Patent Application
20060036168
1. Field of the Invention
The present invention relates to an electrohydraulic shock wave-generating system for extracorporeal therapy of renal stones or musculoskeletal disorders. In particular, the present invention relates to a system that generates underwater shock waves focused on a target in a patient for effective treatment of the target.
2. Description of the Related Art
In the last two decades extracorporeal shock wave lithotripsy (ESWL) provides a new way to treat renal stones in the human body; namely, the traditional invasive surgery for removing the stone out of the patient's body has been replaced by noninvasive extracorporeal lithotripsy using an apparatus that generates shock waves to break the renal stone into smaller pieces. Although the extracorporeal therapy for renal stones has been widely used and accepted by the patients, the successful stone-fragmenting rate under human monitoring was found at best 60-70%, as the stone in the body of the patient receiving the therapy moved when the patient breathed such that the shock waves could not precisely hit the stone. To solve this problem, U.S. patent application Ser. No. 10/061,240 proposes a system for tracing a renal stone during medical treatment.
Extracorporeal shock wave lithotripters currently available on the market include electrohydraulic type, electromagnetic type, and piezoelectric type. The electrohydraulic lithotripters are more widely used than the other two types, as electrohydraulic lithotripters had been invented earlier. Electrohydraulic lithotripters generate shock waves with high-energy flux density (intensity), while the electromagnetic- and piezoelectric-type generate low-energy flux density. During a treating process, about 3000 shock waves are generated for an electrohydraulic lithotripter and about 5000-6000 shock waves for an electromagnetic lithotripter or a piezoelectric lithotripter, both of which take a relatively long time for producing the desired number of shock waves. As a result, most doctors and patients dislike the long treatment process for stone therapy.
For most of electrohydraulic lithotripters, the gap between two electrodes of the shock wave generator is fixed and thus could not be adjusted. Only few of them allow manual adjustment. Problems occur in a case that the gap between the electrodes is not controlled in a predetermined range. More specifically, the more times the shock waves are fired, the larger the gap between the electrodes is. Thus, when the gap between the electrodes is larger than a threshold, the intensity of the shock waves becomes weak. Even worse, no shock waves can be fired. A remedy to this problem is to increase the voltage to an extent sufficient to generate shock waves or to replace the electrodes by new ones, yet the shock wave intensity and the times for fragmenting the stones cannot be controlled, leading to a low stone-fragmenting efficiency.
However, even the gap between the electrodes is manually adjusted, no instant and effective monitoring/measuring device is provided. Hence, the patient has to move away from the shock wave reflector (a truncated ellipsoidal bowl) to allow measurement of the gap between the electrodes by X-ray or other methods. The treating process is interrupted and brings inconvenience to the patient receiving therapy.
In addition to the application of ESWL to the urology, extracorporeal shock wave therapy (or orthotripter) for musculoskeletal disorders, such as calcific tendonitis of shoulder, tennis elbows, epicondylitis, plantar fasciitis, delayed unions, and nonunion fractures, has also been used in recent years. Since electrohydraulic orthotripters use the same principle of underwater shock wave focusing as lithotripters, the present invention can be applied to the orthotripters.
An objective of the present invention is to provide an electrohydraulic shock wave-generating system for extracorporeal therapy of renal stones or musculoskeletal disorders that, given the same operational voltage, generates underwater shock waves with uniform intensity, reducing the number of the shock waves needed for treating a target and thus the time for the target treatment, and reducing injury to the tissue of the patient. This objective is achieved by means of automatically adjusting the gap between two electrodes of a shock wave generator of the system. The adjustment of the gap between the electrodes can be done, regardless of the material of the electrodes used. The softer the material of the electrodes is, the more frequently the gap between the electrodes is adjusted. Thus, given different operational voltage, the times of firing the shock waves for treating the stones can be effectively controlled and the stone-fragmenting efficiency is improved.
Another objective of the present invention is to provide a system that can be incorporated with currently used extracoporeal shock wave therapy machines such as extracorporeal shock wave lithotripters for treating renal calculi and extracorporeal shock wave orthotripters for treating musculoskeletal disorders.
In accordance with an aspect of the invention, an electrohydraulic shock wave-generating system for extracorporeal therapy of renal stones or musculoskeletal disorders comprises a shock wave generator, a micro high-sensitivity camera, and a gap-controlling unit. The shock wave generator includes a bowl (a shock wave reflector) and two electrodes, each electrode having a portion inside the bowl, with a gap being defined between the electrodes. The micro high-sensitivity camera acquires an image of the electrodes for finding the size of the gap. The gap-controlling unit controls the size of the gap and moves at least one of the electrodes to adjust the size of the gap. It was found that a truncated ellipsoidal bowl with eccentricity of approximately 0.71 produces a best result of focusing pressure at a geometric focus where a target (e.g., a kidney stone) is located.
