TITLE:
Markerless Respiratory Motion Tracking Using Single Depth Camera
AUTHORS:
Shinobu Kumagai, Ryohei Uemura, Toru Ishibashi, Susumu Nakabayashi, Norikazu Arai, Takenori Kobayashi, Jun’ichi Kotoku
KEYWORDS:
Depth Camera, Markerless, Motion Tracking, Intra-Fractional Motion, Three-Dimensional Surface
JOURNAL NAME:
Open Journal of Medical Imaging,
Vol.6 No.1,
March
25,
2016
ABSTRACT: The aim of this study is to propose a novel
system that has an ability to detect intra-fractional motion during
radiotherapy treatment in real-time using three-dimensional surface taken by a
depth camera, Microsoft Kinect v1. Our approach introduces three new aspects
for three-dimensional surface tracking in radiotherapy treatment. The first
aspect is a new algorithm for noise reduction of depth values. Ueda’s algorithm
was implemented and enabling a fast least square regression of depth values.
The second aspect is an application for detection of patient’s motion at
multiple points in thracoabdominal regions. The third aspect is an estimation
of three-dimensional surface from multiple depth values. For evaluation of
noise reduction by Ueda’s algorithm, two respiratory patterns are measured by
the Kinect as well as a laser range meter. The resulting cross correlation
coefficients between the laser range meter and the Kinect were 0.982 for
abdominal respiration and 0.995 for breath holding. Moreover, the mean cross
correlation coefficients between the signals of our system and the signals of
Anzai with respect to participant’s respiratory motion were 0.90 for thoracic
respiration and 0.93 for abdominal respiration, respectively. These results
proved that the performance of the developed system was comparable to existing
motion monitoring devices. Reconstruction of three-dimensional surface also
enabled us to detect the irregular motion and breathing arrest by comparing the
averaged depth with predefined threshold values.