Enhancement of Hounsfield unit distribution in cone-beam CT images for adaptive radiation therapy: Evaluation of a hybrid correction approach |
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| Institution: | 1. Department of Physics, Faculty of Sciences, Ferhat Abbas Setif University, El Bez Compus 19000, Setif, Algeria;2. Laboratory of Dosing, Analysis and Characterization with High Resolution (DAC-HR), El Bez Compus 19000, Setif, Algeria;1. Department of Medical Physics and Radiotherapy, Baby Memorial Hospital, Calicut, India;2. Department of Physics, Farook College, Calicut, India;3. University of Calicut, Malapuram, Kerala, India;1. Division of Vascular and Interventional Radiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Hospital, Sheikh Zayed Tower, Ste 7203, 1800 Orleans St, Baltimore, MD 21287;2. Clinical Informatics, Interventional, and Translational Solutions (CIITS), Philips Research North America, Briarcliff Manor, NY;3. Philips Research, Medisys, Suresnes, France;1. Department of Radiation Oncology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan;2. Department of Imaging Physics, Division of Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas;1. Department of Radiation Oncology, Peter MacCallum Cancer Centre, Victoria, Australia;2. Department of Radiation Oncology, Olivia Newton-John Cancer Wellness & Research Centre, Austin Hospital, Victoria, Australia |
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| Abstract: | PurposeThis study aims to evaluate the accuracy of a hybrid approach combining the histogram matching (HM) and the multilevel threshold (MLT) to correct the Hounsfield Unit (HU) distribution in cone-beam CT (CBCT) images.Methods and MaterialsCBCT images acquired for ten prostate cancer patients were processed by matching their histograms to those of deformed planning CT (pCT) images obtained after applying a deformable registration (DR) process. Then, HU values corresponding to five tissue types in the pCT were assigned to the obtained CBCT images (CBCTHM-MLT). Finally, the CBCTHM-MLT images were compared to the deformed pCT visually and using different statistical metrics.ResultsThe visual assessment and the profiles comparison showed that the high discrepancies in the CBCT images were significantly reduced when using the proposed approach. Furthermore, the correlation values indicated that the CBCTHM-MLT were in good agreement with the deformed pCT with correlation values ranging from 0.9893 to 0.9962. In addition, the root mean squared error (RMSE) over the entire volume was reduced from 64.15 ± 9.50 to 51.20 ± 6.76 HU. Similarly, the mean absolute error in specific tissue classes was significantly reduced especially in the soft tissue-air interfaces. These results confirmed that applying MLT after HM worked better than using only HM for which the correlation values were ranging from 0.9878 to 0.9955 and the RMSE was 55.95 ± 10.43 HU.ConclusionEvaluation of the proposed approach showed that the HM + MLT correction can improve the HU distribution in the CBCT images and generate corrected images in good agreement with the pCT. |
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| Keywords: | HU CBCT correction Histogram matching Multilevel threshold Adaptive radiation therapy |
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