Lung Perfused Blood Volume Calculated From Dynamic Contrast Enhanced DECT for Radiation Treatment Planning of Lung Cancer International Journal of Radiation Oncology Biology Physics G. Noid, A. Tai, H. Zhong, J. Shah, E.M. Gore, A. Li, Lung Perfused Blood Volume Calculated From Dynamic Contrast Enhanced DECT for Radiation Treatment Planning of Lung Cancer, International Journal of Radiation Oncology*Biology*Physics, Volume 111, Issue 3, Supplement, 2021
Date
11/01/2021Abstract
Purpose/Objective(s)
In radiation therapy planning for lung cancer, it is desirable to minimize irradiation of functional lung tissue which may be mapped by the spatial distribution of perfused blood volume (PBV). In this exploratory study, we investigate the feasibility of generating PBV distribution based on equilibrium contrast enhanced dual-energy CT (DECT) routinely acquired at the time of CT simulation for lung cancer patients.
Materials/Methods
DECT data with iodine-based intravenous (IV) contrast enhancement along with 4DCT acquired using a Dual Source DECT scanner (Drive, Siemens Healthcare, Germany) for 5 lung cancer patients during routine CT simulation were analyzed. The delay of the IV contrast injection was calculated for each patient via a circular scan monitoring a region of interest (ROI) in the pulmonary trunk for a CT number increase of 150 HU. This increase triggers a further 7 second delay after which the scanner rapidly performs two simultaneous acquisitions, the first at a tubevoltage of 80 kV and the second at a tube voltage of 140 kV with Sn filtration. For each patient the PBV was automatically calculated via post-processing at the console. The obtained PBV maps were compared to ventilation maps calculated in a programming environment using a HU-based method from the 4DCT, which was sorted into 10 bins based on respiratory phase. The image set of the end of the inhale phase was warped to the image set of the end of the exhale phase (target images) in MIM software using an intensity-based deformable image registration algorithm. The HU values of the warped and target images in each associated voxel pair inside lung contours were used to calculate local lung volume changes.
Results
The obtained lung PBV maps demonstrated heterogeneity in lung function for all patients. The average PBV in arbitrary units was 52.3 ± 16.7. The PBV distribution for 4 patients had a single peak, while therewas a bifurcation for one case. For one of the patients, the image quality was degraded by high Z materials in the patient's shoulders. For one of the patients there was a correlation between the PBV map and the ventilation map. The tidal volumes calculated using the ventilation images agree within 5% with those measured through volume difference of lung contours on end of exhale and end of inhale images, indicating the accuracy of the ventilation images.
Conclusion
Lung PBV maps derived from equilibrium contrast enhanced DECT acquired for radiation therapy planning may provide a valuable new tool to assess the spatial distribution of normal lung function, alternative to the lung ventilation map. With additional study the PBV maps may be used to guide radiation treatment planning for lung cancer patients.
Author List
G. Noid A. Tai H. Zhong J. Shah E.M. Gore A. LiAuthor
Elizabeth M. Gore MD Professor in the Radiation Oncology department at Medical College of WisconsinView Online
