Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Computed Tomography - Medical Imaging - Lecture Slides, Slides of Medical Genetics

This is the Lecture Slides of Medical Imaging of Time Domain, Response of the System, Simpler Relationship, Frequency Domain, Graphical Interpretation of Convolution Integral, Input and Output, Graphical Interpretation, Convolution Integral etc. Key important points are: Computed Tomography, Low Soft Tissue Contrast, Not Quantitative, Solves These Problems, Reconstruction From Projections, Other Modalities, Computed Tomography, Clinical Use, Many Clinical, Cancer Diagnosis

Typology: Slides

2012/2013

Uploaded on 02/13/2013

banani
banani 🇮🇳

4.3

(3)

91 documents

1 / 93

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Computed Tomography
Docsity.com
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b
pf1c
pf1d
pf1e
pf1f
pf20
pf21
pf22
pf23
pf24
pf25
pf26
pf27
pf28
pf29
pf2a
pf2b
pf2c
pf2d
pf2e
pf2f
pf30
pf31
pf32
pf33
pf34
pf35
pf36
pf37
pf38
pf39
pf3a
pf3b
pf3c
pf3d
pf3e
pf3f
pf40
pf41
pf42
pf43
pf44
pf45
pf46
pf47
pf48
pf49
pf4a
pf4b
pf4c
pf4d
pf4e
pf4f
pf50
pf51
pf52
pf53
pf54
pf55
pf56
pf57
pf58
pf59
pf5a
pf5b
pf5c
pf5d

Partial preview of the text

Download Computed Tomography - Medical Imaging - Lecture Slides and more Slides Medical Genetics in PDF only on Docsity!

Computed Tomography

  • Radiography: 3 problems
    • 3D collapsed to 2D
    • Low soft-tissue contrast
    • Not quantitative
  • The mathematics behind X-Ray CT (reconstruction from projections) applies to other modalities as well (PET, Spect, etc).
  • Computed tomography (CT) is in its fourth decade of clinical use and has proved valuable as a diagnostic tool for many clinical applications, from cancer diagnosis trauma to osteoporosis screening. - CT was the first imaging modality that made possible to probe the inner depths of the body, slice by slice.
  • Because of the long acquisition times required for the early scanners and the constraints of cardiac and respiratory motion, it was originally thought that CT would be practical only for head scans.
  • CT is one of the many technologies that was made possible by the invention of computer. - The clinical potential of CT became obvious during its early clinical use, and the excitement forever solidified the role of computers in medical imaging.
  • The invention of the CT scanner earned Godfrey Hounsfield of Britain and Allan Cormack of the United States the Nobel Prize for Medicine in 1979. - CT scanner technology today is used not only in medicine but in many other industrial applications, such as nondestructive testing and soil core analysis.

BASIC PRINCIPLES

  • The mathematical principles of CT were first developed by Radon in 1917. - Radon’s treatise proved that an image of an unknown object could be produced if one had an infinite number of projections through the object.
  • With a conventional radiograph of the patient’s anatomy, information with respect to the dimension parallel in the x-ray beam is lost. - This limitation can be overcome, at least for obvious structures, by acquiring both a posteroanterior (PA) projection and a lateral projection of the patient.

For example, the PA chest image yields information concerning height and width, integrated along the depth of the patient, and the lateral projection provides information about the height and depth of the patient integrated over the width dimension.

  • For objects that can be identified in both images, such as a pulmonary nodule on PA and lateral chest radiographs, the two films provide valuable location informarion. - For more complex or subtle pathology, however, the two projections are not sufficient.
  • Imagine that instead of just two projections, a series of 360 radiographs were acquired at 1- degree angular intervals around the patient’s thoracic cavity. - Such a set of images provides essentially the same data as a thoracic CT scan.
  • The tomographic image is a picture of a slab of the parient’s anatomy. - The 2D CT image corresponds to a 3D section of the patient, so that even with CT, three dimensions are compressed into two. - However, unlike the case with plain film imaging, the CT slice-thickness is very thin (1 to 10 mm) and is approximately uniform.
  • The 2D array of pixels (short for picture elements) in the CT image corresponds to an equal number of 3D voxels (volume elements) in the patient. - Voxels have the same in-plane dimensions as pixels, bur they also include the slice thickness dimension.