2023
B1 inhomogeneity‐corrected T1 mapping and quantitative magnetization transfer imaging via simultaneously estimating Bloch‐Siegert shift and magnetization transfer effects
Jang A, Han P, Ma C, Fakhri G, Wang N, Samsonov A, Liu F. B1 inhomogeneity‐corrected T1 mapping and quantitative magnetization transfer imaging via simultaneously estimating Bloch‐Siegert shift and magnetization transfer effects. Magnetic Resonance In Medicine 2023, 90: 1859-1873. PMID: 37427533, PMCID: PMC10528411, DOI: 10.1002/mrm.29778.Peer-Reviewed Original ResearchConceptsBloch-Siegert shiftBloch-SiegertMagnetization transfer effectsMonte Carlo simulationsSpin-lattice relaxationSpin-bath modelMagnetization transferBinary spin-bath modelCarlo simulationsProton fractionOff-resonance irradiationIn vivo brain studiesBloch simulationsPhantom experimentsMagnetizationEstimationTransmitted fieldQuantitative magnetization transferMethod performanceMT effectSignal equation
2017
Use of Monte Carlo Techniques in Nuclear Medicine
Fahey F, Grogg K, Fakhri G. Use of Monte Carlo Techniques in Nuclear Medicine. Journal Of The American College Of Radiology 2017, 15: 446-448. PMID: 29173989, PMCID: PMC6335966, DOI: 10.1016/j.jacr.2017.09.045.Peer-Reviewed Original ResearchFeasibility study of using fall‐off gradients of early and late PET scans for proton range verification
Cho J, Grogg K, Min C, Zhu X, Paganetti H, Lee H, Fakhri G. Feasibility study of using fall‐off gradients of early and late PET scans for proton range verification. Medical Physics 2017, 44: 1734-1746. PMID: 28273345, PMCID: PMC5462437, DOI: 10.1002/mp.12191.Peer-Reviewed Original ResearchMeSH KeywordsFeasibility StudiesHumansMonte Carlo MethodPhantoms, ImagingPositron-Emission TomographyProtonsConceptsProton range verificationProton rangeMonte Carlo simulationsRange verificationFall-offIn-room positron emission tomographyCarlo simulationsResidual proton rangeDose fall-offPostirradiation delayPositron emission tomography imagingSOBP beamProton beamPositron emission tomographyPositron emission tomography scanPhantom studyIn-roomFunction of depthPhantomProtonOff-setMonteAcquisition timeBeamPositron emission tomography signal
2016
Validation of Bayesian analysis of compartmental kinetic models in medical imaging
Sitek A, Li Q, Fakhri G, Alpert N. Validation of Bayesian analysis of compartmental kinetic models in medical imaging. Physica Medica 2016, 32: 1252-1258. PMID: 27692754, PMCID: PMC5720163, DOI: 10.1016/j.ejmp.2016.09.010.Peer-Reviewed Original ResearchConceptsAccurate estimation of uncertaintyComputer simulationsMedical imagesPosterior distributionDistributed noiseTime series of imagesClosed-formSeries of imagesData setsKinetic parametersMarkov chain Monte Carlo methodsPosterior distributions of kinetic parametersNon-linear least squares methodAccurate estimationComputerLeast-squares methodKinetic modelEstimation of kinetic parametersF18-fluorodeoxyglucoseBayesian estimationImagesStatistical inferenceMonte Carlo methodEstimates of uncertaintyInformationA novel approach to assess the treatment response using Gaussian random field in PET
Wang M, Guo N, Hu G, El Fakhri G, Zhang H, Li Q. A novel approach to assess the treatment response using Gaussian random field in PET. Medical Physics 2016, 43: 833-842. PMID: 26843244, PMCID: PMC4714995, DOI: 10.1118/1.4939879.Peer-Reviewed Original ResearchConceptsTherapy response assessmentStandardized uptake valuePositron emission tomographyEarly treatment responseResponse assessmentPositron emission tomography imagingTreatment responseTherapy responsePrediction of early treatment responseTreatment planningResponse to anticancer therapyTherapy response evaluationTumor-to-background contrastPost-therapy imagingClinical practiceEvaluate therapy responseReceiver operating characteristic curveDevelopment of personalized treatment plansEvaluate therapy effectsPersonalized treatment plansUptake valuePretherapy imagingClinical oncologyPatient managementAnticancer therapy
2015
Stochastic simulation of radium-223 dichloride therapy at the sub-cellular level
