2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 1 Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund *** **Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg. PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY sote_logo.jpg dk_fejlec.gif INFOBLOKK 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 2 Peter Pazmany Catholic University Faculty of Information Technology BIOMEDICAL IMAGING COMPUTED TOMOGRAPHY (CT) www.itk.ppke.hu (Orvosbiológiai képalkotás ) (Számítógépes tomográfia) GYÖRGY ERŐSS 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 3 Tomography Tomographyisimagingbysectionsorsectioning.Adeviceusedintomographyiscalledatomograph,whiletheimageproducedisatomogram.Themethodisusedinmedicine,archaeology,biology,geology,materialsscienceandothersciences.Inmostcasesitisbasedonthemathematicalprocedurecalledtomographicreconstruction.Therearemanydifferenttypesoftomography,aslisted:(NotethattheGreekwordtomosconveysthemeaningof"asection"or"acutting").Atomographyofseveralsectionsofthebodyisknownasapolytomography. Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 4 -asectionalimagethroughabodybymovinganX-raysourceandthefilminoppositedirectionsduringtheexposure -structuresinthefocalplaneappearsharper,whilestructuresinotherplanesappearblurred -bymodifyingthedirectionandextentofthemovement,operatorscanselectdifferentfocalplaneswhichcontainthestructuresofinterest ConventionalmedicalX-raytomography: Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 5 Conventional X-RaysComputerized Tomography Single projection image Axial image obtained from hundreds of projections .superimposed tissues Std. Resolution: 500 -1200projections High Resolution: 900 -2400 projections Tissue superposition only withinone slice thickness Measured physical entity: tissue densityInformation provided: organ structure CT density unit:1 Hounsfield Unit (HU) = 0.1% density of waterAir (zero density) = -1000 HU; Water = 0 HU Precision & validity of CT densities: Relative only; CT uses a polychromatic X-ray beam CT densities are voltage, object size & real density dependent Precise density measurements in CT require dedicatedcalibrations Computed tomography (CT) Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 6 CT Spectrum of densities bild1_9 <> eq4 Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 7 Reconstruction: backprojection => see article u y f(x, y) s . x [R f ](s, .) g(s, .)s Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 8 schaller_05 CT generations 1967 => 1972 1975 1976 4th generation: continuous detector ring Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 9 3rd generation CT scanners: • Axial scan only: „back&force” continuous • Helical scan:single slice dual slice (1992) multi-slice: up to 16 slices >16 slices # of detectorrows # of independentdata Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 10 ReconSp Spiral scanner SpGrlSF Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 11 Factors Determining Low Contrast Resolution • Detection System: type, design & efficiency» (Xenon or Solid-state) • X-ray beam filtration: optimal design for beam hardness • Scan Voltage: lower voltage provides improved low contrast resolution • Signal-to-Noise Ratio: – Proportional to Dose (mAs) – Improved when post-collimation is available, protecting the detectors from scattered radiation Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 12 Factors Determining Spatial Resolution • Design Parameters:– Detector aperture width (Aeff) at isocenter – Focal spot size (s) – Sampling density (2001) Filtered back-projection into a 3D matrix (Voxels) Each Voxelreconstructed individually. Only views passing through each individual voxelduring the acquisition process are back-projected into it Pencil beam => Fan beam => Cone beam Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 15 CobraDrw Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 16 Huriblung_zis8_hpfdk_pfilter_trian Huriblung_zis4_hpfdk_pfilter_trian huriblung_2DBP_8p25 Huriblung_2DBP_zis3p75 4 mm from mid -plane 8 mm from mid -plane Cone Beam Recon Fan Beam Recon Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 17 Pitch=2 Pitch=1.5 Pitch=1 Pitch=4 Speed vs. information => Pitch Biomedical Imaging: Computed Tomography (CT) The pitchis the ratio of the patient table increment to the total nominal beam width for the CT scan. The pitch factor relates the volume coverage speed to the thinnest sections that can be reconstructed. In spiral CT, dose is always inversely proportional to pitch. 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 18 Multi-Slice RSVP Advantages Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 19 Multi-Slice RSVP Advantages Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 20 Multi-Slice Resolution Advantage Quad-Slice Dual-Slice Single-Slice RSVPRes 4x2.5mm; 2.5cm/sec 2x5.0mm; 2.5cm/sec 10mm; 2.5cm/sec 72 cm coverage; 28 sec; 120kV / 130 mAs Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 21 RSVPVol 72 cm coverage 36 cm coverage 18 cm coverage 3.2 mm Eff. ST; 28 sec; 120kV / 130mAs Multi-Slice VolumeAdvantage Quad-Slice Dual-Slice Single-Slice Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 22 DosePath Patient Dose Path Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 23 QDO Quarter detector shift Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 24 DFSAnode DoublesRay Density and thus Doubles Spatial Resolutionwith the same numberof detectors Dynamic FocalSpot Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 25 DefinitionConcept Towards „dual energy” solution Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 26 SOTE_RadClin_CT_1 CT examination room with a 16 slice system Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 27 „Anatomy” of a CT Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 28 CER 2 CER 1 SPINE 2 CAR 1 Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 29 Reconstructed 3D images: virtual colonoscopy Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 30 Reconstructed cardiac and vessel images Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 31 Functional CT images Biomedical Imaging: Computed Tomography (CT) Functional CT is a imaging method, made possible by fast CT scanners and improved data analysis techniques, to investigate the physiological basis of function and disease in the human body. 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 32 Future of CTs: -more detector row (128/256/340) / higher coverage => volume CT => specialized CT-s -detector efficiency / lower dose -multi-energy detectors Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 33 TargetTissueRegulatoryLimit WholeBody12.5 mSv/quarterExtremities18,750 mrem/quarter18.75 mSv/quarterSkin/OtherOrgans75 mSv/quarterFetus5 mSv/gestationalperiod CommonRadiationExposures OneCoasttoCoastFlight0.03 mSvChestRadiograph, Anterior/Posteriorview0.15 -0.25 mSv/viewChestRadiograph, Lateralview0.5 –0.65 mSv/viewScreeningMammography(Film/ScreenCombination)0.6 –1.35 mSv/view SignificantRadiationExposures(AcuteDoses) TemporaryBloodCountChange(WholeBody orTorso)250 mSvPermanentSterilizationinMen(Gonads)1000 mSvPermanentSterilizationinWomen(Gonads)2500 mSvSkinErythema(Burn)3000 mSvCataractFormation6000 mSv Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 34 Common units and Conversions: graph • 1 rad = 0.01 Gy*or*100 rads = 1 Gy • 1 rem = 0.01 Sv*or*1 Sv = 100 rem •1 rem = 1000 mrem *or* 1 mrem = 0.001 rem • For x-rays:1 rad = 1 rem (QF = 1) Biomedical Imaging: Computed Tomography (CT) 2011.10.04.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 35 •Prospective Gating Prospective Gating automatically triggers axial multislice scan acquisitions using patient information from the ECG monitor. SpiralRetrospectiveTaggingallowstheCTsystemtoacquireavolumeofdatawhilethepatient'sECGisrecorded. Theacquireddatais"tagged"andreconstructedretrospectivelyatanydesiredphaseofthecardiaccycle. • Retrospective Tagging Biomedical Imaging: Computed Tomography (CT)