Biliary tract cancer(BTC)is a group of heterogeneous sporadic diseases,including intrahepatic,hilar,and distal cholangiocarcinoma,as well as gallbladder cancer.BTC is characterized by high invasiveness and extremely p...Biliary tract cancer(BTC)is a group of heterogeneous sporadic diseases,including intrahepatic,hilar,and distal cholangiocarcinoma,as well as gallbladder cancer.BTC is characterized by high invasiveness and extremely poor prognosis,with a global increased incidence due to intrahepatic cholangiocarcinoma(ICC).The 18Ffludeoxyglucose positron emission tomography(PET)computed tomography(18F-FDG PET/CT)combines glucose metabolic information(reflecting the glycolytic activity of tumor cells)with anatomical structure to assess tumor metabolic heterogeneity,systemic metastasis,and molecular characteristics noninvasively,overcoming the limitations of traditional imaging in the detection of micrometastases and recurrent lesions.18F-FDG PET/CT offers critical insights in clinical staging,therapeutic evaluation,and prognostic prediction of BTC.This article reviews research progress in this field over the past decade,with a particular focus on the advances made in the last 3 years,which have not been adequately summarized and recognized.The research paradigm in this field is shifting from qualitative to quantitative studies,and there have been significant breakthroughs in using 18F-FDG PET/CT metabolic information to predict gene expression in ICC.Radiomics and deep learning techniques have been applied to ICC for prognostic prediction and differential diagnosis.Additionally,PET/magnetic resonance imaging is increasingly demonstrating its value in this field.展开更多
Soft tissue sarcomas(STS)are rare malignant tumors originating from mesoder-mal tissues with a poor prognosis,accounting for approximately 1%of all malig-nancies and comprising around 50 distinct subtypes.Conventional...Soft tissue sarcomas(STS)are rare malignant tumors originating from mesoder-mal tissues with a poor prognosis,accounting for approximately 1%of all malig-nancies and comprising around 50 distinct subtypes.Conventional imaging mo-dalities,such as computed tomography(CT)and magnetic resonance imaging(MRI),primarily provide anatomical information,whereas 18F-fluorodeoxyglucose positron emission tomography/CT(18F-FDG PET/CT)integrates functional metabolic and anatomical imaging,serving as a critical complementary tool in the diagnosis and management of STS.This article reviews recent advances in the application of 18F-FDG PET/CT for STS.The advantages of 18F-FDG PET/CT in STS include:(1)Early detection of metabolic activity changes in tumors,partic-ularly when morphological alterations are insignificant;(2)Effective differen-tiation between benign and malignant soft tissue tumors,as well as aiding in distinguishing high-grade from low-grade sarcomas;(3)Identification of occult metastatic lesions,improving staging accuracy,and facilitating restaging in cases of recurrence or metastasis;(4)Utilization of parameters such as maximum stan-dardized uptake value and metabolic tumor volume to assist in tumor grading and prognostic evaluation;and(5)Monitoring treatment response to guide adjust-ments in personalized therapeutic strategies.However,18F-FDG PET/CT has limitations in diagnosis of certain STS subtypes(e.g.,myxoid liposarcoma),detection and biopsy of metastatic lymph nodes,necessitating integration with clinical evaluation and other imaging techniques.18F-FDG PET/CT is poised to play an increasingly vital role in the precision diagnosis and treatment of STS.展开更多
Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism....Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.展开更多
Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)G...Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)Ga,and^(89)Zr.Among the radiotracers,the radioactive^(18)F-labelled chemical agent as PET probes plays a predominant role in monitoring,detecting,treating,and predicting tumours due to its perfect half-life.In this paper,the^(18)F-labelled chemical materials as PET probes are systematically summarized.First,we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging.It highlights the^(18)F-labelled chemical agents used as PET probes,including[^(18)F]-2-deoxy-2-[^(18)F]fluoro-D-glucose([^(18)F]-FDG),^(18)F-labelled amino acids,^(18)F-labelled nucleic acids,^(18)F-labelled receptors,^(18)F-labelled reporter genes,and^(18)F-labelled hypoxia agents.In addition,some PET probes with metal as a supplementary element are introduced briefly.Meanwhile,the^(18)F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail.The approach and strategies for the fabrication of^(18)F-labelled PET probes are also described briefly.The future development of the PET probe is also prospected.The development and application of^(18)F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours.展开更多
Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are ...Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.展开更多
The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to inv...The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.展开更多
We present the diagnostic performance of[18F]Fluorodeoxyglucose positron emission tomography(FDG PET)for adrenal incidentalomas based on lesion size and unenhanced computed tomography(CT)density in Hounsfield units(HU...We present the diagnostic performance of[18F]Fluorodeoxyglucose positron emission tomography(FDG PET)for adrenal incidentalomas based on lesion size and unenhanced computed tomography(CT)density in Hounsfield units(HU),following current literature and guidelines.A 20 HU cutoff can be applied to differentiate potentially benign from malignant lesions,particularly in ruling in or out adrenocortical carcinoma.While FDG PET provides valuable metabolic information,its likelihood ratios for a positive(LR+)or negative(LR-)result do not exceed the robust diagnostic thresholds of>10.0 or<0.1,respectively.This suggests that positron emission tomography alone is insufficient for definitive characterization and should be integrated with CT or magnetic resonance imaging to leverage their complementary anatomical and functional imaging strengths for optimal diagnostic accuracy.展开更多
