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Simulated near-field radioactive source localization in 3D with Coded Aperture and Convolutional Neural Networks

JOURNAL OF INSTRUMENTATION 2025年第1期20卷

作者： Karafasoulis, K. Kaissas, I. Papadimitropoulos, C. Potiriadis, K. Lambropoulos, C. P. Hellen Army Acad Dept Nat Sci & Applicat Evelpidon Ave Vari Attikis 16673 Greece Aristotle Univ Thessaloniki Fac Engn Dept Elect & Comp Engn Egnatia 54124 Thessaloniki Greece Natl & Kapodistrian Univ Athens Dept Aerosp Sci & Technol Psachna Evia 34400 Greece Greek Atom Energy Commiss Patriarxou Grigoriou & Neapoleos Aghia Paraskevi Greece

Coded Aperture 7-cameras have been extensively used in applications ranging from astrophysics to nuclear medicine for imaging radioactive source distributions. These devices allow the identification of the direction of 7-emitters by analyzing the shadow patterns projected onto pixelated detectors. In this work, we propose a novel approach based on Convolutional Neural Networks (CNNs) for accurately localizing radioactive sources in 3D using one coded aperture gamma camera. The CNN is trained using simulated shadowgrams generated by a custom simulation tool, with sources placed at various positions within the near-field, ranging from 20 cm to 120 cm from the detector. Unlike previous methods that focused on estimating angular coordinates, our model also accurately estimates the distance of the source, achieving a distance estimation accuracy of 10 mm, in addition to determining the polar and azimuthal angles. This capability is particularly relevant for medical imaging applications, where precise localization of radioactive sources is crucial. The results of our study demonstrate the potential of CNN-based algorithms in improving the accuracy and reliability of single-detector systems in near-field radioactive source localization.

关键词： Data processing methods Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software

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Analytic sparse-view CBCT reconstruction using a novel sinogram restoration method based on higher-order Fourier harmonic peaks

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JOURNAL OF INSTRUMENTATION 2024年第11期19卷 C11001页

作者： Lee, Jonghyeok Lim, Hyunwoo Cho, Sanghyun Seo, Changwoo Cha, Bo Kyung Cho, Hyosung Yonsei Univ Dept Radiat Convergence Engn Wonju South Korea Korea Electrotechnol Res Inst Precis Med Device Res Ctr Ansan South Korea

This study presents an analytic sparse-view cone-beam computed tomography (CBCT) reconstruction method using a novel sinogram restoration technique based on higher-order Fourier harmonic peaks to obtain CBCT images of reasonable quality with a reduced radiation dose. The proposed method involves four main steps: (1) acquiring sparse-view (P144) sinogram from a CBCT system, (2) upsampling (P720) the original sparse-view sinogram with equally spaced zero padding, (3) separating higher-order Fourier harmonic peaks of the upsampled sinogram using a band-pass filter, and (4) restoring the sinogram of the higher-order harmonic peaks by taking its magnitude, followed by computationally cost-efficient filtered-backprojection (FBP)-based CBCT reconstruction and denoising processes. The notation P144 indicates that the number of projections is 144. To verify the efficacy of the proposed method, an experiment was performed on a chest phantom using a prototype CBCT system comprising an X-ray tube (90 kVp and 40 mA), a large-area flat-panel detector (388 mu m pixel size), and a rotational gantry. The quality of the restored sparse-view CBCT images was quantitatively evaluated in terms of the image intensity profile, universal quality index (UQI), and peak signal-to-noise ratio (PSNR). The results indicate that the proposed sinogram restoration method effectively recovered zero-padded areas in the original upsampled sinogram with image intensities nearly identical to those of the reference dense-view (P720) sinogram, which demonstrates the efficacy of the proposed sinogram restoration method. The quality of the sparse-view CBCT image restored with higher-order harmonic peaks was close to that of the reference dense-view CBCT image, maintaining the image quality. The UQI and PSNR values of the restored sparse-view CBCT image were 0.93 and 34.84, respectively, which are approximately 1.3 and 1.2 times greater than those of the original sparse-view CBCT image, respectively, improvin

关键词： computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided software

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An improving reconstruction network for sparse view spectral CT based on dual-domain hybrid encoder integrating ResNet and Transformer

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JOURNAL OF INSTRUMENTATION 2025年第5期20卷

作者： Kong, Fanning Shi, Zaifeng Ge, Tianhao Li, Qiwei Cao, Qingjie Tianjin Univ Sch Microelect 92 Weijin Rd Tianjin Peoples R China Tianjin Normal Univ Sch Math Sci 393 Binshui West Rd Tianjin Peoples R China Tianjin Key Lab Imaging & Sensing Microelect Techn 92 Weijin Rd Tianjin Peoples R China

