Dosimetric evaluation of an atlas-based synthetic CT generation approach for MR-only radiotherapy of pelvis anatomy Journal Article


Authors: Farjam, R.; Tyagi, N.; Deasy, J. O.; Hunt, M. A.
Article Title: Dosimetric evaluation of an atlas-based synthetic CT generation approach for MR-only radiotherapy of pelvis anatomy
Abstract: Purpose: To investigate the potential of an atlas-based approach in generation of synthetic CT for pelvis anatomy. Methods: Twenty-three matched pairs of computed tomography (CT) and magnetic resonance imaging (MRI) scans were selected from a pool of prostate cancer patients. All MR scans were preprocessed to reduce scanner- and patient-induced intensity inhomogeneities and to standardize their intensity histograms. Ten (training dataset) of 23 pairs were then utilized to construct the coregistered CT-MR atlas. The synthetic CT for a new patient is generated by appropriately weighting the deformed atlas of CT-MR onto the new patient MRI. The training dataset was used as an atlas to generate the synthetic CT for the rest of the patients (test dataset). The mean absolute error (MAE) between the deformed planning CT and synthetic CT was computed over the entire CT image, bone, fat, and muscle tissues. The original treatment plans were also recomputed on the new synthetic CTs and dose–volume histogram metrics were compared. The results were compared with a commercially available synthetic CT Software (MRCAT) that is routinely used in our clinic. Results: MAE errors (±SD) between the deformed planning CT and our proposed synthetic CTs in the test dataset were 47 ± 5, 116 ± 12, 36 ± 6, and 47 ± 5 HU for the entire image, bone, fat, and muscle tissues respectively. The MAEs were 65 ± 5, 172 ± 9, 43 ± 7, and 42 ± 4 HU for the corresponding tissues in MRCAT CT. The dosimetric comparison showed consistent results for all plans using our synthetic CT, deformed planning CT and MRCAT CT. Conclusion: We investigated the potential of a multiatlas approach to generate synthetic CT images for the pelvis. Our results demonstrate excellent results in terms of HU value assignment compared to the original CT and dosimetric consistency. © 2018 Memorial Sloan Kettering Cancer Center. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
Keywords: synthetic ct; generalized registration error; bone- and fat-suppressed ct; pelvis anatomy
Journal Title: Journal of Applied Clinical Medical Physics
Volume: 20
Issue: 1
ISSN: 1526-9914
Publisher: American College of Medical Physics  
Date Published: 2019-01-01
Start Page: 101
End Page: 109
Language: English
DOI: 10.1002/acm2.12501
PUBMED: 30474353
PROVIDER: scopus
PMCID: PMC6333120
DOI/URL:
Notes: Article -- Export Date: 1 February 2019 -- Source: Scopus
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MSK Authors
  1. Joseph Owen Deasy
    277 Deasy
  2. Margie A Hunt
    228 Hunt
  3. Neelam Tyagi
    54 Tyagi