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Development of a portable gamma camera for accurate 3-D localization of radioactive hotspots

Abstract : A coded aperture gamma camera for retrieving the three-dimensional (3-D) position of radioactive sources is presented. This is of considerable interest for a wide number of applications, ranging from the reconstruction of the 3-D shape of radioactive objects to augmented reality systems. Current portable γ-cameras only provide the relative angular position of the hotspots within their field of view. That is, they do not provide any metric information concerning the located sources. In this study, we propose two approaches to estimate the distance of the surrounding hotspots, and to autonomously determine if they are occluded by an object. The first consists in combining and accurately calibrating the gamma camera with a structured-light depth sensor. The second approach allows the estimation of the source-detector distance by means of stereo gamma imaging. To geometrically align the images obtained by the gamma, depth, and optical cameras used, a versatile calibration procedure has been designed and carried out. Such procedure uses a calibration phantom intentionally easy to build and inexpensive, allowing the procedure to be performed with only one radioactive point source. Experimental results showed that our calibration procedure yields to sub-pixel accuracy both in the re-projection error and the overlay of radiation and optical images. A quantitative analysis concerning the accuracy and resolution of the retrieved source-detector distance is also provided, along with an insight into the respective most influential factors. Moreover, the results obtained validated the choice of the geometry of the pinhole model for a coded aperture gamma camera.
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Submitted on : Tuesday, May 17, 2022 - 3:16:01 AM
Last modification on : Tuesday, June 14, 2022 - 7:09:04 AM

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2017-PARADISO-VINCENZO-VAC.pdf
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  • HAL Id : tel-03669788, version 1

Citation

Vincenzo Paradiso. Development of a portable gamma camera for accurate 3-D localization of radioactive hotspots. Other [cond-mat.other]. Normandie Université, 2017. English. ⟨NNT : 2017NORMC209⟩. ⟨tel-03669788⟩

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