Photodynamic therapy with spatially resolved dual spectroscopic monitoring
An instrument for photodynamic therapy applies treatment light from a dye laser, white light, and ultraviolet fluorescence excitation light from an LED onto a lesion and surrounding areas in a time-multiplexed manner. The reflected white light is analyzed in a spectrometer to determine a correction for the dynamic optical spectral properties of the patient's tissue. Light emitted by fluorescence from the lesion and the surrounding areas is analyzed in another spectrometer, and the results are corrected in a computer, using the correction. An optical switch has been developed for the instrument, using a bistable solenoid and a sled.
1. An instrument for performing photodynamic therapy on a treatment area comprising a target lesion and a perilesion margin of a living patient, the instrument comprising:
light sources for providing treatment light for activating photoactive drugs within the treatment area, broadband light for creating a first reflected light spectrum from the target lesion and a second reflected light spectrum from the perilesion margin, and fluorescence excitation light for creating a first fluorescence from the target lesion and a second fluorescence from the perilesion margin;
first optics for causing the treatment light, the broadband light and the fluorescence excitation light to be incident on the treatment area, whereby the broadband light is reflected from the treatment area and the fluorescence excitation light causes the treatment area to emit fluorescence;
second optics for receiving the first reflected light spectrum from the target lesion and the second reflected light spectrum from the perilesion margin and the first fluorescence from the target lesion and the second fluorescence from the perilesion margin;
a first spectrometer for receiving the first reflected light spectrum and the second reflected light spectrum from the second optics and for producing a signal representing the first reflected light spectrum and the second reflected light spectrum;
a second spectrometer for receiving the first fluorescence and the second fluorescence from the second optics and for producing a signal representing the first fluorescence and the second fluorescence; and
a computer, receiving the signals from the first and second spectrometers, for correcting the spectrum of the first fluorescence and the second fluorescence in accordance with the first reflected light spectrum and the second reflected light spectrum respectively and for providing the corrected first fluorescence and second fluorescence light spectrum for treatment optimization.
2. The instrument of claim 1 , wherein the first optics comprise an optical switch for time-multiplexing the treatment light and the broadband light.
3. The instrument of claim 2 , wherein the optical switch comprises:
a first optical fiber for supplying the treatment light to the optical switch;
a second optical fiber for supplying the broadband light to the optical switch;
a third optical fiber for selectively receiving the treatment light or the broadband light;
a sled for moving the third optical fiber to be in optical communication with the first optical fiber or the second optical fiber; and
a bistable solenoid for moving the sled.
4. The instrument of claim 3 , wherein each of the first, second and third optical fibers comprises a polished fiber end.
5. The instrument of claim 3 , wherein each of the first, second and third optical fibers is terminated by a lens.
6. The instrument of claim 5 , wherein the lens is a gradient index lens.
7. The instrument of claim 2 , wherein the optical switch comprises:
a first optical fiber for supplying the treatment light to the optical switch;
a second optical fiber for supplying the broadband light to the optical switch;
a Y coupler for selectively receiving the treatment light or the broadband light;
a bulkhead, having at least one through hole, for selectively blocking light from the first optical fiber or the second optical fiber to the Y coupler;
a sled for moving the bulkhead to block the light from the first optical fiber or the second optical fiber; and
a bistable solenoid for moving the sled.
8. The instrument of claim 2 , wherein the optical switch time-multiplexes the treatment light, the broadband light and the fluorescence excitation light.
9. The instrument of claim 1 , wherein the first optics comprise spatially resolving optics for causing the fluorescence excitation light to be incident on a plurality of locations in the region of interest.
10. The instrument of claim 9 , wherein the spatially resolving optics comprise a plurality of optical fibers, each for directing a portion of the fluorescence excitation light onto one of the plurality of locations.
11. The instrument of claim 10 , wherein each of the plurality of optical fibers in the spatially receiving optics is terminated by a lens.
12. The instrument of claim 11 , wherein the lens is a gradient index lens.
13. The instrument of claim 10 , wherein each of the plurality of optical fibers receives the reflected broadband light and the fluorescence emission light from said one of the plurality of locations and supplies the reflected broadband light and the fluorescence emission light to the second optics.
14. The instrument of claim 13 , wherein the second optics comprise an optical switch for selectively applying the reflected broadband light and the fluorescence emission light from each of the plurality of optical fibers selectively to each of the first and second spectrometers.
15. The instrument of claim 9 , wherein the spatially resolving optics comprise a scanning system for scanning the fluorescence excitation light onto the plurality of locations.
16. The instrument of claim 15 , wherein the scanning system comprises at least one movable mirror.
17. The instrument of claim 1 , wherein the second optics comprise a dichroic mirror for spectrally separating the fluorescence excitation light from the fluorescence emission light.
18. The instrument of claim 17 , wherein the first optics apply the fluorescence excitation light to the region of interest by using the dichroic mirror.