Program Information
Verification of Stability of An IGRT System to Obtain the Local Image Coordinates From a Known Spatial Deviation
h kaur1*, (1) ,
Presentations
SU-H3-GePD-I-5 (Sunday, July 30, 2017) 4:00 PM - 4:30 PM Room: Imaging ePoster Lounge
Purpose: The purpose of this study was to verify the IGRT system’s ability and stability by using a QUASAR™ Penta-Guide phantom for accurate patient positioning.
Methods: For conducting this study, a QUASAR™ Penta-Guide phantom was used which has an off-center cross hair marking at a known spatial coordinates (x,y,z) from the calibrated isocenter. Penta-guide phantom was placed by aligning these coordinates with radiation isocenter i.e. cross wire and then CBCT images of the phantom were obtained using a standard acquisition procedure for seven months. Coordinates of off-center cross wire were obtained from the isocenter using CBCT system software and it was compared with the phantom specification of those coordinates.
Results: The average values were 1.064 ± 0.03, -1.23 ± 0.06 and -1.15 ± 0.28 in x,y,z directions respectively. The data in all the three directions were statistically significant with p-values of 0.0001, 0.0001 and 0.04 respectively. The standard error of differences were 0.003, 0.002 and 0.02 in x,y and z direction respectively. The standard deviation was seen more in z direction as compared to other directions.
Conclusion: The deviation obtained in the coordinates were highly reproducible in all the directions. The radiation isocenter should be correctly calibrated to rule out the system’s discrepancies. In this study, the daily phantom setup uncertainties are not included but IGRT system’s reproducilbilty and accuracy are within the acceptable range.
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