journal
https://read.qxmd.com/read/38862003/a-greedy-regularized-block-kaczmarz-method-for-accelerating-reconstruction-in-magnetic-particle-imaging
#1
JOURNAL ARTICLE
Yusong Shen, Liwen Zhang, Hui Zhang, Yimeng Li, Jing Zhao, Jie Tian, Guanyu Yang, Hui Hui
OBJECTIVE: Magnetic Particle Imaging (MPI) is an emerging medical tomographic imaging modality that enables real-time imaging with high sensitivity and high spatial and temporal resolution. For the system matrix reconstruction method, the MPI reconstruction problem is an ill-posed inverse problem that is commonly solved using the Kaczmarz algorithm. However, the high computation time of the Kaczmarz algorithm, which restricts MPI reconstruction speed, has limited the development of potential clinical applications for real-time MPI...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38862002/a-comprehensive-assessment-of-a-prototype-high-ratio-antiscatter-grid-in-interventional-cardiology-using-experimental-measurements-and-monte-carlo-simulations
#2
JOURNAL ARTICLE
Rodrigo Trevisan Massera, Michiel Dehairs, Hannelore Verhoeven, Hilde Bosmans, Nicholas W Marshall
To assess the performance of a new antiscatter grid design in interventional cardiology for image quality improvement and dose reduction using experimental measurements and Monte Carlo (MC) simulation. 
Approach: Experimental measurements were performed on an angiography system, using a multi-layered tissue simulating composite phantom made from of poly(methyl methacrylate), aluminium and expanded polystyrene (2/0.2/0.7 cm). The total phantom thickness ranged from 20.3 cm to 40.6 cm. Four conditions were compared; (A) 105 cm source-image receptor distance (SID) without grid, (Bi ) 105 cm SID with grid ratio (r) and strip density (N) (r15N80), (Bii ) 120 cm SID without grid, and (Biii ) 120 cm SID with high ratio grid (r29N80)...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38862001/proton-ct-on-biological-phantoms-for-x-ray-ct-calibration-in-proton-treatment-planning
#3
JOURNAL ARTICLE
Elena Fogazzi, Mara Bruzzi, Elvira D'Amato, Paolo Farace, Roberto Righetto, Monica Scaringella, Marina Scarpa, Francesco Tommasino, Carlo Civinini
To present and characterize a novel method for X-ray CT (xCT) calibration in proton treatment planning, based on proton CT (pCT) measurements on biological phantoms. 
 
Approach: A pCT apparatus was used to perform direct measurements of 3D stopping power relative to water (SPR) maps on stabilized, biological phantoms. Two single-energy xCT calibration curves - i.e. tissue substitutes and stoichiometric - were compared to pCT data. Moreover, a new calibration method based on these data was proposed, and verified against intra- and inter-species variability, dependence on stabilization, beam-hardening conditions, and analysis procedures...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38862000/investigation-of-dosimetric-effect-of-beam-current-fluctuations-in-synchrotron-based-proton-pbs-continuous-scanning
#4
JOURNAL ARTICLE
Chunbo Liu, Keith M Furutani, Jiajian Shen, Hok Wan Chan Tseung, Hong Qi Tan, Heng Li, Thomas Whitaker, Chris J Beltran, Xiaoying Liang

