Alba Magallon-Baro1, Mauro Loi2, Maaike T W Milder3, Patrick V Granton4, Andras G Zolnay5, Joost J Nuyttens6, Mischa S Hoogeman7. 1. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: a.magallonbaro@erasmusmc.nl. 2. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: m.loi@erasmusmc.nl. 3. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: m.milder@erasmusmc.nl. 4. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: p.granton@erasmusmc.nl. 5. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: a.zolnay@erasmusmc.nl. 6. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: j.nuyttens@erasmusmc.nl. 7. Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands. Electronic address: m.hoogeman@erasmusmc.nl.
Abstract
PURPOSE: To characterize daily geometrical variations of gastrointestinal organs with respect to pancreatic tumors, through a population-based statistical model. MATERIALS AND METHODS: The study included 131 CT scans from 35 pancreatic cancer patients treated with Stereotactic Body Radiotherapy (SBRT). For each patient, day-to-day anatomical variations of the stomach, the duodenum and the bowel were assessed from the deformation vector fields (DVF) obtained by non-rigidly registering the contours of the fractions to the planning CT scans. For the whole population, day-to-day motion-deformation patterns were abstracted using principal component analysis (PCA) on the set of DVFs mapped on a reference patient. Based on these geometrical variations, anatomies were generated to create population-based dose-volume histograms (DVH) per patient, which were also compared to clinical values. RESULTS: Through PCA, the most dominant directions of daily deformations were localized in the abdominal organs. Common patterns were found, such as stomach contraction-expansion in the anterior-posterior direction ranging from 5 to 13 mm, and superior-inferior deformations on the bowel from 7 to 14 mm. The duodenum resulted to move laterally, but in a lesser extent (4-8 mm). The population-based DVHs derived from the model mostly included the daily DVHs observed in the clinic (in >90% of the cases). CONCLUSIONS: Anatomical variations influence the delivered doses to healthy organs during SBRT. A motion model was successfully built and explored to extract the larger directions of movement of the gastrointestinal organs. Day-to-day motion modeling can potentially be used to account for geometrical uncertainties in future plan optimization and in online adaptive strategies.
PURPOSE: To characterize daily geometrical variations of gastrointestinal organs with respect to pancreatic tumors, through a population-based statistical model. MATERIALS AND METHODS: The study included 131 CT scans from 35 pancreatic cancerpatients treated with Stereotactic Body Radiotherapy (SBRT). For each patient, day-to-day anatomical variations of the stomach, the duodenum and the bowel were assessed from the deformation vector fields (DVF) obtained by non-rigidly registering the contours of the fractions to the planning CT scans. For the whole population, day-to-day motion-deformation patterns were abstracted using principal component analysis (PCA) on the set of DVFs mapped on a reference patient. Based on these geometrical variations, anatomies were generated to create population-based dose-volume histograms (DVH) per patient, which were also compared to clinical values. RESULTS: Through PCA, the most dominant directions of daily deformations were localized in the abdominal organs. Common patterns were found, such as stomach contraction-expansion in the anterior-posterior direction ranging from 5 to 13 mm, and superior-inferior deformations on the bowel from 7 to 14 mm. The duodenum resulted to move laterally, but in a lesser extent (4-8 mm). The population-based DVHs derived from the model mostly included the daily DVHs observed in the clinic (in >90% of the cases). CONCLUSIONS: Anatomical variations influence the delivered doses to healthy organs during SBRT. A motion model was successfully built and explored to extract the larger directions of movement of the gastrointestinal organs. Day-to-day motion modeling can potentially be used to account for geometrical uncertainties in future plan optimization and in online adaptive strategies.
Authors: Joshua S Niedzielski; Yufei Liu; Sylvia S W Ng; Rachael M Martin; Luis A Perles; Sam Beddar; Neal Rebueno; Eugene J Koay; Cullen Taniguchi; Emma B Holliday; Prajnan Das; Grace L Smith; Bruce D Minsky; Ethan B Ludmir; Joseph M Herman; Albert Koong; Gabriel O Sawakuchi Journal: Int J Radiat Oncol Biol Phys Date: 2021-08-13 Impact factor: 7.038
Authors: Alba Magallon-Baro; Maaike T W Milder; Patrick V Granton; Wilhelm den Toom; Joost J Nuyttens; Mischa S Hoogeman Journal: Front Oncol Date: 2022-06-08 Impact factor: 5.738
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