 200 and in low and intermediate dose-rate beams, and the digitized signal is found to be reproducible to 0.8%. Spatial resolution is determined to be 1.1 mm (1σ) with a 1 ms time resolution. We resolve the range modulator wheel rotational frequency and the thicknesses of its segments and show that this information can be quickly measured owing to the high time resolution of the system. Systems of this type will be extremely useful in future treatment methods involving beams that change rapidly in time and spatial position. The Micromegas design resolves the high dose rate within a proton Bragg peak, and measurements agree with Geant4 simulations to within 5%.