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Usability of Deformable Image Registration for Adaptive Volume Modulated Arc Therapy in Head and Neck Cancers and a Predictive Factor for Replanning
E626
International Journal of Radiation Oncology Biology Physics
3535
Purpose/Objective(s): There are little data to identify the ideal timing to perform repeat computed tomography (CT) for replanning in treatment duration of intensity modulated radiation therapy (IMRT) for head and neck cancers (HNC), although HNC patients develop physical changes including weight loss and tumor shrinkage. Deformable image registration (DIR) has been an important component in adaptive radiation therapy (ART). However, the availability of DIR has been poorly established in ART of IMRT for HNC. The purpose of the present study was to examine the availability of DIR in ART and to identify the optical timing of replanning. Materials/Methods: Between January 2015 and December 2015, 22 patients (17 men and 5 women; median age, 71 years; range, 44-83 years) who received IMRT for pathologically confirmed HNC at Hyogo College of Medicine College Hospital were prospectively enrolled in the present study. The median weight loss was 4.7% (range, -3.2 to 11.2%) in all patients. Radiation therapy was designed for simultaneous integrated boost IMRT (SIB-IMRT) technique in all eligible patients. Gross tumor was typically designed to receive 70 Gy in 2.12 Gy/fraction over 33 days. A second planning CT scan (re-CT) was planned to be performed at fraction 15 prior to treatment commencement. DIR was performed using a commercial deformable registration package. Then, the changes of planning target volumes and organs at risks were analyzed. In addition, the face was analyzed with regard to the volume (whole face) and the face surface. Dice similarity coefficient (DSC) was used to evaluate a similarity between the planning CT and the re-CT. The optimal cutoff value of DSC for replanning was determined using receiver operating characteristic (ROC) curve analysis. Results: Body weights were decreased with time in all patients. No significant differences were observed in body weight at the re-CT, compared with that at the planning CT (PZ0.191). We compared weight loss in the patients who required replanning with that in the patients who did not. In the correlation between weight loss and DSC of each structure, weight loss had strongly negative correlation with DSC of the whole face (rZ-0.447) and the face surface (rZ-0.505). Patients who required replanning tended to decrease rapidly in body weight. The threshold DSC was 0.98 and 0.60 in the whole face and the face surface, respectively. Patients who showed low DSC in the whole face and the face surface required replanning at a significantly high rate (PZ0.030 and 0.008). Moreover, weight loss was correlated with DSC in both the whole face and the face surface with significant differences (PZ 0.042 and 0.019). Conclusion: DSC was a simple and useful parameter to predict the needs for replanning. In IMRT for HNC, the threshold DSC was 0.98 and 0.60 in whole face and face surface, respectively. Author Disclosure: M. Tanooka: None. H. Doi: None. T. Ishida: None. T. Wakayama: None. H. Inoue: None. T. Matsumoto: None. K. Tarutani: None. K. Kosaka: None. N. Kamikonya: None. K. Sakamoto: None.
