7 & 8 Computed Tomography

Cone Beam reconstruction

Cone Beam reconstruction

________: illuminate the object from a point source, and the X- ray flux is measured on a plane to create a 3D image.

Axial Tomography

CAT: Computed ________, same as a CT.

one dimensional Fourier Transform

The ________ of the projection function at an angle θ,) (P t θ, can be.

sinogram

The ________ is a x- Φplot of the projection data PΦ (X)

projection function

The ________ sums the attenuation of the X- ray beam along line t in the s- direction.

CAT

Computed Axial Tomography, same as a CT

Cone Beam reconstruction

illuminate the object from a point source, and the X-ray flux is measured on a plane to create a 3D image

1st Gen

CT type, 1 detector, lasted 30 min

2nd Gen

Ct type, 20-30 detectors, fan bean, less than 90 seconds

3rd Gen

Ct type, 288-1k scanners, fan shaped, rotate-rotatements, 5 seconds

3rd Gen

First CT generation to institute rotate/rotate modality

slip ring

• Uses ___________ technology, brushes along the fixed part of the machine so that cables wouldn’t get wound up in the CT

Increase

More projections yields an _____in the accurately of the reconstructed image

Increased dose to patient

Cons of better CT images that require more scans

Sinogram

The raw data of a CT is the…

Algebraic, iterative, backprojection, filtered backprojection

Methods of CT Reconstruction

Increases

As the number of projection images in CTs increases, the contrast of the image…

Higher dose

What is the con of doing 10000000 projection images in a CT? Doesn’t it give you better images?

Hounsfield units

1000 x (ui - uwater)/uwater

Zero

The Hounsfield value of water is…

Proportional

CT number is approximately ___________ to physical density