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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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A fully automatic, threshold-based segmentation method for the estimation of the Metabolic Tumor Volume from PET images: validation on 3D printed anthropomorphic oncological lesions

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JOURNAL OF INSTRUMENTATION 2016年第1期11卷 C01022-C01022页

作者： Gallivanone, F. Interlenghi, M. Canervari, C. Castiglioni, I. CNR Inst Mol Imaging & Physiol Flli Cervi 93 Segrate Mi Italy IRCCS San Raffaele Sci Inst Div Nucl Med Via Olgettina 60 I-20132 Milan Italy

18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET) is a standard functional diagnostic technique to in vivo image cancer. Different quantitative paramters can be extracted from PET images and used as in vivo cancer biomarkers. Between PET biomarkers Metabolic Tumor Volume (MTV) has gained an important role in particular considering the development of patient-personalized radiotherapy treatment for non-homogeneous dose delivery. Different imaging processing methods have been developed to define MTV. The different proposed PET segmentation strategies were validated in ideal condition (e.g. in spherical objects with uniform radioactivity concentration), while the majority of cancer lesions doesn't fulfill these requirements. In this context, this work has a twofold objective: 1) to implement and optimize a fully automatic, threshold-based segmentation method for the estimation of MTV, feasible in clinical practice 2) to develop a strategy to obtain anthropomorphic phantoms, including non-spherical and non-uniform objects, miming realistic oncological patient conditions. The developed PET segmentation algorithm combines an automatic threshold-based algorithm for the definition of MTV and a k-means clustering algorithm for the estimation of the background. The method is based on parameters always available in clinical studies and was calibrated using NEMA IQ Phantom. Validation of the method was performed both in ideal (e.g. in spherical objects with uniform radioactivity concentration) and non-ideal (e.g. in non-spherical objects with a non-uniform radioactivity concentration) conditions. The strategy to obtain a phantom with synthetic realistic lesions (e.g. with irregular shape and a non-homogeneous uptake) consisted into the combined use of standard anthropomorphic phantoms commercially and irregular molds generated using 3D printer technology and filled with a radioactive chromatic alginate. The proposed segmentation algorithm was feasible in a clin

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

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Analysis of femur head microstructure in ovariectomized rats

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JOURNAL OF INSTRUMENTATION 2013年第7期8卷 C07007-C07007页

作者： Andrade, C. B. V. Nogueira, L. P. Salata, C. da Silva, C. M. Ferreira-Machado, S. C. de Almeida, C. E. Almeida, A. P. Colaco, M. V. Alessio, R. C. P. V. Braz, D. Tromba, G. Barroso, R. C. Univ Estado Rio de Janeiro Lab Ciencias Radiol BR-20550011 Rio De Janeiro Brazil Univ Estado Rio de Janeiro Lab Fis Med BR-20550011 Rio De Janeiro Brazil Univ Fed Fluminense Dept Biol Geral Niteroi RJ Brazil COPPE Univ Fed Rio de Janeiro BR-21945970 Rio De Janeiro Brazil Sincrotrone Trieste ScpA I-34012 Trieste Italy

It is well accepted that rat ovariectomy (OVX) is a model of estrogen deficiency. OVX played a very important role in the initiating and developing of osteoporosis and it has been shown to be a major risk factor for the development of postmenopausal osteoporosis in women. In this work we used synchrotron radiation computed microtomography to investigate the skeletal effects in femoral head of femaleWistar rats after bilateral ovariectomy surgery. The CT system was set up at the SYRMEP beamline in the synchrotron radiation facility ELETTRA (Trieste, Italy). Micro-CT images provided 3D information on precise trabecular microstructure by the reconstruction of multiple 2D images with almost 2 mu m resolution. Our aim was to use histomorphometric analysis to reveal the effect of OVX on the three-dimensional (3D) trabecular bone microarchitecture. Evaluated morphometric parameters were trabecular bone volume-tissue volume ratio (BV/TV), trabecular number (Tb.N), trabecular separation (***) and trabecular thickness (***). OVX group presented noticeable reduction in the Tb.N and *** when compared with control group (P < 0.01). However, trabecular micro-CT parameters showed that BV/TV and *** were slightly lower in the OVX animals than that of the control group during the experimental period, which was not significantly different (P > 0.05). Our data may help to gain more insight into the potential mechanism of osteoporotic femoral head fractures.

