Repurposing the Microsoft Kinect for Windows v2 for external head motion tracking for brain PET

Abstract

Medical imaging systems such as those used in positron emission tomography (PET) are capable of spatial resolutions that enable the imaging of small, functionally important brain structures. However, the quality of data from PET brain studies is often limited by subject motion during acquisition. This is particularly challenging for patients with neurological disorders or with dynamic research studies that can last 90 min or more. Restraining head movement during the scan does not eliminate motion entirely and can be unpleasant for the subject. Head motion can be detected and measured using a variety of techniques that either use the PET data itself or an external tracking system. Advances in computer vision arising from the video gaming industry could offer significant benefits when re-purposed for medical applications. A method for measuring rigid body type head motion using the Microsoft Kinect v2 is described with results presenting ⩽0.5 mm spatial accuracy. Motion data is measured in real-time at 30 Hz using the KinectFusion algorithm. Non-rigid motion is detected using the residual alignment energy data of the KinectFusion algorithm allowing for unreliable motion to be discarded. Motion data is aligned to PET listmode data using injected pulse sequences into the PET/CT gantry allowing for correction of rigid body motion. Pilot data from a clinical dynamic PET/CT examination is shown.

The feasibility of using Microsoft Kinect v2 sensors during radiotherapy delivery

“…The measured distance accuracy of the Kinect v2 sensors is similar to that reported by others for both v1 and v2 sensors: several millimeters which can be reduced to $<2\text{mm}$ or better with an appropriate correction 13 , 14 , 18 , 20 . Where systems are to be used for a clinical application, particularly if that involves monitoring small movements of a patient, it is important to determine the magnitude and impact of any EMI effect.…”

“…Whilst these provide no information about the internal anatomy of the patient, they may be used in conjunction with ionizing radiation imaging to provide frequent or continuous monitoring throughout the radiation delivery, as they do not contribute to the radiation dose burden. Recently some groups have investigated surface monitoring for radiotherapy and PET imaging using consumer‐grade sensors designed for the entertainment industry — the Microsoft Kinect devices 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 . The potential advantage of commercial off‐the‐shelf (COTS) devices is the low cost (less than $~\$\mathrm{1,400}$ for a Kinect device and accessories compared to upwards of $250,000 for the commercial medical systems), thus enabling many sensors in many rooms, depending on the application.…”

Low‐cost Kinect Version 2 imaging system for breath hold monitoring and gating: Proof of concept study for breast cancer VMAT radiotherapy

“…The Kinect v2 has already been used for external head motion tracking in brain PET scans,10 respiratory motion correction in PET scans11 and respiratory motion tracking in radiotherapy using a marker‐based system 12. Previous work has shown that the sensor has distance accuracy and precision of 1 to 2 mm after calibration, which is sufficient for breath‐hold monitoring where changes are 5 to 10 mm in magnitude 10, 11, 13, 14, 15.…”

“…Previous work has shown that the sensor has distance accuracy and precision of 1 to 2 mm after calibration, which is sufficient for breath‐hold monitoring where changes are 5 to 10 mm in magnitude 10, 11, 13, 14, 15. In our previous work,13 we demonstrated that the Kinect v2 can be used safely in a radiation environment without image distortions caused by the radiation beam.…”

Implementation of facial recognition with Microsoft Kinect v2 sensor for patient verification

“…It has been made available as a royalty‐free development platform with a free software development kit (SDK) containing many sample applications . This open‐sourced availability has allowed Kinect developers to create an array of applications for the medical community; from touch‐less panning of CT scans during surgery to respiratory motion tracking for gating . The Kinect has been shown to be a valuable tool in various fields of medicine due to its ability to combine a color, infrared, and depth sensor in a single system.…”