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.

1 . A system for registering ultrasound and fluoroscopy data comprising: 
 a fluoroscope;    a sheath having fiducial marks disposed on a portion of its outer surface;    an ultrasound probe insertable into the sheath;    a computer; and    a computer readable medium encoded with a program for registering a first set of data acquired by the ultrasound probe with a second set of data acquired by the fluoroscope.    
   
   
       2 . The system of  claim 1 , wherein the ultrasonic probe includes a stepper.  
   
   
       3 . The system of  claim 1 , wherein the fiducial marks comprise Tantalum.  
   
   
       4 . The system of  claim 1 , wherein the fiducial marks comprise a wire including a thickness of substantially 1 mm.  
   
   
       5 . The system of  claim 1 , wherein the fluoroscope is a C-arm fluoroscope comprising an image intensifier.  
   
   
       6 . The system of  claim 1 , wherein the sheath comprises a thin plastic.  
   
   
       7 . The system of  claim 1 , further comprising a gel material disposed between the sheath and the ultrasound probe.  
   
   
       8 . A method for registering ultrasound to fluoroscopy comprising the steps of: 
 calibrating a fluoroscope;    acquiring ultrasound data using an ultrasound probe;    acquiring fluoroscopy data from the fluoroscope;    registering the ultrasound data to the fluoroscopy data to create a set of registered data;    identifying at least one radiation seed in the registered data; and    computing a radiation dose corresponding to the at least one radiation seed.    
   
   
       9 . The method of  claim 8 , wherein the step of calibrating the fluoroscope comprises the steps of: 
 attaching a dewarping plate having a bead pattern to the fluoroscope;    acquiring calibration data from the fluoroscope;    correlating the calibration data to the bead pattern;    determining a transformation corresponding to the correlating; and    aligning the calibration data to the bead pattern.    
   
   
       10 . The method of  claim 8 , wherein the step of acquiring fluoroscopy data comprises the steps of: 
 acquiring an image from the fluoroscope;    dewarping the image;    reducing noise in the image;    normalizing the image;    removing background from the image;    thresholding the image; and    pre-labeling the image.