Systems and methods for registering images obtained using various imaging modalities and verifying image registration
Embodiments of the present invention provide systems and methods to detect a moving anatomic feature during a treatment sequence based on a computed and/or a measured shortest distance between the anatomic feature and at least a portion of an imaging system.
1. A method for detecting a moving anatomic feature during a treatment sequence, the method comprising:
(a) prior to the treatment sequence, (i) acquiring a first image of the anatomic feature and at least a portion of a first image-acquisition device, and (ii) processing the first image to compute a first shortest distance between the anatomic feature and the at least a portion of the first image-acquisition device; and
(b) during the treatment sequence, (i) activating the first image-acquisition device to measure-a second shortest distance between the anatomic feature and the at least a portion of the first image-acquisition device, (ii) comparing the measured second shortest distance to the computed first shortest distance obtained in step (a) to determine a deviation therefrom, and (iii) determining movement of the anatomic feature based on the deviation.
2. The method of claim 1 , wherein the first image is acquired using a second image-acquisition device, the method further comprising, prior to the treatment sequence, acquiring a second image of the anatomic feature using a third imaging system.
3. The method of claim 2 , wherein the first, second, and third image-acquisition devices comprise an ultrasound transducer system, a magnetic-resonance imaging (MRI) system, and a computed tomography (CT) system, respectively.
4. The method of claim 3 , further comprising obtaining positions of the at least a portion of the first image-acquisition device in a coordinate system of the first image-acquisition device.
5. The method of claim 4 , wherein the positions of the at least a portion of the first image-acquisition device are determined based on a time-of-flight method.
6. The method of claim 4 , further comprising computing a transformation relating the coordinate system of the first image-acquisition device and a coordinate system of the second image-acquisition device based on the positions of the at least a portion of the first image-acquisition device in the first image and in the coordinate system of the first image-acquisition device.
7. The method of claim 6 , further comprising transforming the positions of the first image-acquisition device from the coordinate system of the first image-acquisition device to the coordinate system of the second image-acquisition device based on the computed transformation.
8. The method of claim 7 , further comprising registering the first image and the second image.
9. The method of claim 8 , further comprising transforming the second image of the anatomic feature from a coordinate system of the third image-acquisition device to the coordinate system of the second image-acquisition device.
10. The method of claim 9 , wherein the first shortest distance is computed based on the transformed positions of the first image-acquisition device and transformed second image in the coordinate system of the second image-acquisition device.
11. The method of claim 10 , wherein the second shortest distance between the anatomic feature and the at least a portion of the first image-acquisition device is measured based on signals transmitted from and received by the first image-acquisition device.
12. The method of claim 11 , further comprising transforming the measured second shortest distance from the coordinate system of the first image-acquisition device to the coordinate system of the second image-acquisition device.
13. The method of claim 12 , further comprising comparing the deviation to a predetermined threshold and determining movement of the anatomic feature based on the comparison.
14. A system for detecting a moving anatomic feature during a treatment sequence, the system comprising:
a first image-acquisition device for acquiring a first image of the anatomic feature and at least a portion of a second image-acquisition device prior to the treatment sequence; and
a controller in communication with the first and second systems, the controller being configured to:
(a) prior to the treatment sequence, process the first image to compute a first shortest distance between the anatomic feature and the at least a portion of the second image-acquisition device; and
(b) during the treatment sequence, (i) activate the second image-acquisition device to measure a second distance between the anatomic feature and the at least a portion of the second image-acquisition device, (ii) compare the measured second shortest distance to the computed first shortest distance obtained in step (a) to determine a deviation therefrom, and (iii) determine movement of the anatomic feature based on the deviation.
15. The system of claim 14 , further comprising a third image-acquisition device for acquiring a second image of the anatomic feature prior to the treatment sequence.
16. The system of claim 15 , wherein the first, second, and third image-acquisition devices comprise a magnetic-resonance imaging (MRI) system, an ultrasound transducer system, and a computed tomography (CT) system, respectively.
17. The system of claim 16 , wherein the controller is further configured to obtain positions of the at least a portion of the second image-acquisition device in a coordinate system of the second image-acquisition device.
18. The system of claim 17 , wherein the controller is further configured to determine the positions of the at least a portion of the second image-acquisition device based on a time-of-flight method.
19. The system of claim 17 , wherein the controller is further configured to compute a transformation relating the coordinate system of the second image-acquisition device and a coordinate system of the first image-acquisition device based on the positions of the at least a portion of the second image-acquisition device in the first image and in the coordinate system of the second image-acquisition device.
20. The system of claim 19 , wherein the controller is further configured to transform the positions of the second image-acquisition device from the coordinate system of the second image-acquisition device to the coordinate system of the first image-acquisition device based on the computed transformation.
21. The system of claim 20 , wherein the controller is further configured to register the first image and the second image.
22. The system of claim 21 , wherein the controller is further configured to transform the second image of the anatomic feature from a coordinate system of the third image-acquisition device to the coordinate system of the first image-acquisition device.
23. The system of claim 22 , wherein the controller is further configured to compute the first shortest distance based on the transformed positions of the second image-acquisition device and transformed second image in the coordinate system of the first image-acquisition device.
24. The system of claim 23 , wherein the controller is further configured to measure the second shortest distance based on signals transmitted from and received by the second image-acquisition device.
25. The system of claim 24 , wherein the controller is further configured to transform the measured second shortest distance from the coordinate system of the second image-acquisition device to the coordinate system of the first image-acquisition device.
26. The system of claim 25 , wherein the controller is further configured to compare the deviation to a predetermined threshold and determine movement of the anatomic feature based on the comparison.