Introduction

• Marco Silari (CERN)

Title: Microdosimetry with GEMTEQ, a novel gas microdosimeter with a highly pixelated readout

• Johannes Leidner (Rheinisch Westfaelische Tech. Hoch. (DE))

Abstract: Microdosimetry is the study of the temporal and spatial distributions of absorbed energy in biological matter and is crucial for the deep understanding of radiation effects in human tissue, for example of a carbon ion beam used in cancer treatments. The GEMTEQ detector is based on two CERN technologies, a small triple Gas Electron Multiplier setup with about 9 cm3 active volume and a quad Timepix ASIC featuring more than a quarter million pixels and a pixel pitch of 55 µm. The GEMTEQ is operated with tissue-equivalent gas. First microdosimetric measurements in neutron and photon fields were performed and results obtained with the GEMTEQ were compared to those obtained with standard microdosimeters. The GEMTEQ was also operated as a Time Projection Chamber and the 3D particle track analysis is on-going. In order to further increase the equivalent spatial resolution of the GEMTEQ and to increase the portability of the system, the development of a sealed and low-pressure detector version has started.

A Large Area GEMPix detector for treatment plan verification in hadron therapy

• Andreia Cristina Maia Oliveira (FCT Fundacao para a Ciencia e a Tecnologia (PT))

An advantageous radiation modality for treating cancer is hadron therapy, which at present uses protons and carbon ions. However, treatment with hadrons requires high spatial and dosimetric accuracy in order to achieve optimal dose delivery, which is in turn guaranteed by proper quality assurance (QA) procedures and tools. For this purpose, a promising tool is the LaGEMPix detector that combines a triple GEM (Gas Electron Multiplier) with a matrix of organic photodiodes coated on an oxide thin film transistor (TFT) backplane. A first prototype of the LaGEMPix with an active area of 60 x 80 mm2 and pixels of 126 x 126 μm2 has been successfully built and tested with X-rays as a preliminary step towards the development of a 20 x 20 cm2 detector.