Acute Radiation SyndromeRadiation InjuriesRadiation Injuries, ExperimentalRadioactive Hazard ReleaseRadiodermatitisRadiation DosageDose-Response Relationship, RadiationSyndromeWhole-Body IrradiationRadiation-Protective AgentsRadiation PneumonitisProctitisRadiation ToleranceLethal Dose 50RadiometryRadiotherapyRadiation, IonizingGamma RaysMyocytes, CardiacRadiationRadiation ProtectionRadiation MonitoringCardiac OutputMice, Inbred C57BLHeartDown SyndromeMetabolic Syndrome XArrhythmias, CardiacCardiac Surgical ProceduresDeath, Sudden, CardiacRadiation OncologyTime FactorsTreatment Outcome