CT basics and principles on 4 generations of CT scanners

1. CT BASICS AND PRINCIPLES
4 GENERATIONS OF CT SCANNERS

2. INVENTION OF CT
• CT WAS INVENTED IN 1972 BY GODFREY HOUNSFIELD AND WAS ONLY ABLE TO
PERFORM HEAD SCANS AT THAT TIME. CT SCANNERS BECAME AVAILABLE IN
THE MEDICAL MARKET IN THE 1980S. THIS TECHNOLOGY WAS FAIRLY NEW AT
THAT TIME, AND THERE WASN’T A HUGE DEMAND DUE TO THE LENGTH OF TIME
IT TOOK TO COMPLETE ONE HEAD SCAN ON A PATIENT.

3. GENERATION OF CT
SCANNERS

4. FIRST
GENERATION
• SINGLE DETECTOR
• PENCIL BEAM
• TRANSLATE-ROTATE TUBE
DETECTOR MOVEMENT
• SCAN TIMES TOOK ABOUT AN
HOUR OR MORE
• ONLY HEAD IMAGING WAS
POSSIBLE

5. SECOND
GENERATION
• MULTIPLE DETECTORS
• PENCIL BEAM
• STILL USED TRANSLATE-ROTATE
METHOD
• 1-2 MINUTES PER SLICE

6. THIRD
GENERATION
• MULTIPLE ROTATING DETECTORS
IN AN ARC
• FAN BEAM
• ROTATE-ROTATE TUBE DETECTOR
METHOD
• SCAN TIME OF 5 SECONDS
• ALL SCANNERS TODAY USE THIS
TECHNOLOGY

7. FOURTH
GENERATION
• STATIONARY DETECTORS
ARRANGED IN OUTER RING
• FAN BEAM
• ONLY THE TUBE ROTATES AROUND
THE PATIENT
• SCAN TIME IS A FEW SECONDS
• AVOIDS RING ARTIFACT

8. CT MACHINE COMPONENTS

9. • A CT UNIT IS DESIGNED WITH THE
FOLLOWING:
• GANTRY
• X-RAY TUBE
• DETECTOR ARRAY
• PATIENT TABLE (COUCH)
• CONTROL CONSOLE

10. CT ADVANCEMENTS

11. ADAPTIVE ITERATIVE RECONSTRUCTION
• THIS ADVANCEMENT HAS HELPED WITH DOSE REDUCTION TO THE PATIENTS
WITHOUT SACRIFICING IMAGE QUALITY BY NOISE REDUCTION TO IMAGES AND
REDUCING PATIENT DOSE BY 30-40%.
• COMMON ITERATIVE RECONSTRUCTION APPLICATIONS ARE:
1. ASIR (GE)
2. SAFIRE (SIEMENS)
3. AIDR 3D (TOSHIBA)
4. I-DOSE 4, IMR (PHILIPS)

12. REFERENCES AND ACKNOWLEDGEMENTS
CT IMAGES COURTESY OF:
• SLIDESHARE.NET
• HTTP://OPENI.NLM.NIH.GOV/