In proton pencil beam scanning (PBS) continuous delivery, the beam is continuously delivered without interruptions between spots. For synchrotron-based systems, the extracted beam current exhibits a spill structure, and recent publications on beam current measurements have demonstrated significant fluctuations around the nominal values. These fluctuations potentially lead to dose deviations from those calculated assuming a stable beam current. This study investigated the dosimetric implications of such beam current fluctuations during proton PBS continuous scanning...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38861997/investigation-of-intra-fractionated-range-guided-adaptive-proton-therapy-part-i-on-line-pet-imaging-and-range-measurement
#5
JOURNAL ARTICLE
Dongxu Yang, Xiaorong Ronald Zhu, Mingli Chen, Lin Ma, Xinyi Cheng, David R Grosshans, Weiguo Lu, Yiping Shao
Develop a prototype on-line PET scanner and evaluate its capability of on-line imaging and intra-fractionated proton-induced radioactivity range measurement.
Approach: Each detector consists of 32×32 array of 2×2×30 mm3 Lutetium-Yttrium Oxyorthosilicate scintillators with single-scintillator-end readout through a 20×20 array of 3×3 mm2 Silicon Photomultipliers. The PET can be configurated with a full-ring of 20 detectors for conventional PET imaging or a partial-ring of 18 detectors for on-line imaging and range measurement...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38861995/investigation-of-intra-fractionated-range-guided-adaptive-proton-therapy-rgapt-part-ii-range-shift-compensated-on-line-treatment-adaptation-and-verification
#6
JOURNAL ARTICLE
Mingli Chen, Dongxu Yang, Xiaorong Ronald Zhu, Lin Ma, David R Grosshans, Yiping Shao, Weiguo Lu
We previously proposed range-guided adaptive proton therapy (RGAPT) that uses mid-range treatment beams as probing beams and intra-fractionated range measurements for online adaptation. In this work, we demonstrated experimental verification and reported the dosimetric accuracy for RGAPT.
A STEEV phantom was used for the experiments, and a 3x3x3 cm3 cube inside the phantom was assigned to be the treatment target. We simulated three online range shift scenarios: reference, overshoot, and undershoot, by placing upstream Lucite sheets, 4, 0, and 8 that corresponded to changes of 0, 6...
June 11, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38843814/neural-network-aided-extended-kalman-filtering-for-inverse-imaging-of-cardiac-transmembrane-potential
#7
JOURNAL ARTICLE
Ao Ran, Shujin Hu, Xufeng Huang, Liuliu Quan, Muqing Liu, Huafeng Liu
The aim of this study is to address the limitations in reconstructing the electrical activity of the heart from the body surface electrocardiogram, which is an ill-posed inverse problem. Current methods often assume values commonly used in the literature in the absence of a priori knowledge, leading to errors in the model. Furthermore, most methods ignore the dynamic activation process inherent in cardiomyocytes during the cardiac cycle.

Approach: To overcome these limitations, we propose an extended Kalman filter (EKF)-based neural network approach to dynamically reconstruct cardiac transmembrane potential...
June 6, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38843812/proton-3d-dose-measurement-with-a-multi-layer-strip-ionization-chamber-mlsic-device
#8
JOURNAL ARTICLE
Shuang Zhou, Qinghao Chen, Jonathan Haefner, Winter Smith, Arash Darafsheh, Tianyu Zhao, Nathan Andrew Harrison, Jun Zhou, Liyong Lin, Weiguo Lu, Liuxing Shen, Hao Jiang, Tiezhi Zhang

In current clinical practice for quality assurance (QA), intensity modulated proton therapy (IMPT) fields are verified by measuring planar dose distributions at one or a few selected depths in a phantom. A QA device that measures full 3D dose distributions at high spatiotemporal resolution would be highly beneficial for existing as well as emerging proton therapy techniques such as FLASH radiotherapy. Our objective is to demonstrate feasibility of 3D dose measurement for IMPT fields using a dedicated multi-layer strip ionization chamber (MLSIC) device...
June 6, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38843809/gpu-accelerated-parallel-image-reconstruction-strategies-for-magnetic-particle-imaging
#9
JOURNAL ARTICLE
Klaus Natorf Quelhas, Mark Henn, Ricardo Farias, Weston Tew, S I Woods
Image reconstruction is a fundamental step in Magnetic Particle Imaging (MPI). One of the main challenges is the fact that the reconstructions are computationally intensive and time-consuming, so choosing an algorithm presents a compromise between accuracy and execution time, which depends on the application. This work proposes a method that provides both fast and accurate image reconstructions.
Approach. Image reconstruction algorithms were implemented to be executed in parallel in graphics processing units (GPUs) using the CUDA framework...
June 6, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38843808/microbubble-detection-on-ultrasound-imaging-by-utilizing-phase-patterned-waves
#10
JOURNAL ARTICLE
Junseok An, Naohiro Sugita, Tadahiko Shinshi

Super-resolution ultrasonography (SR-US) offers the advantage of visualization of intricate microvasculature, which is crucial for disease diagnosis. Mapping of microvessels is possible by localizing microbubbles that act as contrast agents and tracking their location. However, there are limitations such as the low detectability of microbubbles and the utilization of a diluted concentration of microbubbles, leading to the extension of the acquisition time. We aim to enhance the detectability of microbubbles to reduce the acquisition time of acoustic data necessary for mapping the microvessels...
June 6, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38838679/paired-conditional-generative-adversarial-network-for-highly-accelerated-liver-4d-mri
#11
JOURNAL ARTICLE
Di Xu, Xin Miao, Hengjie Liu, Jessica E Scholey, Wensha Yang, Mary Feng, Michael Ohliger, Hui Lin, Yi Lao, Yang Yang, Ke Sheng
4D MRI with high spatiotemporal resolution is desired for image-guided liver radiotherapy. Acquiring densely sampled k-space data is time-consuming. Accelerated acquisition with sparse sampling is desirable but often causes degraded image quality or long reconstruction time. We propose the Reconstruct Paired Conditional Generative Adversarial Network (Re-Con-GAN) for shortening the 4D MRI reconstruction time while maintaining the reconstruction quality. 

Methods: Patients underwent free-breathing liver 4D MRI were included in the study...
June 5, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38838678/enhanced-classification-of-left-ventricular-hypertrophy-in-cardiac-patients-using-extended-siamese-cnn
#12
JOURNAL ARTICLE
Moomal Farhad, Mohammad Masud, Azam Beg, Amir Ahmad, Sehar Memon
Left Ventricular Hypertrophy (LVH) is the thickening of the left ventricle wall of the heart. The objective of this study is to develop a novel approach for the accurate assessment of Left Ventricular Hypertrophy (LVH) severity, addressing the limitations of traditional manual grading systems.

Approach: We propose the Multi-purpose Siamese Weighted Euclidean Distance Model (MSWED), which utilizes convolutional Siamese neural networks and zero-shot/few-shot learning techniques. Unlike traditional methods, our model introduces a cutoff distance-based approach for zero-shot learning, enhancing accuracy...
June 5, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38830366/exact-parameter-identification-in-pet-pharmacokinetic-modeling-using-the-irreversible-two-tissue-compartment-model
#13
JOURNAL ARTICLE
Martin Holler, Erion Morina, Georg Schramm
In quantitative dynamic positron emission tomography (PET), time series of images, reflecting the tissue response to the arterial tracer supply, are reconstructed. This response is described by kinetic parameters, which are commonly determined on basis of the tracer concentration in tissue and the arterial input function. In clinical routine the latter is estimated by arterial blood sampling and analysis, which is a challenging process and thus, attempted to be derived directly from reconstructed PET images...
June 3, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38830365/time-domain-diffuse-optical-imaging-technique-for-monitoring-rheumatoid-arthritis-disease-activity-experimental-validation-in-tissue-mimicking-finger-phantoms
#14
JOURNAL ARTICLE
Seva Ioussoufovitch, Mamadou Diop
Effective treatment within 3 - 5 months of disease onset significantly improves rheumatoid arthritis (RA) prognosis. Nevertheless, 30% of RA patients fail their first treatment, and it takes 3 - 6 months to identify failure with current monitoring techniques. Time-domain diffuse optical imaging (TD-DOI) may be more sensitive to RA disease activity and could be used to detect treatment failure. In this report, we present the development of a TD-DOI hand imaging system and validate its ability to measure simulated changes in RA disease activity using tissue-mimicking finger phantoms...
June 3, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38830364/bias-correction-for-phase-based-cr-mrept-using-low-resolution-b1-magnitude
#15
JOURNAL ARTICLE
Mustafa Kaan Çan, Yusuf Ziya Ider
Objective Full-form Magnetic Resonance Electrical Properties Tomography (MREPT) requires both B1+ magnitude and phase information. Since B1+ phase can be obtained faster and with higher SNR compared to B1+ magnitude, several phase-based methods have been developed for conductivity imaging. However, phase-based methods suffer from a concave bias due to the assumption that ∇|B1+| is negligible in the ROI. Approach In this paper, we re-derive the central equation of phase-based cr-MREPT without assuming that ∇|B1+| is negligible and thus propose a correction method directly integrated into the equation system...
June 3, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38830363/time-domain-diffuse-optical-imaging-technique-for-monitoring-rheumatoid-arthritis-disease-activity-theoretical-development-and-in-silico-validation
#16
JOURNAL ARTICLE
Seva Ioussoufovitch, Mamadou Diop
Effective early treatment---within 3 - 5 months of disease onset---significantly improves rheumatoid arthritis (RA) prognosis. Nevertheless, 1 in 3 patients experiences treatment failure which takes 3 - 6 months to detect with current monitoring techniques. The aim of this work is to develop a method for extracting quantitative features from data obtained with time-domain diffuse optical imaging (TD-DOI), and demonstrate their sensitivity to RA disease activity.
Approach: 80 virtual phantoms of the proximal interphalangeal joint---obtained from a realistic tissue distribution derived from magnetic resonance imaging---were created to simulate RA-induced alterations in 5 physiological parameters...
June 3, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38830362/metrology-for-advanced-radiotherapy-using-particle-beams-with-ultra-high-dose-rates
#17
JOURNAL ARTICLE
Anna Subiel, Alexandra Bourgouin, Rafael Kranzer, Peter Peier, Franziska Frei, Faustino Gomez, Adrian Knyziak, Celeste Fleta, Claude J Bailat, Andreas Schüller
Dosimetry of ultra-high dose-rate (UHDR) beams is one of the critical components which is required for safe implementation of FLASH radiotherapy into clinical practice. In the past years several national and international programmes have emerged with the aim to address some of the needs that are required for translation of this modality to clinics. These involve the establishment of dosimetry standards as well as the validation of protocols and dosimetry procedures. This review provides an overview of recent developments in the field of dosimetry for FLASH radiotherapy, with particular focus on primary and secondary standard instruments, and provides a brief outlook on the future work which is required to enable clinical implementation of FLASH radiotherapy...
June 3, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38821109/deformable-anthropomorphic-pelvis-phantom-for-dose-accumulation-verification
#18
JOURNAL ARTICLE
Yun Ming Wong, Calvin Wei Yang Koh, Kah Seng Lew, Clifford Ghee Ann Chua, Ping Lin Yeap, Ee Teng Zhang, Ashley Li Kuan Ong, Jeffrey Kit Loong Tuan, Bing Feng Ng, Wen Siang Lew, James Cheow Lei Lee, Hong Qi Tan

