Automatic detection and localization of da vinci tool tips in 3d ultrasound

Radical prostatectomy (RP) is viewed by many as the gold standard treatment for clinically localized prostate cancer. State of the art radical prostatectomy involves the da Vinci surgical system, a laparoscopic robot which provides the surgeon with excellent 3D visualization of the surgical site and improved dexterity over standard laparoscopic instruments. Given the limited field of view of the surgical site in Robot-Assisted Laparoscopic Radical Prostatectomy (RALRP), several groups have proposed the integration of Transrectal Ultrasound (TRUS) imaging in the surgical work flow to assist with the resection of prostate and sparing the Neuro-Vascular Bundle (NVB). Rapid and automatic registration of TRUS imaging coordinates to the da Vinci tools or camera is a critical component of this integration. We propose a fully automatic registration technique based on accurate and automatic localization of robot tool tips pressed against the air-tissue boundary of the prostate, in 3D TRUS. The detection approach uses a multi-scale filtering technique to uniquely identify and localize the tool tip in the ultrasound volume and could also be used to detect other surface fiducials in 3D ultrasound. Feasibility experiments using a phantom and two ex vivo tissue samples yield promising results with target registration error (defined as the root mean square distance of corresponding points after registration) of ($1.80\ mm$) that proves the system's accuracy for registering 3D TRUS to the da Vinci surgical system.