Automated slice sensitivity profile measurement of the CT image of the AAPM CT performance phantom: Which stair object should be used?

Purpose: We used an improved algorithm to automatically measure the slice sensitivity profile (SSP) and its full-width at half maximum (FWHM) from all three stair objects within an image of the AAPM CT performance phantom.Methods: The phantom was scanned with a Philips Ingenuity 128-slice CT scanner using slice thicknesses of 1 mm and 5 mm. The three stair objects were named top #1, middle #2, and bottom #3. The software was able to measure the SSP and its FWHM form object #1, #2, #3, and all objects. The SSPs and FWHMs from each stair object were compared with manual measurements. Results: The FWHM values for a slice thickness of 1 mm were 1.3 ± 0.1 mm for all the stair objects. The FWHM values for a slice thickness of 5 mm were 5.2 ± 0.1 mm, 5.1 ± 0.3 mm, 5.2 ± 0.1 mm for the top, bottom, and middle stair objects, respectively. The results of manual measurements had the same trend as those of the automated measurements.Conclusion: The improved algorithm for measuring SSP and its FWHM from any stair object within the AAPM performance phantom was successfully developed. The SSPs and their FWHM values measured from every stair object were similar (p > 0.05).