Gholami Y, Zhu X, Fulton R, Meikle S, El-Fakhri G, Kuncic Z. Stochastic simulation of radium-223 dichloride therapy at the sub-cellular level. Physics In Medicine And Biology 2015, 60: 6087-6096. PMID: 26216391, DOI: 10.1088/0031-9155/60/15/6087.Peer-Reviewed Original ResearchMeSH KeywordsAlpha ParticlesCell NucleusDNA DamageHumansMaleModels, StatisticalMonte Carlo MethodRadioisotopesRadiopharmaceuticalsRadiumConceptsEstimate radiation damageAlpha particle tracksAlpha-particle emittersMonte Carlo modelIonization clustersDose depositionAlpha particlesAlpha emissionParticle therapyAlpha-particle therapyEnergy depositionRadiation damageCarlo modelEfficacy of cell killingParticle emittersRadium-223 dichlorideBone-seeking radionuclidesParticle trackingRadium-223Prostate cancerAverage doseCell nucleiCell killingIndirect DNA damageNucleusMonitoring proton therapy with PET
Paganetti H, Fakhri G. Monitoring proton therapy with PET. British Journal Of Radiology 2015, 88: 20150173. PMID: 25989699, PMCID: PMC4628541, DOI: 10.1259/bjr.20150173.Peer-Reviewed Original ResearchMeSH KeywordsHumansMonte Carlo MethodPositron-Emission TomographyProton TherapyRadiation MonitoringRadiotherapy DosageUncertaintyConceptsPatient set-upDose conformityDose shapingInterfractional changesProton beamBeam deliveryDose calculationProton therapyTumor coveragePhotonic techniquesTreatment volumeTotal energyPatient anatomyBeamRadiation therapyProtonPatientsTherapyReduced total energyDoseSet-upRangeCalculationsRadiationEnergyMapping 15O Production Rate for Proton Therapy Verification
Grogg K, Alpert N, Zhu X, Min C, Testa M, Winey B, Normandin M, Shih H, Paganetti H, Bortfeld T, Fakhri G. Mapping 15O Production Rate for Proton Therapy Verification. International Journal Of Radiation Oncology • Biology • Physics 2015, 92: 453-459. PMID: 25817530, PMCID: PMC4431894, DOI: 10.1016/j.ijrobp.2015.01.023.Peer-Reviewed Original ResearchConceptsDecay constantProton treatment planningMonte Carlo predictionsProton therapyPhantom materialTreatment deliveryPhantomThigh activityPositron emission tomographyProduction rateDynamic PET measurementsTreatment planningRabbit thigh muscleClearance rateProtonIsotopesChanges due to therapyRadionuclide speciesOxygen-15ConstantDecayImaging targetsMontePositronEffects of perfusion
2014
4D numerical observer for lesion detection in respiratory‐gated PET
Lorsakul A, Li Q, Trott C, Hoog C, Petibon Y, Ouyang J, Laine A, Fakhri G. 4D numerical observer for lesion detection in respiratory‐gated PET. Medical Physics 2014, 41: 102504. PMID: 25281979, PMCID: PMC4281099, DOI: 10.1118/1.4895975.Peer-Reviewed Original ResearchMeSH KeywordsAlgorithmsComputer SimulationFluorodeoxyglucose F18HumansImage Interpretation, Computer-AssistedLung DiseasesModels, BiologicalMonte Carlo MethodMotionPhantoms, ImagingPositron-Emission TomographyRadiopharmaceuticalsRegression AnalysisRespiratory-Gated Imaging TechniquesSignal-To-Noise RatioConceptsRespiratory-gated positron emission tomographyMotion-corrected imagesDetection signal-to-noise ratioLesion detection taskNumerical observationsLesion detection performanceSignal-to-noise ratioPositron emission tomography sinogramsSpherical lesionsHotelling observerMotion correction methodPositron emission tomographyGeant4 ApplicationTomographic EmissionChannelized Hotelling observerAnthropomorphic phantomScanner geometryOSEM algorithmMonte Carlo simulationsPET framesImprove lesion detectionLesion detectionSignal-to-noise ratio measurementsActivity distributionConventional 3D approach
2013
Simultaneous 99mTc‐MDP/123I‐MIBG tumor imaging using SPECT‐CT: Phantom and constructed patient studies
Rakvongthai Y, Fakhri G, Lim R, Bonab A, Ouyang J. Simultaneous 99mTc‐MDP/123I‐MIBG tumor imaging using SPECT‐CT: Phantom and constructed patient studies. Medical Physics 2013, 40: 102506. PMID: 24089927, PMCID: PMC3785531, DOI: 10.1118/1.4820977.Peer-Reviewed Original ResearchConceptsScatter correctionDual-radionuclideContrast recoveryPhantom studyAnthropomorphic torso phantomPatient studiesTumor uptakeTumor imagingSPECT projectionsTorso phantomMonte-CarloPhantom dataPhantomIterative reconstructionOSEMProjection dataDR dataIncrease patient throughputNoise realizationsSPECT-CTImage reconstructionClinical studiesTumorTumor projectionPoisson noiseDetermination of elemental tissue composition following proton treatment using positron emission tomography