Energy-variable gamma-rays are produced in Laser Compton Slant-scattering mode at the Shanghai Laser Electron Gamma Source(SLEGS),a beamline of the Shanghai Synchrotron Radiation Facility(also called Shanghai Light So...Energy-variable gamma-rays are produced in Laser Compton Slant-scattering mode at the Shanghai Laser Electron Gamma Source(SLEGS),a beamline of the Shanghai Synchrotron Radiation Facility(also called Shanghai Light Source).Based on the SLEGS energy-variable gamma-ray beam,a positron generation system composed of a gamma-ray-driven section,positron-generated target,magnet separation section and positron experimental section was designed for SLEGS.Geant4 simulation results show that the energy tunable positron beam in the energy range of 1–12.9 MeV with a flux of 3.7×10^(4)–6.9×10^(5)e^(+)∕s can be produced in this positron generation system.The positron beam generation and separation provide favorable experimental conditions for conducting nondestructive positron testing on SLEGS in the future.The positron generation system is currently under construction and will be completed in 2025.展开更多
BACKGROUND Malignant pleural mesothelioma(MPM),a rare aggressive malignancy,is primarily caused by asbestos exposure.MPM typically affects older adults(median age,76 years),is uncommon in those under age 50 years and ...BACKGROUND Malignant pleural mesothelioma(MPM),a rare aggressive malignancy,is primarily caused by asbestos exposure.MPM typically affects older adults(median age,76 years),is uncommon in those under age 50 years and shows male predominance.Based on the American Society of Clinical Oncology guidelines,F-18 fluorodeoxyglucose positron emission tomography/computed tomography(F-18 FDG PET/CT)is essential for initial MPM staging.Integrating quantitative FDG metabolic data with computed tomography(CT)anatomy optimizes biopsy accuracy and staging.CASE SUMMARY A 21-year-old female college student presented with fever(peak 38.4°C),cough,and white mucoid sputum after cold exposure.Initial evaluation revealed elevated C-reactive protein[C-reactive protein(CRP);65.52 mg/L]and Mycoplasma pneumoniae IgM.Despite resolution of fever following a 14-day moxifloxacin regimen,persistent cough prompted chest CT,which demonstrated left pleural mass-like thickenings.Levofloxacin therapy for 2 weeks failed to alleviate symptoms,accompanied by 2.5-kg weight loss over 1 month.Re-evaluation showed rising CRP(88.87 mg/L)with stable CT lesions,and negative T-cell spot test for tuberculosis and tumor markers.Contrast-enhanced CT revealed heterogeneously enhancing masses,while PET/CT detected two broad-based pleural lesions with intense FDG avidity.CT-guided biopsy confirmed epithelioid MPM.Thoracoscopy exposed diffuse fragile,hemorrhagic nodules implanting on diaphragmatic and parietal pleura,confirming metastatic MPM with partial resection performed.This presentation challenges conventional imaging paradigms of MPM,underscoring its diagnostic complexity.CONCLUSION MPM should still be considered an important differential diagnosis in young patients presenting with solitary pleural masses and no history of typical asbestos exposure.F-18 FDG PET/CT,while serving as an essential component of initial staging for MPM,has some inherent limitations.展开更多
BACKGROUND Preoperative prognosis assessment of hepatocellular carcinoma(HCC)is crucial,and pathologic grading is a key prognostic determinant that affects patient prognosis.Therefore,accurate determination of patholo...BACKGROUND Preoperative prognosis assessment of hepatocellular carcinoma(HCC)is crucial,and pathologic grading is a key prognostic determinant that affects patient prognosis.Therefore,accurate determination of pathological grading before surgical intervention is crucial for optimizing treatment strategies and improving prognostic outcomes.AIM To investigate the distinguishing capability of fluorine-18-fluorodeoxyglucosepositron emission tomography/computed tomography(^(18)F-FDG PET/CT)-derived metabolic parameters between Edmondson grade Ⅱ and Ⅲ HCC and to assess their correlation with Ki67 expression levels.METHODS We retrospectively assessed the ^(18)F-FDG PET/CT imaging datasets from 32 patients with solitary HCC,all of whom had pathological confirmation of their diagnosis.Patients were categorized into Edmondson grade Ⅱ and Ⅲ groups according to pathological grading criteria.Comparative analyses were conducted on metabolic parameters,including maximum standardized uptake value(SUV_(max)),mean standardized uptake value(SUV_(mean)),metabolic tumor volume(MTV),total lesion glycolysis(TLG),tumor-to-normal background ratio(TNR),and tumor-to-blood pool ratio(TBR),between the groups.Further,correlations between these parameters and Ki67 expression were investigated.RESULTS Significant differences were observed in SUV_(max),SUV_(mean),TLG,TNR,and TBR between Edmondson grade Ⅱ and Ⅲ HCC groups(P<0.05),whereas MTV was not significantly different(P=0.052).The maximum tumor diameter and Ki67 expression percentage significantly varied between the two groups(P<0.05).SUV_(max) yielded the largest area under the receiver operating characteristic curve,measuring 0.853(95%confidence interval:0.709-0.997,P=0.001).Using an optimal SUV_(max) cut-off of 10.95,the sensitivity and specificity for identifying Edmondson grade Ⅲ HCC were 66.7%and 100%,respectively.Notably,significant positive correlations were identified in terms of SUV_(max),SUV_(mean),TNR,TBR,and the percentage of Ki67 expression(P<0.01).Conversely,MTV,TLG,and maximum tumor diameter exhibited no significant association with Ki67 expression(P>0.05).CONCLUSION ^(18)F-FDG PET/CT-derived metabolic parameters,particularly SUV_(max),SUV_(mean),TNR,TBR,and TLG,are valuable in differentiating Edmondson grade Ⅱ and Ⅲ HCC,with SUV_(max) showing the optimal differential diagnostic efficacy.TLG is a three-dimensional volumetric parameter that holds some differential diagnostic potential,but it fails to display a distinct advantage.Moreover,increased ^(18)F-FDG uptake and Ki67 expression in tumor tissue correlate with poorer HCC prognoses,emphasizing their potential role in prognostic assessments.展开更多
We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-ly...We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.展开更多
