Introduction to Computed Tomography

SIEMENS Healthineers Computed Tomography Workshop on Imaging for the Future Laljith Sivankutty | HC APC IN SV March 2018 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 BME Education_Basic & Advanced X-rays SIEMENS Healthineers x-ray CASE2 MEDANTA MEDICITY ID: TEST CARDIAC SOMATOM Definition Flash Source 12/5/1929 CRANICALO Study 1 12/5/2009 10:06:53 AM 6 IMA Beam Motorized Table- 8 100 453 Detectors O 100 231 -catcher Placeholder Eye for notes and third party logos Placement can be varied in heights. If it is not needed, please delete this element. Unrestricted © Siemens Healthcare GmbH, 2016 HOOD05162002873707 Effective date: 05/06/2018 Unrestricted © Siemens Healthcare GmbH, 2016 SIEMENS Healthineers Computed tomography Also known as CAT scanning (Computed Axial Tomography) • TOMOS –slice or section • Graphia-describing HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Troy. I. We Rontgen • Wilhelm Conrad Roentgen, a German scientist, discovered x-rays • God Frey Hounsfield of EMI laboratories (British engineer) 1972 • Dr. James Ambrose a consultant Radiologist • Allan Cormack of Tufts University(South African American Physicist) • Johann Radon (Austrian mathematician)in 1917 - 2 or 3 dimensional objects could be reproduced fractional infinite set of all its projections. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT broke the barrier SIEMENS Healthineers • The origin of the CT scanner, as a viable imaging modality can be traced back to a period of time circa 1970 to 1973. • The first CT scanner installed for clinical trials took place in England in 1971. • During this period, Godfrey N. Hounsfield , an engineer for EMI Ltd. of England, with Dr. James Ambrose, a consultant Radiologist, successfully introduced the first practical CT scanner. • The mathematical basis for reconstructing a CT image already had been developed in 1917 by J. Radon ,an Austrian Mathematician, but was never intended for that purpose. • The equations were designed to map the internal structure of the earth using gravity measurements, a similar image reconstruction problem. Another gentlemen, Allan M. Cormack , a Nuclear Physicist - born in South Africa, sought to develop a set of mathematical equations to determine the exact amount of exposure that a patient receives during radiation therapy. • He quickly realized that his equations could also be used to mathematically calculate an image of absorption values. • He won a Nobel Laureate for his efforts in the early sixties, but never developed them into a practical device. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Principal of CT SIEMENS Healthineers Internal structure of an object can be reconstructed * x-roy source Detector from multiple projections of Head section the object First scan First clinical prototype EMI Second scon head scanner Atkinson Morley hospital –London. Third scon HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Attenuation Law SIEMENS Healthineers Intensity lo Internal structure of an object can be reconstructed from multiple projections of the object Io The attenuation law for X-ray is Io H1 I=Io e - µ d absorption coefficient u I Intensity of attenuated radiation, = 13 measured with the detector elements Io Intensity of unattenuated radiation, = I measured with the monitor element 1510 Intensity I µ absorption coefficient = H611 d = thickness of the object (voxel) 1512 H HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Algebraic Reconstruction Technique #3 (ART) S2 6 4 Error S3 S12 SA S11 SB S10 Sg Sg SE 0 0 4 3 3 2 Guess 1 X-ray detectors (b) 0 2 1 3 2 Guess 0 Guess 2 4 2 Update a guess based on 2 -2 1 Error data differences X-ray source HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Algebraic Re-construction Technique Healthineers • The horizontal sums are shown on the right and vertical sums are shown below the object • All the vertical and horizontal sums are added to produce a numerical reconstruction of the object • A gray scale value is then assigned to the numbers to produce an image • In x-ray CT, the ray projections are formed by scanning a thin cross section of the body with a narrow x-ray beam and measuring the transmitted radiation with a sensitive radiation detector. • The detector does not form the image • It adds up the energy of all transmitted photons • The numerical data from multiple ray sums are then computer processed to reconstruct an image HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 µ to CT number SIEMENS Healthineers The distribution of µ was originally measured. To get rid from the energy dependency of the linear attenuation coefficient, one takes the advantage that most of the coefficients for different tissues show the same relative dependence from energy. So a quotient of the 2 coefficients of 2 tissues should be energy independent in first order. Mr. Hounsfield had the