Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams.

Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams.
Phys Med Biol. 2016 Mar 18;61(8):2972-2990
Authors: Nichiporov D, Coutinho L, Klyachko AV
Abstract
Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector's performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115-205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosime...

Source: Physica Medica - March 18, 2016 Category: Physics Authors: Nichiporov D, Coutinho L, Klyachko AV Tags: Phys Med Biol Source Type: research