Ovarian cancer(OC)is the most lethal gynecological malignancy.Diagnosis usually occurs late,and even with the most effective treatment relapses are frequent.Early diagnosis and precise staging are critical for achievi...Ovarian cancer(OC)is the most lethal gynecological malignancy.Diagnosis usually occurs late,and even with the most effective treatment relapses are frequent.Early diagnosis and precise staging are critical for achieving better treatment outcomes and prognoses.Conventional imaging methods such as ultrasound(US),computed tomography(CT),and magnetic resonance imaging(MRI)are the main imaging techniques supporting management decisions.However,advancements in molecular imaging have made positron emission tomography/computed tomography(PET/CT)a promising noninvasive imaging option for better management of OC.The literature provides evidence indicating that fluorine‐18‐fluorodeoxyglucose(^(18)F‐FDG)PET/CT(FDG‐PET/CT)is effective in primary tumor diagnosis,staging,prognosis evaluation,treatment response assessment,and relapse surveillance.Looking ahead,significant attention should be paid to tracers beyond FDG,integrated PET/MRI,dynamic PET,and artificial intelligence(AI)‐based radiomics.This review examines the application of PET/CT in OC management at each disease stage and discusses its future potential.展开更多
Parkinson’s disease(PD)is one of the most common neurodegenerative diseases with a complex pathogenesis.Aggregations formed by abnormal deposition of alpha-synuclein(αSyn)lead to synapse dysfunction of the dopamine ...Parkinson’s disease(PD)is one of the most common neurodegenerative diseases with a complex pathogenesis.Aggregations formed by abnormal deposition of alpha-synuclein(αSyn)lead to synapse dysfunction of the dopamine and non-dopamine systems.The loss of dopaminergic neurons and concomitant alterations in non-dopaminergic function in PD constitute its primary pathological manifestation.Positron emission tomography(PET),as a representative molecular imaging technique,enables the non-invasive visualization,characterization,and quantification of biological processes at cellular and molecular levels.Imaging synaptic function with PET would provide insights into the mechanisms underlying PD and facilitate the optimization of clinical management.In this review,we focus on the synaptic dysfunction associated with theαSyn pathology of PD,summarize various related targets and radiopharmaceuticals,and discuss applications and perspectives of PET imaging of synaptic dysfunction in PD.展开更多
As a powerful noninvasive imaging technology,positron emission tomography(PET)has been playing an important role in disease theranostics and drug discovery.The successful application of PET relies on not only the biol...As a powerful noninvasive imaging technology,positron emission tomography(PET)has been playing an important role in disease theranostics and drug discovery.The successful application of PET relies on not only the biological properties of PET tracers but also the availability of facile and efficient radiochemical reactions to enable practical production and widespread use of PET tracers.Most recently,photochemistry is emerging as a novel,mild and efficient approach to generating PET agents.In this review,we focus on the recent advances in newly developed photocatalytic radiochemical reactions,innovation on automated photochemical radiosynthesis modules,as well as implementation in late-stage radiolabeling and radio-pharmaceutical synthesis for PET imaging.We believe that this review will inspire the development of more promising radiolabeling protocols for the preparation of clinically useful PET agents.展开更多
Background:Patients with cold tumors gain limited benefits from immune checkpoint blockade(ICB)therapy owing to low programmed cell death protein ligand 1(PD-L1)expression and minimal immune cell infiltration.Mild pho...Background:Patients with cold tumors gain limited benefits from immune checkpoint blockade(ICB)therapy owing to low programmed cell death protein ligand 1(PD-L1)expression and minimal immune cell infiltration.Mild photothermal therapy(PTT)using black phosphorus nanosheets(BPNSs)is a promising approach to enhance the efficacy of ICB therapy.However,to ensure that BPNS-based PTT-enhanced ICB therapy is clinically adaptable,a noninvasive,bedside-accessible imaging tool capable of monitoring the status of PD-L1 is imperative.We demonstrated that positron emission tomography(PET)using[64Cu]HKP2202 precisely delineated PD-L1 expression in tumors receiving PTT.Methods:BPNSs were modified with polyethylene glycol to prepare BPNS@PEG,which were then characterized.MC38 cells and tumor allografts were treated with BPNS@PEG followed by 808 nm near-infrared light expo-sure.PET using[64Cu]HKP2202 was performed to monitor PD-L1 expression in vivo.We also evaluated whether the efficacy of ICB therapy improved after delivering BPNS@PEG-based PTT.Results:BPNS@PEG had a well-defined lamellar structure with clear edges and an average size of 150 nm.PET and Western blotting assays indicated that PD-L1 expression was upregulated after BPNS@PEG and NIR-light treatment.Notably,the antitumor effect of anti PD-L1 therapy was enhanced in mice treated with BPNS@PEG-based PTT.Conclusions:BPNS@PEG had the capacity to convert cold tumors into hot tumors to facilitate the efficacy of ICB therapy.Importantly,the comple-mentary diagnostic PET radiotracer targeting PD-L1 allowed real-time moni-toring of PD-L1 expression in the tumor microenvironment to guide ICB administration,holding great potential to achieve efficient and precise tumor immunotherapy.展开更多
This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser(PETAL)laser.The experiments were performed during the commissioning of the laser.The laser h...This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser(PETAL)laser.The experiments were performed during the commissioning of the laser.The laser had an energy of about 400 J,an intensity of 8×10^(18)W cm^(−2),and a pulse duration of 660 fs(FWHM).It was shot at a 2 mm-thick solid tungsten target.The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target.This paper reports measurements of electrons,protons and photons.Hot electrons up to35 MeV with a few-MeV temperature were recorded by a spectrometer,called SESAME(SpectreÉlectronS Angulaire MoyenneÉnergie).K-and L-shells were clearly detected by a photon spectrometer called SPECTIX(Spectromètre PetalàCristal en TransmIssion pour le rayonnnement X).High-energy photons were diagnosed by CRACC-X(Cassette de RAdiographie Centre Chambre-rayonnement X),a bremsstrahlung cannon.Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape.Different shapes can exhibit similar reproductions of the experimental data.To eliminate dependence on the shape hypothesis and to facilitate analysis of the data,simulations of the interaction were performed.To model the mechanisms involved,a simulation chain including hydrodynamic,particle-in-cell,and Monte Carlo simulations was used.The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse,the acceleration of electrons inside the plasma,the generation of MeV-range photons from these electrons,and the response of the detector impacted by the energetic photon beam.All this work enabled reproduction of the experimental data.The high-energy photons produced have a large emission angle and an exponential distribution shape.In addition to the analysis of the photon spectra,positron production was also investigated.Indeed,if high-energy photons are generated inside the solid target,some positron/electron pairs may be produced by the Bethe–Heitler process.Therefore,the positron production achievable within the PETAL laser facility was quantified.To conclude the study,the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.展开更多
The relativistic binary-encounter-Bethe model with Wannier-type threshold law is employed to obtain the inner-shell ionization cross sections of multi-electron atoms(Ni,Cu,Y,Ag,Au,Yb,Ta,and Pb)for positron impact ener...The relativistic binary-encounter-Bethe model with Wannier-type threshold law is employed to obtain the inner-shell ionization cross sections of multi-electron atoms(Ni,Cu,Y,Ag,Au,Yb,Ta,and Pb)for positron impact energies from the thresholds up to 105ke V.There is good agreement between the present calculations and the experimental data.The constant in the acceleration term derived from the Wannier law is determined to be 0.2 and 0.5 for the K-and L-shells,respectively.展开更多
We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasib...We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasibility for diverse applications.By utilizing a stacked acceleration structure and far-infrared laser technology,we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods.Additionally,we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process,compared with the traditional methods,the positron beam is compressed to a greater extent.We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam.展开更多
Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth...Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth titanate Bi_(4-x)Er_(x)Ti_(3)O_(12)(x=0,0.1,0.2,0.3,0.4,0.5)ceramics were synthesized via solid-state reaction method.The x-ray diffraction analysis confirmed the orthorhombic crystalline structure of the Bi4-xErxTi_(3)O_(12) ceramics without any secondary phases.Experiments and calculations of positron annihilation spectroscopy were carried out to characterize their defect structure.The comparison between the experimental and calculated lifetime revealed that vacancy clusters were the main defects in the ceramics.The increase of the intensity of the second positron lifetime component(I_(2))of Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics indicated the presence of a high concentration of vacancy clusters.The UCPL spectra showed the sudden enhanced UCPL performance in Bi3.7Er0.3Ti3O12and Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics,which were consistent with the variation of the second positron lifetime component(I2).These results indicate that the enhanced UCPL properties are influenced not only by the concentrations of rare earth ions but also by the concentration of vacancy clusters present within the ceramics.展开更多
AIM:To explore the role of positron emission tomographycomputed tomography(PET-CT)examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma(OAML).METHODS:The general clini...AIM:To explore the role of positron emission tomographycomputed tomography(PET-CT)examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma(OAML).METHODS:The general clinical data,postoperative PET-CT results,treatment regimens,and the prognosis of 21 histopathologically confirmed OAML patients between October 2017 and September 2021 were collected.Among the 21 patients,five patients underwent surgical treatment alone,13 patients underwent surgical treatment combined with radiotherapy,and three patients underwent surgical treatment combined with chemotherapy.RESULTS:The follow-up period ranged from 8 to 79mo,with four cases of recurrence and no deaths.Through PETCT examination,two patients exhibited both local ocular metabolic elevation and systemic metastasis,and one of these patients had cervical lymph node metastasis,while the other had submandibular and parotid gland metastasis.Nine patients showed only local ocular metabolic elevation,while 10 patients had no abnormal metabolic activity locally.CONCLUSION:PET-CT examination plays a crucial role in detecting residual lesions and recurrence following tumor resection,aiding in precise disease staging,and facilitating the development of personalized treatment plans,ultimately improving patient prognosis.展开更多
文摘Biliary tract cancer(BTC)is a group of heterogeneous sporadic diseases,including intrahepatic,hilar,and distal cholangiocarcinoma,as well as gallbladder cancer.BTC is characterized by high invasiveness and extremely poor prognosis,with a global increased incidence due to intrahepatic cholangiocarcinoma(ICC).The 18Ffludeoxyglucose positron emission tomography(PET)computed tomography(18F-FDG PET/CT)combines glucose metabolic information(reflecting the glycolytic activity of tumor cells)with anatomical structure to assess tumor metabolic heterogeneity,systemic metastasis,and molecular characteristics noninvasively,overcoming the limitations of traditional imaging in the detection of micrometastases and recurrent lesions.18F-FDG PET/CT offers critical insights in clinical staging,therapeutic evaluation,and prognostic prediction of BTC.This article reviews research progress in this field over the past decade,with a particular focus on the advances made in the last 3 years,which have not been adequately summarized and recognized.The research paradigm in this field is shifting from qualitative to quantitative studies,and there have been significant breakthroughs in using 18F-FDG PET/CT metabolic information to predict gene expression in ICC.Radiomics and deep learning techniques have been applied to ICC for prognostic prediction and differential diagnosis.Additionally,PET/magnetic resonance imaging is increasingly demonstrating its value in this field.
