Room: ePoster Forums
Purpose: To investigate the impact of CT image resconstruction thickness and filter on the precision of volume of spherical phantoms.
Methods: Spherical phantoms of different diameters was scanned in 0.75mm-thickness at 120kV/300mAs using Philips Big-Bore Brilliance CT scanner. The CT images were reconstructedunder the matrix of 512 * 512 at the thickness of 1.0mm, 2.0mm, 3.0mm and 5.0mm with B fileter or at different reconstruction filters with 1.0 mm thickness and then transferred to BrainLab treatment planning system via ARIA workstation. The images for the phantoms were delineated and read out for the measured volume. The difference between the calculated and measured volume for specific phantom at certain circumstances was analyzed.
Results: The impact on the difference between the calculated and measured volume for specific phantom at different thickness of reconstruction is significant, especially for phantom with small diameter. The difference for phantom of diameter in 6.0 mmï¼Œ10.0 mmï¼Œ30.0 mmï¼Œ40.0 mmï¼Œ50.0 mm is -11.50%, -15.30%, -4.75%, 0.23%, 0.30% and -0.40%, spectively at the reconstruction thickness of 1.0mm; it was -22.10%, -22.0%, -9.07%, -0.83%, -0.83% and -1.12%, respectively at the reconstruction thickness of 3.0mm; it was -45.10%, -26.10%, -10.62%, -3.87%, -4.60 % and -2.89%, respectively at the reconstruction thickness of 5.0mm. The difference between the calculated and measured volume under different filter is greater for phantoms with smaller diameter.
Conclusion: The significance of reconstruction parameters such as thickness and filter on the volume measured on the image for spherical phantoms especially of small size should be carefully considered in the era of stereotactical radiation therapy, especially for those with relatively small lesion.