Resolution recovery reconstruction for a Compton camera

Kim, Soo Mee; Seo, Hee; Park, Jin Hyung; Kim, Chan Hyeong; Lee, Chun Sik; Lee, Soojin; Lee, Dong Hoon; Lee, Jae Sung

doi:10.1088/0031-9155/58/9/2823

Cited by 30 publications

(28 citation statements)

References 23 publications

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“…Some preliminary simulations including energy resolution for the scatterers and absorber show a non-negligible degradation of the shift estimates. To a certain extend, some compensation should be achieved by modeling the limited resolution into the reconstruction, either in the system matrix or in the selection of the cone parameters [14]- [17]. For the considered CC configuration with seven scatterers including multiple coincidences into the reconstruction helped to increase the statistical quality of the data and compensate for the effects of miscalculated E 0 introduced by two-interaction coincidences.…”

Section: Discussionmentioning

confidence: 99%

Capability of MLEM and OE to Detect Range Shifts With a Compton Camera in Particle Therapy

Kohlhase

Wegener

Schaar

et al. 2020

IEEE Trans. Radiat. Plasma Med. Sci.

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To identify range deviations by using Compton cameras (CCs), tomographic image reconstruction of CC data is needed. Within this context, image reconstruction is usually performed using maximum likelihood expectation maximization (MLEM), and more recently, the origin ensemble (OE) algorithm. In this article, we investigate how MLEM and OE affect the precision and accuracy of estimated range deviations. In particular, we focus on the effects of data selection, statistical fluctuations, and artifact reduction. The use of external information of the beam path through a hodoscope was also explored. Additionally, two methods to calculate range deviations were tested. To this aim, realistic proton beams were simulated using GATE and data from single spots as well as from seven contiguous spots of an energy layer were reconstructed. MLEM and OE reacted differently to the poor data statistics. In general, both algorithms were able to detect range shifts for single spots, particularly when multiple coincidences were also considered. Selection of events corresponding to the most relevant energy peaks decreased the identification performance due to the lower statistics. When data from several contiguous spots were jointly reconstructed, the accuracy of the results degraded significantly, and nonzero shifts were assigned when no shifts had occurred. The limited size of the cameras and the subsequent restriction in the orientation and aperture of detected cones, as well as in the number of detected events are major challenges. Future efforts should be devoted to noise regularization and compensation for data truncation. Index Terms-Compton camera (CC), image reconstruction, particle therapy, prompt gamma imaging, range verification. I. INTRODUCTION I N RECENT years, Compton cameras (CCs) have attracted attention for range verification in particle therapy [1]-[6]. Within this context, the goal of the CC is to detect prompt gamma-rays (PG) that are emitted during de-excitation of Manuscript

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Section: Discussionmentioning

confidence: 99%

Capability of MLEM and OE to Detect Range Shifts With a Compton Camera in Particle Therapy

Kohlhase

Wegener

Schaar

et al. 2020

IEEE Trans. Radiat. Plasma Med. Sci.

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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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“…In Reader et al [3] the method was applied to PET imaging resolution recovery with a Gaussian model for the stationary PSF. Its use for the Compton camera imaging was originally proposed by Kim et al [4] and was further developed by Jan et al [5].…”

Section: A Image-space Psf Deconvolutionmentioning

confidence: 99%

Total variation and point spread function priors for MLEM reconstruction in Compton camera imaging

Feng¹,

Etxebeste²,

Létang³

et al. 2018

2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC)

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The Compton camera is a gamma ray imaging device already employed in astronomy and still in investigation for clinical domain. A key point in the imaging process is the tomographic reconstruction step. When the acquisition parameters and the a priori information are correctly accounted for, iterative algorithms are able to produce accurate images by compensating for measurement uncertainties and statistical noise. In this work we focus on the list-mode maximum likelihood expectation maximization (LM-MLEM) algorithm with smoothness a priori information expressed by the total variation norm. This type of regularization is particularly well suited for low-dose acquisitions, as it is the case in the applications foreseen for the camera. We show that the TV a priori strongly improves the images when data are acquired in ideal conditions. For realistic data, this a priori is not sufficient and deconvolution with a pre-calculated image-space kernel should also be considered.

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Resolution recovery reconstruction for a Compton camera

Cited by 30 publications

References 23 publications

Capability of MLEM and OE to Detect Range Shifts With a Compton Camera in Particle Therapy

Capability of MLEM and OE to Detect Range Shifts With a Compton Camera in Particle Therapy

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

Total variation and point spread function priors for MLEM reconstruction in Compton camera imaging

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