文摘Soft tissue sarcomas(STS)are rare malignant tumors originating from mesoder-mal tissues with a poor prognosis,accounting for approximately 1%of all malig-nancies and comprising around 50 distinct subtypes.Conventional imaging mo-dalities,such as computed tomography(CT)and magnetic resonance imaging(MRI),primarily provide anatomical information,whereas 18F-fluorodeoxyglucose positron emission tomography/CT(18F-FDG PET/CT)integrates functional metabolic and anatomical imaging,serving as a critical complementary tool in the diagnosis and management of STS.This article reviews recent advances in the application of 18F-FDG PET/CT for STS.The advantages of 18F-FDG PET/CT in STS include:(1)Early detection of metabolic activity changes in tumors,partic-ularly when morphological alterations are insignificant;(2)Effective differen-tiation between benign and malignant soft tissue tumors,as well as aiding in distinguishing high-grade from low-grade sarcomas;(3)Identification of occult metastatic lesions,improving staging accuracy,and facilitating restaging in cases of recurrence or metastasis;(4)Utilization of parameters such as maximum stan-dardized uptake value and metabolic tumor volume to assist in tumor grading and prognostic evaluation;and(5)Monitoring treatment response to guide adjust-ments in personalized therapeutic strategies.However,18F-FDG PET/CT has limitations in diagnosis of certain STS subtypes(e.g.,myxoid liposarcoma),detection and biopsy of metastatic lymph nodes,necessitating integration with clinical evaluation and other imaging techniques.18F-FDG PET/CT is poised to play an increasingly vital role in the precision diagnosis and treatment of STS.
基金supported by the Research Project of the Shanghai Health Commission,No.2020YJZX0111(to CZ)the National Natural Science Foundation of China,Nos.82021002(to CZ),82272039(to CZ),82171252(to FL)+1 种基金a grant from the National Health Commission of People’s Republic of China(PRC),No.Pro20211231084249000238(to JW)Medical Innovation Research Project of Shanghai Science and Technology Commission,No.21Y11903300(to JG).
文摘Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.
文摘Malignant tumours always threaten human health.For tumour diagnosis,positron emission tomography(PET)is the most sensitive and advanced imaging technique by radiotracers,such as radioactive^(18)F,^(11)C,^(64)Cu,^(68)Ga,and^(89)Zr.Among the radiotracers,the radioactive^(18)F-labelled chemical agent as PET probes plays a predominant role in monitoring,detecting,treating,and predicting tumours due to its perfect half-life.In this paper,the^(18)F-labelled chemical materials as PET probes are systematically summarized.First,we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging.It highlights the^(18)F-labelled chemical agents used as PET probes,including[^(18)F]-2-deoxy-2-[^(18)F]fluoro-D-glucose([^(18)F]-FDG),^(18)F-labelled amino acids,^(18)F-labelled nucleic acids,^(18)F-labelled receptors,^(18)F-labelled reporter genes,and^(18)F-labelled hypoxia agents.In addition,some PET probes with metal as a supplementary element are introduced briefly.Meanwhile,the^(18)F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail.The approach and strategies for the fabrication of^(18)F-labelled PET probes are also described briefly.The future development of the PET probe is also prospected.The development and application of^(18)F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours.
文摘Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.
基金supported by the National Natural Science Foundation of China(Nos.12005289,52072397)State Key Laboratory of Nuclear Detection and Electronics,University of Science and Technology of China(SKLPDE-KF-202316).
文摘The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.
文摘We present the diagnostic performance of[18F]Fluorodeoxyglucose positron emission tomography(FDG PET)for adrenal incidentalomas based on lesion size and unenhanced computed tomography(CT)density in Hounsfield units(HU),following current literature and guidelines.A 20 HU cutoff can be applied to differentiate potentially benign from malignant lesions,particularly in ruling in or out adrenocortical carcinoma.While FDG PET provides valuable metabolic information,its likelihood ratios for a positive(LR+)or negative(LR-)result do not exceed the robust diagnostic thresholds of>10.0 or<0.1,respectively.This suggests that positron emission tomography alone is insufficient for definitive characterization and should be integrated with CT or magnetic resonance imaging to leverage their complementary anatomical and functional imaging strengths for optimal diagnostic accuracy.
基金supported by the National Key Research and Development program(Nos.2022YFA1602404,2023YFA1606901)the National Natural Science Foundation of China(Nos.12275338,12388102,and U2441221)the Key Laboratory of Nuclear Data foundation(JCKY2022201C152)xm。
文摘Energy-variable gamma-rays are produced in Laser Compton Slant-scattering mode at the Shanghai Laser Electron Gamma Source(SLEGS),a beamline of the Shanghai Synchrotron Radiation Facility(also called Shanghai Light Source).Based on the SLEGS energy-variable gamma-ray beam,a positron generation system composed of a gamma-ray-driven section,positron-generated target,magnet separation section and positron experimental section was designed for SLEGS.Geant4 simulation results show that the energy tunable positron beam in the energy range of 1–12.9 MeV with a flux of 3.7×10^(4)–6.9×10^(5)e^(+)∕s can be produced in this positron generation system.The positron beam generation and separation provide favorable experimental conditions for conducting nondestructive positron testing on SLEGS in the future.The positron generation system is currently under construction and will be completed in 2025.
