Term
| The path xray beam takes from the tube to the detector |
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Definition
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Term
| The detector senses the arriving ray and measures how much of the beam has been attenuated. |
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Term
| A complete set of Ray Sums |
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Definition
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Term
| The system accounts for the attenuation properties of each ray sum and correlates it to the position of the ray |
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Definition
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Term
| The data includes all measurements obtained from the detector array. Requires much more storage than image data. |
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Definition
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Term
| The result once the computer has processed the raw data.One Houndsfield unit value is assigned to each pixel. |
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Term
| Method to study waves of many different sorts and solve several kinds of linear differential equations by separating a function into its frequency components. |
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Term
| Mathematical method of of estimating the value of an unknown function using the known value on either side of the function |
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Term
| The process when an attenuation profile is created for each view in a scan and then projected onto a matrix. The process of converting the data from an attenuation profile to a matrix is known as _________ |
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Definition
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Term
| The process of applying a filter function to an attenuation profile |
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Definition
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Term
| Technique used for reconstructive algorithms that begin with an assumption and then improving image by analyzing data and adjusting it to fit the assumption. An alternative to filtered back construction that reduces patient dose by as much as 50% and reduces noise and improves image clarity. |
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Definition
| Iterative Reconstruction (IR) |
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Term
| What is SFOV and the 3 most common sizes? |
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Definition
Scan Field of View determines the area within the gantry from which raw data will be acquired during the scan, determining the number of detector cells that will be collecting data;
Small for head = 25-cm
Med for chest = 35-cm
large for abdomen = 42-50cm |
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Term
| This occurs when patient is positioned partially outside of the SFOV. (Not everything in the gantry opening will be within the SFOV) |
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Definition
Out-Of-Field Artifacts
streaking, shading and incorrect Houndsfield numbers |
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Term
| What is the DFOV and does it impact pixel size? |
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Definition
Display Field of View determines how much of the raw data is used to create an image. It is a subset of the SFOV. A large DFOV shows more of the SFOV. A small DFOV shows less of the SFOV in a more magnified image. The larger the DFOV, the larger the pixel will be. Smaller pixel sizes have better spatial resolution, larger pixel sizes have poorer spatial resolution.
PIXEL SIZE = DFOV/MATRIX SIZE
25CM DFOV, 512 MATRIX PIXEL SIZE?
25 CM/512 = 250 MM/512 = .98MM |
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