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

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reconstruction method for grating-based x-ray phase-contrast images without knowledge of the grating positions

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JOURNAL OF INSTRUMENTATION 2015年第12期10卷 P12017-P12017页

作者： Pelzer, G. Rieger, J. Hauke, C. Horn, F. Michel, T. Seifert, M. Anton, G. Univ Erlangen Nurnberg Erlangen Ctr Astroparticle Phys Erwin Rommel Str 1 D-91058 Erlangen Germany

To retrieve the phase information of x-rays using a Talbot-Lau interferometer, the knowledge of the grating positions is mandatory. Transferring the interferometer technique from the laboratory to a conventional x-ray imaging system, this requirement is no longer guaranteed. This is due to distortions and vibrations which are coupled into the interferometer. Therefore, we applied a principal-component analysis to Talbot-Lau x-ray phase-contrast data. In experiments we compared this alternative approach for image reconstruction to the conventional procedure. As a result, a superior robustness of the principal-component analysis against imperfect phase-stepping data was found. Furthermore, using the proposed method, the reconstruction of x-ray phase-contrast images from randomly distributed phase-step positions is possible.

关键词： medical-image reconstruction methods and algorithms, computer-aided software Xray radiography and digital radiography (DR)

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A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect: a simulation study

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JOURNAL OF INSTRUMENTATION 2014年第10期9卷 P10004-P10004页

作者： Yang, Renhuan Song, Aiguo Li, Xiao Dong Lu, Yang Yan, Ruqiang Xu, Baoguo Li, Xu Jinan Univ Coll Informat & Technol Guangzhou 510632 Guangdong Peoples R China Southeast Univ Sch Instrument Sci & Engn Nanjing 210096 Jiangsu Peoples R China Johns Hopkins Univ Dept Radiol & Radiol Sci Baltimore MD 21205 USA

A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.

关键词： image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided diagnosis Multi-modality systems 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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Least squares estimate algorithm based on particle swarm optimization for position reconstruction of scintillation crystal

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JOURNAL OF INSTRUMENTATION 2018年第12期13卷 P12029-1-P12029-13页

作者： Shi, R. G. Chen, Y. Wei, M. F. China Acad Engn Phys Inst Mat Jiangyou 621907 Mianyang Peoples R China

reconstruction algorithm is a key technology for improving the performance of gamma cameras. This paper presents a least squares estimate (LSE) algorithm based on particle swarm optimization (PSO) to estimate the position of a scintillation event detected in a continuous crystal by a position sensitive photomultiplier tube (PSPMT). The theoretical framework of this algorithm consists of two parts: an enhanced objective function with a coefficient established by LSE via fitting the charge signals with the Scrimger-Backer formula;PSO method to search the global optimum solution of the objective function. The constant coefficient eta = Q/I introduced to objective function is demonstrated to effectively improve the position linearity response and expand the useful field of view (UFOV) up to almost the dimension of the PSPMT for both wide and narrow light distribution. More powerful global searching ability and highier computational efficiency are shown in PSO-based LSE algorithm in comparison with the gradient-descent-based LSE (GD-based LSE) algorithm. Furthermore, the PSO-based LSE algorithm overcomes the compression effect produced by trunction of light distribution in CoG algorithm and exhibits an almost idea position linearity response as well as 96 similar to 99% ratios of FOV/crystal size for different light distributions.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided software Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators)

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Limited Angle Tomography reconstruction for non-standard MBI system by means of parallel-hole and pinhole optics

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JOURNAL OF INSTRUMENTATION 2020年第4期15卷

作者： Poma, G. E. Garibaldi, F. Giuliani, F. Insero, T. Lucentini, M. Marcucci, A. Musico, P. Nuyts, J. Santavenere, F. Schramm, G. Sutera, C. Cisbani, E. Ist Nazl Fis Nucl Sez Catania Via S Sofia 64 I-95123 Catania Italy Univ Catania Dipartimento Fis & Astron Via S Sofia 64 I-95123 Catania Italy ISS Ist Super Sanita Viale Regina Elena 199 I-00161 Rome Italy Osped Pediat Bambin Gesu Viale San Paolo 15 I-00146 Rome Italy Aeronaut Mil Italiana Viale Univ 4 I-00185 Rome Italy Ist Nazl Fis Nucl Sez Genova Via Dodecaneso 33 I-16146 Genoa Italy Univ Leuven KU Leuven Dept Imaging & Pathol Nucl Med & Mol Imaging Med Imaging Res Ctr MIRC B-3000 Leuven Belgium

The purpose of the present work is the study of reconstruction properties of a new Molecular Breast Imaging (MBI) device for the early diagnosis of breast cancer, in Limited Angle Tomography (LAT), by using two asymmetric detector heads with different collimators. The detectors face each other in anti-parallel viewing direction and, mild-compressing the breast phantom, they are able to reconstruct the inner tumour of the phantoms with only a limited number of projections using a dedicated maximum-likelihood expectation maximization algorithm. The phantoms, the MBI system, as well as the Monte Carlo simulator, are briefly described. The MBI system's model has been implemented in IDL, in order to evaluate the best LAT configuration of the system and its reconstruction ability by varying tumour's size, depth and uptake. The LAT setup in real and simulated configurations, as well as the maximum-likelihood method and the preliminary reconstruction results, are discussed.

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

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Preliminary performance evaluation of adjustable-FOV full-body PET

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JOURNAL OF INSTRUMENTATION 2020年第6期15卷

作者： Ozsahin, I. Near East Univ Fac Engn Dept Biomed Engn Mersin 10 TRNC TR-99138 Nicosia Turkey Near East Univ DESAM Inst Mersin 10 TRNC TR-99138 Nicosia Turkey

Recent developments in molecular imaging have led to increases in the performance and area of utilization of positron emission tomography (PET) systems. There are several ways that PET system sensitivity can be increased including changing the scanner's geometry. I recently proposed a novel PET design with adjustable field of view (FOV) to improve the system sensitivity up to 40 times higher than the conventional systems, depending on the size of the transaxial FOV. This study aims to evaluate the spatial resolution characteristics of the proposed design. Geant4-based Architecture for Medicine Oriented Simulations (GAMOS) toolkit was used to simulate the system. The proposed PET geometry was designed to cover and scan the full-body of the patient in one bed position. The spatial resolution tests were conducted using a point like source placed at different locations throughout the FOV when the transaxial FOV of the scanner was changed from 70 cm to 30 cm. The results showed that the spatial resolution slightly degrades when the FOV is reduced.

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

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Integrated ultrasound and gamma imaging probe for medical diagnosis

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JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03037-C03037页

作者： Pani, R. Pellegrini, R. Cinti, M. N. Polito, C. Orlandi, C. Fabbri, A. De Vincentis, G. Univ Roma La Sapienza Dept Sci & Med & Surg Biotechnol Rome Italy Ist Nazl Fis Nucl Roma Sect 1 Rome Italy Univ Roma La Sapienza Dept Mol Med Rome Italy Univ Roma La Sapienza SAIMLAL Dept Doctorate Sch Biol & Mol Med Morphogenesis & Tissue EngnCurriculum Cell & Tis Rome Italy Bambino Gesu Pediat Hosp Dept Med Phys Enterprise Risk Management Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Anat Pathol Rome Italy

In the last few years, integrated multi-modality systems have been developed, aimed at improving the accuracy of medical diagnosis correlating information from different imaging techniques. In this contest, a novel dual modality probe is proposed, based on an ultrasound detector integrated with a small field of view single photon emission gamma camera. The probe, dedicated to visualize small organs or tissues located at short depths, performs dual modality images and permits to correlate morphological and functional information. The small field of view gamma camera consists of a continuous NaI:Tl scintillation crystal coupled with two multi-anode photomultiplier tubes. Both detectors were characterized in terms of position linearity and spatial resolution performances in order to guarantee the spatial correspondence between the ultrasound and the gamma images. Finally, dual-modality images of custom phantoms are obtained highlighting the good co-registration between ultrasound and gamma images, in terms of geometry and image processing, as a consequence of calibration procedures.

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

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