Modern surgical procedures often have a fusion of video and other imaging modalities to provide the surgeon with information support. This requires interventional guidance equipment and surgical navigation systems to register different tools and devices together, such as stereoscopic endoscopes and ultrasound (US) transducers. In this work, we focus specifically on the registration between these two devices. Electromagnetic (EM) and optical trackers are typically used to acquire this registration, but they have various drawbacks typically leading to target registration errors (TRE) of approximately 3mm. In this work, we introduce photoacoustic (PA) markers for direct 3D US to video registration.
Our approach is to create virtual fiducial landmarks, made of light, at the air-tissue interface. A projection system will be used to project these landmarks onto the surface of the organ through air. At the air-tissue interface, these landmarks can be seen both in US with the photoacoustic effect and in video. These landmarks are referred to as photoacoustic markers.
The feasibility of this method was demonstrated on synthetic, and ex vivo porcine liver, kidney, and fat phantoms with an air-coupled laser and a motorized 3D US probe. The resulting TRE for each experiment ranged from 380 to 850um with standard deviations ranging from 150 to 450um.
Fereshteh Aalamifar, M. Kendal Ackerman, Alexis Cheng, Xiaoyu Guo, Hyun Jae Kang, Haichong Zhang, Dr. Emad M. Boctor, Dr. Gregory S. Chirikjian
Ultrasound calibration is a necessary process to enable ultrasound-guided interventions. It recovers the relationship between a rigidly attached tracked rigid body and the ultrasound image. In this work, we develop various phantoms and algorithms to solve spatial ultrasound calibration and the associated issues of temporal calibration and pose recovery.
Alexis Cheng, Nishikant Deshmukh, David S. Lee, Dr. Emad M. Boctor
Optical tracking is an integral component of guidance systems, tracking tools or devices. There are some limitations to using this technology, especially size constraints in the limited surgical workspace. In this work, we present the use of a 3D rigid body made of light. By viewing a projection of this rigid body on some arbitrary surface, its pose can be recovered, thereby tracking the device projecting the rigid body.
Active Ultrasound Pattern Injection System (AUSPIS)
Xiaoyu Guo, Hyun-Jae Kang, Ralph Etienne-Cummings, Emad M Boctor
In laparoscopic medical procedures, accurate tracking of interventional tools such as catheters are necessary. Photoacoustic imaging is an emerging imaging modality that does not currently have a general tool tracking solution. Photoacoustic-based catheter tracking would increase its attractiveness, by providing both an imaging and tracking solution. We present a catheter tracking method based on the photoacoustic effect. Photoacoustic markers are simultaneously observed by a stereo camera as well as a piezoelectric element attached to the tip of a catheter. The signals received by the piezoelectric element can be used to triangulate its position relative to the photoacoustic markers. This combined information can be processed to localize the position of the piezoelectric element with respect to the stereo camera system.