Multirow detector

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z: 0.6mm. ☑ Radiometric Resolution: - 12bit data = 4096 shades of gray. - Hounsefield Units (HU): ▫ Minimum: -1024 HU = air. ▫ Zeropoint: 0 HU = water. ▫ Fat:.
How CT / MSCT works

How CT / MSCT works

; Imageaquisition: Imageaquisition:

Gerätetechnik: Generationen

Single vs Multirow X-Ray tube

1 Slice

Multirow Detector CT: ; Fixed Matrix Detektor

4 Slices +??

Multirow detector CT: ; Adaptive Array Detector

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Multirow detector CT:

Single Detector CT

; Adaptive Array Detector

Image Plane

increasing pitch ->by Slice broadening slice profile spiralWider interpolation

Detector

Collimation

Slice Sensitivity Profile (SSP) Provided by Siemens Erlangen

Single vs Multirow Single-slice scanner

Pitch 1

„Magic Triangle“ Pitch 2

Pitch 1.5

Blurring

Pitch 3

Larger Volume

Pitch 7

Pitch 5

Shorter Scan Time

Volume Zoom SURE VIEW

Isotropic Resolution

Provided by Siemens Erlangen

Resolution ; Isotropic Imaging

Provided by Siemens Erlangen

Speed ; 64 slices /rotation ; Rotation times < 0.5s possible Î Dynamic studies

No isotropic voxels

isotropic voxel

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CT -- Benchmarking ; Geometric Resolution: - xy: xy: - z:

0.30.3-0.5mm 0.6mm

; Radiometric Resolution: - 12bit data = 4096 shades of gray - Hounsefield Units (HU): Minimum: Zeropoint: Zeropoint: „ Fat: Fat: „ Bones: Bones: „ „

CT -- Benchmarking

-1024 HU = air 0 HU = water -120 – 80 HU > 200 HU

Resolution Thickness 5.0mm Increment 2.5mm

; Time Resolution: - Standard: - Cardiac Mode:

0.5s 0.33s

; Maximal Scanlength: Scanlength:

Thickness 2.5mm Increment 2.0mm Thickness 1.25mm Increment 1.0 mm

- ca. 150cm

Resolution Thickness 5.0mm Increment 2.5mm

Thickness 1.25mm Increment 1.0 mm

Thickness 2.5mm Increment 2.0mm

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CT – New: Dual Source CT

CT & Radiaten ; CT ~ 10% of Xray Examinations ; CT Æ source of ~50% medical related radiation ; Incresases stochastic risk for cancer development: development: - 1mSv Totalbody irradation Æ 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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