Directionality for wearable, closely packed radiation detector arrays

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2021-01, Vol.986 (C), p.164708, Article 164708
• Main Authors: Britt, C., Wen, X., Qi, H., Hayward, J.P.
• Format: Article
• Language: English
• Subjects: Detector array; Directionality; Maximum Likelihood Estimation; Radiation detection
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2020.164708

This work defines directionality as the act of estimating a radiation source’s angular coordinate on the horizontal plane within a single measurement, usually up to a few seconds. This work develops a directionality algorithm for general use in wearable, closely packed detector arrays. The algorithm was demonstrated on three 2″×2″×4″ NaI(Tl) detectors. Directionality performance was quantitatively assessed by observing misclassification rates within the confusion matrices. These misclassification behaviors were condensed into a single number, the Mean Absolute Error (MAE), and a trend between directionality performance and uncollided gamma fluence is reported. The MAE was measured to be 8.2° using a 113.4 μCi Cs-137 source and 17.8° using a 34.6 μCi Co-60 source, where both sources were placed 172.4 cm away. Finally, this directionality algorithm was demonstrated in the case of static detector array with a moving source where an MAE of 12.7° was observed for a 113 μCi Cs-137 source at an average distance of 350.0 cm away.