Portable X-ray imaging of simulated radiological dispersal devices

Radiological dispersal devices (RDDs), often described as dirty bombs, represent a specific operational problem for explosive ordnance disposal (EOD) units because they combine the tactical requirements of an improvised explosive device response with radiation protection constraints. This article evaluates portable radiation detection and X-ray imaging systems under field conditions simulating radiological dispersal devices. Sealed sources of ¹³⁷Cs and ⁶⁰Co with activities ranging from 6.3 MBq to 4.74 GBq, together with a liquid ²⁴¹Am source and an Am-Be neutron source, were placed in simulated IED configurations enclosed in metal, wood, cardboard and plastic. Dose-rate measurements were performed at 20 cm and 100 cm using an identiFINDER® R400 and a MultiRAE Pro multi-threat monitor. Radiographic diagnostics were performed using a NOVO digital X-ray system and a DÜRR computed radiography system. The results show that increasing source activity and gamma-ray energy substantially affect radiation detector performance and radiographic image quality. In contrast, the low-energy alpha emitter ²⁴¹Am and the Am-Be neutron source had negligible effects on radiographic image quality despite presenting distinct detection challenges for field responders. The NOVO system maintained diagnostically useful images even in the presence of multi-giga-becquerel gamma sources, whereas the DÜRR system showed progressive radiation-induced image degradation, particularly for high-activity ⁶⁰Co. The findings indicate that radioactive material does not automatically prevent successful radiographic diagnostics of a suspected RDD, but the choice of imaging technology and detector has direct operational consequences for EOD response. The findings provide practical guidance for equipment selection and integrated EOD-CBRN response to suspected RDD incidents.