Adaptive Lithotripsy For Cancer Risk Reduction

Abstract

Adaptive lithotripsy systems assist diagnosis and treatment of patients with kidney stones (stones being associated with subsequent development of cancer). As stimulation vibration is transmitted to the patient, both its total transmitted power and power spectral density (PSD) are tailored to individual patient needs. One such need is for progressive stone fragmentation (a hallmark of adaptive lithotripsy systems) at minimum power levels. And minimum power levels are achieved through two adaptive mechanisms for shifting PSD to concentrate transmitted vibration power in more effective frequency ranges. This concentration necessarily reduces power in relatively ineffective ranges, thus minimizing collateral tissue damage. Effective ranges for vibration power concentration are estimated in near-real time using backscatter vibration that is retransmitted from resonating stones while encoding information on the stones' existence, size and composition. Backscatter vibration thus informs adaptive tailoring of stimulation vibration for lithotripsy that is (1) relatively safer and (2) more efficient.

Claims

1. An adaptive stimulator comprising a hollow cylindrical housing having a longitudinal axis, a first end, and a second end, said first end being closed by a fluid interface for transmitting and receiving vibration, said fluid interface comprising at least one vibration detector for producing vibration electrical signals representing vibration transmitted and received by said fluid interface; a transverse coil peripheral to and surrounding said fluid interface, said transverse coil for generating a time-varying longitudinal magnetic field intersecting said fluid interface; an electromagnetic hammer driver reversibly sealing said second end; and a hammer longitudinally movable within said housing between said electromagnetic hammer driver and said fluid interface; wherein said electromagnetic hammer driver comprises an electromagnetic controller having cyclical magnetic polarity reversal characterized by a variable polarity reversal frequency; wherein said fluid interface is magnetostrictively responsive to said longitudinal magnetic field by altering its effective elastic modulus; wherein longitudinal movement of said hammer is responsive to said electromagnetic hammer driver cyclical magnetic polarity reversal for striking, flexing, and rebounding from, said fluid interface; and wherein longitudinal movement of said hammer striking, flexing, and rebounding from, said fluid interface is in phase with said time-varying longitudinal magnetic field.

2. The stimulator of claim 1 wherein said fluid interface comprises a plurality of vibration detectors, each said vibration detector having a resonant frequency.

3. The stimulator of claim 2 wherein all said vibration detector resonant frequencies are similar.

4. The stimulator of claim 1 wherein said fluid interface comprises at least one disc-shaped thin member, each said disc-shaped thin member having a resonant frequency and being oriented substantially perpendicular to said longitudinal magnetic field.

5. The stimulator of claim 4 wherein at least one said disc-shaped thin member comprises amorphous ferromagnetic alloy.

6. The stimulator of claim 5 wherein said amorphous ferromagnetic alloy comprises Metglas 2605SC.

7. The stimulator of claim 4 wherein at least one said disc-shaped thin member's resonant frequency is responsive to said longitudinal magnetic field.

8. The stimulator of claim 4 wherein said fluid interface comprises a plurality of said disc-shaped thin members.

9. The stimulator of claim 8 wherein each said disc-shaped thin member produces said vibration electrical signals representing vibration transmitted and received by said fluid interface.

10. An adaptive stimulator comprising a hollow cylindrical housing having a longitudinal axis, a first end, and a second end, said first end being closed by a fluid interface for transmitting and receiving vibration, said fluid interface comprising at least one vibration detector for producing vibration electrical signals representing vibration transmitted and received by said fluid interface; a transverse coil peripheral to and surrounding said fluid interface, said transverse coil for generating a time-varying longitudinal magnetic field intersecting said fluid interface; an electromagnetic hammer driver reversibly sealing said second end; and a hammer longitudinally movable within said housing between said electromagnetic hammer driver and said fluid interface, said hammer being responsive to said electromagnetic hammer driver for striking, flexing, and rebounding from, said fluid interface; wherein said electromagnetic hammer driver comprises an electromagnetic controller having cyclical magnetic polarity reversal characterized by a variable polarity reversal frequency; wherein said polarity reversal frequency is responsive to said vibration electrical signals; and wherein longitudinal movement of said hammer is in phase with said polarity reversal frequency.

11. The stimulator of claim 10 wherein said fluid interface comprises a plurality of vibration detectors, each said vibration detector having a resonant frequency.

12. The stimulator of claim 11 wherein all said vibration detector resonant frequencies are similar.

13. The stimulator of claim 10 wherein said fluid interface comprises at least one disc-shaped thin member, each said disc-shaped thin member having a resonant frequency and being oriented substantially perpendicular to said longitudinal magnetic field.

