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27 Cards in this Set

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What is the purpose of 3D imaging?
To use vast amounts of data collected from the patient to provide both quantitative and quality information.
What is qualitative information?
Qualitative information is used to to compare how observers perform on a specific task to demostrate the diagnostic value of 3D.
What is quantitative information?
Quantitative information is used to assess three elemens of the technique: precision, accuracy, and efficiency.
What are the 4 coordinate systems that relate to the CT Scanner in regards to 3D images?
1. scanner coordinate system (abc)
2. display coordinate system (rst)
3. object coordinate system (www)
4. scene coordinate system (xyz)
What is the scanner coordinate system (abc)?
The scanner coordinate system (abc)
What is the scene or Cartesian coordinate system (xyz)?
the x, y, and z axises are positioned at right angles to one another (orthogonal)
What is orthogonal?
Where the x, y, and z axises are positioned at right angles to one another.
What is does the x axis stand for?
The width of an object is described by the x axis.
What is does the y axis stand for?
The height of an object is described by the y axis.
What is does the z axis stand for?
The z axis describes the demention of an object isand adds perspective realism to the image.
What does a coordinate system do?
It allows descriptions of an object be measuring distances from point of intersection. Or the zero point.
What does the term scene stand for?
-Multidemential images, rectanglular array with assigned values.
What is scene domain?
-Anatomic region represented by the scene.
What is scene intensity?
The values assigned to the voxels in a scene
What is modeling in regards to 3D imaging?
The generation of a 3D object using computer software is called modeling. It uses mathmatics to describe physical properties.
What is rendering?
Rendering is the final step in the process of generating a 3D object. It involves the creation of the simulated 3D image, a computer program that converts anatomic data collected from the patient into the 3D image seen.
What are the two types of rendering used in radiology?
1. Surface rendering- only uses contour data from the set
2. Volume rendering- uses the entire data set.
What are the three classes of 3D imaging approaches?
1. slice imaging-(MPR) saggital and coronal
2. protective imaging- volume rendering (2.5D)not a true 3D
3. volume imaging-true 3D visualization mode
What are the four steps needed to create a 3D image?
1.Data acquisition.
2.Creation of 3D space or scene space
3. Processing for 3D image display
4. 3D image display
What is voxel based processing?
Voxel based processing determines which voxels will make up the the final 3D display. MPRs
What is object based processing?
Object based processing uses voxel information to transform the images into collections of objects, which undergo several processing methods.
What are the four steps that change a object model into a 3D image?
1. Segmentation
2. Thresholding
3. Object delineation
4. Rendering
What is Segmentation in regards to 3D imaging?
Segmentation is a processing technique used to identify the structure of interest in a given scene. It determines which voxels to keep and which are not needed.
What is Thresholding in regards to 3D imaging?
Thresholding is a method of classifying the different types of tissues and assigning CT numbers to them.
What is Object delineation in regards to 3D imaging
Object delineation is portraying an object by drawing it. It involves boundry and volume extraction and detection methods.
What is surface rendering?
Also called shaded surface display (SSD), it uses the internal representation of surfaces and then lights them according to standard protocols.
What is MIP?
Maximum Intensity Projection- originated in MR for MRAs. It does not require sophisitcated computer hardware because it uses less than 10% of the collected data