A system comprising: - a positioning tool for assisting treatment of a subject in an external radiotherapy programme comprising two or more external radiotherapy treatment sessions; - a robotic arm disposed with a gripper; and - a processing unit comprising at least one processor and a memory, wherein the processing unit is configured to control movement of the robotic arm; wherein - the positioning tool comprises: - a steering guide having a proximal and distal end comprising: - a rigid effector shaft at the distal end configured for insertion into a canal of the subject, or for attachment to an inserter configured for insertion into the canal of the subject, and - a rigid handle portion disposed at the proximal end in fixed relation to the effector shaft for controlling the position and/or direction of the effector shaft, - the positioning tool is configured to move and/or fix the canal and the bodily tissue for the external radiotherapy treatment session; - the handle portion is provided with a grip locator configured for position-repeatable co-operation with the gripper of the robotic arm, wherein the gripper has an open state and a closed state; - the gripper comprises jaws or arms containing one or more complementary structures that engage with the grip locator when the gripper is in the closed state, - the grip locator is configured to be seated within the gripper in the closed state, in which movements of the seated grip locator relative to the gripper are limited and prevented; - the handle portion is provided with a docking beacon configured to provide information as to the position and optionally orientation of the steering guide relative to the gripper; and - the processing unit is configured to adjust a pose of the gripper in real-time as it approaches the handle portion using the information, and to couple the gripper to the handle portion without changing the pose of steering guide already inserted in the subject canal. - a positioning tool for assisting treatment of a subject in an external radiotherapy programme comprising two or more external radiotherapy treatment sessions; - a robotic arm disposed with a gripper; and - a processing unit comprising at least one processor and a memory, wherein the processing unit is configured to control movement of the robotic arm; wherein - the positioning tool comprises: - a steering guide having a proximal and distal end comprising: - a rigid effector shaft at the distal end configured for insertion into a canal of the subject, or for attachment to an inserter configured for insertion into the canal of the subject, and - a rigid handle portion disposed at the proximal end in fixed relation to the effector shaft for controlling the position and/or direction of the effector shaft, - a steering guide having a proximal and distal end comprising: - a rigid effector shaft at the distal end configured for insertion into a canal of the subject, or for attachment to an inserter configured for insertion into the canal of the subject, and - a rigid handle portion disposed at the proximal end in fixed relation to the effector shaft for controlling the position and/or direction of the effector shaft, - a rigid effector shaft at the distal end configured for insertion into a canal of the subject, or for attachment to an inserter configured for insertion into the canal of the subject, and - a rigid handle portion disposed at the proximal end in fixed relation to the effector shaft for controlling the position and/or direction of the effector shaft, - the positioning tool is configured to move and/or fix the canal and the bodily tissue for the external radiotherapy treatment session; - the handle portion is provided with a grip locator configured for position-repeatable co-operation with the gripper of the robotic arm, wherein the gripper has an open state and a closed state; - the gripper comprises jaws or arms containing one or more complementary structures that engage with the grip locator when the gripper is in the closed state, - the grip locator is configured to be seated within the gripper in the closed state, in which movements of the seated grip locator relative to the gripper are limited and prevented; - the handle portion is provided with a docking beacon configured to provide information as to the position and optionally orientation of the steering guide relative to the gripper; and - the processing unit is configured to adjust a pose of the gripper in real-time as it approaches the handle portion using the information, and to couple the gripper to the handle portion without changing the pose of steering guide already inserted in the subject canal.