Sparse-view Computed Tomography (CT) is an effective method for reducing radiation dose. However, the incompleteness of the projection results in streaking artifacts in the reconstructed images. Dual energy CT Data complementarity and diversity in both the projection and image domains represent a promising solution to recover the missing information from sparse views. We proposed an end-to-end sparse-view dual-domain improved dual-energy CT reconstruction network (DdDe-Net) to recover the missing information due to the reduced number of projections. The network is comprised of a projection domain data correction module (PDDC-Net) and an image domain data correction module (IDDC-Net). In PDDC-Net, ResNet and Transformer architectures are combined with a residual module to create a hybrid encoder structure, effectively suppressing noise and artifacts in the projection domain. The IDDC-Net further reduces streaking artifacts and preserves tissue details through the prior image and differential learning process. DdDe-Net was trained and validated on a sparse-view extended dataset of simulated breast DECT data and an abdominal slice simulation dataset. Compared to several mainstream CT image reconstruction algorithms, our proposed algorithm demonstrates a notable advantage, achieving a RMSE of 0.0118 +/- 0.0032, a SSIM of 0.9688 +/- 0.0177, and a PSNR of 39.83 +/- 1.14 dB. The experimental results indicate that DdDe-Net effectively mitigates artifacts while preserving image details in sparse-view DECT, underscoring its potential for practical applications.

关键词： computerized Tomography (CT) and Computed Radiography (CR) image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software

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Minimizing inconsistencies in gray values in small field-of-view dental computed tomography by modulating reconstruction filter intensity: simulation study

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JOURNAL OF INSTRUMENTATION 2024年第12期19卷

作者： Kim, Woosung Shim, Jiyong Jeon, Duhee Lim, Younghwan Lee, Soohyun Kim, Kyuseok Park, Chulkyu Cho, Hyosung Yonsei Univ Dept Radiat Convergence Engn Wonju South Korea Eulji Univ Dept Biomed Engn Seongnam South Korea Vatech Co R&D Ctr Hwaseong South Korea

Small field-of-view (FOV) cone-beam computed tomography (CBCT), which employs low-cost, small-area flat-panel detectors, is often used in dental CT where only a limited volume of an examined object is reconstructed using the standard filtered-backprojection algorithm. However, when examining with a small FOV, the surrounding structures located outside the FOV exacerbate the inhomogeneity of the inherent distribution of gray values (GVs) in the reconstructed CBCT volume. To address this issue, this study presents an effective method to minimize the inconsistencies in GVs in small FOV CBCT images by modulating reconstruction filter (ramp filter) intensity. To verify the efficacy of the proposed method, a feasibility study was conducted via a simulation using three-dimensional numerical mouth phantoms without metal insert and with metal inserts as highly attenuating dental materials. The mean GVs of the innermost FOV without correction were 60.3 and 63.1 for the cases of no metal and two metal inserts, respectively, which were approximately 7.8% and 6.5% greater than those of the corresponding reference FOVs. In contrast, the mean GVs with correction for all target FOVs were very close (<0.1%) to that of the reference FOV, indicating the efficacy of the proposed method. Consequently, small FOV dental CT images with good homogeneity of the GV distribution were successfully obtained using the proposed method, which is critical, particularly for assessing bone density in dental implantation surgery plan.

关键词： Data processing methods image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software Dental computed tomography Small field of view Exomass effect Gray value Ramp filter

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Tracking a moving point source using triple gamma imaging

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JOURNAL OF INSTRUMENTATION 2024年第1期19卷 P01001页

作者： Chmeissani, Mokhtar Kolstein, Machiel Arino-Estrada, Gerard Gabriel Macias-Montero, Jose Puigdengoles, Carles Garcia, Jorge Barcelona Inst Sci & Technol BIST Inst Fis Altes Energies IFAE Campus UAB E-08193 Bellaterra Barcelona Spain Univ Calif Davis Dept Biomed Engn Davis CA 95616 USA

With positron emission tomography (PET), the positron of a beta(+) emitter radioisotope annihilates with a nearby electron producing a pair of back-to-back 511 keV gamma rays that can be detected in a scanner surrounding the point source. The position of the point source is somewhere along the Line of Response (LOR) that passes through the positions where the 511 keV gammas are detected. In standard PET, an image reconstruction algorithm is used to combine these LORs into a final image. This paper presents a new tomographic imaging technique to locate the position of a beta(+) emitting point source without using a standard PET image reconstruction algorithm. The data were collected with a Proof-of-Concept (PoC) PET scanner which has high spatial and energy resolutions. The imaging technique presented in this paper uses events where a gamma undergoes Compton scattering. The positions and energies deposited by the Compton scattered gamma define the surface of a Compton cone (CC) which is the locus of all possible positions of the point source, allowed by the Compton kinematics. The position of the same point source is also located somewhere on the LOR. Therefore, the position of the point source is defined by the 3 gammas and is given by the intersection point of the LOR and the Compton cone inside the Field of View (FOV) of the scanner. We refer to this method as CCxLOR. This new technique can locate the point source with an uncertainty of about 1 mm, after collecting a minimum of 200 CCxLOR events.

