Design and Comparison of a Passive and Active Multiple Radiological Point Source Localisation Algorithm

Abstract

Over the past years, automated, robotic radiation source localisation has become of emerging interest due to a variety of reasons, e.g. disaster response, homeland security, or dismantling and decommissioning of nuclear contaminated areas. Nowadays, to perform in-the-field measurements, radiation protection officers are tasked with characterising an environment before dismantling and decommissioning can take place. This is challenging because of the absence of a priori information on the potentially contaminated area. Besides the health risks involved, this preparatory task is very time-consuming and prone to errors concerning the taken measurements and the post-processing of these measurements. To further automate this key preliminary task, this paper presents two search algorithms to localise multiple radiological point sources in the environment: a passive localisation algorithm where a robotic platform scans a surface using a predefined pattern, and an active source localisation algorithm that chooses the next best position to take a measurement in order to characterise an environment. The developed approaches are first tested in a simulation environment and then validated using in-situ laboratory measurements using a Kromek CZT sensor and a two-dimensional linear guidance system. The experiments show that a correct representation of the environment is contained both for the passive and active localisation approach. Furthermore, the active localisation approach demonstrates that a large reduction in the amount of measurements to char-acterise an environment can be obtained without compromising on the estimation accuracy.