How CT MSCT works Imageaquisition How CT MSCT

How CT / MSCT works þ Imageaquisition:

How CT / MSCT works

Gerätetechnik: Generationen

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

Multirow Detector CT: þ Fixed Matrix Detektor

Multirow detector CT: þ Adaptive Array Detector

Multirow detector CT: þ Adaptive Array Detector

Single Detector CT Image Plane Detector Collimation increasing pitch ->by Slice broadening slice profile spiral. Wider interpolation Slice Sensitivity Profile (SSP) Provided by Siemens Erlangen

Single vs Multirow Single-slice scanner Pitch 1. 5 Pitch 2 Blurring Pitch 3 Pitch 5 Pitch 7 Volume Zoom SURE VIEW Provided by Siemens Erlangen

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

Resolution þ Isotropic Imaging No isotropic voxels isotropic voxel

Speed þ 64 slices /rotation þ Rotation times < 0. 5 s possible Dynamic studies

CT -- Benchmarking þ Geometric Resolution: - xy: z: 0. 3 -0. 5 mm 0. 6 mm þ Radiometric Resolution: - 12 bit data = 4096 shades of gray Hounsefield Units (HU): Minimum: n Zeropoint: n Fat: n Bones: n -1024 HU = air 0 HU = water -120 – 80 HU > 200 HU

CT -- Benchmarking þ Time Resolution: - Standard: - Cardiac Mode: 0. 5 s 0. 33 s þ Maximal Scanlength: - ca. 150 cm

Resolution Thickness 5. 0 mm Increment 2. 5 mm Thickness 2. 5 mm Increment 2. 0 mm Thickness 1. 25 mm Increment 1. 0 mm

Resolution Thickness 5. 0 mm Increment 2. 5 mm Thickness 1. 25 mm Increment 1. 0 mm Thickness 2. 5 mm Increment 2. 0 mm

CT – New: Dual Source CT

CT & Radiaten þ CT ~ 10% of Xray Examinations þ CT source of ~50% medical related radiation þ Incresases stochastic risk for cancer development: - 1 m. Sv Totalbody irradation risk for lethal cancer is increased by 5% - USA: maybe about 500 children dying a year by cancer due to CT