关键词： Compton imaging Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software

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Spectral micro-CT for simultaneous gold and iodine detection, and multi-material identification

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JOURNAL OF INSTRUMENTATION 2024年第4期19卷 C04023页

作者： Perion, P. Arfelli, F. Menk, R. H. Brombal, L. Univ Trieste Dept Phys Via Alfonso Valerio 2 Trieste Italy Ist Nazl Fis Nucl Div Trieste Via Alfonso Valerio 2 Trieste Italy Elettra Sincrotrone Trieste SS 14Km 1635 Area Sci Pk Trieste Italy Mid Sweden Univ Dept Comp & Elect Engn Holmgatan 10 Sundsvall Sweden

Multiple energy bin spectral micro -CT (SCT) is an advanced imaging technique that allows multi -material decomposition according to their specific absorption patterns at a sub -100 mu m scale. Typically, iodine is the preferred CT contrast agent for cardiovascular imaging, while gold nanoparticles have gained attention in recent years owing to their high absorption properties, biocompatibility and ability to target tumors. In this work, we demonstrate the potential for multi -material decomposition through SCT imaging of a test sample at the PEPI lab of INFN Trieste. The sample, consisting of gold, iodine, calcium, and water, was imaged using a Pixirad1/PixieIII chromatic detector with multiple energy thresholds and a wide spectrum (100 kV) produced by a micro -focus X-ray tube. The results demonstrate the simultaneous detection and separation of the four materials at a spatial scale of 35 mu m, suggesting the potential of this technique in improving material detectability and quantification in a range of pre -clinical applications, including cardiovascular and oncologic imaging.

关键词： computerized Tomography (CT) and Computed Radiography (CR) image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software X-ray detectors

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Impact of uterine deformation induced by applicator on brachytherapy dosimetric value: an uterine-mimicking-phantom study

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JOURNAL OF INSTRUMENTATION 2023年第8期18卷 P08027页

作者： Seiri, Mahnaz Jaberi, Ramin Solgi, Razieh Shakeri, Mahsa Ghadiri, Hossein Univ Tehran Med Sci Sch Med Dept Med Phys & Biomed Engn Tehran Iran Univ Tehran Med Sci Adv Med Technol & Equipment Inst Res Ctr Mol & Cellular Imaging RCMCI Tehran Iran Univ Tehran Med Sci Preclin Core Facil Tehran Iran Univ Tehran Med Sci Canc Inst Radiat Oncol Res Ctr RORC Tehran Iran Univ Surrey Dept Phys Guildford England

Brachytherapy (BT) is subjected to uncertainties from imaging, treatment planning, and anatomical variations. It is necessary to identify the uncertainties, their magnitude, and their impact on the overall uncertainty of dose delivery. The aim of the present phantom-based study is to investigate the deformation of the uterus anatomy induced by BT applicator insertion and the relationship between dose and location of the inserted applicator. A novel flexible phantom was designed based on female pelvic anatomy by the 3D printing process to simulate the deformation and movement of the uterine during the BT process. The applicator was inserted into the uterus and in order to simulate the uterus motion, the phantom was moved in four directions, right, left, down, and up. The CT and ultrasound images were obtained. A two-stage registration algorithm was designed to register the ultrasound and CT images in order to calculate the applicator displacements map. This map was used to calculate delivered dose error to uterus and rectum and to correct the planned dose values in treatment planning procedure. The results showed that in a planned D90 (dose) of 9.4 Gy for the uterus and maximum dose of 1.8 Gy to the rectum, movement of applicator leads to a big deviation in final delivered doses. After the applicator moved to the right and left directions, the D90 delivered to the uterus was 6.2 Gy and 5.6 Gy, respectively. Moreover, by moving downwards and upwards, the uterus received 0.4 and 1.2 Gy lower than 9.4 Gy. Similarly, the maximum dose to the rectum in right, left, down, and up directions after applicator movement were 3.4 Gy, 3.3 Gy, 3.7 Gy and 3.2 Gy, respectively which highlighted the higher delivered dose to the rectum. The results of the study demonstrate that applicator displacement can lead to uterine underdosing and also increase the risk of rectum irradiation. Ultimately, image-guided brachytherapy and using image registration can increase the accuracy of treatmen

