An Ultrasound-Guided Robotic HIFU Ablation System with Respiration Induced Displacement and Time Delay Compensation

Abstract

Introduction In recent years, high-intensity focused ultrasound (HIFU) has commonly been applied in non-invasive tumor therapy, such as to treat uterine fibroids or prostate tumors. However, respiration may cause tumor displacement, such as liver tumor displacement, which may lead to errors in localization or inadequate thermal effects on the tumor. Therefore, a compensating mechanism for target localization is important. Methods This paper introduces an ultrasound imaging-assisted robotic HIFU ablation system with a displacement compensatory mechanism. According to the correlation between the measured displacements of the heaving chest and the target tumor, a respiration simulation device was designed, which used a tumor phantom and a cam-driving mechanism to simulate displacements of the tumor and of the heaving chest. Then, a polynomial function of the tumor position relative to the position of the heaving chest was generated. After the coordinate frames of the robotic arm, optical tracker and tumor phantom had been registered, the robotic arm was able to guide the HIFU probe to track and ablate the target tumor automatically and synchronously by inputting the displacement values of the heaving chest. Results The average positioning error in the single-point tracking experiment was 1.72 ± 1.26 mm, while the ablation temperature was stabilized at 80 °C. Furthermore, the average positioning error in the cross-section ablation experiment was 3.04 ± 1.24 mm.

Assessment of Collaborative Robot (Cobot)-Assisted Histotripsy for Venous Clot Ablation

“…A limitation of the system is a lack of optical input for visualizing changes in the path due to, for instance, respiratory motion [37]. For the ablation of venous thromboembolism, predominately in the iliofemoral venous segments of the leg, very little respiratory motion is expected [38].…”

Tumor phantom model for MRI‐guided focused ultrasound ablation studies

“…investigated the impact of obstacles such as bone and metallic implants on FUS thermal therapy in a novel tumor‐bearing phantom. This phantom was a mixture of PAA gel and BSA protein containing several metallic and plastic objects, as well as a water‐filled rubber balloon mimicking a cyst 32 . In another study, 33 an agar‐based tumor model was utilized to evaluate the effectiveness of a newly proposed dual modality combining magnetic and FUS heating for cancer therapy.…”