1. Module A Computed Tomography Physics, Instrumentation, and Imaging

2. Disclaimer  This workforce solution was funded by a grant awarded under the President’s Community-Based Job Training Grants as implemented by the U.S. Department of Labor’s Employment and Training Administration. The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. This solution is copyrighted by the institution that created it. Internal use by an organization and/or personal use by an individual for non-commercial purposes is permissible. All other uses require the prior authorization of the copyright owner.

3. Historical development of Computed Tomography  Godfrey Newbold Hounsfield (1919 – 2004) 1979 Nobel Prize in Medicine 1979 Nobel Prize in Medicine Attenuation scale used in CT Attenuation scale used in CT  Allan McLeod (1924 – 1998) South African physicist South African physicist

4. Continue……. Timeline for the Historical development of Computed Tomography  1917 Johann Radon Austrian mathematician Austrian mathematician Work resulted in the mathematical basis for tomography Work resulted in the mathematical basis for tomography  1955 K.C. Tsien Introduced computers in Radiology Introduced computers in Radiology

5. Continue……. Timeline for the Historical development of Computed Tomography  1957 Allan McLeod Cormack First x-ray reconstruction using aluminum/wood phantom First x-ray reconstruction using aluminum/wood phantom  1967 Godfrey Newbold Hounsfield Developed first CT scanner Developed first CT scanner headhead

6. Continue……. Timeline for the Historical development of Computed Tomography  1970 Godfrey Newbold Hounsfield 1 st demonstration 1 st demonstration  1971 James Ambrose Atkinson-Morley’s Hospital Atkinson-Morley’s Hospital Installation of scanner Installation of scanner

7. Continue……. Timeline for the Historical development of Computed Tomography  1972 Hounsfield and Ambrose Atkison-Morley’s Hospital Atkison-Morley’s Hospital 1 st patient scanned 1 st patient scanned  1973 First scanners installed in US Mayo Clinic and Massachusetts General Hospital

8. Continue……. Timeline for the Historical development of Computed Tomography  1974 Robert S. Ledley and staff 1 st whole body scanner 1 st whole body scanner National Biomedical Research Foundation National Biomedical Research Foundation Georgetown University Medical Center Georgetown University Medical Center ACTA ACTA

9. Continue……. Timeline for the Historical development of Computed Tomography  1979 Cormack and Hounsfield Nobel Prize in Medicine Nobel Prize in Medicine Computerized Axial Tomography (CAT) Computerized Axial Tomography (CAT)

10. Continue……. Timeline for the Historical development of Computed Tomography  1989 Dr. Willi Kalender RSNA RSNA 1 st Spiral/Helical 1 st Spiral/Helical Volumetric Acquisition CT ScannersVolumetric Acquisition CT Scanners Siemens and Toshiba Siemens and Toshiba

11. Continue……. Timeline for the Historical development of Computed Tomography 1998 Multidetector-Row CT Scanner Additional milestones in the development of CT can be found in Chapter 1, Seeram, Computed Tomography 2 nd edition.

12. CT Generations  generation – refers to the geometry used in data acquisition. scanning geometry scanning geometry scanning motion scanning motion number of detectors number of detectors

13. CT  CT is defined as a three-step process 1. Data acquisition 2. Image reconstruction 3. Image display, manipulation, communication, archival, etc.

14. First Generation  EMI  Head only  Pencil (parallel) beam  1 – 2 detectors  Translate – Rotate mode  1 degree increments  > 60 second scan times per slice

15. Second Generation  Fan – Beam Geometry  Full body  Translate – Rotate mode  Multiple detectors (solid – state – sodium iodide)  20 – 60 second scan time per slice

16. Third Generation  GE Medical Systems  Rotate – Rotate mode Incorporation of slip ring technologyIncorporation of slip ring technology  Focused tube and detectors  Detector Array XenonXenon  5 – 8 second scan times

17. Fourth Generation  Rotate – Stationary Tube rotation/stationary detectorsTube rotation/stationary detectors  < 5 second scan time per rotation/slice

18. Fifth Generation  Emitron No moving x-ray or detector partsNo moving x-ray or detector parts  Electron Gun  Photons accelerated upwards through patient to DAS

19. Continue …… Fifth Generation  Also called Electron Beam CT  Heart imaging  1/20 th second scan time  Chapter 5 in Seeram’s text shows picture

20. Beam Geometry  Pencil/Parallel - 1 st generation  Fan - 2 nd generation and used today in conventional CT.  Cone - due to use of multiple detector rows  Total of 3 beam geometries used in CT today

21. continue …….. Beam Geometry Pencil (parallel) beam geometry – is defined by a set of parallel rays that generate a projection profile Fan beam geometry – defined by its divergent ray. Cone beam geometry – introduced as a result of the incorporation of multiple rows of detectors. The beam diverges in y axis and in the Z axis.