Exploring radiation effects on CMOS image sensors (CIS) for dosimetry
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Date
2026-02-27
Authors
Βασιλειάδη, Ελευθερία
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Abstract
The increasing radiation levels encountered in modern particle accelerator facilities and space applications create a growing demand for compact, reliable, and real-time radiation monitoring systems. CMOS Image Sensors (CISs), widely used in consumer and industrial imaging, exhibit intrinsic sensitivity to ionising radiation and therefore represent a promising candidate for radiation dosimetry. This thesis investigates the feasibility of using a commercial CIS as a radiation-sensitive device by characterising its response under different radiation environments and operational conditions.
A dedicated radiation testing protocol was developed, comprising a Commercial Off-The-Shelf (COTS) CIS, a microcontroller-based readout system, and Ethernet communication to the test computer for continuous data acquisition during irradiation. The sensor was operated in real time, enabling the study of both instantaneous dose-rate effects and cumulative radiation damage. Radiation campaigns were carried out at three complementary facilities: the Cobalt-60 (CC60) γ-irradiation facility, providing a controlled environment dominated by Total Ionising Dose (TID); the Paul Scherrer Institute (PSI) proton
beamline, enabling high-energy proton irradiation and high instantaneous dose rates; and the CERN High energy AcceleRator Mixed field (CHARM) facility, which reproduces realistic accelerator mixed-field conditions combining TID, Displacement Damage (DD), and Single Event Effects (SEEs).
Across all facilities, a consistent increase in the average greyscale pixel value was observed during irradiation and with increasing accumulated dose, confirming the sensor’s intrinsic radiation sensitivity. Measurements at CC60 demonstrated that the cumulative response is primarily driven by TID, manifesting as a shift of the dark signal distribution toward higher greyscale values, with saturation at high doses. Proton irradiation at PSI showed that the instantaneous sensor response is linear with dose rate below saturation for a fixed gain and that the response to high-energy protons is consistent with that observed under γ-irradiation. Mixed-field measurements at CHARM further demonstrated that the sensor is sensitive to different TID/DD ratios achieved through shielding configurations, with TID primarily affecting the mean dark signal and DD contributing to a broadening of the pixel value distribution.
The results show that a COTS CIS can provide a robust and interpretable response to radiation across a wide range of environments. The observed separation between TID- and DD-related signatures supports the potential of CIS-based systems as compact radiation monitors capable of delivering complementary dosimetric information in accelerator environments.
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Keywords
CMOS image sensors, Radiation effects, Dosimetry