Ultrafast Volumetric Cine Magnetic Resonance Imaging (UVC-MRI) for Real-Time 3-Dimensional Target Localization/Tracking W. Harris, F.F. Yin, C. Wang, Z. Chang, J. Cai, Y. Zhang, and L. Ren; Duke University Medical Center, Durham, NC Purpose/Objective(s): Recently we developed a VC MRI technique to generate quasi-real-time (3 frames/s) 3D MRI based on motion modeling and 2D cine MRI for target localization. In this study, we hypothesize that the frame rate of VC MRI can be substantially accelerated using sparsely sampled 2D cine MRI. This Ultrafast VC MRI (UVC MRI) can minimize the motion artifacts for irregular breathing and provide truly real-time 3D guidance for gating/target tracking. The purpose of this study is to validate the feasibility of UVC MRI and evaluate the effects of different scanning parameters on UVC MRI. Materials/Methods: The 4D MRI acquired during patient simulation are used as prior images. Principal component analysis is used to extract 3 major respiratory deformation patterns from the deformation field maps (DFM) registered between end expiration phase and all other phases of the 4D MRI. Onboard UVC MRI at any instant is considered as a deformation of the prior MRI at the end expiration phase. The DFM for UVC MRI is represented by a linear combination of the 3 major deformation patterns. Coefficients of the deformation patterns are solved by matching the corresponding 2D slice of UVC MRI with the acquired onboard 2D cine MRI. The ultrafast onboard 2D cine MRI are acquired at 30 frames/s by sampling only 10% of the k-space on Cartesian grid, with 85% of that taken at the central k-space and the other 15% randomly sampled elsewhere. UVC MRI was evaluated using both XCAT (computerized patient model) simulation of lung cancer patients and MRI data from liver cancer patients. Three scenarios were simulated from prior to onboard volume in XCAT, including phase shift, synchronous and asynchronous motion amplitude change between tumor and body motion. The accuracy of UVC MRI was evaluated using volume percent difference (VPD) and center of mass shift (COMS) of the estimated tumor volume. Effects of region of interest (ROI) selection, 2D cine slice orientation, slice location, and slice number on the estimation accuracy were evaluated. Results: In XCAT study, the UVC MRI estimated using a single sparsely sampled sagittal 2D cine MRI with a ROI around tumor achieved VPD/ COMS of 8.542.27%/0.240.05 mm among all scenarios. Using the entire cine image instead of ROI reduced the accuracy to 37.3743.45%/ 4.036.02 mm. Changing the 2D cine orientation to axial or coronal view reduced the accuracy to 9.261.30%/0.760.72 mm and 15.562.91%/1.800.56 mm, respectively. Estimation using the sagittal cine was the most robust against slice location change among all views. Using multiple parallel or orthogonal cine images did not further improve UVC MRI estimation as single cine was sufficient to fit the motion model. In patient study, profiles in the estimated and ground truth UVC MRI agreed within 5% error. Conclusion: Preliminary studies showed it is feasible to generate UVC MRI up to 30 frames/s to provide truly real-time 3D target verification. UVC MRI can potentially minimize/eliminate treatment errors in liver or lung SBRT to improve treatment outcome. Author Disclosure: W. Harris: Research Grant; NIH, Varian Medical Systems. F. Yin: Research Grant; NIH, Varian Medical Systems. C. Wang: None. Z. Chang: None. J. Cai: Research Grant; NIH. Y. Zhang: None. L. Ren: Research Grant; NIH, Varian Medical Systems.
3536 Usability of Deformable Image Registration for Adaptive Volume Modulated Arc Therapy in Head and Neck Cancers and a Predictive Factor for Replanning M. Tanooka,1 H. Doi,2,3 T. Ishida,1 T. Wakayama,1 H. Inoue,1 T. Matsumoto,1 K. Tarutani,3 K. Kosaka,3 N. Kamikonya,3 and K. Sakamoto1; 1Department of Radiological Technology, Hyogo College of Medicine College Hospital, Nishinomiya-shi, Hyogo, Japan, 2 Meiwa Cancer Clinic, Nishinomiya-shi, Hyogo, Japan, 3Department of Radiology, Hyogo College of Medicine, Nishinomiya-shi, Hyogo, Japan