基金Supported by the Tianjin Science and Technology Project,No.TJWJ2025RC008。
文摘BACKGROUND Malignant pleural mesothelioma(MPM),a rare aggressive malignancy,is primarily caused by asbestos exposure.MPM typically affects older adults(median age,76 years),is uncommon in those under age 50 years and shows male predominance.Based on the American Society of Clinical Oncology guidelines,F-18 fluorodeoxyglucose positron emission tomography/computed tomography(F-18 FDG PET/CT)is essential for initial MPM staging.Integrating quantitative FDG metabolic data with computed tomography(CT)anatomy optimizes biopsy accuracy and staging.CASE SUMMARY A 21-year-old female college student presented with fever(peak 38.4°C),cough,and white mucoid sputum after cold exposure.Initial evaluation revealed elevated C-reactive protein[C-reactive protein(CRP);65.52 mg/L]and Mycoplasma pneumoniae IgM.Despite resolution of fever following a 14-day moxifloxacin regimen,persistent cough prompted chest CT,which demonstrated left pleural mass-like thickenings.Levofloxacin therapy for 2 weeks failed to alleviate symptoms,accompanied by 2.5-kg weight loss over 1 month.Re-evaluation showed rising CRP(88.87 mg/L)with stable CT lesions,and negative T-cell spot test for tuberculosis and tumor markers.Contrast-enhanced CT revealed heterogeneously enhancing masses,while PET/CT detected two broad-based pleural lesions with intense FDG avidity.CT-guided biopsy confirmed epithelioid MPM.Thoracoscopy exposed diffuse fragile,hemorrhagic nodules implanting on diaphragmatic and parietal pleura,confirming metastatic MPM with partial resection performed.This presentation challenges conventional imaging paradigms of MPM,underscoring its diagnostic complexity.CONCLUSION MPM should still be considered an important differential diagnosis in young patients presenting with solitary pleural masses and no history of typical asbestos exposure.F-18 FDG PET/CT,while serving as an essential component of initial staging for MPM,has some inherent limitations.
基金Supported by National Natural Science Foundation of China,No.82171983Henan Provincial Science and Technology Research Project,No.242102311089.
文摘BACKGROUND Preoperative prognosis assessment of hepatocellular carcinoma(HCC)is crucial,and pathologic grading is a key prognostic determinant that affects patient prognosis.Therefore,accurate determination of pathological grading before surgical intervention is crucial for optimizing treatment strategies and improving prognostic outcomes.AIM To investigate the distinguishing capability of fluorine-18-fluorodeoxyglucosepositron emission tomography/computed tomography(^(18)F-FDG PET/CT)-derived metabolic parameters between Edmondson grade Ⅱ and Ⅲ HCC and to assess their correlation with Ki67 expression levels.METHODS We retrospectively assessed the ^(18)F-FDG PET/CT imaging datasets from 32 patients with solitary HCC,all of whom had pathological confirmation of their diagnosis.Patients were categorized into Edmondson grade Ⅱ and Ⅲ groups according to pathological grading criteria.Comparative analyses were conducted on metabolic parameters,including maximum standardized uptake value(SUV_(max)),mean standardized uptake value(SUV_(mean)),metabolic tumor volume(MTV),total lesion glycolysis(TLG),tumor-to-normal background ratio(TNR),and tumor-to-blood pool ratio(TBR),between the groups.Further,correlations between these parameters and Ki67 expression were investigated.RESULTS Significant differences were observed in SUV_(max),SUV_(mean),TLG,TNR,and TBR between Edmondson grade Ⅱ and Ⅲ HCC groups(P<0.05),whereas MTV was not significantly different(P=0.052).The maximum tumor diameter and Ki67 expression percentage significantly varied between the two groups(P<0.05).SUV_(max) yielded the largest area under the receiver operating characteristic curve,measuring 0.853(95%confidence interval:0.709-0.997,P=0.001).Using an optimal SUV_(max) cut-off of 10.95,the sensitivity and specificity for identifying Edmondson grade Ⅲ HCC were 66.7%and 100%,respectively.Notably,significant positive correlations were identified in terms of SUV_(max),SUV_(mean),TNR,TBR,and the percentage of Ki67 expression(P<0.01).Conversely,MTV,TLG,and maximum tumor diameter exhibited no significant association with Ki67 expression(P>0.05).CONCLUSION ^(18)F-FDG PET/CT-derived metabolic parameters,particularly SUV_(max),SUV_(mean),TNR,TBR,and TLG,are valuable in differentiating Edmondson grade Ⅱ and Ⅲ HCC,with SUV_(max) showing the optimal differential diagnostic efficacy.TLG is a three-dimensional volumetric parameter that holds some differential diagnostic potential,but it fails to display a distinct advantage.Moreover,increased ^(18)F-FDG uptake and Ki67 expression in tumor tissue correlate with poorer HCC prognoses,emphasizing their potential role in prognostic assessments.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602501)the National Natural Science Foundation of China(Grant No.12011530060)+1 种基金supported solely by the Russian Science Foundation(Grant No.22-12-00043)supported by the Chinese Academy of Sciences(CAS)Presidents International Fellowship Initiative(PIFI)(Grant Nos.2018VMB0016 and 2022VMC0002),respectively。
文摘We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.
