Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy

Nagata, J.; Yamamoto, Seiichi; Noguchi, Yasuhisa; Nakaya, Takayoshi; Okudaira, Kuniyasu; Kamada, Kei; Yoshikawa, Akira

doi:10.1088/1748-0221/16/12/t12005

Cited by 3 publications

(11 citation statements)

References 15 publications

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“…The list‐mode data were fed to a personal computer (PC) via a ∼40‐m long local area network (LAN) cable. The expected system spatial resolution from calculation in addition to the results measured with the previous system 17 was ∼3 mm FWHM at 10 cm from the collimator surface.…”

Section: Methodsmentioning

confidence: 55%

“…To reduce the sensitivity as well as improving the system spatial resolution of the camera,we selected the 0.1-mm pinhole collimator. 17 We show the schematic drawing of the pinhole part of the collimator and the photo in Figure 1a,b, respectively.…”

Section: Gamma Camera System Using List-mode Data Acquisition Systemmentioning

confidence: 99%

“…17 These were the same as the system we previously developed for simultaneous imaging of gamma photons and an optical image, and thus the camera was placed in a black container in which two mirrors and a CMOS camera were also placed to measure an optical image with a gamma photon image at the same position. 17 The 64-analog signals from the FP-PMT formed four weight-summed analog signals that were fed to the developed list-mode data acquisition system. The listmode data were fed to a personal computer (PC) via a ∼40-m long local area network (LAN) cable.…”

Section: Gamma Camera System Using List-mode Data Acquisition Systemmentioning

confidence: 99%

“…The advantage of the data acquisition system combined with the YAP(Ce) gamma camera system compared with the previous system 16,17 are the larger image size (512 × 512), capability of acquiring the energy and pulse shape spectra, as well as temporal information by sorting the list-mode data. The disadvantages of the new data acquisition system compared with the previous system 16,17 are inability of the real-time display of the images and the time required for sorting the list-mode data. Real-time display may be possible by designing new electronics.…”

Section: Developed List-mode Data Acquisition Systemmentioning

confidence: 99%

“…16 Moreover, we adopted an optical camera to image the absolute position of the Ir-192 source. 17 However, the developed gamma camera system measured the images only in frame mode with a 1-s interval, so the dwell times could not be precisely measured. Furthermore, the moving speeds of the source before and after dwelling are so fast that they cannot be imaged nor measured.…”

Section: Introductionmentioning

confidence: 99%

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Technical note: Short‐time sequential high‐energy gamma photon imaging using list‐mode data acquisition system for high‐dose‐rate brachytherapy

et al. 2022

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Purpose Measurement of the dwell time and moving speed of a high‐activity iridium‐192 (Ir‐192) source used for high‐dose‐rate (HDR) brachytherapy is important for estimating the precise dose delivery to a tumor. For this purpose, we used a cerium‐doped yttrium aluminum perovskite (YA1O3:YAP(Ce)) gamma camera system, combined with a list‐mode data acquisition system that can acquire short‐time sequential images, and measured the dwell times and moving speeds of the Ir‐192 source. Methods Gamma photon imaging was conducted using the gamma camera in list mode for the Ir‐192 source of HDR brachytherapy with fixed dwell times and positions. The acquired list‐mode images were sorted to millisecond‐order interval time sequential images to evaluate the dwell time at each position. Time count rate curves were derived to calculate the dwell time at each source position and moving speed of the source. Results We could measure the millisecond‐order time sequential images for the Ir‐192 source. The measured times for the preset dwell times of 2 s and 10 s were 1.98 to 2.00 s full width at half maximum (FWHM) and 10.0 s FWHM, respectively. The dwell times at the first dwell position were larger than those at other positions. We also measured the moving speeds of the source after the dwells while moving back to the afterloader and found the speed increased with the distance from the edge of the field of view to the last dwell position. Conclusion We conclude that millisecond‐order time sequential imaging of the Ir‐192 source is possible by using a gamma camera and is useful for evaluating the dwell times and moving speeds of the Ir‐192 source.

