FFF.1.2.5.1 Detector

The following concepts illustrate the model of the X-Ray detector:

Physical detector array (or physical detector matrix) is the matrix composed of physical detector elements .

Note: Not all the detector elements are activated during an X-Ray exposure. The active detector elements are in the detector active area, which can be equal to or smaller than the physical detector area.

Physical detector element coordinates represented as (i det, j det ) are columns and rows of the physical detector element in the physical detector array.

Detector TLHC element is the detector element in the Top Left Hand Corner of the physical detector array and corresponds to (i det, j det ) = (0,0).

The attribute Detector Element Physical Size (0018,7020) represents the physical dimensions in mm of a detector element in the row and column directions.

The attribute Detector Element Spacing (0018,7022) contains the two values Δ jdet and Δ idet , which represent the physical distance in mm between the centers of each physical detector element:

The attribute Detector Element Physical Size (0018,7020) may be different from the Detector Element Spacing (0018,7022) due to the presence of spacing material between detector elements.

The attribute Position of Isocenter Projection (0018,9430) contains the point (ISO_P idet, ISO_P jdet ), which represents the projection of the Isocenter on the detector plane, measured as the offset from the center of the detector TLHC element. It is measured in physical detector elements.

The attribute Imager Pixel Spacing (0018,1164) contains the two values Δ j and Δ i , which represent the physical distance measured at the receptor plane between the centers of each pixel of the FOV image:

The zoom factor represents the ratio between Imager Pixel Spacing (0018,1164) and Detector Element Spacing (0018,7022). It may be different from the detector binning (e.g., when a digital zoom has been applied to the pixel data).

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Figure FFF.1.2-9Physical Detector and Field of View Areas