Registration of ultrasound to fluoroscopy for real time optimization of radiation implant procedures

Abstract

Transrectal ultrasound guided transperineal low dose-rate brachytherapy has been emerged as one of the definitive treatments of low-risk prostate cancer. Ultrasound has been an excellent tool in guiding the implant needles with respect to prostate anatomy, yet it cannot show reliably the location of radioactive seeds after they are released in the prostate. Intraoperative C-arm fluoroscopy can show the implanted seeds, but it cannot detect prostate anatomy. Intra-operative fusion of these two complementary modalities offers significant clinical benefit by allowing for real-time optimization of the brachytherapy implant as the procedure progresses in the operating room. Disclosed is a system and method for mitigating this problem and providing registration of seeds seen by fluoroscopy with live prostate anatomy visualized by transrectal ultrasound.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60 / 488,965, filed on Jul. 21, 2003, which is hereby incorporated by reference for all purposes as if fully set forth herein.[0002] Research and development efforts associated with the subject matter of this patent application was supported by the National Science Foundation under Grant No. #ERC 9731478.BACKGROUND OF THE INVENTION FIELD OF THE INVENTION [0003] The present invention relates to the registration of ultrasound and C-arm fluoroscopy imagery for the purposes of providing real-time optimization of medical procedures such as transperineal low-dose rate brachytherapy. [0004] Adenocarcinoma of the prostate is the most commonly diagnosed cancer in the U.S. male population. During the last half decade, there have been approximately 200,000 new cases of prostate cancer diagnosed each year, which is comparable to breast cancer diagnosis, and there is no evidence that this number would significant...

AI Technical Summary

Benefits of technology

The present invention is a system that combines ultrasound and fluoroscopy data to improve the visualization and control during radiation implant procedures. The system includes a fluoroscope, a sheath with fiducial marks, an ultrasound probe, and a computer. The system allows for better localization of radiation doses in cancer treatment, optimizes dose as the implant progresses, and enables dynamic dose calculation. The technical effects of the invention include improved visualization and control during radiation implant procedures, as well as better optimization of dose distribution.

Problems solved by technology

While C-arm fluoroscopy has been used intra-operatively, it has not been utilized in quantitative intra-operative analysis.

Very few attempts have been made to relate fluoroscopic images to soft tissue anatomy with little success.

Here the fundamental problem is matching large number of seeds with their projections in multiple X-ray images when some seeds obscure each other and solid objects also can get in the way.

Automated methods have been explored, but they also assume conditions that most likely cannot be met on a C-arm, particularly in a realistic intra-operative scenario.

Such assumptions include no extrinsic object in the field, optimal beam energy, arbitrary number and orientation of X-ray shots, or unlimited processing time and computational resources—none of which is realistic in real-time image-guided surgery.

In conclusion, “off-the-shelf” post-implant seed matching and reconstruction techniques cannot be expected to work in the operating room.

Many approaches have met with great difficulty due to the inability to accurately determine the imaging angles relative to the prostate for reconstruction of the multiple projection images.

This not only reduces accuracy, but makes the process too lengthy to be used intraoperatively.

The use of implanted needles as fiducial markers for registration of biplane TRUS data has been explored, but several key problems have been left unsolved: (1) The use of implanted needles as fiducials may not be practical, because most practitioners implant only one needle at a time and they do not use stabilizing needles.

During TRUS scanning, however, the prostate deforms, dislocates, and the needles dislocate relative to the prostate.

(4) Previous attempts did not account for the need to pre-operatively calibrate the C-arm fluoroscope, including removing image distortion and some form of intra-operative tracking to know where the multiple X-ray shots are coming with respect to one another.

Currently known dewarping and calibration kits are custom designed for each C-arm, making them hard to transfer from device to another.

Ultrasound has been an excellent tool in guiding the implant needles with respect to prostate anatomy, yet it cannot show reliably the location of radioactive seeds after they are released in the prostate.

Intraoperative C-arm fluoroscopy can show the implanted seeds, but it cannot detect prostate anatomy.

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