14. The stimulator of claim 13 wherein at least one said disc-shaped thin member comprises amorphous ferromagnetic alloy.

15. The stimulator of claim 14 wherein said amorphous ferromagnetic alloy comprises Metglas 2605SC.

16. An adaptive stimulator array comprising a plurality of adaptive stimulators, all said stimulators being connected to a programmable stimulator controller comprising a reflex cycle time estimator and a fluid interface resonant frequency estimator, and each said stimulator comprising a hollow cylindrical housing having a longitudinal axis, a first end, and a second end, said first end being closed by a fluid interface for transmitting and receiving vibration, said fluid interface comprising at least one vibration detector for producing vibration electrical signals representing vibration transmitted and received by said fluid interface; a transverse coil peripheral to and surrounding said fluid interface, said transverse coil for generating a time-varying longitudinal magnetic field intersecting said fluid interface; an electromagnetic hammer driver reversibly sealing said second end; and a hammer longitudinally movable within said housing between said electromagnetic hammer driver and said fluid interface; wherein each said electromagnetic hammer driver comprises an electromagnetic controller having cyclical magnetic polarity reversal characterized by a variable polarity reversal frequency; wherein longitudinal movement of each said hammer is responsive to said electromagnetic hammer driver cyclical magnetic polarity reversal for striking, flexing, and rebounding from, said fluid interface during a reflex cycle time; wherein the inverse of each said reflex cycle time is a reflex characteristic frequency; and wherein each said time-varying longitudinal magnetic field is in phase with one said reflex characteristic frequency.

17. The stimulator array of claim 16 wherein each said fluid interface comprises a plurality of vibration detectors, each said vibration detector having a resonant frequency.

18. The stimulator array of claim 17 wherein all said vibration detector resonant frequencies are similar.

19. The stimulator array of claim 16 wherein each said fluid interface comprises at least one disc-shaped thin member, each said disc-shaped thin member being oriented substantially perpendicular to said longitudinal magnetic field.

20. The stimulator array of claim 19 wherein at least one said disc-shaped thin member comprises amorphous ferromagnetic alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0119] FIG. 1 illustrates a schematic 3-dimensional view of an adaptive stimulator comprising a vibration detector and a tunable vibration generator. A hammer is longitudinally movable within a hollow cylindrical housing, one end of the housing being closed by a fluid interface, and the other end being closed by an electromagnetic hammer driver. The fluid interface is shown with a MEMS accelerometer for detecting vibration of the interface.

[0120] FIG. 2 illustrates a schematic 3-dimensional exploded view of the adaptive stimulator embodiment of FIG. 1, a first electrical cable being shown to schematically indicate a feedback path (for an accelerometer signal) from the accelerometer to the electromagnetic hammer driver. A second electrical cable is shown to schematically indicate an interconnection path for, e.g., communication with one or more additional stimulators and/or associated equipment such as a programmable controller.

[0121] FIG. 3 illustrates a schematic 3-dimensional exploded view of an adaptive stimulator embodiment that differs from the embodiment of FIGS. 1 and 2 in part because it comprises a fluid interface comprising three disc-shaped thin members. Electrical leads signify that each disc-shaped thin member functions as a vibration detector, and electrical leads also draw attention to an electromagnetic hammer driver and a transverse peripheral coil for creating a longitudinal magnetic field.

[0122] FIG. 4 schematically illustrates a 2-dimensional view of major components, subsystems, and interconnections of an adaptive lithotripsy system comprising the adaptive stimulator embodiment of FIG. 3. As aids to orientation, communication pathways are indicated between stimulator components (tunable vibration generator and vibration detector), a stimulator controller running frag diagnostics, and estimators for reflex cycle time and fluid interface resonant frequency. Schematic pathways are shown for transmitted stimulation vibration energy and for backscatter vibration energy.

[0123] FIG. 5 schematically illustrates an embodiment of an adaptive lithotripsy system analogous in part to that in FIG. 4, but differing in the presence of a linear array of 3 adaptive stimulators instead of the single adaptive stimulator of FIG. 4. Appropriate timing of stimulation vibration bursts from each stimulator facilitates directional propagation of combined-vibration wave fronts. Further, feedback-control of total transmitted power and transmitted vibration PSD make the embodiment exceptionally flexible for diagnosis and treatment.

