An ultrasound image navigation robotic prostate brachytherapy system based on US to MRI deformable image registration method.

OBJECTIVE: This paper describes an ultrasound image navigation robotic prostate brachytherapy system. It uses a 2D ultrasound (US) probe rigidly fixed to a robotic needle insertion mechanism. Combined with the US probe registration and image registration, this system will help to navigate the prostate brachytherapy to increase the inserting accuracy.

SUBJECTS AND METHODS: The novelty of the system is that after the US probe registration using an improved iterative closest point (ICP) registration method, the initial registration for the magnetic resonance imaging (MRI) and US image can be completely automatically. Moreover, a deformable registration method based on statistical measurement was proposed to register US to MRI images intra-operatively.

RESULTS: The 6-degree of freedom (6-DOF) of robot and ultrasound probe are calibrated together with an accuracy of 0.9mm, allowing the needles to be precisely inserted to the seed targets after the image registration. Experiments were conducted by using US/MRI images, capturing from patients. Results showed that the accuracies of probe registration and US-MRI registration were: 0.44±0.12mm and 2.30±0.41mm, respectively.

CONCLUSION: With the help of this robotic system, the accuracy and the costing of time for prostate brachytherapy will greatly improve.