Crosstalk Reduction Using a Dual Energy Window Scatter Correction in Compton Imaging.

Makoto Sakai,Yoshiki Kubota,Mutsumi Tashiro,Raj Kumar Parajuli,Nobuteru Kubo,Kazuo Arakawa,Mikiko Kikuchi,Yuto Nagao,Mitsutaka Yamaguchi,Naoki Kawachi

doi:10.3390/s20092453

Abstract

Compton cameras can simultaneously detect multi-isotopes; however, when simultaneous imaging is performed, crosstalk artifacts appear on the images obtained using a low-energy window. In conventional single-photon emission computed tomography, a dual energy window (DEW) subtraction method is used to reduce crosstalk. This study aimed to evaluate the effectiveness of employing the DEW technique to reduce crosstalk artifacts in Compton images obtained using low-energy windows. To this end, in this study, we compared reconstructed images obtained using either a photo-peak window or a scatter window by performing image subtraction based on the differences between the two images. Simulation calculations were performed to obtain the list data for the Compton camera using a 171 and a 511 keV point source. In the images reconstructed using these data, crosstalk artifacts were clearly observed in the images obtained using a 171 keV photo-peak energy window. In the images obtained using a scatter window (176–186 keV), only crosstalk artifacts were visible. The DEW method could eliminate the influence of high-energy sources on the images obtained with a photo-peak window, thereby improving quantitative capability. This was also observed when the DEW method was used on experimentally obtained images.

Highlights

The Compton camera is the most promising device for the detection of gamma rays ranging from tens of keV to several MeV; it can identify the direction of gamma rays originating from radioisotopes based on the kinematics of Compton scattering
The scattered in the θ, can calculatedenergies from: Both detectorsangle record thescatterer, positions andbedeposited of the interaction
A large number keV gamma rays were observed in the photo-peak window of 171 scattered events were involved in the photo-peak window of 171

Summary

Introduction

The Compton camera is the most promising device for the detection of gamma rays ranging from tens of keV to several MeV; it can identify the direction of gamma rays originating from radioisotopes based on the kinematics of Compton scattering. An elementary Compton camera consists of two types of position-sensitive detectors. The first detector (scatterer) detects a series of Compton scattering events; the second detector (absorber) detects absorption phenomena (Figure 1). Both detectors record the Sensors 2020, 20, 2453; doi:10.3390/s20092453 www.mdpi.com/journal/sensors. Sensors 2020, 20, x FOR PEER REVIEW positions and deposited energies of the interaction (the Compton scattering and the photo-absorption). The scattered in the θ, can calculatedenergies from: Both detectorsangle record thescatterer, positions andbedeposited of the interaction (the Compton scattering and the photo-absorption).

Objectives

Methods

Results

Conclusion