基金supported by the National Natural Science Foundation of China(Grant 32027802)Key Research and Development Program of Zhejiang Province(Grant 2022C03071)+1 种基金Medical and Health Research Project of Zhejiang Province(Grant 2024KY1222)Teaching Reform Project of the Education Department of Zhejiang Province(Grant JGBA2024231).
文摘Ovarian cancer(OC)is the most lethal gynecological malignancy.Diagnosis usually occurs late,and even with the most effective treatment relapses are frequent.Early diagnosis and precise staging are critical for achieving better treatment outcomes and prognoses.Conventional imaging methods such as ultrasound(US),computed tomography(CT),and magnetic resonance imaging(MRI)are the main imaging techniques supporting management decisions.However,advancements in molecular imaging have made positron emission tomography/computed tomography(PET/CT)a promising noninvasive imaging option for better management of OC.The literature provides evidence indicating that fluorine‐18‐fluorodeoxyglucose(^(18)F‐FDG)PET/CT(FDG‐PET/CT)is effective in primary tumor diagnosis,staging,prognosis evaluation,treatment response assessment,and relapse surveillance.Looking ahead,significant attention should be paid to tracers beyond FDG,integrated PET/MRI,dynamic PET,and artificial intelligence(AI)‐based radiomics.This review examines the application of PET/CT in OC management at each disease stage and discusses its future potential.
基金supported by the National Key Research and Development Program of China(2022YFC2009900,2021YFE0108300,2022YFE0118000,and 2021YFA1101700)the National Natural Science Foundation of China(82030049)Fundamental Research Funds for the Central Universities of China.
文摘Parkinson’s disease(PD)is one of the most common neurodegenerative diseases with a complex pathogenesis.Aggregations formed by abnormal deposition of alpha-synuclein(αSyn)lead to synapse dysfunction of the dopamine and non-dopamine systems.The loss of dopaminergic neurons and concomitant alterations in non-dopaminergic function in PD constitute its primary pathological manifestation.Positron emission tomography(PET),as a representative molecular imaging technique,enables the non-invasive visualization,characterization,and quantification of biological processes at cellular and molecular levels.Imaging synaptic function with PET would provide insights into the mechanisms underlying PD and facilitate the optimization of clinical management.In this review,we focus on the synaptic dysfunction associated with theαSyn pathology of PD,summarize various related targets and radiopharmaceuticals,and discuss applications and perspectives of PET imaging of synaptic dysfunction in PD.
基金the financial support from the Basic Research Program of Jiangsu Province(No.BK20220408).
文摘As a powerful noninvasive imaging technology,positron emission tomography(PET)has been playing an important role in disease theranostics and drug discovery.The successful application of PET relies on not only the biological properties of PET tracers but also the availability of facile and efficient radiochemical reactions to enable practical production and widespread use of PET tracers.Most recently,photochemistry is emerging as a novel,mild and efficient approach to generating PET agents.In this review,we focus on the recent advances in newly developed photocatalytic radiochemical reactions,innovation on automated photochemical radiosynthesis modules,as well as implementation in late-stage radiolabeling and radio-pharmaceutical synthesis for PET imaging.We believe that this review will inspire the development of more promising radiolabeling protocols for the preparation of clinically useful PET agents.
基金National Natural Science Foundation of China,Grant/Award Number:82372002Nonprofit Central Research Institute Fund of Chinese Academy of Medical Sciences,Grant/Award Number:2022-RC350-04+7 种基金CAMS Innovation Fund for Medical Sciences,Grant/Award Numbers:2021-I2M-1-026,2022-I2M-2-002-2,2021-I2M-3-001National Key Research and Development Program of China,Grant/Award Number:2022YFE0111700Beijing Nova Program awarded to K.H.,Grant/Award Number:0104002Beijing Natural Science Foundation,Grant/Award Number:L234044Fundamental Research Funds for the Central Universities,Grant/Award Numbers:3332023044,3332023151CIRP Open Fund of Radiation Protection Laboratories“Technological innovation”special project of CNNC Medical Industry Co.Ltd,Grant/Award Number:ZHYLYB2021005China National Nuclear Corporation Young Talent Program。
文摘Background:Patients with cold tumors gain limited benefits from immune checkpoint blockade(ICB)therapy owing to low programmed cell death protein ligand 1(PD-L1)expression and minimal immune cell infiltration.Mild photothermal therapy(PTT)using black phosphorus nanosheets(BPNSs)is a promising approach to enhance the efficacy of ICB therapy.However,to ensure that BPNS-based PTT-enhanced ICB therapy is clinically adaptable,a noninvasive,bedside-accessible imaging tool capable of monitoring the status of PD-L1 is imperative.We demonstrated that positron emission tomography(PET)using[64Cu]HKP2202 precisely delineated PD-L1 expression in tumors receiving PTT.Methods:BPNSs were modified with polyethylene glycol to prepare BPNS@PEG,which were then characterized.MC38 cells and tumor allografts were treated with BPNS@PEG followed by 808 nm near-infrared light expo-sure.PET using[64Cu]HKP2202 was performed to monitor PD-L1 expression in vivo.We also evaluated whether the efficacy of ICB therapy improved after delivering BPNS@PEG-based PTT.Results:BPNS@PEG had a well-defined lamellar structure with clear edges and an average size of 150 nm.PET and Western blotting assays indicated that PD-L1 expression was upregulated after BPNS@PEG and NIR-light treatment.Notably,the antitumor effect of anti PD-L1 therapy was enhanced in mice treated with BPNS@PEG-based PTT.Conclusions:BPNS@PEG had the capacity to convert cold tumors into hot tumors to facilitate the efficacy of ICB therapy.Importantly,the comple-mentary diagnostic PET radiotracer targeting PD-L1 allowed real-time moni-toring of PD-L1 expression in the tumor microenvironment to guide ICB administration,holding great potential to achieve efficient and precise tumor immunotherapy.