Cho J, Ibbott G, Gillin M, Gonzalez-Lepera C, Min C, Zhu X, Fakhri G, Paganetti H, Mawlawi O. Determination of elemental tissue composition following proton treatment using positron emission tomography. Physics In Medicine And Biology 2013, 58: 3815-3835. PMID: 23681070, PMCID: PMC3763743, DOI: 10.1088/0031-9155/58/11/3815.Peer-Reviewed Original ResearchMeSH KeywordsFeasibility StudiesHumansMonte Carlo MethodPhantoms, ImagingPositron-Emission TomographyProton TherapyRadiotherapy Planning, Computer-AssistedConceptsIn-room PET scannerProton treatmentSOBP beamPET scannerMonte Carlo simulationsTissue elemental compositionComposite decay curvePristine Bragg peakProton treatment planningIn-roomElemental tissue compositionCarlo simulationsDecay curvesRange verificationMonoenergetic beamsBeam rangeProton dosePhantom sectionsEmitted positronsPositron emission tomographyProton therapyBragg peakPhantom compositionDelivered dosePositron emission tomography imagingClinical Application of In-Room Positron Emission Tomography for In Vivo Treatment Monitoring in Proton Radiation Therapy
Min C, Zhu X, Winey B, Grogg K, Testa M, Fakhri G, Bortfeld T, Paganetti H, Shih H. Clinical Application of In-Room Positron Emission Tomography for In Vivo Treatment Monitoring in Proton Radiation Therapy. International Journal Of Radiation Oncology • Biology • Physics 2013, 86: 183-189. PMID: 23391817, PMCID: PMC3640852, DOI: 10.1016/j.ijrobp.2012.12.010.Peer-Reviewed Original ResearchConceptsIn-room positron emission tomographyProton therapyIn-roomPositron emission tomography scanIn-room PET scannerPassive scattering proton therapyShapes of target volumesPositron emission tomographyMC predictionBeam range uncertaintiesMeasured PET imagesMonte CarloProton radiation therapyLocal elemental compositionBiological washoutScan timeTreatment headTreatment verificationRange uncertaintiesTarget volumePET scan timePET scannerPET systemComputed tomographyMC results
2011
Monitoring proton radiation therapy with in-room PET imaging
Zhu X, España S, Daartz J, Liebsch N, Ouyang J, Paganetti H, Bortfeld T, Fakhri G. Monitoring proton radiation therapy with in-room PET imaging. Physics In Medicine And Biology 2011, 56: 4041-4057. PMID: 21677366, PMCID: PMC3141290, DOI: 10.1088/0031-9155/56/13/019.Peer-Reviewed Original ResearchConceptsIn-room positron emission tomographyIn-roomProton therapy treatment roomPositron emission tomography systemProton range verificationSoft tissue-equivalent materialMonte Carlo predictionsTissue-equivalent materialsPositron emission tomography acquisition timesProton radiation therapyPositron emission tomographyBiological washoutRange verificationProton therapyList-modeActivity distribution patternsPhantom studyTreatment roomPET acquisitionSoft tissue regionsIn vivo verificationDeep-siteOff-line modalityPositron emission tomography dataAdenoid cystic carcinoma
2010
Dual-Radionuclide Brain SPECT for the Differential Diagnosis of Parkinsonism
El Fakhri G, Ouyang J. Dual-Radionuclide Brain SPECT for the Differential Diagnosis of Parkinsonism. Methods In Molecular Biology 2010, 680: 237-246. PMID: 21153385, DOI: 10.1007/978-1-60761-901-7_16.Peer-Reviewed Original ResearchConceptsDopamine transporter functionBrain SPECTDifferential diagnosis of parkinsonismDifferential diagnosisDiagnosis of parkinsonismIdiopathic Parkinson's diseaseDifferential diagnosis of idiopathic Parkinson’s diseaseDiagnosis of idiopathic Parkinson's diseaseCorticobasal degenerationProgressive supranuclear palsyParkinson's diseaseMultiple system atrophyParkinsonSPECT protocol
2009
Monte Carlo modeling of cascade gamma rays in 86Y PET imaging: preliminary results
Zhu X, Fakhri G. Monte Carlo modeling of cascade gamma rays in 86Y PET imaging: preliminary results. Physics In Medicine And Biology 2009, 54: 4181-4193. PMID: 19521011, PMCID: PMC3111055, DOI: 10.1088/0031-9155/54/13/014.Peer-Reviewed Original ResearchConceptsCascade gamma raysScatter fractionGamma raysPhoton energy distributionLow count ratesHigh-energy photonsMonte Carlo programScatter correction methodGATE simulation packageMonte Carlo modelDevelopment of correction methodsSpatial resolutionGamma photonsEnergy windowCount rateScattering eventsRandom coincidencesEnergy distributionPhantom acquisitionsPersonal dosimetryPET imagingVariance reduction techniquesPhotonsCorrection methodSimSETQuantitative simultaneous cardiac SPECT using MC‐JOSEM
