Cardiac motion signal derived from optical images

(canceled)

A method of operating a medical apparatus, wherein the medical apparatus comprises an optical imaging system configured for acquiring a series of optical images descriptive of cardiac motion of a subject, wherein the method comprises repeatedly:

• acquiring a series of images using the optical imaging system, wherein the series of images are acquired at a rate of at least 10 frames per second;
• and
• deriving a cardiac motion signal from the series of images, wherein the cardiac motion signal is derived by tracking motion of a group of pixels within the series of images, wherein tracking is performed by extracting an anterior-posterior component of a body surface motion of the subject.

A computer program product comprising a non-transitory computer readable medium configured to store machine executable instructions for execution by a processor controlling a medical apparatus, wherein the medical apparatus comprises an optical imaging system configured for acquiring a series of optical images descriptive of cardiac motion of a subject, wherein execution of the machine executable instructions causes the processor to repeatedly:

• acquire a series of images using the optical imaging system, wherein the series of images are acquired at a rate of at least 10 frames per second;
• and
• derive a cardiac motion signal from the series of images, wherein the cardiac motion signal is derived by tracking motion of at least a group of pixels within the series of images, wherein tracking is performed by extracting an aterior-posterior component of a body surface motion of the subject.