3537 Reproducibility With Repeat Computed Tomography in Radiomics Study for Rectal Cancer P. Hu, J. Wang, H. Zhong, Z. Zhou, L. Shen, W. Hu, and Z. Zhang; Fudan University Shanghai Cancer Center, Shanghai, China Purpose/Objective(s): To evaluate the reproducibility of radiomics features by repeating computed tomographic (CT) scans in rectal cancer. To choose stable radiomics features for rectal cancer. Materials/Methods: A total of 40 rectal cancer patients were enrolled in this study, each of whom underwent 2 CT scans within an average of 8.7 days (5 days to 17 days) before any treatment was delivered. Both scans were obtained in the same CT scanner with the same protocol. The rectal gross tumor volume (GTV) was distinguished and segmented by an experienced oncologist in both CTs. The delineation was double-checked, and the noninvaded rectal wall and the air inside the rectum were carefully excluded. Totally, more than 2000 radiomics features were defined in this study, which were divided into 4 groups (I: GLCM, II: GLRLM, III: Wavelet GLCM, and IV: Wavelet GLRLM). For each group, 5 types of features were extracted (Max slice: features from the largest slice of target
International Journal of Radiation Oncology Biology Physics
3535
Purpose/Objective(s): There are little data to identify the ideal timing to perform repeat computed tomography (CT) for replanning in treatment duration of intensity modulated radiation therapy (IMRT) for head and neck cancers (HNC), although HNC patients develop physical changes including weight loss and tumor shrinkage. Deformable image registration (DIR) has been an important component in adaptive radiation therapy (ART). However, the availability of DIR has been poorly established in ART of IMRT for HNC. The purpose of the present study was to examine the availability of DIR in ART and to identify the optical timing of replanning. Materials/Methods: Between January 2015 and December 2015, 22 patients (17 men and 5 women; median age, 71 years; range, 44-83 years) who received IMRT for pathologically confirmed HNC at Hyogo College of Medicine College Hospital were prospectively enrolled in the present study. The median weight loss was 4.7% (range, -3.2 to 11.2%) in all patients. Radiation therapy was designed for simultaneous integrated boost IMRT (SIB-IMRT) technique in all eligible patients. Gross tumor was typically designed to receive 70 Gy in 2.12 Gy/fraction over 33 days. A second planning CT scan (re-CT) was planned to be performed at fraction 15 prior to treatment commencement. DIR was performed using a commercial deformable registration package. Then, the changes of planning target volumes and organs at risks were analyzed. In addition, the face was analyzed with regard to the volume (whole face) and the face surface. Dice similarity coefficient (DSC) was used to evaluate a similarity between the planning CT and the re-CT. The optimal cutoff value of DSC for replanning was determined using receiver operating characteristic (ROC) curve analysis. Results: Body weights were decreased with time in all patients. No significant differences were observed in body weight at the re-CT, compared with that at the planning CT (PZ0.191). We compared weight loss in the patients who required replanning with that in the patients who did not. In the correlation between weight loss and DSC of each structure, weight loss had strongly negative correlation with DSC of the whole face (rZ-0.447) and the face surface (rZ-0.505). Patients who required replanning tended to decrease rapidly in body weight. The threshold DSC was 0.98 and 0.60 in the whole face and the face surface, respectively. Patients who showed low DSC in the whole face and the face surface required replanning at a significantly high rate (PZ0.030 and 0.008). Moreover, weight loss was correlated with DSC in both the whole face and the face surface with significant differences (PZ 0.042 and 0.019). Conclusion: DSC was a simple and useful parameter to predict the needs for replanning. In IMRT for HNC, the threshold DSC was 0.98 and 0.60 in whole face and face surface, respectively. Author Disclosure: M. Tanooka: None. H. Doi: None. T. Ishida: None. T. Wakayama: None. H. Inoue: None. T. Matsumoto: None. K. Tarutani: None. K. Kosaka: None. N. Kamikonya: None. K. Sakamoto: None.
Ultrafast Volumetric Cine Magnetic Resonance Imaging (UVC-MRI) for Real-Time 3-Dimensional Target Localization/Tracking W. Harris, F.F. Yin, C. Wang, Z. Chang, J. Cai, Y. Zhang, and L. Ren; Duke University Medical Center, Durham, NC Purpose/Objective(s): Recently we developed a VC MRI technique to generate quasi-real-time (3 frames/s) 3D MRI based on motion modeling and 2D cine MRI for target localization. In this study, we hypothesize that the frame rate of VC MRI can be substantially accelerated using sparsely sampled 2D cine MRI. This Ultrafast VC MRI (UVC MRI) can minimize the motion artifacts for irregular breathing and provide truly real-time 3D guidance for gating/target tracking. The purpose of this