The present disclosure relates to a tool manipulator, comprising a base, mountable on an operation table. A caliper is supported by the base and a tool holder is mounted on the caliper. An actuator positionable below a patient supporting surface of the operation table receives positioning commands for moving a tool in at least three degrees of freedom. The tool manipulator can be made part of a system for positioning a needle for diagnosis or treatment of the prostate of a patient. The system also comprises a power source connected to the actuator and a controller controlling the provision of the positioning commands to the actuator.
