In this paper we analyse the response of two different Commercial Off The shelf CMOS image sensors as particle detectors. Sensors were irradiated using X-ray photons, gamma photons, beta particles and alpha particles from diverse sources. The amount of charge produced by different particles, and the size of the spot registered on the sensor are compared, and analysed by an algorithm to classify them. For a known incident energy spectrum, the employed sensors provide a dose resolution lower than microGray, showing their potentials in radioprotection, area monitoring, or medical applications.

Particle detection and classification using commercial off the shelf CMOS image sensors

Wireless sensor networks are an important technology for large-scale monitoring, providing sensor measurements at high temporal and spatial resolution. In healthcare applications, a variety of system prototypes and commercial products have been designed and manufactured with the aim to provide an alternative and more efficient method for real-time operator monitoring during medical procedures. In the framework of the Real-Time Active Pixel Dosimetry project, the attention has been focused on dose monitoring of interventional radiology (IRad) operators. A sensor network has been developed, which consists of several personal sensor nodes (PSNs), monitoring the absorbed dose in different positions of the operator body (e.g., on the head or arms) and providing a measurement of the absorbed dose for each medical procedure. In this paper, we describe the first characterization of the final version of a system by measuring the radiation diagram and exposing the system to a direct X-ray beam showing a linearity of the response up to 3.3 mGy/s of dose rate. The system has been characterized during several IRad procedures when two PSNs have been simultaneously used in the network. The packet error rate of the network has been measured and the absorbed dose has been evaluated for each medical procedure, showing an uncertainty on the dose measurement lower than 10% with respect to the reference dosimetric devices.

Experimental Characterization of a Personal Wireless Sensor Network for the Medical X-Ray Dosimetry

Surveying ionizing radiations in real time using a smartphone

We present the response of a Commercial-Off-The-Shelf (COTS) CMOS image sensor to different ionizing particles, with the aim of developing a low cost radiation detector We first analyze the images obtained by exposing the imagers to X-rays from 55Fe, gamma and beta particles from 137Cs Then the detector is successfully used to monitor different gamma fluxes produced by the RA6 nuclear research reactor, Argentina, during a startup procedure

Commercial CMOS pixel array for beta and gamma radiation particle counting

Wireless sensor networks featuring portable devices are widely used for healthcare applications such as real-time patient monitoring. For such applications, design constraints are limited in the amount of energy, network capacity (short communication range and low bandwidth), and processing and memory resources in each node. In the framework of the real-time active pixel dosimetry project, the attention has been focused on the design of a dosimetric system for online dose monitoring of interventional radiology (IRad) operators. This paper describes the experimental characterization of the prototype used during several IRad procedures. The wireless link of the prototype has been characterized by measuring the packet error rate of the network in different scenarios: the worst obtained result was lower than 0.4%, which is acceptable for the specific application. The prototype has also been compared with a reference acquisition system to fully validate the system in operating condition. A linear correlation has been observed between the observables for all the working conditions. Moreover, the average pixel response could be used as an indicator of the goodness of the data acquisition for a given procedure showing that it does not depend on the procedure, hence on the particular spectrum of the diffused radiation. Finally, the measurement of absorbed dose ( $\mu $ Gy) has been calculated for different IRad procedures.

Experimental Characterization of a Wireless Personal Sensor Node for the Dosimetry During Interventional Radiology Procedures

Interventional radiologists and staff members, during all their professional activities, are frequently exposed to protracted and fractionated low doses of ionizing radiation. Due to skin tissues and peripheral blood irradiation, these exposures can result in deterministic effects (radiodermatitis, aged skin, and hand depilation) or stochastic ones (skin and non-solid cancer incidence). The authors present a novel approach to perform online monitoring of the staff during their interventions by using a device based on an Active Pixel Sensor. The performance of the sensor as an X-ray radiation detector has been evaluated with a proper experimental setup: the number of photons and the generated charge have been assessed as dosimetric observables from the frames acquired by the sensor using a two-threshold clustering algorithm, the efficiency of which has been evaluated as well. The correlation of these observables with passive dosimeter dose measurements has been analyzed: a good linearity has been demonstrated, and the response difference between pulsed and continuous operational modes is reduced to less than 10%, marking a distinct improvement with respect to commercial Active Personal Dosimeters.

Bruno Checcucci

Papers

Use of a CMOS Image Sensor for an Active Personal Dosimeter in Interventional Radiology