great idea to scale the µ values relative to water by µtissue - µwater µwater CT number = X 1000 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT number SIEMENS Healthineers Water has CT number 0 tissues more dense than water have a positive CT number tissues less dense than water have a negative CT number. Water = 0 HU Bone = +1000 HU Air = 1000 HU - HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT number flexibility SIEMENS Healthineers • We can change the appearance of the image by varying the window width and level. • This can spread a small range of CT numbers over a larger range of grey scale values. • This makes it easy to detect very small changes in CT number. • The value of the CT number is not influenced by the appearance on the screen. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Image Display - Windowing SIEMENS Healthineers HU 3000 Blood Liver 60 Tumor Spleen Kidneys Heart Bone Pancreas 40 Adrenal Bladder Intestine Gland Water 0 Rule of thumb -100 The CT value of water is 0 and air -1000. The relative Mamma values of the other tissues are calculated relative to that of water. -200 Fat -900 Air Lung HU = Hounsfield Unit, also known as CT number -1000 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Windowing – see the Impact SIEMENS Healthineers The range of CT density values is defined from –1000 to +3000. The human eye can distinguish only 30 – 40 grey shades at best. Lung window Mediastinum-window So, the window settings must be in accordance with the structures to be visualized. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Windowing – see the Impact SIEMENS Healthineers Hounsfield- Units Grey scale display +3000 white Window Window width W centre C 0 black -1000 CT-Windowing Window width (W): the density range represented within the grey scale Window centre (C): the centre of the density range. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT components SIEMENS Healthineers SIEMENS System Overview SOMATOME HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT components SIEMENS Healthineers Spiral CT Scanner Gantry Network Source Table Computer Display Recording Parallel Control proces sor console Detectors Data acquisition system Storage units: Tapes, disks HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SOMATOM Definition AS Block Diagram 00001 SIEMENS Healthineers XGR X-Ray Generator Gantry Rotating Rotating 80, 100 .... kV DC DMS Raw data HV Tank XTA Data IRS disks Measurement Image XGR Box X-Ray Tube Assembly System Reconstruction System Filament TCO Control Tube Collimator Data Rotating Anode Control PDR 370V DC UMAR 400V AC Power Universal Distribution Master Rotating ICS IES Rotating 24V Image Control Image System Evaluation Rear SRS Slipring System Front "Acquisition System 'Workplace" "CT Workplace" KGS X-Ray Generator 2kVAC Stationary PDS Medium Power Distribution UMAS Voltage 400V Stationary 24V Universal Patient Transf. AC Data Base CAN Master Stationary 565V AC CAN 20 .... 70KHz Stop Report Stop Report Control DC Fast Link Box Main Fast Link Imaging Inverter Internal Ethernet AC Internal Ethernet 565V DC External Ethernet External Ethernet System DC CAN Open DC Link AC Gantry Gantry Cooling 400V AC Panels System PD Stop Patient Power Handling Distribution SCR FCT System Power Distribution Frequency Frequency Converter Rotation Converter Tilt Gantry Stationary LH Cabinet Mains HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 What does a CT look like SIEMENS Healthineers 1 2 1. X-ray tube assembly (XTA) 2. Expansion vessel for the cooling oil 15 3 3. Power supply (D573) for the DMS 2004 4., 5 Power Distribution Rotating (PDR) and Power Supply Rotating (PSR) 6. Rotation motor 14 7. Brush holder for ICVcomp (325VDC), Control Signals and the Stationary antenna for the measured data to be transmitted to the IRS 4 8. SRS Adapter Stationary, also known as SAS 9. Electronic Box with: D400 (main control), D115 (anode power board), 12 5 D470 (filament power board) 10. 9 Frequency converter rotation 11. Frequency converter tilt / vertical table 13 7 12. Power box with filters for the 565VDC (also known as UDC) and the main inverter 8 13. MAS, D301 (Master Stationary) ..... 10 6 14. PSS, D302 (Power Supply Stationary) 15. HV tank, HV transformer 11 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers X-ray tubes HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 X- ray tubes SIEMENS Healthineers • The design of an X-ray tube is very challenging. • An X-ray tube is extensively stressed, both electrically and thermally. • Electrically it has to withstand and isolate a voltage of up to 150kV in diagnostic X-ray and up to 300kV in therapy applications. • The tube must also be able to absorb and dissipate a large amount of heat. • Approximately 99% of all the energy supplied to the X-ray tube is converted into heat while only the leftover 1% is transformed into useful X-ray radiation. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Rotating tube SIEMENS Healthineers Stator Rotor on ball bearings Glass housing Cathode with filament UA Anode disc UA = Anode voltage Molybdenum shaft HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 X-ray tube basics SIEMENS Healthineers HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Straton Tube SIEMENS Healthineers The Tube Assembly -X-Ray Tube -Motor X-ray tube Oil pump -Motor Controller -Deflection Control -Oil pump Deflection control Voice Text The tube assembly consists of: X-ray tube Motor Motor controller Motor Motor controller Deflection control Oil pump HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Straton Principle SIEMENS Healthineers Anode -Uses rotating envelope tube principle -Is designed for high rotation speed -Evacuated tube envelope out of steel with shape like double cone e-beam -X-ray window is a closed ring and part of the housing -Ball bearings on both sides located outside the vacuum for smooth rotation x-rays -High heat dissipation through anode disk directly Cathode connected to the cooling oil. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 STRATON: SIEMENS Healthineers Most compact tube design to enable 0.30 s rotation time Image © of GE Image © of Philips Image © of TOSHIBA Healthcare Medical Systems Medical Systems STRATON Manufacturer A Manufacturer B Manufacturer C  150 ms temporal resolution due to compact design  Allows for excellent bariatric imaging with 100 kW power  Elimination of cooling delay due to direct anode cooling Competitive information provided is based on interpretation of available data and may require independent verification. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 CT components SIEMENS Healthineers Gantry Basics SIEMENS SOMATOME HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Gantry Rotation SIEMENS Healthineers Belt driven systems: Rotation Motor Emotion 2007 Ball Bearing Belt tension mechanism Guide wheel Measurement Field Motor Gear Belt wheel Rotate Motor with Parking Brake HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Gantry Rotation SIEMENS Healthineers Linear motor driven systems: Coils of the linear motor Permanent magnets Gantry Left Front View Stand Linear Metal rod Motor Slot Ring with Rotate 1440 angular slots and Converter 1 index slot Measurement Field Master Controll Unit Rotating and Tilt Controller Right Stand Light Barrier Safety Switch HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Angular Pulse & Index Pulse generation SIEMENS Healthineers Gantry Front View Measuring Rotation Encoder tape System - 2 LPS sensor GINO AMO Gmbh Light Barrier Board Front View one Indexpulse Slot IP AP OO Index sensor System - 1 Light Barrier Sensor S1 Board System - 3 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Slip Ring Systems SIEMENS Healthineers CT Image Carbon Brushes Silver Brushes Generator Components Processor stationary X20 Communication Stationary Part & Control of Gantry Signals measured data Electronics 0005 Sliprings Generator rotating Communication & Power Control Supply measured Signals data Capacitive Slip rings Contactless power transmission Detector Electronics DMS measured data Rotating Part of Gantry HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS CT components Healthineers Mains power supply 3 phases CT - unit Generator basics Parameter General Power Start and Stop supply safety and control The generator is used to supply the x-ray tube with energy for the x-ray generation. It also controls the filament current and the rotation of the anode. Generator CT-generators use inverter circuits, driven with frequencies in the range of 20KHz-100KHz approximately. Supply of X-ray tube Control of X-ray tube X-ray tube HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Main functions SIEMENS Healthineers CT - unit Power supplies Supply Filament Supply High voltage Supply Rotating anode Control system of the Generator Supply Filament Supply High voltage Supply Rotating anode Filament High voltage Rotating anode control control control High voltage Transformer D+ High voltage Stator supply Filament st HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Principle of inverters SIEMENS Healthineers Tube Rotating Anode Control I Tube 3 » AC Line Input Inverter High Voltage EMI Filter Transformer UDC DC DC f an = 4 - 300 Hz IGBT U Tube S = 10 - 20 kVA PWM AC 400 V 0 » UDC = 566 V U T = 40 - 150 kV IGBT: fres = 30 - 100 kHz I = 0,1 - 1000 mA T AC I F P Puls = 4 W - 100 kW P 60s £ 40 kW DC P 10min £ 10 kW IGBT f res = 20 - 100 kHz PH = 100 - 150 W HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 High Voltage Generator Overview SIEMENS Healthineers x-ray tube DC Link Main High voltage Inverter transformer main full wave capacitor bank DC AC full wave high voltage power rectifier inverter rectifier capacitors III + H TTT TTT + AA MN - 400V AC