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Published byPolly Collins Modified over 10 years ago
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How CT / MSCT works Imageaquisition:
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How CT / MSCT works
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Gerätetechnik: Generationen
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Single vs Multirow 4 Slices +?? 1 Slice X-Ray tube
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Multirow Detector CT: Fixed Matrix Detektor
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Multirow detector CT: Adaptive Array Detector
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Multirow detector CT: Adaptive Array Detector
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Image Plane Detector Slice broadening by spiral interpolation Collimation Slice Sensitivity Profile (SSP) increasing pitch -> Wider slice profile Single Detector CT Provided by Siemens Erlangen
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Pitch 2 Pitch 3Pitch 5 Pitch 7 Pitch 1 Pitch 1.5 Blurring Single vs Multirow Single-slice scanner Volume Zoom SURE VIEW Provided by Siemens Erlangen
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„Magic Triangle“ Larger Volume Shorter Scan Time Isotropic Resolution Provided by Siemens Erlangen
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Resolution Isotropic Imaging isotropic voxel No isotropic voxels
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Speed 64 slices /rotation Rotation times < 0.5s possible Dynamic studies
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CT -- Benchmarking Geometric Resolution: -xy: 0.3-0.5mm -z: 0.6mm Radiometric Resolution: -12bit data = 4096 shades of gray -Hounsefield Units (HU): n Minimum:-1024 HU = air n Zeropoint:0 HU = water n Fat:-120 – 80 HU n Bones:> 200 HU
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CT -- Benchmarking Time Resolution: -Standard: 0.5s -Cardiac Mode: 0.33s Maximal Scanlength: -ca. 150cm
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Resolution Thickness 5.0mm Increment 2.5mm Thickness 2.5mm Increment 2.0mm Thickness 1.25mm Increment 1.0 mm
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Resolution Thickness 5.0mm Increment 2.5mm Thickness 2.5mm Increment 2.0mm Thickness 1.25mm Increment 1.0 mm
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CT – New: Dual Source CT
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CT & Radiaten CT ~ 10% of Xray Examinations CT source of ~50% medical related radiation Incresases stochastic risk for cancer development: -1mSv Totalbody irradation risk for lethal cancer is increased by 5% -USA: maybe about 500 children dying a year by cancer due to CT
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