Illumination-Corrected NIR Imaging for Surgical Margin Detection

The patent introduces a reference signal as an intermediary element that mediates between the excitation energy variations and the fluorescence signal measurements. By capturing both the reference signal (representing excitation energy) and the fluorescence signal, then normalizing the fluorescence by the reference, the system achieves accurate dye concentration measurement without requiring complex hardware modifications. The reference signal acts as a mediator that carries information about excitation energy variations to enable correction.

The patent changes the parameter being measured from raw fluorescence intensity to normalized fluorescence intensity (fluorescence/reference ratio). This parameter transformation eliminates the dependency on excitation energy variations, as the ratio remains constant regardless of endoscope position or excitation intensity changes. By transforming the measurement parameter rather than the measurement process itself, the system achieves precision without proportional complexity increase.

The patent implements a feedback mechanism where the reference signal (capturing excitation energy levels) continuously informs the normalization process. As the endoscope moves and excitation energy varies, the reference signal captures these changes in real-time, and the normalization algorithm uses this feedback to adjust the fluorescence measurement accordingly. This closed-loop approach maintains measurement precision despite positional flexibility.

Instead of trying to maintain constant excitation energy through rigid endoscope positioning (conventional approach), the patent inverts the strategy: it allows excitation energy to vary freely with endoscope movement, then compensates by normalizing the fluorescence signal with the reference signal. This inversion transforms a constraint (positioning rigidity) into a solution (post-capture normalization).