Program Information
Clinical Applicability of An Optical-Surface-Imaging-Based Technique for Spirometric Measurement, Breathing Pattern Monitoring and Body Drift Correction
S Zhang1 , H Huang2 , J Wei3 , G Li4*, (1) Memorial Sloan Kettering Cancer Center, New York, NY, (2) Memorial Sloan Kettering Cancer Center, New York, NY, (3) City College of New York, New York, NY, (4) Memorial Sloan Kettering Cancer Center, New York, NY
Presentations
SU-D-202-7 (Sunday, July 31, 2016) 2:05 PM - 3:00 PM Room: 202
Purpose: To explore the capabilities of optical surface imaging (OSI) as a comprehensive tumor motion surrogate to provide dynamic spirometric measurements, breathing pattern monitoring and body positioning correction.
Methods: OSI captures the moving surface of the torso with all respiration-induced external motions in real time. Tidal volume (TV) and its time derivative (TV’, airflow) were measured based on the volume conservation rule within the pseudo-closed torso system: torso volume change equals TV in reference to full exhalation. In addition, breathing pattern (BP=ΔVchest/TV), indicating TV distribution within the torso, was quantified using this OSI-based technique. Moreover, slow body position changes were detected by OSI via surface image registration in every breathing cycle at full-exhalation phases, which are most reproducible phases unless voluntary body shift occurs. Volume changes due to body shift out of the volume of interest (VOI) were calculated to correct TV baseline drifts. Real-time OSI images captured in both high-resolution and low-resolution was applied for TV, TV’ and BP measurements and baseline drift correction. Eleven volunteers participated in the IRB-approved protocol study and performed free-breathing, belly-breathing and chest-breathing exercises during OSI image acquisition.
Results: Small TV baseline shifts are often observed in OSI-based spirometry measurement with an average rate of ~0.4cc/s. Using surface registration among full-exhalation phases and volume calculation from the body shifts relative to the fixed VOI, 80-90% baseline drift on average is corrected in three breathing exercises. The baseline drift is a useful indication of patient body shift and can be effectively corrected. When reducing OSI resolution from high to low, image capture rate increases from 5Hz to 10Hz, while the TV measurement accuracy is retained.
Conclusion: The OSI-based spirometric technique provides multiple parameters for monitoring patient respirations and body shift. The spirometric measurements, BP monitoring, and body-shift detection are useful for tumor motion surrogating.
Funding Support, Disclosures, and Conflict of Interest: This study is in part supported by the NIH (U54CA137788/U54CA132378).
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