Week 6 A Chapter 29, 30 Computed Tomography 45

Week 6 A Chapter 29, 30 Computed Tomography 45 - Chapters...

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Chapters 29 & 30 Computed Tomography Godfrey Hounsfield of EMI, LTD demonstrated the principle for computed tomography in 1970. Alan Cormack developed the mathematics used to reconstruct the CT images. They shared the 1982 Nobel Prize for physics.
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Computed Tomography Computed Tomography is the most significant development in radiology in the past 40 years. MRI and Ultrasound are also significant developments but they do not use x-ray to produce the image. The x-ray tube spins around the patient.
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Basic C T Principles Instead of film, radiation detectors measure the radiation attenuation as the beam passes through the body. The detectors are connected to a computer that uses algorithms to process the data into useful images that are then recorded on film and viewed on a computer monitor.
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Basic C T Principles Conventional tomography has the image parallel to the long axis of the body. This is referred to as Axial Tomography.
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Basic C T Principles Computed Tomography has the x-ray tube move across the so the image is called a transverse image or one perpendicular to the long axis of the body.
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Computed Tomography Development Computed tomography has gone through five major design advancements since 1970 Each development improved both scan time and resolution or image quality. Scan time have been reduced from 5 minutes to 50 ms. First scanner used a very tightly collimated pencil beam.
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First Generation CT Scanner Pencil Beam Translate-Rotate Design 180 one degree images or translations. One or two detectors. 5 minutes scan time
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Second Generation CT Scanner Translate-Rotate Fan beam collimation so there is more scatter radiation. 5 to 30 detectors 10 degrees /translation 18 per scan. 30 second scan times Faster scan time
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Third Generation CT Scanner Rotate-Rotate Fan shaped beam of 30 to 60° for full patient coverage. Constant Source to detector distance due to curvilinear detector array.
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Third Generation CT Scanner If one detector fails, a ring artifact appears. 1 second scan times Superior reconstruction and resolution.
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Fourth Generation CT Scanner The tube rotates around a stationary ring of detectors. Fan beam Variable slice thickness with pre and post patient collimation.
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As many as 8000 detectors. 1 second scan time.
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This note was uploaded on 01/03/2012 for the course LC 232 taught by Professor Wilson during the Fall '08 term at Palmer Chiropractic.

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Week 6 A Chapter 29, 30 Computed Tomography 45 - Chapters...

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