关键词： algorithms and software for radiotherapy Multi-modality systems Radiotherapy concepts medical-image reconstruction methods and algorithms, computer-aided software

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image reconstruction method in grating interferometer with phase stepping using grating position and dose fluctuation correction

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JOURNAL OF INSTRUMENTATION 2023年第7期18卷 P07006页

作者： Oh, Ohsung Kim, Daeseung Kim, Kyung Lee, Seung Wook Pusan Natl Univ Sch Mech Engn Busandaehak Ro 63beon Gil Busan 46241 South Korea

In this paper, we propose a method for reducing artifacts in X-ray and neutron grating interferometer imaging by optimizing the grating position and dose fluctuation. Grating interferometer can obtain additional information about the object, such as phase-contrast image and dark-field image, compared to traditional X-ray imaging. However, several errors such as inaccurate grating positions and non-uniform X-ray intensity can cause artifacts in the image and degrade image quality. The proposed method can reduce the artifacts by minimizing the value in the sample-free region in the transmission and dark-field images. We conducted experiments on both simulated and X-ray and neutron experimental data and demonstrated the effectiveness of our method.

关键词： image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software Data processing methods X-ray radiography and digital radiography (DR)

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Designs of three different octagonal-shaped antennas for microwave-based breast cancer detection

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JOURNAL OF INSTRUMENTATION 2023年第9期18卷 P09013页

作者： Aydin, Emine Avsar Aydin, Ahmet Saribas, Gozde Adana Alparslan Turkes Sci & Technol Univ Dept Aerosp Engn Saricam Adana Turkiye Cukurova Univ Dept Biomed Engn Balcali Adana Turkiye

Today, there are numerous studies on Microwave Imaging methods. Thanks to these studies, the success and accuracy rate, especially in breast cancer diagnosis, increases. Microstrip antennas are used in the microwave imaging method. In this study, three different antenna models aimed to be used in microwave imaging methods were designed on the CST Studio Suite program. The designed antennas have been tested on the phantom model in the simulation environment. The test results were examined, and the designed antennas were produced using 3D printing technology. The built antennas were tested in the laboratory using the phantom and tumor-containing phantom models and obtained results were compared.

关键词： Manufacturing MRI (whole body, cardiovascular, breast, others), MR-angiography (MRA) Simulation methods and programs medical-image reconstruction methods and algorithms, computer-aided software

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Large-Area SiPM Pixels (LASiPs) in SPECT

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JOURNAL OF INSTRUMENTATION 2022年第7期17卷 C07021-C07021页

作者： Wunderlich, C. Guberman, D. Paoletti, R. Rugliancich, A. Passeri, A. Ist Nazl Fis Nucl Sez Pisa Largo Bruno Pontecorvo 3 Edificio C I-56126 Pisa Italy Univ Siena Dipartimento Sci Fis Terra & Ambiente Via Roma 56 I-53100 Siena Italy Univ Firenze Dipartimento Sci Biomed Sperimentali & Clin SBSC Viale Morgagni 50 I-50134 Florence Italy

A standard camera for Single Photon Emission Computed Tomography (SPECT) contains 50-100 photomultiplier tubes (PMTs) that occupy at least 50% of its volume. It is shielded by a thick layer of lead which makes it heavy and bulky. Replacing PMTs by silicon photomultipliers (SiPMs) could significantly reduce the weight and size of a SPECT camera. However, the main obstacle is the limited size of SiPMs: even with the largest commercially available SiPM of 6 x 6 mm(2) a few thousand channels would be needed to fill a camera. As a solution, we propose to use Large Area SiPM Pixels (LASiPs) which are built by summing the currents of several SiPMs into a single output. We developed a LASiP prototype summing 8 SiPMs using the MUSIC ASIC. To test the feasibility of using this solution in SPECT, we built a proof-of-concept micro camera that consisted of four of our LASiP prototypes coupled to a 40 x 40 x 8 mm(3) NaI(Tl) crystal. We were able to reconstruct simple images of a Tc-99m capillary with an intrinsic spatial resolution of similar to 2mm and an energy resolution of similar to 11.6%. We also simulated the system with Geant4, finding a good agreement with our experimental results. The simulations were extended to a larger camera, aiming to study the impact of pixel size, shape and noise.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-mage reconstruction methods and algorithms, computer-aided diagnosis medical-image reconstruction methods and algorithms, computer-aided software

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