SU-E-T-524: The Effect of CT Contrast on CyberKnife Treatment Planning

Medical Physics
H KimSung-Joon Ye

Abstract

To investigate the effect of CT contrast enhancement (CE) on the 3D dose distributions of non-coplanar small field beams in the CyberKnife (CK) treatment planning system. Twenty patients treated by pre-CE CT plans were recruited to this retrospective plan study. Their post-CE CT plans were based on the pre-CE CT plan data and calculated using the same MU and beam paths in either Ray-Tracing or Monte Carlo (MC) algorithms. The differences in doses of the beam path and the reference point and in DVHs of target and OARs between the pre-CE CT and the post-CE CT plans were compared. The minimum dose, the maximum dose, the mean dose, and the dose received to 50% of the target and OARs volumes, and the target volume coverage were also compared. The dose differences between the pre-CE and post-CE plans in a single beam path were less than 50 cGy in both calculation algorithms. At the center of target volume, it was 1.9% (maximum 6.2%) in Ray-Tracing and 1.5% (maximum 4.0%) in MC, with respect to the prescription dose. The post-CE plans showed on average 2% decrease in the OAR maximum dose (maximum 6.4% in Ray-Tracing and 5.8% in MC). Regardless of the algorithms, the dose to the target and the target volume coverage of post-CE plans we...Continue Reading

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