基金support by GENCI France through awarding us access to HPC resources at TGCC/CCRT(Grant Nos.A0110512943 and A0130512943)funded by the French Agence Nationale de la Recherche under Grant No.ANR-10-EQPX-42-01funded by the LabEx LAPHIA of the University of Bordeaux under Grant No.ANR-10-IDEX-03-02.
文摘This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser(PETAL)laser.The experiments were performed during the commissioning of the laser.The laser had an energy of about 400 J,an intensity of 8×10^(18)W cm^(−2),and a pulse duration of 660 fs(FWHM).It was shot at a 2 mm-thick solid tungsten target.The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target.This paper reports measurements of electrons,protons and photons.Hot electrons up to35 MeV with a few-MeV temperature were recorded by a spectrometer,called SESAME(SpectreÉlectronS Angulaire MoyenneÉnergie).K-and L-shells were clearly detected by a photon spectrometer called SPECTIX(Spectromètre PetalàCristal en TransmIssion pour le rayonnnement X).High-energy photons were diagnosed by CRACC-X(Cassette de RAdiographie Centre Chambre-rayonnement X),a bremsstrahlung cannon.Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape.Different shapes can exhibit similar reproductions of the experimental data.To eliminate dependence on the shape hypothesis and to facilitate analysis of the data,simulations of the interaction were performed.To model the mechanisms involved,a simulation chain including hydrodynamic,particle-in-cell,and Monte Carlo simulations was used.The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse,the acceleration of electrons inside the plasma,the generation of MeV-range photons from these electrons,and the response of the detector impacted by the energetic photon beam.All this work enabled reproduction of the experimental data.The high-energy photons produced have a large emission angle and an exponential distribution shape.In addition to the analysis of the photon spectra,positron production was also investigated.Indeed,if high-energy photons are generated inside the solid target,some positron/electron pairs may be produced by the Bethe–Heitler process.Therefore,the positron production achievable within the PETAL laser facility was quantified.To conclude the study,the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.
基金supported by the National Natural Science Foundation of China(Grant No.12174147)the Chinese Scholarship Council(Grant Nos.202108210152 and 202006175016).
文摘The relativistic binary-encounter-Bethe model with Wannier-type threshold law is employed to obtain the inner-shell ionization cross sections of multi-electron atoms(Ni,Cu,Y,Ag,Au,Yb,Ta,and Pb)for positron impact energies from the thresholds up to 105ke V.There is good agreement between the present calculations and the experimental data.The constant in the acceleration term derived from the Wannier law is determined to be 0.2 and 0.5 for the K-and L-shells,respectively.
基金supported by the National Natural Science Foundation of China(Grant No.11975214).
文摘We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasibility for diverse applications.By utilizing a stacked acceleration structure and far-infrared laser technology,we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods.Additionally,we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process,compared with the traditional methods,the positron beam is compressed to a greater extent.We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam.
基金Project supported by the National Key Research and Development Program of China(Grant No.2019YFA0210000)the National Natural Science Foundation of China(Grant No.12175232)。
文摘Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth titanate Bi_(4-x)Er_(x)Ti_(3)O_(12)(x=0,0.1,0.2,0.3,0.4,0.5)ceramics were synthesized via solid-state reaction method.The x-ray diffraction analysis confirmed the orthorhombic crystalline structure of the Bi4-xErxTi_(3)O_(12) ceramics without any secondary phases.Experiments and calculations of positron annihilation spectroscopy were carried out to characterize their defect structure.The comparison between the experimental and calculated lifetime revealed that vacancy clusters were the main defects in the ceramics.The increase of the intensity of the second positron lifetime component(I_(2))of Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics indicated the presence of a high concentration of vacancy clusters.The UCPL spectra showed the sudden enhanced UCPL performance in Bi3.7Er0.3Ti3O12and Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics,which were consistent with the variation of the second positron lifetime component(I2).These results indicate that the enhanced UCPL properties are influenced not only by the concentrations of rare earth ions but also by the concentration of vacancy clusters present within the ceramics.
基金Supported by the Beijing Science and Technology Rising Star Program-Cross-cooperation Project(No.20220484218)the Tai’an City Science and Technology Innovation Development Project(No.2021NS207).
文摘AIM:To explore the role of positron emission tomographycomputed tomography(PET-CT)examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma(OAML).METHODS:The general clinical data,postoperative PET-CT results,treatment regimens,and the prognosis of 21 histopathologically confirmed OAML patients between October 2017 and September 2021 were collected.Among the 21 patients,five patients underwent surgical treatment alone,13 patients underwent surgical treatment combined with radiotherapy,and three patients underwent surgical treatment combined with chemotherapy.RESULTS:The follow-up period ranged from 8 to 79mo,with four cases of recurrence and no deaths.Through PETCT examination,two patients exhibited both local ocular metabolic elevation and systemic metastasis,and one of these patients had cervical lymph node metastasis,while the other had submandibular and parotid gland metastasis.Nine patients showed only local ocular metabolic elevation,while 10 patients had no abnormal metabolic activity locally.CONCLUSION:PET-CT examination plays a crucial role in detecting residual lesions and recurrence following tumor resection,aiding in precise disease staging,and facilitating the development of personalized treatment plans,ultimately improving patient prognosis.