In an embodiment of the invention, the shock wave generator includes a base on which the bowl is mounted. The base includes a transparent window through which the image of the electrodes is acquired by the micro high-sensitivity camera.
The gap-controlling unit includes two servomotors and two servomotor drivers for driving the servomotors. In an embodiment of the invention, the gap-controlling unit includes a multi-axis control card to thereby control the gap between the electrodes. The gap-controlling unit includes two transmission assemblies each including a first member driven by an associated servomotor and a rotatably supported second member. Each electrode is coupled to the second member of an associated transmission assembly such that rotation of each servomotor causes rectilinear movement of the electrode along a longitudinal direction of the electrode. In an embodiment of the invention, the first member and the second member are pulleys with an endless belt mounted around the pulleys. Each electrode is fixed to a copper base that is connected to one of the pulleys and rotatably supported by a fixed seat.
The system includes a computer control unit programmed to compare the size of the gap between the electrodes with an optimal gap size and to activate the gap-controlling unit when a difference between the size of gap of the electrodes and the optimal gap size is greater than a threshold. The computer control unit may include a program based on C language or other computer graphic languages.
Moreover, the system includes an image-grabbing card with which the micro high-sensitivity camera is coupled. The system also includes an I/O card for controlling the voltage setting and shock wave firing of a shock wave generator.
Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Referring to
The gap image grabbing/feeding unit 1 includes a micro high-sensitivity camera 11 and an image-grabbing card 12. The camera 11 is mounted below a base 40 (see
Referring to
The computer control unit 3 includes a program 31 for controlling the gap between the electrodes 42 and the program 32 for analyzing the gap size between the electrodes 42 mentioned above. The programs 31 and 32 are written into the memory of the computer control unit 3. The computer control unit 3 is also connected to the shock wave generator 4 through the I/O card 33 for controlling the voltage setting and shock wave firing of the shock wave generator 4.
Referring to
The pulleys 250 and 43 and the endless belt 251 can be replaced with any other suitable members, such as gears and chain. Furthermore, other transmission assemblies can be used without departing from the scope of the invention. The reducers 211 can be omitted whenever appropriate. The servomotors 21 can be replaced with other suitable means for moving the electrodes 42 toward or away from each other. For example, the gap between the electrodes 42 can be adjusted through hydraulic or pneumatic control. Moreover, it is noted that the gap between the electrodes 42 can be adjusted through use of a set of a servomotor 21, a reducer 211, a servomotor driver 22, and a transmission assembly 25. In this case, the middle of the gap can be adjusted to a focus of the bowl 41 for subsequent firing of shock waves.
The computer control unit 3 uses programs to control the gap between the electrodes 42 (see
Secondly, the camera 11 is activated to acquire the image of the electrodes 42 to find the actual gap size. The actual gap size is compared with the optimal gap size. If the difference between the actual gap size and the optimal gap size is smaller than the threshold, shock wave is fired. If the difference between the actual gap size and the optimal gap size is greater than the threshold, no shock wave is fired and the distance between the electrodes 42 is adjusted. The procedure continues until the treatment ends, i.e., the summing parameter (the number of the fired shock waves) equals the total number of shock waves required for the patient decided by the doctor. The medical treatment process is thus carried out without increasing the voltage applied to the electrodes 42.
The electrode 42 used in the present invention may have a length tenfold of that of a conventional one. Thus, a pair of electrodes 42 may be used to treat ten patients, while a pair of conventional electrodes can be used to treat only one patient.
In addition, the medical treatment can be carried out without increasing the operational voltage applied to the electrodes 42. Given the same operational voltage, the system in accordance with the present invention generates shock waves with uniform intensity, reducing the times for generating the shock waves and reducing injury to the tissue of the patient, as the gap between the electrodes 42 can be automatically adjusted. Adjustment of the gap between the electrodes 42 can be done regardless of the material of the electrodes used. The softer the material of the electrodes is, the more frequently the gap between the electrodes is adjusted. Thus, given different operational voltage, the number of shock waves for treating the stone can be effectively controlled and the stone-fragmenting efficiency is improved.
Moreover, the system in accordance with the present invention can be used in any extracoporeal shock wave lithotripters or orthotripters. Orthotripters aim at the treatments of musculoskeletal disorders such as calcific tendonitis of shoulder, tennis elbows, epicondylitis, plantar fasciitis, delayed unions, and nonunion fractures.
Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.