The validation of deformable image registration (DIR) for contour propagation is often done using contour-based metrics. Meanwhile, dose accumulation requires evaluation of voxel mapping accuracy, which might not be accurately represented by contour-based metrics. By fabricating a deformable anthropomorphic pelvis phantom, we aim to (1) quantify the voxel mapping accuracy for various deformation scenarios, in high- and low-contrast regions, and (2) identify any correlation between Dice similarity coefficient (DSC), a commonly used contour-based metric, and the voxel mapping accuracy for each organ...
May 31, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38815617/design-and-development-of-the-de-spect-system-a-clinical-spect-system-for-broadband-multi-isotope-imaging-of-peripheral-vascular-disease
#19
JOURNAL ARTICLE
Elena Maria Zannoni, Sankar Poopalasingam, Yifei Jin, Chi Liu, Albert J Sinusas, Scott D Metzler, Ling-Jian Meng
Objective 
Peripheral Vascular Disease (PVD) affects more than 230 million people worldwide and is one of the leading causes of disability among people over age 60. Nowadays, PVD remains largely underdiagnosed and undertreated, and requires the development of tailored diagnostic approaches. We present the full design of the Dynamic Extremity SPECT (DE-SPECT) system, the first organ-dedicated SPECT system for lower extremity imaging, based on 1-cm thick Cadmium Zinc Telluride (CZT) spectrometers and a dynamic dual field-of-view (FOV) synthetic compound-eye collimator...
May 30, 2024: Physics in Medicine and Biology
https://read.qxmd.com/read/38815615/optical-crosstalk-of-protective-cover-on-mppc-array-for-tof-pet-detector
#20
JOURNAL ARTICLE
Eiji Yoshida, Fujino Obata, Taiga Yamaya

Time-of-flight (TOF) is an important factor that directly affects the image quality of PET systems, and various attempts have been made to improve the coincidence resolving time (CRT) of PET detectors. For independent readout detectors, the timing is acquired for each silicon photomultiplier (SiPM), so they are less sensitive to diffused scintillation light, resulting in a better CRT. Further improvement can be expected if the light can be focused on a single SiPM. However, existing SiPM arrays have a thin protective cover on the SiPM and the gap between the SiPMs is filled with either air or the protective cover, so the light must diffuse through the cover...
May 30, 2024: Physics in Medicine and Biology
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