Three-dimensional localization and radioactivity quantification of radiation sources through inverse estimation based on Compton camera measurements.

To minimize the radiation exposure of workers and plan effective remediation strategies at the decommissioning site of the Fukushima Daiichi Nuclear Power Station, accurately locating radioactive substances is extremely important. Accordingly, this study presents a method to accurately determine the locations of multiple radiation sources in three dimensions and quantify their radioactivity levels. In particular, the proposed method involves the application of an inverse estimation technique to images captured using a Compton camera. Here, the target region is initially divided into multiple regions of interest, and images are then acquired by placing a radiation source of known radioactivity in each region of interest. These obtained images are subsequently multiplied by coefficients and summed to reproduce the image data of multiple unknown radiation sources. The radioactivity of each unknown radiation source is then estimated based on the coefficients determined via inverse estimation.