Apparatus and method for generating 3-D data for an anatomical target using optical fiber shape sensing
A fiber housing includes multiple shape sensing cores and a single optical core. A distal end of the fiber housing is positionable to direct the single optical core to a current point of an anatomical target. Collimated light over a first range of frequencies is projected from the single optical core to the current point. OFDR is used to detect reflected light scattered from the current point and to process the detected light to determine a distance to the current point. Light over a second range of frequencies is projected through the multiple shape sensing optical cores to the distal end of the fiber housing. OFDR is used to measure light reflected from the distal end of the fiber housing back through the multiple shape sensing optical cores and to process the measurement to determine a position in three dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing. A position in three dimensional space of the current point is determined based on the determined position in three dimensional space of the distal end of the fiber housing, the pointing direction of the distal end of the fiber housing, and the determined distance.
1. A method of operating an interferometric system to use multiple shape-sensing optical cores and a single optical core in a fiber housing to generate a three-dimensional data set for at least a portion of a target based on distance measurements of multiple points of the target from a distal end of the fiber housing and measurements of respective three-dimensional positions of the distal end, the multiple shape-sensing cores located alongside the single optical core, the method comprising:
(a) projecting, over a first range of multiple frequencies, collimated light from the single optical core to a current point of the target while the distal end of the fiber housing is directed toward the current point;
(b) using optical frequency domain reflectometry to detect reflected light scattered from the current point and to process the reflected light to determine a distance of the distal end to the current point;
(c) projecting, over a second range of multiple frequencies, light through the multiple shape-sensing optical cores to the distal end of the fiber housing;
(d) using optical frequency domain reflectometry to obtain a measurement of light reflected from the distal end of the fiber housing back through the multiple shape-sensing optical cores and to process the measurement to determine a position in three-dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing;
(e) using the determined position in three-dimensional space of the distal end of the fiber housing, the pointing direction of the distal end of the fiber housing, and the determined distance to determine a position in three-dimensional space of the current point; and
repeating (a)-(e) multiple times for multiple additional current points of the target to generate the three-dimensional data set for at least the portion of the target,
wherein, to generate the three-dimensional data set, the single optical core is used only to determine distances of the distal end to the multiple points of the target, and wherein generating the three-dimensional data set requires combining the distances with the respective three-dimensional positions of the distal end.
2. The method in claim 1 , further comprising:
expressing the pointing direction of the distal end of the fiber housing as a unit vector pointing in a direction of the distal end of the fiber housing along a pointing axis;
multiplying the unit vector by the determined distance to generate a reflection distance vector; and
combining the determined position in three-dimensional space of the distal end of the fiber housing with the reflection distance vector to generate the determined position in three-dimensional space of the current point in or on the target.
3. The method in claim 1 , further comprising generating a tomographical map of at least a portion of a surface of the target based on the three-dimensional data set.
4. The method in claim 1 , further comprising generating a tomographical map of at least a portion of the target beneath a surface of the target based on the three-dimensional data set.
5. The method in claim 1 , further comprising using the three-dimensional data set to provide navigation guidance relative to the target.
6. The method in claim 1 , further comprising:
detecting relative optical phase shifts in the reflected light caused by motion of the target and compensating the three-dimensional data set for motion of the target based on the detected relative optical phase shifts.
7. The method in claim 1 , further comprising:
determining a position in three-dimensional space of points on an outside of the target to determine a location of the target in three-dimensional space, and
using the determined location of the target in three-dimensional space and a radiation-based scan of the target to determine a location of one or more structures inside the target in three-dimensional space.
8. An interferometric measurement system for generating a three-dimensional data set for at least a portion of an anatomical target based on distance measurements of multiple points of the target from a distal end of a fiber housing and measurements of respective three-dimensional positions of the distal end, the system comprising:
the fiber housing and, contained in the fiber housing, multiple shape-sensing optical cores and a single optical core alongside the multiple shape-sensing optical cores, the fiber housing being positionable to direct the single optical core to a current point of the anatomical target;
a tunable light source configured to (a) project, over a first range of multiple frequencies, light through the single optical core and a collimator to the current point; and
circuitry configured to (b) detect reflected light scattered from the current point and to process the reflected light to determine a distance of the distal end of the fiber housing to the current point using optical frequency domain reflectometry (OFDR);
the tunable light source being further configured to (c) project, over a second range of multiple frequencies, light through the multiple shape-sensing optical cores to the distal end of the fiber housing;
the circuitry being further configured to (d) measure light reflected from the distal end of the fiber housing back through the multiple shape-sensing optical cores and to (e) process the measured light to determine a position in three-dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing using OFDR;
the circuitry being further configured to (f) determine a position in three-dimensional space of the current point based on the determined position in three-dimensional space of the distal end of the fiber housing, the pointing direction of the distal end of the fiber housing, and the determined di stance,
wherein the tunable light source and the circuitry are configured to perform respective ones of (a)-(f) multiple times to generate the three-dimensional data set for at least the portion of the anatomical target, wherein the single optical core is used only to determine distances of the distal end to the multiple points of the target, and wherein generating the three-dimensional data set requires combining the distances with the respective three-dimensional positions of the distal end.
