Program Information
Evaluation of Dose Distribution in Intensity Modulated Radiosurgery for Lung Cancer Under Condition of Respiratory Motion
M Yoon , J Song*, Chonnam National University Medical School, Gwanju, Korea
Presentations
MO-RAM-GePD-T-3 (Monday, July 31, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Lounge
Purpose: To estimate dose distribution in the real volume of tumor target and organ at risks (OARs) during the treatment process of lung intensity modulated radiosurgery (IMRS) based on internal target volume (ITV), which covers the whole respiratory motion range.
Methods: A humanoid phantom and a dynamic phantom, which simulate respiratory motion, were used to acquire 4DCT data in the different motion ranges. In each set of the 4DCT data, ITV and OAR within the humanoid phantom were delineated and IMRS plans were designed. The delivery quality assurance (DQA) process for verifying the dosimetric accuracy was performed under the same conditions with real target motion. The dose distributions in the real volume of tumor target and OAR were evaluated based on the measured dosimetric data in the DQA process, and the difference between the calculated dose in the plan and the evaluated dose was analyzed considering the moving condition. DQA was performed using ArcCHECK and MapCHECK2 and the real dose inside the humanoid phantom was evaluated using the 3DVH program.
Results: The evaluated dose in the tumor target and OAR using the 3DVH program was higher than the calculated dose in the plan, and a greater difference was seen for the RapidArc treatment than for the standard intensity modulated radiation therapy (IMRT) with fixed gantry angle beams.
Conclusion: The results of this study show that for IMRS plans based on target volume, including the whole tumor motion range, tighter constraints of the OAR should be considered in the optimization process. The method devised in this study can be applied effectively to analyze the dose distribution in the real volume of tumor target and OARs in IMRT plans targeting the whole tumor motion range.
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