A soft hydraulic endorectal actuator for prostate radiotherapy

Abstract

Despite advances in radiotherapy, motion error remains a challenge in prostate radiotherapy. Rectal obturators and endorectal balloons may reduce motion error and improve outcomes but have limitations. We aimed to create a deployable rectal obturator with precise angle control to personalise to a patient’s rectal anatomy, by using an antagonistic pair of "muscle" actuators to flex and extend the device. Results on deployability, angle control, and radial stiffness are presented here. The device can be compressed down to 16 x 3 x 91 mm, and be deployed to maximum dimensions of 24 x 25.5 x 77 mm. The device provides radial stiffness that may be sufficient to stabilise the rectum during radiotherapy. Angle control can be achieved with an average change of 7.5°/ml inflation in the extensor actuator.