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How CT / MSCT works  Imageaquisition:. How CT / MSCT works.

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Presentation on theme: "How CT / MSCT works  Imageaquisition:. How CT / MSCT works."— Presentation transcript:

1 How CT / MSCT works  Imageaquisition:

2 How CT / MSCT works

3 Gerätetechnik: Generationen

4 Single vs Multirow 4 Slices +?? 1 Slice X-Ray tube

5 Multirow Detector CT:  Fixed Matrix Detektor

6 Multirow detector CT:  Adaptive Array Detector

7 Multirow detector CT:  Adaptive Array Detector

8 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

9 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

10 „Magic Triangle“ Larger Volume Shorter Scan Time Isotropic Resolution Provided by Siemens Erlangen

11 Resolution  Isotropic Imaging isotropic voxel No isotropic voxels

12 Speed  64 slices /rotation  Rotation times < 0.5s possible  Dynamic studies

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14 CT -- Benchmarking  Geometric Resolution: -xy: mm -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

15 CT -- Benchmarking  Time Resolution: -Standard: 0.5s -Cardiac Mode: 0.33s  Maximal Scanlength: -ca. 150cm

16 Resolution Thickness 5.0mm Increment 2.5mm Thickness 2.5mm Increment 2.0mm Thickness 1.25mm Increment 1.0 mm

17 Resolution Thickness 5.0mm Increment 2.5mm Thickness 2.5mm Increment 2.0mm Thickness 1.25mm Increment 1.0 mm

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19 CT – New: Dual Source CT

20 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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