System for monitoring a subject, the system comprising: an imaging unit configured to acquire image data over time from a field of view containing at least part of a subject, a projection unit configured to at least temporarily illuminate the field of view, the projection unit having a field of projection that substantially overlaps with the field of view of the imaging unit, and/or to indicate through illumination of the field of view if the spatial configuration of the subject with respect to the imaging unit can be maintained or shall be changed, and a device for monitoring a subject, the device comprising: - an input interface configured to obtain image data acquired over time by the imaging unit, - a monitoring signal determination unit configured to determine a monitoring signal from the obtained image data of the subject, - a processing unit configured to evaluate the image data to determine the spatial configuration of the subject with respect to the imaging unit and to generate a feedback signal for providing feedback about the determined spatial configuration, wherein the feedback signal is configured to control the projection unit to illuminate selected areas in the field of view and/or project one or more of symbols, colors, letters, and text to indicate through said illumination of the field of view and/or said projection if the spatial configuration can be maintained or shall be changed, and - an output interface configured to output the feedback signal. an imaging unit configured to acquire image data over time from a field of view containing at least part of a subject, a projection unit configured to at least temporarily illuminate the field of view, the projection unit having a field of projection that substantially overlaps with the field of view of the imaging unit, and/or to indicate through illumination of the field of view if the spatial configuration of the subject with respect to the imaging unit can be maintained or shall be changed, and a device for monitoring a subject, the device comprising: - an input interface configured to obtain image data acquired over time by the imaging unit, - a monitoring signal determination unit configured to determine a monitoring signal from the obtained image data of the subject, - a processing unit configured to evaluate the image data to determine the spatial configuration of the subject with respect to the imaging unit and to generate a feedback signal for providing feedback about the determined spatial configuration, wherein the feedback signal is configured to control the projection unit to illuminate selected areas in the field of view and/or project one or more of symbols, colors, letters, and text to indicate through said illumination of the field of view and/or said projection if the spatial configuration can be maintained or shall be changed, and - an output interface configured to output the feedback signal. - an input interface configured to obtain image data acquired over time by the imaging unit, - a monitoring signal determination unit configured to determine a monitoring signal from the obtained image data of the subject, - a processing unit configured to evaluate the image data to determine the spatial configuration of the subject with respect to the imaging unit and to generate a feedback signal for providing feedback about the determined spatial configuration, wherein the feedback signal is configured to control the projection unit to illuminate selected areas in the field of view and/or project one or more of symbols, colors, letters, and text to indicate through said illumination of the field of view and/or said projection if the spatial configuration can be maintained or shall be changed, and - an output interface configured to output the feedback signal.