DETAILED DESCRIPTION

[0124] FIGS. 1 and 2 illustrate partial schematic 3-dimensional views of an adaptive stimulator of class 599, FIG. 2 being an exploded view. Numerical labels may appear in only one view. A hollow cylindrical housing 590 has a longitudinal axis, a first end 594, and a second end 592. First end 594 is closed by fluid interface 520 for transmitting and receiving vibration. Fluid interface 520 comprises at least one accelerometer 518 for producing a vibration electrical signal (i.e., an accelerometer-generated feedback signal) representing vibration transmitted and received via fluid interface 520.

[0125] Electromagnetic hammer driver 560 (comprising a field emission structure which itself comprises electromagnet face 564 and electromagnetic controller 562) reversibly seals second end 592, and hammer (or movable mass) 540 is longitudinally movable within cylindrical housing 590 between electromagnetic hammer driver 560 and fluid interface 520. In some embodiments, hammer 540 may itself be a field emission structure consisting of a permanent magnet (or a plurality of permanent magnets). Polarity of any such permanent magnets is not specified because it would be assigned in light of the electromagnetic controller 562. Alternatively, hammer 540 may be analogous in part to the armature of a linear electric motor, as in a railgun. (See, e.g., the '205 and '877 patents noted above). Note that the above accelerometer-generated vibration electrical signal may be augmented by a sensorless control means (e.g., controlling operating parameters of electromagnetic controller 562 such as magnetic field strength and polarity) in free piston embodiments of the adaptive stimulator. (See, e.g., U.S. Pat. No. 6,883,333, incorporated by reference).

[0126] Thus, hammer 540 is responsive to the magnetic field emitted by electromagnet face 564 of electromagnetic hammer driver 560 for striking, flexing, and rebounding from, fluid interface 520. The duration of each such striking, flexure and rebounding cycle (termed herein the reflex cycle time) has the dimension of seconds. And the inverse of this duration has the dimension of frequency. Hence, the term herein characteristic reflex frequency is the inverse of a reflex cycle time, and the reflex cycle time itself is inversely proportional to the bandwidth of transmitted vibration spectra resulting from each hammer strike and rebound from fluid interface 520.

[0127] Fluid interface 520 transmits vibration spectra generated by hammer impacts on fluid interface 520 as well as receiving backscatter vibration from renal calculi excited by a stimulator of class 599. Fluid interface 520 comprises, for example, a MEMS accelerometer 518 for producing an accelerometer signal representing vibration transmitted and received by fluid interface 520. (See MicroElectro-Mechanical Systems in Harris, pp. 10-26, 10-27).

[0128] Hammer 540 comprises a striking face 542 (see FIG. 2) which has a predetermined modulus of elasticity (e.g., that of mild steel, about 29,000,000 psi) which can interact with the effective elastic modulus of fluid interface 520. In an illustrative example, interaction of the two suggested moduli of elasticity predetermines a relatively short reflex cycle time for hammer 540, which is associated with a corresponding relatively broad-spectrum of vibration to be transmitted by fluid interface 520. In other words, striking face 542 strikes fluid interface 520 and rebounds to produce a relatively short-duration, high-amplitude mechanical shock. (See, e.g., Harris p. 10.31).

[0129] Both FIGS. 1 and 2 schematically illustrate a tunable resilient circumferential seal 580 for sealing cylindrical housing 590 within a lithotripsy bath, thus partially isolating vibration transmitted by fluid interface 520 within the bath. Circumferential seal 580 comprises at least one circular tubular area 582 which may contain at least one shear-thickening fluid which may be useful in part for tuning purposes. The shear-thickening fluid, in turn, may comprise nanoparticles for, e.g., facilitating heat scavenging.

[0130] FIG. 2 also schematically illustrates a first electrical power/data cable 516 for carrying vibration electrical signals (representing vibration data transmitted by and/or received by fluid interface 520) from accelerometer 518 to electromagnetic hammer driver 560. A second electrical power/data cable 514 also connects to electromagnetic hammer driver 560 of each adaptive stimulator to schematically represent interconnection of two or more such stimulators (to form an adaptive stimulator array) and/or for connecting one or more adaptive stimulators to related equipment (e.g., a programmable stimulator controller as shown in FIGS. 4 and 5). Vibration electrical signals provide feedback on transmitted vibration and also on received characteristic backscatter vibration to electromagnetic hammer driver 560.

[0131] While accelerometer-mediated feedback may be desired for tailoring stimulation to specific renal calculi and/or to progress in producing desired vibration frequencies for diagnosis and/or fracture of calculi, predetermined stimulation protocols may be used instead to simplify operations and/or lower costs.

