Target point correction optimized based on the dose distribution of each fraction in daily IGRT

17th International Conference on the Use of Computers in Radiation Therapy

物理学;计算机科学

Stoll, Markus^1 ; Giske, Kristina^1 ; Stoiber, Eva M^1,2 ; Schwarz, Michael^1 ; Bendl, Rolf^1,3

Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany^1

Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany^2

Faculty of Informatics, Heilbronn University, Heilbronn, Germany^3

关键词: Anatomical changes;    Clinical target volumes;    Deformable image registration;    Dose distributions;    Head-and-neck cancer;    Image-guided radiation therapy;    Intensity-modulated radiation therapy;    Registration methods;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/489/1/012081/pdf
DOI  :  10.1088/1742-6596/489/1/012081

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Purpose: To use daily re-calculated dose distributions for optimization of target point corrections (TPCs) in image guided radiation therapy (IGRT). This aims to adapt fractioned intensity modulated radiation therapy (IMRT) to changes in the dose distribution induced by anatomical changes. Methods: Daily control images from an in-room on-rail spiral CT-Scanner of three head-and-neck cancer patients were analyzed. The dose distribution was re-calculated on each control CT after an initial TPC, found by a rigid image registration method. The clinical target volumes (CTVs) were transformed from the planning CT to the rigidly aligned control CTs using a deformable image registration method. If at least 95% of each transformed CTV was covered by the initially planned D95 value, the TPC was considered acceptable. Otherwise the TPC was iteratively altered to maximize the dose coverage of the CTVs. Results: In 14 (out of 59) fractions the criterion was already fulfilled after the initial TPC. In 10 fractions the TPC can be optimized to fulfill the coverage criterion. In 31 fractions the coverage can be increased but the criterion is not fulfilled. In another 4 fractions the coverage cannot be increased by the TPC optimization. Conclusions: The dose coverage criterion allows selection of patients who would benefit from replanning. Using the criterion to include daily re-calculated dose distributions in the TPC reduces the replanning rate in the analysed three patients from 76% to 59% compared to the rigid image registration TPC.