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Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres
摘要： Objective: The aim of our study was to compare yttrium -90 (90Y) dosimetry obtained from pre-therapy 99mTc-macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors. Materials and methods: Prior to 90Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking 90Y distribution. After RE with 90Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate 90Y dosimetry. The Passing-Bablok regression scatter diagram and the Bland and Altman method were used to analyze the difference between dosimetry values. Results: For MAA and PET/MRI modalities, the mean liver doses for all 32 subjects were 43.0 ± 20.9 Gy and 46.5 ± 22.7 Gy, respectively, with a mean difference of 3.4 ± 6.2 Gy. The repeatibility coefficient was 12.1 (27.0% of the mean). The Spearman rank correlation coefficient was high (ρ = 0.92). Although, there was a substantial difference in the maximum doses to the liver between the modalities, the mean liver doses were relatively close, with a difference of 24.0% or less. Conclusions: The two main contributors to the difference between dosimetry calculations using MAA versus 90Y PET/MRI can be attributed to the changes in catheter positioning as well as the liver ROIs used for the calculations. In spite of these differences, our results demonstrate that the dosimetry values obtained from pre-therapy MAA SPECT/CT scans and PET/MRI post-therapy 90Y studies were not significantly different.
关键词： MAA,90Y PET/MRI,Dosimetry
更新于2025-09-10 09:29:36
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Compton camera based on Timepix3 technology
摘要： The Compton camera concept is based on the reconstruction of recorded Compton scattering events of incoming gamma rays. The scattering of primary gamma ray occurs in the first detector (called scattering detector — usually thin) recording the position and energy of the recoiled electron. The scattered gamma quantum continues towards the second detector (called absorption detector - usually thick) where it is absorbed. The second detector records the energy and the position of this scattered gamma. Using the Compton scattering equation it is possible to determine the scattering angle, and estimate possible directions of the original gamma ray as a surface of a cone. When the Compton camera records the number of such events, the location and the shape of the gamma source can be reconstructed. Timepix3, a hybrid single photon counting imaging pixel detector, is a perfect device for creation of a compact Compton camera. Timepix3 is an event based readout chip (every hit pixel is immediately sent to a readout) and can record the time-of-arrival (ToA) and energy of an incident gamma simultaneously in each pixel. The chip offers high energy resolution (1 keV at 60 keV, 7 keV at 356 keV), as well as time resolution (1.6 ns). The Timepix3 readout chip can be combined with different sensor materials (Si, CdTe, CZT). In this contribution, we present a very compact detector system for imaging with gamma-rays using the Compton camera principle. The system consists of at least two layers of hybrid pixel detectors Timepix3 with the sensors being optimized for gamma-ray tracking. The front detector layer (scattering) is made of silicon of 1 mm thickness, while the last layer (absorbing) is equipped with thick CdTe or CZT sensors up to 2 mm in thickness. The total absorption of the whole detector can be very high if several CdTe or CZT layers are used. The maximal number of layers is not limited, but the practical evaluation was performed with 2 layers. Thanks to Timepix3 simultaneous measurement of ToA and energy, it is possible to precisely detect coincidence events in the detector layers. Based on the energy and position of these events, it is possible to estimate the possible direction of the original gamma. The angular resolution of the presented Compton camera depends on the detected energy, and it is in the order of 1 degree.
