PhotonsTomography, Emission-Computed, Single-PhotonOrganotechnetium CompoundsTechnetium Tc 99m ExametazimeThallium RadioisotopesOximesRadiopharmaceuticalsTomography, Emission-ComputedTechnetiumIofetamineIodine RadioisotopesIodobenzenesCerebrovascular CirculationXenon RadioisotopesTechnetium Tc 99m SestamibiThalliumTechnetium Tc 99m PyrophosphatePhantoms, ImagingTropanesLightScattering, RadiationPositron-Emission TomographyElementary ParticlesBrainMonte Carlo MethodAmphetaminesRadiationDiagnostic ImagingRetinal Rod Photoreceptor CellsTomography, X-Ray ComputedCardiac-Gated Single-Photon Emission Computer-Assisted TomographyRadiometrySensitivity and SpecificityGamma CamerasRadiation DosageScintillation CountingRadioisotopesImage Processing, Computer-AssistedMagnetic Resonance ImagingAcetazolamideSpectrometry, GammaMyocardial Perfusion ImagingHeartVision, OcularOrganophosphorus CompoundsRhodopsinOrganometallic CompoundsMicroscopy, Fluorescence, MultiphotonCinanserinRadionuclide ImagingDopamine Plasma Membrane Transport ProteinsRadiusParticle AcceleratorsEquipment DesignIndium RadioisotopesPhotoreceptor CellsExercise TestTechnetium Tc 99m MedronateLight Signal TransductionMolecular ImagingImage EnhancementFrontal LobeThalamic DiseasesNight VisionTime FactorsPhotoreceptor Cells, InvertebrateCerebral RevascularizationModels, StructuralTechnology, RadiologicSpondylolysisReproducibility of ResultsNiobiumTissue SurvivalNortropanesMultimodal ImagingEquipment Failure AnalysisRadiotherapy Planning, Computer-AssistedRelative Biological EffectivenessRadioactive TracersRegional Blood FlowDark AdaptationTelluriumImage Interpretation, Computer-AssistedTechnetium Tc 99m Aggregated AlbuminRadiotherapy, High-EnergyBufo marinusDipyridamoleComputer SimulationMineralsDominance, CerebralWhole Body ImagingAlgorithmsRadiotherapy DosageTomography, OpticalProton TherapyMoyamoya DiseasePredictive Value of TestsSemiconductorsMyocardial IschemiaTemporal Lobe