A model for gastrointestinal tract motility in a 4D imaging phantom of human anatomy Journal Article
| Authors: | Subashi, E.; Segars, P.; Veeraraghavan, H.; Deasy, J.; Tyagi, N. |
| Article Title: | A model for gastrointestinal tract motility in a 4D imaging phantom of human anatomy |
| Abstract: | Background: Gastrointestinal (GI) tract motility is one of the main sources for intra/inter-fraction variability and uncertainty in radiation therapy for abdominal targets. Models for GI motility can improve the assessment of delivered dose and contribute to the development, testing, and validation of deformable image registration (DIR) and dose-accumulation algorithms. Purpose: To implement GI tract motion in the 4D extended cardiac-torso (XCAT) digital phantom of human anatomy. Materials and Methods: Motility modes that exhibit large amplitude changes in the diameter of the GI tract and may persist over timescales comparable to online adaptive planning and radiotherapy delivery were identified based on literature research. Search criteria included amplitude changes larger than planning risk volume expansions and durations of the order of tens of minutes. The following modes were identified: peristalsis, rhythmic segmentation, high amplitude propagating contractions (HAPCs), and tonic contractions. Peristalsis and rhythmic segmentations were modeled by traveling and standing sinusoidal waves. HAPCs and tonic contractions were modeled by traveling and stationary Gaussian waves. Wave dispersion in the temporal and spatial domain was implemented by linear, exponential, and inverse power law functions. Modeling functions were applied to the control points of the nonuniform rational B-spline surfaces defined in the reference XCAT library. GI motility was combined with the cardiac and respiratory motions available in the standard 4D-XCAT phantom. Default model parameters were estimated based on the analysis of cine MRI acquisitions in 10 patients treated in a 1.5T MR-linac. Results: We demonstrate the ability to generate realistic 4D multimodal images that simulate GI motility combined with respiratory and cardiac motion. All modes of motility, except tonic contractions, were observed in the analysis of our cine MRI acquisitions. Peristalsis was the most common. Default parameters estimated from cine MRI were used as initial values for simulation experiments. It is shown that in patients undergoing stereotactic body radiotherapy for abdominal targets, the effects of GI motility can be comparable or larger than the effects of respiratory motion. Conclusion: The digital phantom provides realistic models to aid in medical imaging and radiation therapy research. The addition of GI motility will further contribute to the development, testing, and validation of DIR and dose accumulation algorithms for MR-guided radiotherapy. © 2023 American Association of Physicists in Medicine. |
| Keywords: | controlled study; comparative study; nuclear magnetic resonance imaging; magnetic resonance imaging; radiotherapy; patient monitoring; diagnostic imaging; retrospective study; algorithms; simulation; algorithm; image enhancement; medical imaging; computer simulation; phantoms, imaging; gastrointestinal tract; stereotactic body radiation therapy; small intestine; organ size; peristalsis; respiratory motions; image registration; respiratory mechanics; parameter estimation; phantoms; gastrointestinal motility; procedures; inverse problems; large intestine; heart left ventricle; three-dimensional imaging; humans; human; article; magnetic resonance imaging, cine; digital phantoms; cine magnetic resonance imaging; adaptive planning; dose accumulation; mr-guided rt; rational functions; t2 weighted imaging; four-dimensional imaging; images registration; digital phantom; cine-mri; tonic contraction |
| Journal Title: | Medical Physics |
| Volume: | 50 |
| Issue: | 5 |
| ISSN: | 0094-2405 |
| Publisher: | American Association of Physicists in Medicine |
| Date Published: | 2023-05-01 |
| Start Page: | 3066 |
| End Page: | 3075 |
| Language: | English |
| DOI: | 10.1002/mp.16305 |
| PUBMED: | 36808107 |
| PROVIDER: | scopus |
| PMCID: | PMC10561541 |
| DOI/URL: | |
| Notes: | The MSK Cancer Center Support Grant (P30 CA008748) is acknowledged in the PubMed record and PDF. Corresponding author is MSK author Ergys Subashi -- Source: Scopus |
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