关键词： PET PET/CT,coronary CT angiography (CTA),Gamma camera,Particle tracking detectors,Compton imaging,SPECT
更新于2025-09-09 09:28:46
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Simulation and evaluation of high-performance cost-effective positron emission mammography scanner
摘要： Breast cancer is the main cause of tumor deaths in women, thus several imaging modalities have been introduced recently to better diagnose the disease. New breast cancer cases were estimated to reach up to 246,660 in 2017, and the mortality rate was above 40,000. Early diagnosis is widely approved as being essential for an e?ective treatment and it also helps to reduce the incidences and mortality rates. Positron Emission Mammography (PEM) is a breast-dedicated imaging device which uses a pair of annihilation gamma photons to detect abnormalities in the breast tissue. PEM device is compact in nature with a reduced ?eld of view to cover the entire breast region, and it employs few detector modules which makes it cost-e?cient. To e?ectively diagnose breast cancer at a very early stage, a device with high spatial resolution and high sensitivity is required. PEM detectors based on semiconductor materials are characterized by an excellent intrinsic spatial resolution but are not cost-e?ective, whereas detectors based on scintillator crystals are cost-e?ective but have limited intrinsic resolution to detect small breast lesions. This study focuses on improving the resolution of scintillator detectors by simulating a PEM scanner employing 1 × 1 × 10 mm3 laser processed scintillator crystal. The simulation was done with a GEANT4 application for emission tomography (GATE) software, and performance evaluation tests were carried out according to the National Electrical Manufacturers Association (NEMA) standards. The scanner geometry has 90 mm transaxial ?eld of view (FOV) and 105 mm axial FOV. Evaluation results showed that the scanner has 10.6% system sensitivity, 1.0 mm spatial resolution at the center of the FOV (CFOV) and at 2.5 cm transaxial direction. The resolution at the axial 2.5 cm position is 2.1 mm. NEMA image quality test and Derenzo phantom study showed that the scanner can easily resolve 1 mm in diameter hot rods.
关键词： PET PET/CT,X-ray mammography and scinto- and MRI-mammography,coronary CT angiography (CTA),Gamma camera,SPECT
更新于2025-09-09 09:28:46
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PET-Computed Tomography and PET-MR Imaging and Their?Applications in the Twenty-First Century
摘要： Since the discovery of x-ray by Roentgen in 1895, planar radiography has remained a major imaging technique in assessing skeletal abnormalities with reasonable success. However, poor contrast between diseased sites and the background results in low sensitivity of this modality in detecting early disease and monitoring its course over time. The introduction of computed tomography (CT) in 1971 by Hounsfield further enhanced the role of x-ray-based disease assessment, and as such, XCT has played an important role in the day-to-day management of musculoskeletal (MSK) disorders. Since the early 1980s, when the first MR imaging instruments were introduced for human studies, the impact of imaging for examining soft tissue abnormalities in MSK disorders has been substantially enhanced. Currently, XCT and MR imaging are the main imaging modalities available in this domain but suffer from many deficiencies that need to be addressed by employing more advanced approaches. Since the early 1970s, 99m-Technitium (Tc)-labeled phosphates have been extensively used to detect benign and malignant disorders of the skeletal system. These radiotracers allow planar and tomographic imaging (SPECT [single-photon emission computed tomography]), but the quality of images generated is somewhat suboptimal for detection of the affected sites and quantification of the disease activity.
关键词： PET-CT-MRI,musculoskeletal disorders,radiotracers,FDG-PET,imaging,18F-NaF
更新于2025-09-09 09:28:46
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How to harmonize SUVs obtained by hybrid PET/CT scanners with and without point spread function correction
摘要： State of the art point-spread function (PSF) corrections implemented in positron emission tomography/computed tomography (PET/CT) reconstruction improved image quality and diagnostic performance but caused an increase in the standardized uptake value (SUV) compared to a conventional OSEM reconstruction system. The EANM suggested one produce two reconstructions, one optimised for maximum lesion detection and one for semi-quantitative analysis. In this work we investigated an alternative methodology, using a single reconstruction data set together with a post-reconstruction algorithm for SUV harmonization. Data acquisition was performed on a Siemens Biograph mCT system equipped with lutetium oxyorthosilicat crystals, PSF and time-of-flight algorithms and on a General Electric Discovery STE system equipped with BGO crystals. Both a EANM double reconstruction method and a dedicated post-reconstruction algorithm (marketed as EQ-filter) were tested to harmonize the quantitative values of the two PET/CT scanners. For phantom measurements we used a NEMA IQ phantom and a Jaszczak cylindrical phantom equipped with small spheres (lesion to background ratios of 8:1 and 4:1). Several different reconstruction settings were tested in order to provide a general methodology. Data obtained by phantom measurements were validated on seven oncologic patients who performed a one-bed extra acquisition on a different scanner. The evaluation regarded 39 small lesions (diameters: 0.3–2.6 cm) and was performed by two experienced nuclear medicine physicians. The SUV recoveries measured with the PSF reconstruction exceeded those obtained by the OSEM reconstruction with deviations ranging from 16% to 150%. These discrepancies resulted below 7% applying the optimized value of the EQ.filter or the double-reconstruction methods. For each reconstruction setting the optimal value of the EQ.filter was identified in order to minimize these discrepancies. Patient data, analyzed by Wilcoxon statistical test, confirmed and validated phantom measurements. EQ.filter can harmonize SUV values between different PET/CT scanners using a single reconstruction optimized to maximum lesion detectability. In this way, the second reconstruction proposed by EANM/EARL is avoided.
