SLP: A Zero-Contact Non-Invasive Method for Pulmonary Function Testing

Abstract

Structured Light Plethysmography (SLP) is a novel non-invasive method that uses structured light to perform pulmonary function testing that does not require physical contact with a patient. The technique produces an estimate of chest wall volume changes over time. A patient is observed continuously by two cameras and a known pattern of light (i.e. structured light) is projected onto the chest using an off-the-shelf projector. Corner features from the projected light pattern are extracted, tracked and brought into correspondence for both camera views over successive frames. A novel self calibration algorithm recovers the intrinsic and extrinsic camera parameters from these point correspondences. This information is used to reconstruct a surface approximation of the chest wall and several novel ideas for 'cleaning up' the reconstruction are used. The resulting volume and derived statistics (e.g. FVC, FEV) agree very well with data taken with a spirometer.

3D Data Acquisition and Registration Using Two Opposing Kinects

“…The first is based on dynamic human trunk 3D reconstruction for use in remote respiratory monitoring system. A relatively new area in remote depth-based lung function assessment using a single RGBD sensor is in formation, exemplified by [15,31,32,44,47]. These methods attempt to simulate traditional breathing tests, such as spirometry, however, none of these methods is able to decouple the subject's trunk motion from the subject's chest surface motion, which greatly affects the test results.…”

Tidal breathing parameters measured using structured light plethysmography in healthy children and those with asthma before and after bronchodilator

“…Average axial displacement of the light grid measures displacement over time from which tidal breathing indices can be calculated (De Boer et al. ; Motamedi‐Fakhr et al. ).…”

Non-contact respiratory monitoring in neonates

“…A major contributor to structured light plethysmography research is Cambridge University. Cambridge researchers (in cluding Brand [13], Usher-Smith [14] and deBoer [15]) com pared structured light techniques to pneumotachography and found a close match [13], and conducted a pilot study on infants and children finding an r-squared value of 0.97 when comparing volumes obtained using structured-light to those obtained using pneumatic methods [14]. Cambridge University has commercialised their system.…”

“…Cambridge University has commercialised their system. The system described be deBoer [15] uses two cameras for imaging.…”