Detailed Pediatric Heart Models for Dose Reconstruction of Children in the National Wilms Tumor Study
C Lee1*, M Mille2, C Rigsby3, A Popescu4, K Griffin5, M Gopalakrishnan6, J Jung7, C Lee8, J Kalapurakal9, (1) University of Michigan, Ann Arbor, MI, (2) National Cancer Institute, Bethesda, MD, (3) Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, (4) Ann & Robert H. Lurie Children's Hospital of Chicago, ,,(5) National Cancer Institute, Rockville, MD, (6) Northwestern Memorial Hospital, Chicago, IL, (7) East Carolina Univ, Greenville, NC, (8) University of Michigan, Ann Arbor, MI, (9) Northwestern Memorial Hospital,
Presentations
SU-K-202-2 (Sunday, 7/10/2022) 5:00 PM - 6:00 PM [Eastern Time (GMT-4)]
Room 202
Purpose: Cardiac complication is one of the concerns in the long-term survivors of childhood cancer and emerging data suggest that cardiac substructure doses may be better predictive of toxicity in patients than the whole heart doses. However, detailed pediatric heart models for sophisticated dosimetry are scarce. We developed a series of pediatric heart models with detailed substructures and applied them to the calculation of heart substructure doses for selected Wilms tumor patients treated with external radiotherapy.
Methods: We created three pediatric heart models with 15 detailed heart substructures segmented from the high-resolution MR images of 1-, 5-, and 10-year-old reference size patients by a cardiac MRI radiologist. We implemented the heart models into the body size-dependent computational human phantom library by using 3D mesh registration techniques. The computational phantom library was then converted into DICOM-RT format and imported into a commercial treatment planning system for radiotherapy plan reconstruction. Finally, we conducted Monte Carlo dose calculations for 13 Wilms tumor patients selected from the National Wilms Tumor Study cohort to evaluate the dosimetric performance of the new heart models.
Results: We developed three detailed heart models for 1, 5, and 10 years including two atria, two ventricles, left ventricle myocardium, four arteries, four valves, and two nodes, and implemented them into the six existing body size-dependent phantoms. From Monte Carlo dose calculations, we found the absolute dose differences between the whole heart and the substructures were about 6 - 8% of the mean prescribed dose (about 2700 cGy).
Conclusion: We created a series of pediatric heart models with detailed substructures and implemented them into the computational human phantom library in DICOM-RT format. The improved phantom library should be useful for estimating more accurate heart substructure doses for pediatric and adult radiotherapy patients involved in late-effects studies.
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