Program Information
Assessment of Adaptive Radiation Therapy Withdeformable Image Registration Software
N Mukumoto1*, R Yada1 , Y Shimizu1 , K Okumura2 , T Wang1 , S Osuga1 , H Akasaka1 , Y Aoyama2 , R Sasaki1 , (1) Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe City, Hyogo, Japan (2) Center for Radiology and Radiation Oncology, Kobe University Hospital, Kobe City, Hyogo, Japan
Presentations
SU-I-GPD-J-5 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: It often happens that patients’ body figure varies over time while the irradiation period of Head and neck IMRT. It is necessary to retake the second CT simulation for the relocation of target and exact dose calculation. However, it is very difficult to say when to redo it the best. By applying the CBCT for geographic verification as a substitution, it is possible to reschedule on appropriate timing. The Velocity Ver. 3.2, the DIR software, mounts a function called “CBCT reshape” that allows to refer and to apply the first CT simulation values on the deformed first CT simulation image by CBCT image. This study compares the CBCT reshape and the second CT simulation in terms of the abilities of localizing targets and OAR minimizing radiation dose difference.
Methods: Four patients who have been treated IMRT and taken the second CT simulation from November 2015 to September 2016 at Kobe University Hospital are investigated for this study. CBCT reshape image is created from the first CT simulation and CBCT taken on the day of the second CT simulation, and then the dose optimization as done on a regular CT simulation is computed to make a renewal IMRT plan. This plan is to be compared to the second CT simulation PTV and OAR doses.
Results: There is no significant difference between two plans created by different methods in respect of MU, PTV parameters and doses of OAR.
Conclusion: The CBCT reshape function is only available at the first simulation and at the CBCT, and enables to make a renewal plan with adequate doses simulation to the second CT simulation dose. This feature prevents over exposure to OAR, and also helps to schedule to take the second CT simulation.
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