Technical note: Patient-morphed mesh-type phantoms to support personalized nuclear medicine dosimetry - A proof of concept study Journal Article


Authors: Carter, L. M.; Ocampo Ramos, J. C.; Bolch, W. E.; Lewis, J. S.; Kesner, A. L.
Article Title: Technical note: Patient-morphed mesh-type phantoms to support personalized nuclear medicine dosimetry - A proof of concept study
Abstract: Purpose: Current standard practice for clinical radionuclide dosimetry utilizes reference phantoms, where defined organ dimensions represent population averages for a given sex and age. Greater phantom personalization would support more accurate dose estimations and personalized dosimetry. Tailoring phantoms is traditionally accomplished using operator-intensive organ-level segmentation of anatomic images. Modern mesh phantoms provide enhanced anatomical realism, which has motivated their integration within Monte Carlo codes. Here, we present an automatable strategy for generating patient-specific phantoms/dosimetry using intensity-based deformable image registration between mesh reference phantoms and patient CT images. This work demonstrates a proof-of-concept personalized dosimetry workflow, presented in comparison to the manual segmentation approach. Methods: A linear attenuation coefficient phantom was generated by resampling the PSRK-Man reference phantom onto a voxel grid and defining organ regions with corresponding Hounsfield unit (HU) reference values. The HU phantom was co-registered with a patient CT scan using Plastimatch B-spline deformable registration. In parallel, major organs were manually contoured to generate a “ground truth” patient-specific phantom for comparisons. Monte Carlo derived S-values, which support nuclear medicine dosimetry, were calculated using both approaches and compared. Results: Application of the derived B-spline transform to the polygon vertices comprising the PSRK-Man yielded a deformed variant more closely matching the patient’s body contour and most organ volumes as-evaluated by Hausdorff distance and Dice metrics. S-values computed for fluorine-18 for the deformed phantom using the Particle and Heavy Ion Transport code System showed improved agreement with those derived from the patient-specific analog. Conclusions: Deformable registration techniques can be used to create a personalized phantom and better support patient-specific dosimetry. This method is shown to be easier and faster than manual segmentation. Our study is limited to a proof-of-concept scope, but demonstrates that integration of personalized phantoms into clinical dosimetry workflows can reasonably be achieved when anatomical images (CT) are available. © 2021 American Association of Physicists in Medicine
Keywords: computerized tomography; dosimetry; nuclear medicine; deformation; phantoms; image segmentation; manual segmentation; deformable registration; monte carlo methods; monte carlo simulation; monte carlo codes; linear attenuation coefficients; heavy ions; deformable image registration; interpolation; hausdorff distance; standard practices; mesh phantoms; personalized dosimetry; mesh generation; particle and heavy ion transport code systems
Journal Title: Medical Physics
Volume: 48
Issue: 4
ISSN: 0094-2405
Publisher: American Association of Physicists in Medicine  
Date Published: 2021-04-01
Start Page: 2018
End Page: 2026
Language: English
DOI: 10.1002/mp.14784
PUBMED: 33595863
PROVIDER: scopus
PMCID: PMC8058313
DOI/URL:
Notes: Article -- Export Date: 3 May 2021 -- Source: Scopus
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  1. Jason S Lewis
    458 Lewis
  2. Adam Leon Kesner
    68 Kesner
  3. Lukas M Carter
    79 Carter