关键词： EQ.filter,PSF,EARL accreditation program,PET/CT scanners,SUV harmonization
更新于2025-09-09 09:28:46
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Patient motion correction for dynamic cardiac PET: Current status and challenges
摘要： For dynamic cardiac PET of quantifying myocardial blood flow (MBF), patient motion is a major factor that affects the ROI definition and absolute quantification accuracy. In a recent study, an 82rubidium (82Rb)-dynamic-tailored motion-correction framework has been proposed to address the voluntary body motion for all the dynamic frames, including both early and late phases. This approach brings us one step closer to the practical and full motion correction for dynamic cardiac PET studies. In this editorial, we discussed the current status and limitations of motion-correction methods for dynamic cardiac PET, including the recent publication at JNC, and also pointed out the remaining challenges for future developments.
关键词： 82rubidium,dynamic cardiac PET,myocardial blood flow,motion-correction framework,patient motion correction
更新于2025-09-09 09:28:46
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Residual Stress Image Inspections based on Bending Testing for Flexible Transparent Conducting Substrates by Single-direction Common-path Image Interferometry
摘要： This paper proposes a method for automatic inspection of residual stress images based on bending testing for flexible transparent conducting substrates. A flexible characteristics inspection system with single-direction common-path image interferometry is utilized to inspect residual stress images automatically during the bending testing operation. Accordingly, a 5×5 cm2 residual stress image of a 203-μm line pattern on a conducting indium tin oxide (ITO) film deposited on polyethylene terephthalate (PET) substrate with up to 11,000 bending cycles is inspected and analyzed. The relationship between the residual stresses and resistance characteristics of the 203-μm line pattern on the ITO-deposited-on-PET substrate based on bending testing is also analyzed. It was found that the change results of residual stress can predict the resistance characteristics of the ITO-deposited-on-PET substrate sufficiently. Therefore, the inspection results of residual stress images depicted on flexible electronics may help designers and manufacturers to develop products and ensure quality control, respectively, in a manufacturing process.
