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Ultramicroscopy Jan 2024Event-driven hybrid pixel detectors with nanosecond time resolution have opened up novel pathways in modern ultrafast electron microscopy, for example in hyperspectral...
Event-driven hybrid pixel detectors with nanosecond time resolution have opened up novel pathways in modern ultrafast electron microscopy, for example in hyperspectral electron-energy loss spectroscopy or free-electron quantum optics. However, the impinging electrons typically excite more than one pixel of the device, and an efficient algorithm is therefore needed to convert the measured pixel hits to real single-electron events. Here we present a robust clustering algorithm that is fast enough to find clusters in a continuous stream of raw data in real time. Each tuple of position and arrival time from the detector is continuously compared to a buffer of previous hits until the probability of a merger with an old event becomes irrelevant. In this way, the computation time becomes independent of the density of electron arrival and the algorithm does not break the operation chain. We showcase the performance of the algorithm with a 'timepix' camera in two regimes of electron microscopy, in continuous beam emission and laser-triggered femtosecond mode.
PubMed: 37839354
DOI: 10.1016/j.ultramic.2023.113864 -
Circulation. Cardiovascular Imaging Oct 2023Single-center studies have shown that single photon emission computed tomography myocardial blood flow (MBF) measurement is accurate compared with MBF measured with...
BACKGROUND
Single-center studies have shown that single photon emission computed tomography myocardial blood flow (MBF) measurement is accurate compared with MBF measured with microspheres in a porcine model, positron emission tomography, and angiography. Clinical implementation requires consistency across multiple sites. The study goal is to determine the intersite processing repeatability of single photon emission computed tomography MBF and the additional camera time required.
METHODS
Five sites (Canada, Italy, Japan, Germany, and Singapore) each acquired 25 to 35 MBF studies at rest and with pharmacological stress using technetium-99m-tetrofosmin on a pinhole-collimated cadmium-zinc-telluride-based cardiac single photon emission computed tomography camera with standardized list-mode imaging and processing protocols. Patients had intermediate to high pretest probability of coronary artery disease. MBF was measured locally and at a core laboratory using commercially available software. The time a room was occupied for an MBF study was compared with that for a standard rest/stress myocardial perfusion study.
RESULTS
With motion correction, the overall correlation in MBF between core laboratory and local site was 0.93 (range, 0.87-0.97) at rest, 0.90 (range, 0.84-0.96) at stress, and 0.84 (range, 0.70-0.92) for myocardial flow reserve. The local-to-core difference in global MBF (bias) was 5.4% (-3.8% to 14.8%; median [interquartile range]) at rest and 5.4% (-6.2% to 19.4%) at stress. Between the 5 sites, bias ranged from -1.6% to 11.0% at rest and from -1.9% to 16.3% at stress; the interquartile range in bias was between 9.3% (4.8%-14.0%) and 22.3% (-10.3% to 12.0%) at rest and between 17.0% (-11.3% to 5.6%) and 33.3% (-10.4% to 22.9%) at stress and was not significantly different between most sites. Both bias and interquartile range were like previously reported interobserver variability and less than the SD of the test-retest difference of 30%. The overall difference in myocardial flow reserve was 1.52% (-10.6% to 11.3%). There were no significant differences between with and without motion correction. The average additional acquisition time varied between sites from 44 to 79 minutes.
CONCLUSIONS
The average bias and bias values were small with standard deviations substantially less than the test-retest variability. This demonstrates that MBF can be measured consistently across multiple sites and further supports that this technique can be reliably implemented.
REGISTRATION
URL: https://www.
CLINICALTRIALS
gov; Unique identifier: NCT03427749.
Topics: Animals; Humans; Coronary Artery Disease; Coronary Circulation; Feasibility Studies; Heart; Myocardial Perfusion Imaging; Positron-Emission Tomography; Swine; Tomography, Emission-Computed, Single-Photon
PubMed: 37800325
DOI: 10.1161/CIRCIMAGING.122.015009 -
Cancers Sep 2023Prostate cancer (PCa) is one of the most prevalent cancer diagnoses among men in the United States and in several other developed countries. The prostate specific... (Review)
Review
Prostate cancer (PCa) is one of the most prevalent cancer diagnoses among men in the United States and in several other developed countries. The prostate specific membrane antigen (PSMA) has been recognized as a promising molecular target in PCa, which has led to the development of specific radionuclide-based tracers for imaging and radiopharmaceuticals for PSMA targeted therapy. These compounds range from small molecule ligands to monoclonal antibodies (mAbs). Monoclonal antibodies play a crucial role in targeting cancer cell-specific antigens with a high degree of specificity while minimizing side effects to normal cells. The same mAb can often be labeled in different ways, such as with radionuclides suitable for imaging with Positron Emission Tomography (β+ positrons), Gamma Camera Scintigraphy (γ photons), or radiotherapy (β- electrons, α-emitters, or Auger electrons). Accordingly, the use of radionuclide-based PSMA-targeting compounds in molecular imaging and therapeutic applications has significantly grown in recent years. In this article, we will highlight the latest developments and prospects of radiolabeled mAbs that target PSMA for the detection and treatment of prostate cancer.
