The particle tracking silicon microscope PTSM

Abstract

A novel position-and energy-sensitive particle detector for radiobiological application is described. The aim is to support research in radiation response of biological systems, for example in the induction of mutations in C. elegans, where precise knowledge of location and intensity of the radiation is crucial to understand radiation sensitivity of individual cells. The "Particle Tracking Silicon Microscope" (PTSM) consists of a silicon strip detector in direct contact with radiobiological samples (e.g., C. elegans), such that the location and intensity of particle radiation can be controlled at the 10 m scale. The readout is performed with low-noise readout electronics, which allows the determination of the particle's position from the hit strip address and its energy from the specific energy loss. In our implementation, the energy loss is measured through the time-over-threshold (TOT). The noise rate at acceptable thresholds is so low that the single particles can be detected with 100% efficiency. The performance of the front-end ASIC is described, and the results of initial environmental tests are reported. These include placing biological samples and saline solutions in direct contact with the silicon detectors.Index Terms-Biomedical applications of radiation, silicon radiation detectors.

Proton Radiography Studies for Proton CT

“…The challenge of proton-by-proton CT can be evaluated by a comparison with its established alternative, x-ray CT. A detection of individual protons requires a data acquisition system capable of recording particle rates in excess of 1 MHz. We have developed such a system for the readout of silicon strip detectors [9]. The curved trajectories of the protons inside the phantom create difficulties for the image reconstruction as well, and instead of a straightforward filtered back-projection algorithm, algebraic reconstruction techniques have been employed [10], [11].…”

“…The long-term goal of our project is to develop the capability to use proton CT (pCT) instead of x-ray CT to minimize these uncertainties from the current value of 3-10 mm to 1-3 mm. Previous work reviewed in [2] and our own preliminary studies [3][4][5][6][7][8][9] indicate that proton CT based on tracking of individual protons traversing an object from many different directions and measuring their energy loss and scattering angle may yield accurate reconstructions of electron density maps with good density and spatial resolution, despite the fundamental limitation of energy straggling and multiple Coulomb scattering (MCS). Fig.…”