9. The interferometric measurement system in claim 8 , wherein the circuitry is further configured to:
express the pointing direction of the distal end of the fiber housing as a unit vector pointing in a direction of the distal end of the fiber housing along a pointing axis;
multiply the unit vector by the determined distance to generate a reflection distance vector; and
combine the determined position in three-dimensional space of the distal end of the fiber housing with the reflection distance vector to generate the determined position in three-dimensional space of the current point.
10. The interferometric measurement system in claim 8 , wherein the circuitry is further configured to process a time delay from a reflection at the collimator to a first reflection scattered from the current point as an indication of the distance from the distal end of the fiber housing to the current point.
11. The interferometric measurement system in claim 8 , wherein the multiple cores and the single core are in a same fiber.
12. The interferometric measurement system in claim 8 , wherein the multiple shape-sensing cores and the single core are in different fibers, and wherein the different fibers are fixed in a known positional relationship with each other.
13. The interferometric measurement system in claim 8 , further comprising:
an actuator configured to direct the distal end of the fiber housing at a second current point of the anatomical target.
14. The interferometric measurement system in claim 8 , wherein the three-dimensional data set provides information about a distribution of tissue of an area in the anatomical target.
15. The interferometric measurement system in claim 8 , wherein the circuitry is configured to generate a tomographical map of at least a portion of a surface of the anatomical target based on the three-dimensional data set.
16. The interferometric measurement system in claim 8 , wherein the circuitry is configured to generate a tomographical map of at least a portion of the anatomical target beneath a surface of the anatomical target based on the three-dimensional data set.
17. The interferometric measurement system in claim 8 , wherein the circuitry is configured to:
determine a position in three-dimensional space of points on an outside of the anatomical target to determine a location of the anatomical target in three-dimensional space, and
use the determined location of the anatomical target in three-dimensional space and a radiation-based scan of the anatomical target to determine a location of one or more structures inside the anatomical target in three-dimensional space.
18. The interferometric measurement system in claim 8 , wherein the circuitry is configured to detect relative optical phase shifts in the reflected light caused by motion of anatomical target tissue and compensate the three-dimensional data set for motion of anatomical target tissue based on the relative optical phase shifts.
19. A non-transitory machine-readable medium comprising a plurality of machine-readable instructions which when executed by one or more processors associated with a medical device are adapted to cause the one or more processors and the medical device, under control of the one or more processors, to perform a method for generating a three-dimensional data set for at least a portion of a target based on distance measurements of multiple points of the target from a distal end of a fiber housing and measurements of respective three-dimensional positions of the distal end, the medical device comprising the fiber housing and, located in the fiber housing alongside each other, a single optical core and multiple shape-sensing optical cores, the method comprising the steps of:
(a) projecting, over a first range of multiple frequencies, collimated light from the single optical core to a current point of the target, while the distal end of the fiber housing is directed toward the current point;
(b) using optical frequency domain reflectometry to detect reflected light scattered from the current point and to process the reflected light to determine a distance of the distal end to the current point;
(c) projecting, over a second range of multiple frequencies, light through the multiple shape-sensing optical cores to the distal end of the fiber housing;
(d) using optical frequency domain reflectometry to obtain a measurement of light reflected from the distal end of the fiber housing back through the multiple shape-sensing optical cores and to process the measurement to determine a position in three-dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing;
(e) using the determined position in three-dimensional space of the distal end of the fiber housing, the pointing direction of the distal end of the fiber housing, and the determined distance to determine a position in three-dimensional space of the current point; and
repeating steps (a)-(e) multiple times for multiple additional current points of the target to generate the three-dimensional data set for at least the portion of the target,
wherein the single optical core is used only to determine distances of the distal end to the multiple points of the target, and wherein generating the three-dimensional data set requires combining the distances with the respective three-dimensional positions of the distal end.
20. The non-transitory machine-readable medium of claim 19 , wherein the steps further comprise detecting relative optical phase shifts in the reflected light caused by motion of the target, and compensating the three-dimensional data set for motion of the target based on the relative optical phase shifts.