Effect of number of views on cross-sectional Compton imaging: A fundamental study with backprojection

Sakai, Makoto; Parajuli, Raj Kumar; Kikuchi, Mikiko; Yamaguchi, Mitsutaka; Nagao, Yuto; Kawachi, Naoki; Arakawa, Kazuo; Nakano, Takashi

doi:10.1016/j.ejmp.2018.11.006

Cited by 15 publications

(9 citation statements)

References 16 publications

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“…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.…”

Section: Types Of Compton Camerasmentioning

confidence: 99%

Development and Applications of Compton Camera—A Review

Parajuli

Sakai

Parajuli³

et al. 2022

Sensors

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The history of Compton cameras began with the detection of radiation sources originally for applications in astronomy. A Compton camera is a promising γ-ray detector that operates in the wide energy range of a few tens of keV to MeV. The γ-ray detection method of a Compton camera is based on Compton scattering kinematics, which is used to determine the direction and energy of the γ-rays without using a mechanical collimator. Although the Compton camera was originally designed for astrophysical applications, it was later applied in medical imaging as well. Moreover, its application in environmental radiation measurements is also under study. Although a few review papers regarding Compton cameras have been published, they either focus very specifically on the detectors used in such cameras or the particular applications of Compton cameras. Thus, the aim of this paper is to review the features and types of Compton cameras and introduce their applications, associated imaging algorithms, improvement scopes, and their future aspects.

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Section: Types Of Compton Camerasmentioning

confidence: 99%

Development and Applications of Compton Camera—A Review

Parajuli

Sakai

Parajuli³

et al. 2022

Sensors

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“…To generate data for testing our algorithm, Geant4-based Monte Carlo simulations were conducted [19]. The simulation codes used to emulate our existing Compton camera have already been verified in previous studies [6,7,20,21]. Fig 1(A) shows the geometry of the simulation model.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…Compton cameras have been developed for use in the field of γ-ray astronomy [3,4]. We have been developing a semiconductor-based Compton camera for a nuclear medical imaging system that was originally developed by the Japan Aerospace eXploration Agency (JAXA) [5][6][7]. Our Compton camera used a silicon (Si) semiconductor detector with low noise, allowing low-energy gamma emitters to be imaged with high accuracy [8].…”

Section: Introductionmentioning

confidence: 99%

Improved iterative reconstruction method for Compton imaging using median filter

et al. 2020

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A Compton camera is a device for imaging a radio-source distribution without using a mechanical collimator. Ordered-subset expectation-maximization (OS-EM) is widely used to reconstruct Compton images. However, the OS-EM algorithm tends to over-concentrate and amplify noise in the reconstructed image. It is, thus, necessary to optimize the number of iterations to develop high-quality images, but this has not yet been achieved. In this paper, we apply a median filter to an OS-EM algorithm and introduce a median root prior expectation-maximization (MRP-EM) algorithm to overcome this problem. In MRP-EM, the median filter is used to update the image in each iteration. We evaluated the quality of images reconstructed by our proposed method and compared them with those reconstructed by conventional algorithms using mathematical phantoms. The spatial resolution was estimated using the images of two point sources. Reproducibility was evaluated on an ellipsoidal phantom by calculating the residual sum of squares, zero-mean normalized cross-correlation, and mutual information. In addition, we evaluated the semi-quantitative performance and uniformity on the ellipsoidal phantom. MRP-EM reduces the generated noise and is robust with respect to the number of iterations. An evaluation of the reconstructed image quality using some statistical indices shows that our proposed method delivers better results than conventional techniques.

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“…A Gaussian function is the most common function to express PSFs. Unfortunately, however, the Gaussian function is not suitable, and GPF possesses better PSFs in Compton imaging than Gaussian, Lorentzian, and Voigt functions (35,36).…”

Section: Point Source Studymentioning

confidence: 99%

Use of a Si/CdTe Compton Camera for In vivo Real-Time Monitoring of Annihilation Gamma Rays Generated by Carbon Ion Beam Irradiation

et al. 2020

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The application of annihilation gamma-ray monitoring to the adaptive therapy of carbon ion radiotherapy (C-ion RT) requires identification of the peak intensity position and confirmation of activated elements with annihilation gamma-rays generated at the C-ion-irradiated site from those transported to unirradiated sites. Real-time monitoring of C-ion-induced annihilation gamma-rays was implemented using a Compton camera in a mouse model. An adult C57BL/6 mouse was anesthetized, and C-ion beams were directed into the abdomen at 1 × 10 9 particles/s for 20 s. The 511 keV annihilation gamma-rays, generated by the interaction between the irradiated C-ion beam and the target mouse, were detected using a silicon/cadmium telluride (Si/CdTe) Compton camera for 20 min immediately after irradiation. The irradiated site and the peak intensity position of 511 keV gamma emissions due to C-ion beam irradiation on a mouse were observed at the abdomen of the mouse by developing Compton images. Moreover, the positron emitter transport was observed by evaluating the range of gamma-ray emission after the C-ion beam irradiation on the mouse. Our data suggest that by confirming the peak intensity and beam range of C-ion RT with Si/CdTe-based Compton camera, it would be possible to reduce the intra-fractional and inter-fractional dose distribution degradation. Therefore, the results of this study would contribute to the future development of adaptive therapy with C-ion RT for humans.

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Effect of number of views on cross-sectional Compton imaging: A fundamental study with backprojection

Cited by 15 publications

References 16 publications

Development and Applications of Compton Camera—A Review

Development and Applications of Compton Camera—A Review

Improved iterative reconstruction method for Compton imaging using median filter

Use of a Si/CdTe Compton Camera for In vivo Real-Time Monitoring of Annihilation Gamma Rays Generated by Carbon Ion Beam Irradiation

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