Apparatus and method for non-invasive and minimally-invasive sensing of parameters relating to blood

A system for monitoring one or more parameters relating to blood of a patient comprising:

• one or more optical transmitters configured to generate pulsed radiation containing photons having a specific interaction with at least one target chromophore in a target structure within the patient, said one or more optical transmitters configured and positioned to transmit the pulsed radiation from the optical transmitter into at least a first area including a substantial portion of the target structure and into a second area not including a substantial portion of the target structure;
• one or more optical receivers configured and positioned to detect a portion of the pulsed radiation scattered from at least the first area and the second area;
• and a processor configured to estimate the one or more parameters relating to the patient's blood, the estimation based in part on the scattered pulsed radiation detected from the first area, and the scattered pulsed radiation from the second area, wherein the processor comprises a central processing unit and a memory device and said one or more optical receivers are configured and adapted to measure optical properties associated with the second area, and wherein said processor is further configured to calculate a probability for the pulsed radiation to pass through the first area and the second area.