[IEEE 2020 42nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) in conjunction with the 43rd Annual Conference of the Canadian Medical and Biological Engineering Society - Montreal, QC, Canada (2020.7.20-2020.7.24)] 2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Quantification of Advanced Dementia Patients’ Engagement in Therapeutic Sessions: An Automatic Video Based Approach using Computer Vision and Machine Learning