SU-E-J-100: The Combination of Deformable Image Registration and Regions-Of-Interest Mapping Technique to Accomplish Accurate Dose Calculation On Cone Beam Computed Tomography for XXXX .

@entity1 @entity6480 @entity5 @entity343 @entity418 @entity347
PURPOSE: We introduce a new method combined with the deformable image registration (DIR) and regions-of-interest mapping (ROIM) technique to accurately calculate dose on daily CBCT for @entity418 . METHODS: @entity1 suffered from @entity418 were enrolled in the study. Prescription was set to 66 Gy/30 F and 54 Gy/30 F to the @entity5 (PTV66) and subclinical disease (PTV54) . Planning CT (pCT) were segmented into 8 substructures in terms of their differences in physical density, such as gross target volume (GTV), venae cava superior ( @entity6480 ), aorta, heart, spinal cord, lung, muscle and bones. The pCT and its substructures were transferred to the MIM software to readout their mean HU values. Afterwards, a deformable planning CT to daily KV-CBCT image registration method was then utilized to acquire a new structure set on CBCT. The newly generated structures on CBCT were then transferred back to the treatment planning system (TPS) and its HU information were overridden manually with mean HU values obtained from pCT. Finally, the treatment plan was projected onto the CBCT images with the same beam arrangements and monitor units (MUs) to accomplish dose calculation. Planning target volume ( @entity343 ) and @entity347 ( @entity347 ) from both of the pCT and CBCT were compared to evaluate the dose calculation accuracy. RESULTS: It was found that the dose distribution in the CBCT showed little differences compared to the pCT, regardless of whether @entity343 or @entity347 were concerned. Specifically, dose variation in GTV, PTV54, PTV66, @entity6480 , lung and heart were within 0.1%. The maximum dose variation was presented in the spinal cord, which was up to 2.7% dose difference. CONCLUSION: The proposed method combined with DIR and ROIM technique to accurately calculate dose distribution on CBCT for @entity418 is feasible.
