Journal article
M. Lauria, Ruvini Navaratna, D. O'Connell, A. Santhanam, Percy Lee, D. Low
Medical physics, 2021
Medical physics, 2021
Semantic Scholar
DOI
PubMed
Cite
Cite
APA
Click to copy
Lauria, M., Navaratna, R., O'Connell, D., Santhanam, A., Lee, P., & Low, D. (2021). Technical Note: Investigating internal-external motion correlation using fast helical CT. Medical Physics.
Chicago/Turabian
Click to copy
Lauria, M., Ruvini Navaratna, D. O'Connell, A. Santhanam, Percy Lee, and D. Low. “Technical Note: Investigating Internal-External Motion Correlation Using Fast Helical CT.” Medical physics (2021).
MLA
Click to copy
Lauria, M., et al. “Technical Note: Investigating Internal-External Motion Correlation Using Fast Helical CT.” Medical Physics, 2021.
BibTeX Click to copy
@article{m2021a,
title = {Technical Note: Investigating internal-external motion correlation using fast helical CT.},
year = {2021},
journal = {Medical physics},
author = {Lauria, M. and Navaratna, Ruvini and O'Connell, D. and Santhanam, A. and Lee, Percy and Low, D.}
}
Abstract
PURPOSE To quantify the use of anterior torso skin surface position measurement as a breathing surrogate.
METHODS Fourteen patients were scanned 25 times in alternating directions using a free-breathing low-mA fast helical CT protocol. Simultaneously, an abdominal pneumatic bellows was used as a real-time breathing surrogate. The imaged diaphragm dome position was used as a gold-standard surrogate, characterized by localizing the most superior points of the diaphragm dome in each lung. These positions were correlated against the bellows signal acquired at the corresponding scan times. The bellows system has been shown to have a slow linear drift, and the bellows-to-CT synchronization process had a small uncertainty, so the drift and time offset were determined by maximizing the correlation coefficient between the craniocaudal diaphragm position and the drift-corrected bellows signal. The corresponding fit was used to model the real-time diaphragm position. To estimate the effectiveness of skin surface positions as surrogates, the anterior torso surface position was measured from the CT scans and correlated against the diaphragm position model. The residual error was defined as the root-mean square correlation residual with the breathing amplitude normalized to the 5th to 95th breathing amplitude percentiles. The fit residual errors were analyzed over the surface for the fourteen studied patients and reported as percentages of the 5th to 95th percentile ranges.
RESULTS A strong correlation was measured between the diaphragm motion and the abdominal bellows signal with an average residual error of 9.21% and standard deviation of 3.77%. In contrast, the correlations between the diaphragm position model and patient surface positions varied throughout the torso and from patient to patient. However, a consistently high correlation was found near the abdomen for each patient, and the average minimum residual error relating the skin surface to the diaphragm was 11.8% with a standard deviation of 4.61%.
CONCLUSIONS The thoracic patient surface was found to be an accurate surrogate, but the accuracy varied across the surface sufficiently that care would need to be taken to use the surface as an accurate and reliable surrogate. Future studies will use surface imaging to determine surface patch algorithms that utilize the entire chest as well as thoracic and abdominal breathing relationships.