study is to validate the feasibility of UVC MRI and evaluate the effects of different scanning parameters on UVC MRI. Materials/Methods: The 4D MRI acquired during patient simulation are used as prior images. Principal component analysis is used to extract 3 major respiratory deformation patterns from the deformation field maps (DFM) registered between end expiration phase and all other phases of the 4D MRI. Onboard UVC MRI at any instant is considered as a deformation of the prior MRI at the end expiration phase. The DFM for UVC MRI is represented by a linear combination of the 3 major deformation patterns. Coefficients of the deformation patterns are solved by matching the corresponding 2D slice of UVC MRI with the acquired onboard 2D cine MRI. The ultrafast onboard 2D cine MRI are acquired at 30 frames/s by sampling only 10% of the k-space on Cartesian grid, with 85% of that taken at the central k-space and the other 15% randomly sampled elsewhere. UVC MRI was evaluated using both XCAT (computerized patient model) simulation of lung cancer patients and MRI data from liver cancer patients. Three scenarios were simulated from prior to onboard volume in XCAT, including phase shift, synchronous and asynchronous motion amplitude change between tumor and body motion. The accuracy of UVC MRI was evaluated using volume percent difference (VPD) and center of mass shift (COMS) of the estimated tumor volume. Effects of region of interest (ROI) selection, 2D cine slice orientation, slice location, and slice number on the estimation accuracy were evaluated. Results: In XCAT study, the UVC MRI estimated using a single sparsely sampled sagittal 2D cine MRI with a ROI around tumor achieved VPD/ COMS of 8.542.27%/0.240.05 mm among all scenarios. Using the entire cine image instead of ROI reduced the accuracy to 37.3743.45%/ 4.036.02 mm. Changing the 2D cine orientation to axial or coronal view reduced the accuracy to 9.261.30%/0.760.72 mm and 15.562.91%/1.800.56 mm, respectively. Estimation using the sagittal cine was the most robust against slice location change among all views. Using multiple parallel or orthogonal cine images did not further improve UVC MRI estimation as single cine was sufficient to fit the motion model. In patient study, profiles in the estimated and ground truth UVC MRI agreed within 5% error. Conclusion: Preliminary studies showed it is feasible to generate UVC MRI up to 30 frames/s to provide truly real-time 3D target verification. UVC MRI can potentially minimize/eliminate treatment errors in liver or lung SBRT to improve treatment outcome. Author Disclosure: W. Harris: Research Grant; NIH, Varian Medical Systems. F. Yin: Research Grant; NIH, Varian Medical Systems. C. Wang: None. Z. Chang: None. J. Cai: Research Grant; NIH. Y. Zhang: None. L. Ren: Research Grant; NIH, Varian Medical Systems.
3536 Usability of Deformable Image Registration for Adaptive Volume Modulated Arc Therapy in Head and Neck Cancers and a Predictive Factor for Replanning M. Tanooka,1 H. Doi,2,3 T. Ishida,1 T. Wakayama,1 H. Inoue,1 T. Matsumoto,1 K. Tarutani,3 K. Kosaka,3 N. Kamikonya,3 and K. Sakamoto1; 1Department of Radiological Technology, Hyogo College of Medicine College Hospital, Nishinomiya-shi, Hyogo, Japan, 2 Meiwa Cancer Clinic, Nishinomiya-shi, Hyogo, Japan, 3Department of Radiology, Hyogo College of Medicine, Nishinomiya-shi, Hyogo, Japan
3537 Reproducibility With Repeat Computed Tomography in Radiomics Study for Rectal Cancer P. Hu, J. Wang, H. Zhong, Z. Zhou, L. Shen, W. Hu, and Z. Zhang; Fudan University Shanghai Cancer Center, Shanghai, China Purpose/Objective(s): To evaluate the reproducibility of radiomics features by repeating computed tomographic (CT) scans in rectal cancer. To choose stable radiomics features for rectal cancer. Materials/Methods: A total of 40 rectal cancer patients were enrolled in this study, each of whom underwent 2 CT scans within an average of 8.7 days (5 days to 17 days) before any treatment was delivered. Both scans were obtained in the same CT scanner with the same protocol. The rectal gross tumor volume (GTV) was distinguished and segmented by an experienced oncologist in both CTs. The delineation was double-checked, and the noninvaded rectal wall and the air inside the rectum were carefully excluded. Totally, more than 2000 radiomics features were defined in this study, which were divided into 4 groups (I: GLCM, II: GLRLM, III: Wavelet GLCM, and IV: Wavelet GLRLM). For each group, 5 types of features were extracted (Max slice: features from the largest slice of target