关键词： residual stress image,bending testing,image single-direction common-path interferometry,flexible characteristics inspection system,ITO-deposited-on-PET substrate
更新于2025-09-09 09:28:46
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Radiobiological Modeling Based on 18F-Fluorodeoxyglucose Positron Emission Tomography Data for Esophageal Cancer
摘要： Background: We investigated the relationship of standardized uptake values (SUVs) to radiobiological parameters, such a 25 s tumor control probability (TCP), to allow for quantitative prediction of tumor response based on SUVs from 18F fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) before and after treatment for esophageal cancer. Methods: We analyzed data from 20 esophageal cancer patients treated with chemoradiotherapy (CRT) followed by surgery. Tumor pathologic response to CRT was assessed in surgical specimens. Patients underwent 18F-FDG PET imaging before and after CRT. Rigid image registration was performed between both images. Because TCP in a heterogeneous tumor is a function of average cell survival, we modeled TCP as a function of <SUVR>, a possible surrogate for average cell survival (<SUVR>=<SUVafter/SUVbefore>). TCP was represented by a sigmoid function with two parameters: SUVR50, the <SUVR> at which TCP=0.5, and γ50, the slope of the curve at SUVR50. The two parameters and their confidence intervals (CIs) were estimated using the maximum-likelihood method. The correlation between SUV before CRT and SUV change <SUVbefore – SUVafter> was also studied. Results: A TCP model as a function of SUV before and after treatment was developed for esophageal cancer patients. The maximum-likelihood estimate of SUVR50 was 0.47 (90% CI, 0.30-0.61) and for γ50was 1.62 (90% CI, 0-4.2). High initial SUV and larger metabolic response (larger <SUVbefore –SUVafter>) were correlated, and this correlation was stronger among responders. Conclusions: Our TCP model indicates that <SUVafter/SUVbefore> is a possible surrogate for cell survival in esophageal cancer patients. Although CIs are large as a result of the small patient sample, parameters for a TCP curve can be derived and an individualized TCP can be calculated for future patients. Initial SUV does not predict response, whereas a correlation is found between surrogates for initial tumor burden and cell kill during therapy.
关键词： Quantitative imaging,Esophageal cancer,18F-FDG PET/CT,Tumor response,Radiation therapy
更新于2025-09-09 09:28:46
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Integrated Whole Body MR/PET: Where Are We?
摘要： Whole body integrated magnetic resonance imaging (MR)/positron emission tomography (PET) imaging systems have recently become available for clinical use and are currently being used to explore whether the combined anatomic and functional capabilities of MR imaging and the metabolic information of PET provide new insight into disease phenotypes and biology, and provide a better assessment of oncologic diseases at a lower radiation dose than a CT. This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions. Various early clinical applications of integrated MR/PET are also addressed. Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.
关键词： Positron emission tomography,MR/PET,Magnetic resonance imaging,Hybrid imaging
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Pico-TDC: a novel FPGA-based TDC with 2.2ps RMS timing resolution
摘要： The purpose of this work is to develop low-cost high-performance TDCs to meet the requirement from the next generation sub-10ps TOF-PET camera. A TOF-PET system may need hundreds of high resolution TDCs to read timing from many detectors. FPGA-based TDC designs, such as conventional delay-line (DL) TDCs and Wave-Unions (WU) TDCs, are a more viable solutions compared with expensive ASIC-based TDCs. However, the performances of those FPGA-based TDCs are more or less depended on the specific structures and performances of the delay lines, which are usually the carry chains in the adders of a FPGA. In this paper, we present a new method called Pico-TDC method to construct the TDCs in FPGA. The uniqueness of the Pico-TDC method is to use single registers in the FPGA as low-precision TDCs, and to combine many of those low-precision TDCs to construct a high-precision TDC. The advantages of Pico-TDC method are: (1) the timing performance of a Pico-TDC is not limited by the performance of delay lines in the FPGA. As a result, it is possible to achieve unprecedented resolution with a low-cost FPGA. (2) Hundreds of high-performance Pico-TDCs can be constructed in a low-cost FPGA which normally has millions of registers. (3) Theoretically, the Pico-TDCs can be conveniently migrated from one FPGA to another, regardless of the differences in the internal structures of the FPGAs. We have successfully constructed four channels of Pico-TDCs in a low-cost FPGA (Altera Cyclone V 5CEBA4F23C7N, price: $66.63). Each TDC uses 640 registers (low-precision TDCs). The four Pico-TDCs were tested with both the internal and the external pulses. The RMS of the timing measurements is 2.2 ps. The temperature stability is excellent. We conclude that Pico-TDCs have excellent timing performance which meets the requirement of the next generation sub-10ps TOF-PET.
关键词： TDC,TOF-PET,timing resolution,FPGA,Pico-TDC
更新于2025-09-09 09:28:46