Spatial Linearity (Pixel Size)

The spatial linearity is measured on the four aluminum beads as shown below.

Figure 3.1: This diagram is oriented so that one is viewing the phantom from underneath it. The left side of the image is considered the ‘right’ side or the top half of the phantom (See Phantom Positioning Help Page or the Phantom configurations section in the Tomophan® product guide). The four aluminum beads used to measure spatial linearity in the x and y direction are 0.5mm in diameter and located in the test plane of the phantom. 

In the table provided by Smári analysis, the following measurements are displayed:

• Measured pixel size x (AP) [mm]: The x-direction pixel size from the DICOM headers
• Measured pixel size y (AP) [mm]: The y-direction pixel size from the DICOM headers
• Measured pixel x:y ratio: The ratio of the two previous measurements
• Pixel based X Spatial Linearity measurement [%]: (Number of pixels along 85mm distance * Measured pixel size x)/85mm*100%
• Pixel based Y Spatial Linearity measurement [%]: (Number of pixels along 170mm distance * Measured pixel size x)/170mm*100%