rectified 560 V DC 560 V AC high high voltage high capacitive constant DC voltage 50/60 Hz capacitive frequency frequency rectified smoothed 70kV….140kV smoothed 20….100kHz HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS High Voltage Tank Healthineers High voltage tank C R1 kV measurement resistors W2 R2 UAK mA measurement resistor m W3 R2 kV measurement resistors C High voltage R1 transformer filament transformer mAact -kVact + kVact Ufil HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Picture of HV Tank SIEMENS Healthineers dumping resistor smoothing capacity rectifier diodes transformer with ferrite coil compact dimensions - high power - (up to 80kW) HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS CT Components Healthineers + Tilt PPU Basics (Patient Positioning Unit) Gantry Feed Lift + Table + HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS PPU Tasks Healthineers General Task The main task of the PPU (Patient Positioning Unit) is to make the scanning of the diagnostically relevant range possible. A single scan delivers information only about one slice in the object (patient), in other words, about a volume of the object determined by the slice thickness and the scanned area. Feed In order to cover all diagnostic relevant range, several consecutive slices have to be scanned. This is done by feeding the tabletop in or out of the Gantry between the scans (in a sequence mode) or during the scan (in a spiral mode). Tilt In many examinations, the slices obtained have to be tilted in respect to the y-direction (lift direction). For example, to scan parallel to the cranial base, the Gantry is often tilted negatively, following the eye-ear line. To scan the discs of the back spine, the Gantry tilt has to follow the gap between the vertebral bodies, leading to positive or negative tilt angle, depending on the vertebral bodies to be scanned. Lift The table lift serves two purposes: First, allows the patient to get onto the tabletop conveniently and Second, adjusts the table height so that the volume under examination is centered in the scan field. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 PPU Basics SIEMENS Healthineers (Patient Positioning Unit) Lift several cutlines for typical anatomical areas Center of the head Center of the vertebra + Cutline for direct coronal cut HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS DAS Basics Healthineers Data Acquisition System (DAS) or Data Measurement System (DMS) .... HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Scan System SIEMENS Healthineers Fan beam scanner All SOMATOM´s are fan beam scanners with rotating Tube-Detector-System. The detector array consists of solid state detector elements. Detector elements The detector elements measure the radiation intensities during a scan. Detector DAS/DMS The electronic system that transfers the detector Slipring System element signals to the Image Reconstruction System is DMS data called Data Acquisition System DAS or Data Measurement system DMS. Image Reconstruction System HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 The Xenon Gas Detector SIEMENS Healthineers Front view of a gas detector Entrance window Pressure chamber X-ray quanta Kathode Anode Kathode Xe Xe Xe Xe Gas Detector Xe Xe Xe Xenon Xe Xe gas Xe Xe Xe Xe Insulation + 250 V H.V. power supply Idetector [nA] HOOD05162002873707 electric current processed in the DAS DAS BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 The Solid State Detector SIEMENS Healthineers Solid State Detector The solid state detector, consists of individual detector elements. Detector X-rays Each element consists of encapsulated TTTTT UFC (Ultra Fast Ceramic) scintillation crystals UFC scintillator fixed to the surface of light sensitive diodes. Light These elements are mounted on a printed circuit board. Photodiode Detector element X-ray quanta are absorbed in the crystal and generate Detector Electrical electronics photons of visible light. The number of photons generated signal in the crystal depends on the X-ray intensity and energy absorbed by the crystal. ASIC High-speed electronics The light quanta reach the photo diode Digital and generate an electric current in the range of 0...2µA. signal This current is then measured and processed in the CT detection principle - three step conversion Detector electronics. from X-rays into digital signals HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Module SIEMENS Healthineers Detector Module Anti-Scatter Collimator Plates X-ray Sensitive 16 Columns --- ______ UFC Elements 1 Column = 40 Segments Photodiodes FEE Board- -Detector Array Base Plate - Radiation Protection Carrier Detector module The detector elements and the corresponding electronics are organized as modules. The example shown represents a module of the SOMATOM Definition. