4DCBCT Detection of Lung Compliance Change in Irradiated Rats: A Validation Study
K Ding1,3*, J Deng2,3, Q Chen3, J Larner3, J Wong1, P Kazanzides1, (1) Johns Hopkins University, Baltimore, MD, (2) Fourth Military Medical University and Xijing Hospital, Xi'an, Shanxi, (3) University of Virginia, Charlottesville, VASU-E-J-190 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: The lung is often included in the radiation field in the treatment of malignant tumors in the thoracic region and is often the dose-limiting normal tissue. Different interventions, such as fractionation design, lung radioprotector and tumor radiosensitizer drugs are increasingly common in human clinical trials. We propose a 4DCBCT based small animal lung compliance imaging technique on small animal research platform (SARRP) to facilitate testing of the radiation induced lung injuries and the interventions in animal models.
Methods: The end of inhale and end of exhale phases of 4DCBCT are first registered. The compliance at each voxel is derived from the regional expansion calculated from tissue volume preserved deformable image registration and the lung pressure monitored from the pressure sensor. Two lab rats were used in this study. One was irradiated with the 60 Gy using 3 x 9 mm cone to the left lower lung and the other served as the control. Compliance maps were acquired with the pressure triggered 4DCBCT on SARRP seven months after radiation. Both the control and the test rat were perfused with normal saline and the whole lung was taken out for post-fixation overnight.
Results: Significant compliance difference is found after seven month of radiation between the irradiated rat left lower lung (0.57±0.08) and the counter part of the right lower lung (0.75±0.06). Significant compliance difference is also found between the irradiated rat left lower lung and the counter part of the control rat (0.79±0.06). The low compliance region was confirmed from the scar as indicated by digital pictures from post-fixation lung.
Conclusion: We proposed a method that uses 4DCBCT based compliance imaging and compared the irradiated animal seven months after radiation with the control animal. Our study validated the compliance measurement by the anatomical change observed from post-fixation.
Funding Support, Disclosures, and Conflict of Interest: This study is supported in part by UVa George Amorino Pilot Grant.