Aiming beam detection for safe laser lithotripsy

#The present invention relates generally to minimally-invasive medical devices and procedures, and particularly to an apparatus and method to control targeted energy procedures that use an endoscope.

#Laser lithotripsy is a minimally-invasive procedure that is widely used in remove stones from the urinary tract, including the urethra, bladder, ureters and kidneys. In order to perform laser lithotripsy, an endoscope (such as a cystoscope, ureteroscope or renoscope) is inserted into the urinary tract to the stone location, and an optical fiber is introduced into the working channel of the endoscope. The fiber is pushed forward until it exits the distal opening of the working channel and comes into close proximity with the stone. A laser beam is fired through the fiber onto the stone, causing the stone to absorb the laser beam energy and disintegrate.

#If the laser beam is fired while the fiber is still inside the working channel of the endoscope, rather than protruding out of the distal opening, the beam can damage the working channel, as well as surrounding tissues. Various solutions to this problem have been proposed. For example, U.S. Patent Application Publication 2013/0072753 describes a system for preventing inadvertent actuation of a medical device. The system includes an elongate tube having a proximal end, a distal end, and a lumen extending from the proximal end to the distal end. The lumen is configured to receive a medical device having an actuated state and an inactive state. A detection system determines the position of the distal end of the medical device relative to the distal end of the elongate tube and controls the activation of the medical device.

#FIG. 1 is a schematic, pictorial illustration showing a system for laser lithotripsy, in accordance with an embodiment of the present invention;

#FIG. 2 is a block diagram that schematically shows elements of a control console in a laser lithotripsy system, in accordance with an embodiment of the present invention;

#FIG. 3 is a flow chart that schematically illustrates a method for control of a lithotripsy procedure, in accordance with an embodiment of the present invention; and

#It is believed that laser lithotripsy systems are known in the art and typically use a high-power infrared laser, such as a holmium YAG laser, to generate energy pulses that are fired at the target stone. It is also believed that the laser beam used for breaking the stone is typically invisible to the human eye and to standard image sensors, and thus another illumination source, such as a visible LED or laser source, may be used to generate a visible aiming beam. This aiming beam typically may be directed through an optical fiber or other similar device and arranged to strike the target of the laser beam. With the use of the aiming beam, an aiming beam spot can appear in the images formed when an endoscope is being used to view the target area and thus enables the physician operating the system to see where the energy from the fiber will be incident.

#In order to avoid damage to surrounding tissues, the physician should make sure that the aiming beam is incident on the stone before firing the laser. Proper observation of the aiming beam spot on the stone should also help prevent misfiring of the laser while the fiber is still inside the working channel, rather than protruding out distally toward the target as it should be. In practice, however, stones tend to move during treatment, and maneuvering the endoscope and the fiber is difficult, requiring substantial dexterity and care. As a result, misfires occur all too commonly, resulting in damage to patient tissues and to the endoscope.

#Embodiments of the present invention that are described hereinbelow are intended to prevent misfiring of the laser by verifying that the aiming beam is properly incident on the target stone before allowing the laser to be actuated. One way this objective may be accomplished by processing images captured by the endoscope camera. In addition to the benefits of preventing damage to tissues and equipment, this approach may be particularly advantageous in that it can be implemented simply by adding the appropriate processing and control capabilities to existing laser lithotripsy systems, without substantial modifications or additions to the system hardware.