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

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.

Hybrid PET/Compton-camera imaging: an imager for the next generation

“…These additional scans would support the calculation of the attenuation and scatter contributions. Instead, more practical but less accurate procedures have been implemented [120,121].…”

Development and Applications of Compton Camera—A Review

“…The camera consists of eight layers of Si detectors and four layers of CdTe detectors of (size: 5 cm × 5 cm and weights: 8–13 kg). These Si/CdTe cameras exhibit good energy and angular (2.2% at half maximum (FWHM) and 5°, respectively) resolutions for photons with an energy of 662 keV, and a high-count rate of 0.16 cps/MBq at a distance of 1 m. The medical applications of the Si/CdTe Compton camera were introduced by Sakai et al [ 79 ], especially in nuclear imaging of different RIs, followed by improvements in the Compton imaging algorithms [ 80 , 81 , 82 ]. The in vivo [ 83 ] and human imaging [ 84 ] applications of Si/CdTe Compton cameras are vital achievements of these devices in the field of nuclear medical imaging.…”

“…As a continuation, the in vivo 3D imaging of 131 I, 18 F-FDG (511keV), and 67 Ga-citrate (300 keV) was conducted [ 157 ]. Sakai et al [ 79 , 80 , 81 , 82 ] at the Gunma University Heavy Ion Medical Center (GHMC) tested a Si/CdTe Compton camera, and successful measurements with 99m Tc and 18 F within human phantoms were demonstrated in their studies. Finally, the in vivo results [ 83 ] in mice followed by human experiments [ 84 ] using a Si/CdTe Compton camera have been studied by researchers for its application in the medical field.…”

Double photon coincidence crosstalk reduction method for multi-nuclide Compton imaging

“…One of the challenges in multi-nuclide imaging is the crosstalk artifact caused by scattered photons of higher energy gamma-rays [21]. Additionally, finite energy and time resolutions will lead to misclassifications in the Compton event (generally a coincidence pair of a Compton scattering event and a fully absorbed event of the scattered gamma-ray).…”

“…The standard Compton imaging method using only energy information cannot distinguish whether the detected Compton event is a true event or a background event. Sakai et al applied the dual energy window (DEW) method to Compton imaging, which is commonly utilized in SPECT imaging to reduce crosstalk artifacts by applying a photo-peak window and a scatterer window [21]. In the study, the crosstalk-reduced images were obtained by subtracting two images reconstructed separately, which were an image using a photo-peak window and one using a scatter window.…”