A ureteroscope for dusting stones in a body cavity with a laser fiber, the ureteroscope comprising: a flexible probe comprising a proximal end and a distal end, the flexible probe comprising: a working channel configured to accommodate the laser fiber in the distal end of the flexible probe at a working position, the laser fiber to be deflected against a target stone for dusting, the working position being a predefined distance of the laser fiber from the distal end of the flexible probe and defined by laser energy settings and composition of the target stone; and a handle extending proximally from the flexible probe, the handle comprising: a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel, the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction. a flexible probe comprising a proximal end and a distal end, the flexible probe comprising: a working channel configured to accommodate the laser fiber in the distal end of the flexible probe at a working position, the laser fiber to be deflected against a target stone for dusting, the working position being a predefined distance of the laser fiber from the distal end of the flexible probe and defined by laser energy settings and composition of the target stone; and a handle extending proximally from the flexible probe, the handle comprising: a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel, the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction. a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel, the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction.