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X-Ray Beam Profile Characterization for Two Modern Wide-Beam CT Scanners

K Yang1*, C Ruan2 , X Li1 , B Liu1 , (1) Massachusetts General Hospital, Boston, MA, (2) Brigham and Women's Hospital, Boston, MA


(Sunday, 7/29/2018) 1:00 PM - 1:55 PM

Room: Davidson Ballroom B

Purpose: To characterize and compare the x-ray beam profiles of two modern wide-beam CT scanners.

Methods: The beam profiles from two multidetector CT scanners with a 160mm beam collimation (Toshiba Aquilion One Vision and GE Revolution CT) were measured using a solid state linear detector (0.8f3-512, Detection Technology, Finland). This GOS-based linear detector has a pixel size of 0.8x0.8 mm² and an effective length of 51.2 cm. The CT beam profiles were first measured as transmission profiles along the lateral direction (within x,y plane) for three different bowties (small, medium, large) at four different kVs (80,100,120,135/140) from each scanner. The data were collected under rotational mode, using a previously developed method with simultaneous geometrical calibration. The equivalent Al thickness profiles were derived from the measured transmission profiles. The effect of beam collimation width on bowtie profile measurements was studied by comparing the results with 5 mm and 160 mm beam collimation. Then the z-direction beam profile was measured by placing the linear detector along the longitudinal direction, with different beam collimation widths (from 160 mm to 4/5 mm).

Results: A total of six different bowtie filter profiles were measured and derived from the two wide-beam CT scanners. The beam collimation width has a small impact on the bowtie profiles due to different levels of scatter. The z-direction beam profiles clearly demonstrated the heel effect for both scanners due to the wide beam collimation and relative large differences in the actual beam collimation width.

Conclusion: The x-ray beam profiles from two modern wide-beam CT scanners were accurately measured and derived. The provided non-proprietary information can be useful for the field to evaluate and compare the performance of these scanners.


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