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Signal Processing SIEMENS Healthineers Data Acquisition System Image Processor Comp FPA Gain Information; 2 Bit P S D S D A P D 14 BIT T D 16 BIT Detector Current to Integration Floating Point (= Programmable voltage S/P Element Amplifier Analog to Digital Gain) Converter P/S converter Amplifier Converter Converter The radiation detected by the The signal is The FPA or PGA is an amplifier The signal is The signal is serialized detector element is converted integrated. which selects its gain analogue to digital and sent to the into a current and afterwards automatically. The gain selection converted Image Reconstruction System to a voltage. 1, 8 or 64 depends on the input signal amplitude. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Overview Detectors Spirit Emotion Definition AS Definition AS+ Definition Definition Flash System A: 672 System A: 736 Channels 670 734 736 736 System B: 352 System B: 480 Emo 6: 6 20 no z-defl 64 no z-deflection 32 no z-deflection 64 no z-deflection Rows 2 Emo 16: 16 40 with z-defl 128 with z-deflection 64 with z-deflection 128 with z-deflection 64 with z-defl Physical Emo 6: 16 Row number 2 Emo 16: 24 32 64 40 64 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Examples for Detectors Detector Specs SIEMENS Emotion 6 16 Slices per Rotation Detector Material: UFC 4 x 1,2 mm 6 Slices per Rotation 1472 Channels per slice 17,5 Ip/cm @ 0% MTF Detector Material:UFC d Tomography. hinking Ahead. Z coverage = 18mm 16 × 0,6 mm 736 Elements 16 x 736 = 11776 Elements 2500 Projections / s 24 detector rows 1472 Channels per slice 4 x 1,2 mm 17,5 lp/cm @ 0% MTF Collimation:: Emotion 16 (2007) 6 × 0,5mm (High Res.) Emotion 16 (2003) 6 x 1,0mm 6 x 2,0mm 16 channels 6 × 3,0mm 2 * 5.0 mm Spiral Slice widths: 2 1 1 8 x 0,5mm 1 1 2 0,63mm, 0,75mm (High Res) 3mm 3mm 1; 1,25; 2; 3; 5; 6; 8; 10 16 Elements / 18mm NEW: 2.5mm+4mm X35 ISX HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Industry`s highest isotropic resolution of 0.33 SIEMENS Healthineers mm and fast rotation speed of 0.33 s SHADE SOMATOM Sensation 64-slice configuration Spatial resolution 0.33 STRATON mm z-Sharp and 0.3 mm rotation time 0.33 s 0.6 mm and 10s for 437 mm coverage 120 kV 180 effective mAs B 97 100 02 HOOD05162002873707 BME Education_Computed Tomography Courtesy of German Heart Center / Munich, Germany Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 2 Slice CT SIEMENS Healthineers 2x5.0mm 2x1 mm 2x1.5mm 2x2.5mm 2x4mm 2x5mm HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 6 Slice SIEMENS Healthineers 1x3mm 1x2mm 1x2mm 1x3mm 2x1mm 8x0.5mm 2x1mm 6x0.5mm 6x1mm Detail Mode 6x2mm Routine Mode 6x3mm Volume Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 16 Slice CT SIEMENS Healthineers 4x1.2mm 16x0.6mm 4x1.2mm Detail Mode 16x0.6 mm 16x1.2 mm HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 10 Slice CT SIEMENS Healthineers 4x1.5mm 16x0.75mm 4x1.5mm 10x0.75mm Detail Mode 8x1.5mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 16 Slice CT SIEMENS Healthineers 4x1.5mm 16x0.75mm 4x1.5mm 16x0.75mm Detail Mode 16x1.5mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 40 Slice CT SIEMENS Healthineers 4x1.2mm 32x0.6mm 4x1.2mm 20x0.6mm Detail Mode 24x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 20 Slice CT SIEMENS Healthineers 4x1.2mm 32x0.6mm 4x1.2mm 20x0.6mm Detail Mode 24x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration 64 Slice CT SIEMENS Healthineers 4x1.2mm 32x0.6mm 4x1.2mm 32 (64)x0.6mm Detail Mode 24x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration SIEMENS Healthineers 128 Slice 64x0.6mm 64 (128) x0.6mm Detail Mode 32x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration SIEMENS Healthineers 64 Slice 32x0.6mm 32 (64) x0.6mm Detail Mode 16x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration SIEMENS Healthineers 40 Slice 32x0.6mm 20 (40) x0.6mm Detail Mode 16x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Detector Configuration SIEMENS Healthineers 20 Slice 32x0.6mm 20 x0.6mm (no z-sharp) Detail Mode 16x1.2mm Routine Mode HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Generations of CT scanners SIEMENS Healthineers 1 st Generation 2 nd Generation 3 rd Generation 4 th Generation Translate than rotate with Translate than rotate with Continuing rotation of Tube and Continuing rotation of Tube with pencil beam. small fan beam. detector with fan beam. fan beam, detector ring fixed. High patient dose Faster Acq. Time Actual systems! Complex and expensive. Long Acq. Time. ~20sec. Per slice Min. 1min per slice HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers First Generation One detector Translation-rotation Parallel-beam HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Second Generation Multiple detectors Translation-rotation Small fan-beam HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Third Generation Multiple detectors Translation-rotation Large fan-beam HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Fourth Generation Detector ring Source-rotation Large fan-beam HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Data Acquisition System SIEMENS Healthineers (DAS) Deflection Detectors Coil Gun Couch Target Rings HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Spiral/Helical Scanning Sim ultaneous ·Source rotation · Table translation ·Data acquisition HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Block diagram Image Calculation SIEMENS Healthineers DMS Data Preprocessing Raw Data Convolution Back projection HU Matrix HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Block diagram Image Calculation SIEMENS Healthineers • The Data Measurement System supplies the serial scan data via a fiber optic cable to the receiver module inside the Image Reconstruction System. • The Image Reconstruction System calculates the image in 3 steps: • Preprocessing • Convolution • Back projection • The result of the image calculation is a 512 x 512 HU matrix. It is sent into the patient data base inside the Image Control System. • After Preprocessing the data are called Raw Data. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Preprocessing steps SIEMENS Healthineers Preprocessing steps of System 1. Process Steps Save Raw Data MoniNorm M ChanCorr Transfer Raw Data M DefChan AirCal Spacecorr CrossScatt SliceNom M BeamHard M Reconstruction InvLog M WedgeCon M WaterScaling Use MBH Preprocessing steps of System 2. Process Steps Save Raw Data M All M MoniNorm M ChanCorr Transfer Raw Data Acq (FPA) M AirCal Spacecorr M Offset M SliceNorm M LostFan M Reconstruction (BlkScale) Decode M BeamHard M DefChan Log M WedgeCorr WaterScaling Use MBH HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Purpose of Preprocessing SIEMENS Healthineers • Preprocessing has to compensate the measured data for : • Electrical drifts • Dose variations • X-ray attenuation law • Beam hardening • Mechanical deviations of the scanning system HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 PGA decoding PGA (FPA)-ADC SIEMENS Healthineers A Integrator Signal PGA (FPA) 1/8/64 D FPA-Bits A=1 O O 14 Bit A=8 0 1 14 Bit A=64 1 O 14 Bit DMS 15 SMI 14 Bit 0 0 0 0 0 0 19 O 0 0 14 Bit 0 0 0 O 0 0 0 14 Bit O O O HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 PGA decoding SIEMENS Healthineers The signals from the detector have a very wide range. To cover the whole dynamic range of input signals, a „Programmable Gain Amplifier“ (PGA) is used (also called FPA, floating point amplifier). PGA: The PPA is an amplifier which selects its gain automatically. The selected gain can be 1, 8 or 64. The gain used is indicated by the two bits called `PGA Bits´. PGA Decoding: In order to calculate the actual attenuation, the PGA bits are decoded in the SMI. This is done in the preprocessing step „PGA decoding“ (also called „FPA decoding“). Amplification 64:If the signal from the detector was very small (i.e., high absorption in the scan field), the amplifier will have used a factor of 64. The resulting data in the SMI will be the 14 bit from the ADC, preceded by many zeroes, in other words, a rather small numerical value. Amplification 8:If the amplification was 8, the signal was larger. In the SMI, the 14 bit are shifted 3 bit to the left, equaling a multiplication by 8, or a larger numerical value. Amplification 1:If the signal from the detector was large (e.g., only air in the scan field), the PGA will have used an amplification of 1. This will result in a large number in the SMI, because the 14 bit are shifted 6 bit to the left, equaling a multiplication by 64 or a rather large numerical value. Note: For new systems we use a 20bit A/D conversion HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Floating-Point A/D - Conversion SIEMENS Healthineers Floating-Point A/D – Conversion Amplification The amplification factor is selected according Output [bit] factor 64 to the input voltage. Amplification 214 factor 1 Amplification Factor 64 0….610µV factor 8 Factor 8 611….1V Factor 1 >1V The resulting resolution can be calculated as follows: -- Resolution without FPA: - For 16 bit resolution: 20 -- 10V÷2 16 ≈ 152µV 1 2 3 4 5 6 7 8 9 O Voit - 10V Resolution with FPA: 610µV ÷64 is app. 9.5µV Dynamic Range: HOOD05162002873707 9.5µV÷10V is app. 1÷1.000.000 (resulting dynamic range) BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Offset correction SIEMENS Healthineers signal + Falsified average- True average = 0 signal time ADC can't measure negative signal components True average + Offset Offset O time After adding an offset voltage in the DMS, signals can be measured properly. This Offset must be subtracted from the signal in the SMI. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Offset correction SIEMENS Healthineers Offset voltage : In the DMS, ADCs are used that can't measure negative voltages. This would falsify the measurement, if very small detector signals ( = high absorptions ) have to be measured. To avoid this, in the DMS an offset voltage is added to the signal, the signal is measured, and in the SMI the offset signal subtracted again, leaving the true value only. Offsets are channel specific: Because the analogue offset may be slightly different for each ADC, or, to be precise, even for every integrator board channel, the actual offset has to be measured prior to the scan for every channel. Offset measurement: With each scan start, a measurement is started without X-ray and the data are stored in the image processor as offset data. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Logarithmisation SIEMENS Healthineers Attenuation 1= lo . e - Hd Intensity lo Law ud =In lo - In | = Attenuation A absorption A= In lo - In l coefficient u SMI In 1 In 1 Intensity I HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Logarithmation SIEMENS Healthineers Logarithmation is done because the attenuation of an X-ray beam follows an exponential law. I = Io e - µ d I……..Intensity measured with object Io……Intensity measured without object (air scan) The calculation of the object attenuation „A“ requires the calculation of the logarithmic value of the measured radiation intensities I and I 0: A= ln I 0 – ln I The logarithmation is done using a table of log values. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Normalization SIEMENS Healthineers X-Ray Tube Monitor Detector IM Doserate lo Object Detector 1512 Time Monitorvalue Time Corrected lo Time HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Normalization SIEMENS Healthineers During the measurement, the intensity Io of the X-ray beam varies (exaggerated in the picture for clear visualization). Monitor value: A monitor element measures the untenanted radiation as a reference value. This value is called “Monitor value”. At newer systems the monitor value is supplied by the phi-PSD element inside the collimator box. Normalization : During the preprocessing step “Normalization” , this monitor value IM is subtracted from each channel value I: In 1/I – In 1/IM HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Calibration SIEMENS Healthineers X-Ray Tube Detector 512 Any channel Output (mV) Correction values from last calibration and from tune- up - Input (dose) HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Calibration SIEMENS Healthineers • The measurement of the untenanted intensity values are made by an air scan with the checkup every morning. • Each detector has a different sensitivity. This can vary with the time and must be compensated. • The channel specific sensitivity differences are compensated by calibration. • The measured values from the scan with an object are subtracted from the air values. • During the last tune up, the differences of each combination of kV, mA, slice width etc. were measured, • so that only the base calibration is required on a daily basis. • The other calibration tables for different settings of kV, mA etc are calculated from the difference tables and the base calibration table. • HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Channel Correction SIEMENS Healthineers X-Ray Tube Object Detector 512 Attenuation "A" Beam hardening COS- Channel Coefficient Water correction Correction Correction Scaling Table Corrected Attenuation 'Ac' HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Channel Correction SIEMENS Healthineers • Technically, the pre- processing step „channel correction“ is a multiplication of each channel value with a correction factor. • Because a correction is needed for many reasons, several individual tune- up tables contribute to the resulting one factor in the pre- processing. • Channel correction includes: • Beam hardening correction - Cosine correction - Channel coefficient correction and - Water scaling - HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Beam – Hardening Correction SIEMENS Healthineers A 100 % Measured Softer Harder Attenuation Beamhardening Energy Correction ( kev ) 1st object, 50% absorption Corrected Attenuation 50% d Beamhardening Correction Energy ( kev ) 2nd (identical) object 25 % more than the "expected" 25% Energy ( kev ) Beamhardening Effect HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Beam – Hardening Correction SIEMENS Healthineers X-ray spectrum: • Tubes generate polychromatic radiation, i.e. different wavelength are contained in the spectrum. • Just as with visible light, the higher energies or shorter wavelength can penetrate the objects better than the softer part of the spectrum. • Beam hardening causes in homogenous objects (e.g. a water phantom) an in homogeneity. That means, the CT values in the center are different from the outer values. • The correction is done by taking data of a reference phantom (mostly a 20cm water phantom) and the correction data are used during pre- processing step „beam hardening“ for the correction of the scan data. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Cosine - Correction SIEMENS Healthineers Object d 512 A ................ Difference ................ Measured Attenuation 512 cosine A Corrected Attenuation 512 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Cosine - Correction SIEMENS Healthineers Measured attenuation: The Cosine – Correction considers that the x-ray beam is fan shaped. The length of the path of the radiation through an object depends on the angle alpha between the central beam and any other beam. Corrected attenuation: The correction of the different channel outputs is done by using the cosine function. For each channel, the table contains the cosine-value of the corresponding fan angle „alpha“. The measured attenuation is multiplied with the table values. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Channel Coefficient Correction SIEMENS Healthineers Object d Detector - - 512 Any channel A ." -". Measurement Errors -- -- d Channel Coefficient Tables A Measured Attenuation Channel Coefficient Values Corrected Attenuation HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Channel Coefficient Correction SIEMENS Healthineers Just like „Calibration“, the pre-processing step ´Channel Correction´ compensates for sensitivity differences of the detector. The difference is that the Channel correction compensates for nonlinearities in the area of attenuated radiation, i.e., with an object is in the scan field. Parameter: The parameters which determine the detected radiation energy are: Tube Voltage Slice Thickness Object Attenuation (Head or body) Correction tables: The sensitivity compensation is done with values which are determined during the tune-up. HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Water Scaling SIEMENS Healthineers X-Ray Tube HU Water Phantom ............. CT-Value Scale 3072 Detector ...... 512 HU value of water = 0 HU Water Scaling Factor Attenuation of Water - 1024 HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Water Scaling SIEMENS Healthineers The water scaling sets CT value of water to 0 HU. This factor depends on the energy received by the detector; the parameters for the scaling are: tube voltage - tube current - slice thickness - HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Simple back-projection w/o and with convolution SIEMENS Healthineers without convolution with convolution 0 projections 1 projection 3 projections No projections N. projections CT value profile HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 Example Image Recostruction System SIEMENS Healthineers SOMATOM Definition AS Image Reconstruction System mx2c Overview C0001 VV7 L. N, PE X105 W33 PE PE133 Power Distribution Cabinet Gantry Internal Ethernet VV57 W61 Image X3 Control V65 X4 Ethernet X40 UMAS X5 Switch internal System X1 Fast Link W70 X10 PE IRS Power T X4 KVM-over-IP PCI -X Bus Distribution L, N, PE Mouse PCe Bus PCe Bus 5VDC Keyboard Video X3 USB- VGA X2 PSM 3 Standard Interfaces 12V PBX-10 CBR 3D. DIRex PSM 2 Back Mainboard 12V projector Back Dual Input Receiver PSM 1 3D-ASA projector D27 Standard Interfaces 12V D6 D10/D11 A (DL1) B (DL2) X1.1 n.c. X1.1 n.c. 5VDC 12V Image n.u. n. u. 12VDC SATA EIDE-Bus Reconstruction Test 12V System mx2c output 5VDC 5VDC 12V 12VDC HD 12VDC DVD DataStream_A ₩98 System System X395 SATA 12Y_ ₩395 12V Sliprings ₩598 DMS 5VDC. 12VDC HD HD HD HD HD Harddisk RAID FODL1 2 3 4 5 Raw data Storage DASCon HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SOMATOM Definition AS | Block Diagram 00001 SIEMENS Healthineers XGR X-Ray Generator Gantry Rotating Rotating 80, 100 .... kV DC HV Tank XTA DMS Raw data Data IRS disks Measurement Image XGR Box X-Ray Tube Assembly System Reconstruction System Filament TCO Control Tube Collimator Data Rotating Anode Control E PDR 370V DC UMAR 400V AC Power Universal Distribution Master Rotating ICS IES Rotating 24V Image Control Image System Evaluation Rear SRS Slipring System Front "Acquisition System Workplace" "CT Workplace" XGS X-Ray Generator 2kVAC Stationary PDS Medium Power Distribution Voltage 400V Stationary UMAS 24V Universal Patient Transf. AC Data Base CAN Master Stationary 565V AC CAN 20 .... 70KHz Stop Report Stop Report Control DC Fast Link Box Main Fast Link Imaging Inverter Internal Ethernet AC Internal Ethernet External Ethernet System 565V DC External Ethernet DC CAN Open DC Link AC Gantry Gantry 400V AC Panels Cooling System PD Stop Patient Power Handling Distribution SCR FCT System Power Distribution Frequency Frequency Converter Rotation Converter Tilt Gantry Stationary HI Cabinet Mains HOOD05162002873707 BME Education_Computed Tomography Effective date: 05/06/2018 Page ‹#› | Restricted © Siemens Healthcare GmbH, 2017 SIEMENS Healthineers Thank you for your Attention HOOD05162002873707 Effective date: 05/06/2018 Unrestricted © Siemens Healthcare GmbH, 2017