PubMed: 37760506
DOI: 10.3390/cancers15184537 -
PET Clinics Jan 2024Compton imaging has been recognized as a possible nuclear medicine imaging method following the establishment of SPECT and PET. Whole gamma imaging (WGI), a combination... (Review)
Review
Compton imaging has been recognized as a possible nuclear medicine imaging method following the establishment of SPECT and PET. Whole gamma imaging (WGI), a combination of PET and Compton imaging, could be the first practical method to bring out the potential of Compton imaging in nuclear medicine. With the use of such positron emitters as Zr and Sc, WGI may enable highly sensitive imaging of antibody drugs for early tumor detection and quantitative hypoxia imaging for effective tumor treatment. Some of these concepts have been demonstrated preliminarily in physics experiments and small animal imaging tests with a developed WGI prototype.
Topics: Animals; Humans; Tomography, Emission-Computed, Single-Photon; Radionuclide Imaging; Radiopharmaceuticals; Nuclear Medicine; Neoplasms
PubMed: 37718218
DOI: 10.1016/j.cpet.2023.08.003 -
Molecules (Basel, Switzerland) Aug 2023Glomerular filtration rates for individual kidneys can be measured semi-quantitatively by a gamma camera using [Tc]Tc-DTPA, with limited diagnostic accuracy. A more...
Glomerular filtration rates for individual kidneys can be measured semi-quantitatively by a gamma camera using [Tc]Tc-DTPA, with limited diagnostic accuracy. A more precise measurement can be performed on a PET/CT scanner using the radiotracer [Ga]Ga-EDTA, which has been validated in animal studies. The purpose of this study was to develop an easy kit-based synthesis of [Ga]Ga-EDTA that is compliant with good manufacturing practice (GMP) and applicable for human use. The production of the cold kit and its labeling were validated, as were the radiochemical purity measurement and analytical procedures for determining the NaEDTA dihydrate content in the kits. In this study, we validated a GMP kit for the simple production of [Ga]Ga-EDTA, with the intention of applicability for human use.
Topics: Animals; Humans; Edetic Acid; Gallium Radioisotopes; Positron Emission Tomography Computed Tomography; Glomerular Filtration Rate; Kidney
PubMed: 37630382
DOI: 10.3390/molecules28166131 -
Medical Physics Oct 2023Positron probes can accurately localize malignant tumors by directly detecting positrons emitted from positron-emitting radiopharmaceuticals that accumulate in malignant...
BACKGROUND
Positron probes can accurately localize malignant tumors by directly detecting positrons emitted from positron-emitting radiopharmaceuticals that accumulate in malignant tumors. In the conventional method for direct positron detection, multilayer scintillator detection and pulse shape discrimination techniques are used. However, some γ-rays cannot be distinguished by conventional methods. Accordingly, these γ-rays are misidentified as positrons, which may increase the error rate of positron detection.
PURPOSE
To analyze the energy distribution in each scintillator of the multilayer scintillator detector to distinguish true positrons and γ-rays and to improve the positron detection algorithm by discriminating true and false positrons.
METHODS
We used Autoencoder, an unsupervised deep learning architecture, to obtain the energy distribution data in each scintillator of the multilayer scintillator detector. The Autoencoder was trained to separate the combined signals generated from the multilayer scintillator detector into two signals of each scintillator. An energy window was then applied to the energy distribution obtained using the trained Autoencoder to distinguish true positrons from false positrons. Finally, the performance of the proposed method and conventional positron detection algorithm was evaluated in terms of the sensitivity and error rate for positron detection.
RESULTS
The energy distribution map obtained using the trained Autoencoder was proven to be similar to that of the simulated results. Furthermore, the proposed method demonstrated a 29.79% (+0.42%p) increase in positron detection sensitivity compared to the conventional method, both having an equal error rate of 0.48%. However, when both methods were set to have the same sensitivity of 1.83%, the proposed method had an error rate that was 25.0% (-0.16%p) lower than that of the conventional method.
CONCLUSIONS
We proposed and developed an Autoencoder-based positron detection algorithm that can discriminate between true and false positrons with a smaller error rate than conventional methods. We verified that the proposed method could increase the positron detection sensitivity while maintaining a low error rate compared to the conventional method. If the proposed algorithm is implemented in handheld positron detection probes or cameras, diseases such as cancers can be more accurately localized in a shorter time compared with using traditional methods.
Topics: Humans; Positron-Emission Tomography; Deep Learning; Beta Particles; Algorithms; Neoplasms
PubMed: 37469146
DOI: 10.1002/mp.16634 -
Sensors (Basel, Switzerland) Jun 2023The European Shock Tube for High-Enthalpy Research is a new state-of-the-art facility, tailored for the reproduction of spacecraft planetary entries in support of future...
The European Shock Tube for High-Enthalpy Research is a new state-of-the-art facility, tailored for the reproduction of spacecraft planetary entries in support of future European exploration missions, developed by an international consortium led by Instituto de Plasmas e Fusão Nuclear and funded by the European Space Agency. Deployed state-of-the-art diagnostics include vacuum-ultraviolet to ultraviolet, visible, and mid-infrared optical spectroscopy setups, and a microwave interferometry setup. This work examines the specifications and requirements for high-speed flow measurements, and discusses the design choices for the main diagnostics. The spectroscopy setup covers a spectral window between 120 and 5000 nm, and the microwave interferometer can measure electron densities up to 1.5 × 10 electrons/m. The main design drivers and technological choices derived from the requirements are discussed in detail herein.
Topics: Spectrum Analysis; Interferometry; Spacecraft; Planets
PubMed: 37447875
DOI: 10.3390/s23136027