Ouyang J, Zhu X, Trott C, Fakhri G. Quantitative simultaneous cardiac SPECT using MC‐JOSEM. Medical Physics 2009, 36: 602-611. PMID: 19292000, PMCID: PMC2673670, DOI: 10.1118/1.3063544.Peer-Reviewed Original ResearchConceptsMC-JOSEMEnergy windowWater-filled torso phantomScatter correctionPhotopeak energy windowStandard OSEMCardiac SPECT imagingActivity concentration ratioIterative reconstruction algorithmReconstruction algorithmMyocardium wallTorso phantomActivity estimationDetector responseEmission energyBackground compartmentPhantom dataCardiac SPECTActivity distributionRest/stress imagingScatteringCases of patientsOSEMChest painCardiac protocols
2008
Sequential and simultaneous dual‐isotope brain SPECT: Comparison with PET for estimation and discrimination tasks in early Parkinson disease
Trott C, Fakhri G. Sequential and simultaneous dual‐isotope brain SPECT: Comparison with PET for estimation and discrimination tasks in early Parkinson disease. Medical Physics 2008, 35: 3343-3353. PMID: 18697558, PMCID: PMC2673561, DOI: 10.1118/1.2940605.Peer-Reviewed Original ResearchConceptsEnergy resolutionTime-of-flight PET scannerRealistic Monte Carlo simulationsAcquisition energy windowSequential SPECTSystem energy resolutionGamma cameraEnergy windowThree-head cameraPET scannerEmission energyMonte Carlo simulationsDual-isotope SPECTSimultaneous SPECTBrain PETTwo-headed cameraCarlo simulationsProdromal disease stagesIdentical physiological conditionsSpatial resolutionDiscrimination taskStriatal sizeActivity concentrationsEarly identification of PDCamera headImproved activity estimation with MC‐JOSEM versus TEW‐JOSEM in SPECT
Ouyang J, Fakhri G, Moore S. Improved activity estimation with MC‐JOSEM versus TEW‐JOSEM in SPECT. Medical Physics 2008, 35: 2029-2040. PMID: 18561679, PMCID: PMC2673642, DOI: 10.1118/1.2907561.Peer-Reviewed Original ResearchMeSH KeywordsAlgorithmsEquipment DesignImage Processing, Computer-AssistedIndium RadioisotopesLungModels, StatisticalMonte Carlo MethodPhantoms, ImagingRadiotherapy Planning, Computer-AssistedReproducibility of ResultsScattering, RadiationSoftwareTomography, Emission-Computed, Single-PhotonTomography, X-Ray ComputedConceptsMC-JOSEMWater-filled torso phantomMC scatter estimationTriple-energy-windowActivity estimationIterative reconstruction algorithmTorso phantomPhantom studyBackground compartmentScatter estimationActivity distributionAverage relative biasPhantomReconstruction algorithmActivity concentrationsSynthetic projectionsSphere locationScattering
2007
Fast Monte Carlo based joint iterative reconstruction for simultaneous SPECT imaging
Ouyang J, Fakhri G, Moore S. Fast Monte Carlo based joint iterative reconstruction for simultaneous SPECT imaging. Medical Physics 2007, 34: 3263-3272. PMID: 17879789, DOI: 10.1118/1.2756601.Peer-Reviewed Original ResearchConceptsMC-JOSEMEnergy windowFast Monte CarloSignal-to-noise ratioScatter correction methodOrdered-subsets expectation-maximizationMonte CarloOrdered-subsets expectation-maximization algorithmIterative reconstruction algorithmPrimary photonsReconstruction algorithmPhoton transportSeptal penetrationDetector responseMC simulationsIterative reconstructionAttenuation distributionStandard OSEMPhotonsProjection dataPatient-specific activityDetectorReconstructed imagesScatteringEstimation of scattering
2002
Optimization of Ga‐67 imaging for detection and estimation tasks: Dependence of imaging performance on spectral acquisition parameters
Fakhri G, Moore S, Kijewski M. Optimization of Ga‐67 imaging for detection and estimation tasks: Dependence of imaging performance on spectral acquisition parameters. Medical Physics 2002, 29: 1859-1866. PMID: 12201433, DOI: 10.1118/1.1493214.Peer-Reviewed Original ResearchConceptsIdeal signal-to-noise ratioEnergy windowSignal-to-noise ratioMonte Carlo programDetection of spheresTorso phantomPhantom acquisitionsSphere of radiusEstimation taskPhantom dataLower-energyGa-67 imagingPhantomAcquisition parametersActivity concentrationsSpectral acquisition parametersGa-67Sphere sizeEnergyPhotopeakTumor imagingOptimal windowTaskClinicMonte