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Section: Methodsmentioning

confidence: 55%

Section: Gamma Camera System Using List-mode Data Acquisition Systemmentioning

confidence: 99%

Section: Gamma Camera System Using List-mode Data Acquisition Systemmentioning

confidence: 99%

Section: Developed List-mode Data Acquisition Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical note: Short‐time sequential high‐energy gamma photon imaging using list‐mode data acquisition system for high‐dose‐rate brachytherapy

et al. 2022

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Estimating blurless and noise-free Ir-192 source images from gamma camera images for high-dose-rate brachytherapy using a deep-learning approach

Nakanishi,

Yamamoto,

Yabe

et al. 2023

Biomed. Phys. Eng. Express

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Objective: Precise monitoring of the position and dwell time of iridium-192 (Ir-192) during high-dose-rate (HDR) brachytherapy is crucial to avoid serious damage to normal tissues. Source imaging using a compact gamma camera is a potential approach for monitoring. However, images from the gamma camera are affected by blurring and statistical noise, which impact the accuracy of source position monitoring. This study aimed to develop a deep-learning approach for estimating ideal source images that reduce the effect of blurring and statistical noise from experimental images captured using a compact gamma camera.Approach: A double pix2pix model was trained using the simulated gamma camera images of an Ir-192 source. The first model was responsible for denoising the Ir-192 images, whereas the second model performed super resolution. Trained models were then applied to the experimental images to estimate the ideal images. Main results: At a distance of 100 mm between the compact gamma camera and the Ir-192 source, the difference in full width at half maximum (FWHM) between the estimated and actual source sizes was approximately 0.5 mm for a measurement time of 1.5 s. This difference has been improved from approximately 2.7 mm without the use of DL. Even with a measurement time of 0.1 s, the ideal images could be estimated as accurately as in the 1.5 s measurements. This method consistently achieved accurate estimations of the source images at any position within the field of view; however, the difference increased with the distance between the Ir-192 source and the compact gamma camera.Significance: The proposed method successfully provided estimated images from the experimental images within errors smaller than 0.5 mm at 100 mm. This method is promising for reducing blurring and statistical noise from the experimental images, enabling precise real-time monitoring of Ir-192 sources during HDR brachytherapy.

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Monte Carlo simulation study of an in vivo four-dimensional tracking system with a diverging collimator for monitoring radiation source (Ir-192) location during brachytherapy: proof of concept and feasibility

Oh,

Lee,

Kim

et al. 2024

Front. Physiol.

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Introduction: The aim of this study was to demonstrate the potential of an in vivo four-dimensional (4D) tracking system to accurately localize the radiation source, Iridium-192 (Ir-192) in high-dose rate brachytherapy.Methods: To achieve time-dependent 3D positioning of the Ir-192 source, we devised a 4D tracking system employing multiple compact detectors. During the system’s design phase, we conducted comprehensive optimization and analytical evaluations of the diverging collimator employed for detection purposes. Subsequently, we executed 3D reconstruction and positioning procedures based on the 2D images obtained by six detectors, each equipped with an optimized diverging collimator. All simulations for designing and evaluating the 4D tracking system were performed using the open-source GATE (v9.1) Monte Carlo platform based on the GEANT4 (v10.7) toolkit. In addition, to evaluate the accuracy of the proposed 4D tracking system, we conducted simulations and 3D positioning using a solid phantom and patient data. Finally, the error between the reconstructed position coordinates determined by the tracking system and the original coordinates of the Ir-192 radiation source was analyzed.Results: The parameters for the optimized diverging collimator were a septal thickness of 0.3 mm and a collimator height of 30 mm. A tracking system comprising 6 compact detectors was designed and implemented utilizing this collimator. Analysis of the accuracy of the proposed Ir-192 source tracking system found that the average of the absolute values of the error between the 3D reconstructed and original positions for the simulation with the solid phantom were 0.440 mm for the x coordinate, 0.423 mm for the y coordinate, and 0.764 mm for the z coordinate, and the average Euclidean distance was 1.146 mm. Finally, in a simulation based on data from a patient who underwent brachytherapy, the average Euclidean distance between the original and reconstructed source position was 0.586 mm.Discussion: These results indicated that the newly designed in vivo 4D tracking system for monitoring the Ir-192 source during brachytherapy could determine the 3D position of the radiation source in real time during treatment. We conclude that the proposed positioning system has the potential to make brachytherapy more accurate and reliable.

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Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy

Cited by 3 publications

References 15 publications

Technical note: Short‐time sequential high‐energy gamma photon imaging using list‐mode data acquisition system for high‐dose‐rate brachytherapy

Technical note: Short‐time sequential high‐energy gamma photon imaging using list‐mode data acquisition system for high‐dose‐rate brachytherapy

Estimating blurless and noise-free Ir-192 source images from gamma camera images for high-dose-rate brachytherapy using a deep-learning approach

Monte Carlo simulation study of an in vivo four-dimensional tracking system with a diverging collimator for monitoring radiation source (Ir-192) location during brachytherapy: proof of concept and feasibility

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