[0132] Note that transmitted vibration power levels suitable for diagnosis may be significantly lower than vibration power levels needed for fracturing calculi. Since lower vibration power levels are more consistent with patient comfort and safety, screening diagnostic tests will typically employ adaptive lithotripsy systems adjusted for minimum transmitted vibration power levels needed to generate detectable backscatter vibration from any renal calculi that may be present.

[0133] In certain embodiments, frag diagnostic software and data to implement sensorless control via operating parameters (e.g., magnetic field strength and polarity) of electromagnetic controller 562, or to implement feedback control incorporating accelerometer 518, are conveniently stored and executed in a microprocessor (located, e.g., in electromagnetic controller 562). (See, e.g., U.S. Pat. No. 8,386,040, incorporated by reference). See FIGS. 5 and 6 of the '040 patent, for example, with their accompanying specification.

[0134] Note, however, that while certain of the electrodynamic control characteristics of an adaptive stimulator may be represented in earlier devices, the adaptive stimulator's reliance on mechanical shock (e.g., generated by hammer strike and rebound) to generate tuned vibration (i.e., vibration characterized by approximately predetermined magnitude and/or frequency and/or PSD) imposes unique requirements indicated by the dynamic responsiveness of certain mechanical structures (e.g., hammers and fluid interfaces) to electromagnetic effects of field-emitting components (e.g., electromagnets and electret materials) as described herein. Variability of stimulation vibration is further responsive to one or more programmable stimulator controllers via, e.g., the power/data cable 514, and/or an analogous-in-part combined electrical cable (see, e.g., FIG. 3). Such responsiveness may extend to other adaptive stimulators and/or to other auxiliary equipment (see, e.g., FIG. 5).

[0135] Note also that in addition to individual applications of an adaptive stimulator, two or more such stimulators may operate in a combined adaptive stimulator array during a given stage of adaptive lithotripsy. A single adaptive stimulator or an interconnected adaptive stimulator array may be programmed in near-real time to alter stimulation parameters in response to changing conditions in biologic materials to be adaptively stimulated. A record of such changes, together with results, guides future changes to increase stimulation efficiency.

[0136] In summary, the responsiveness of certain components of an adaptive stimulator to other components and/or to parameter relationships facilitates operational advantages in various alternative stimulator embodiments. Examples involving such responsiveness and/or parameter relationships include, but are not limited to: (1) electromagnetic hammer driver 560 comprises a field emission structure comprising an electromagnetic controller 562 having cyclical magnetic polarity reversal characterized by a variable polarity reversal frequency; (2) longitudinal movement of hammer 540 (or movable mass) striking, flexing, and rebounding from, the fluid interface 520 is responsive to the electromagnetic hammer driver cyclical magnetic polarity reversal; (3) longitudinal movement of hammer 540 striking, flexing, and rebounding from, fluid interface 520 may be in-phase with the polarity reversal frequency to generate vibration transmitted by fluid interface 520; (4) the polarity reversal frequency of electromagnetic hammer driver 560 may be responsive to accelerometer 518's vibration electrical signal, and thus responsive to vibration sensed by accelerometer 518; (5) longitudinal movement of hammer 540 may be in-phase with the polarity reversal frequency; (6) longitudinal movement of hammer 540 striking, flexing, and rebounding from, fluid interface 520 has a characteristic reflex frequency which is the inverse of the reflex cycle time; (7) the hammer 540 characteristic reflex frequency may be in-phase with polarity reversal and; (8) the reflex cycle time is a function of the cyclical magnetic polarity of electromagnetic hammer driver 560 and/or the moduli of elasticity of striking face 542 of hammer 540 and that of fluid interface 520.

[0137] FIG. 3 illustrates a schematic 3-dimensional exploded view of one embodiment of an adaptive stimulator of class 699. Stimulators of class 699 share several structural and functional features analogous to structural and functional features of an adaptive stimulator of class 599 (schematically illustrated in FIGS. 1 and 2). But stimulators of class 699 differ materially in several respects from the stimulator illustrated in FIGS. 1 and 2. Subsequent description herein identified with class 699 or FIG. 3 should be understood as relating to a group comprising stimulators which demonstrate common structural features of, as well as one or more material structural and/or functional differences from, stimulators of class 599.

[0138] Within class 699, material differences among embodiments include, but are not limited to (1) the number of disc-shaped thin members comprising a fluid interface, (2) the composition of individual disc-shaped thin members (e.g., various magnetostrictively-responsive amorphous ferromagnetic alloys), (3) surface shapes of disc-shaped thin members, (4) manufacturing treatment of magnetostrictively-responsive disc-shaped thin members such as annealing in a magnetic field which alters magnetostrictive responsiveness, (5) vibration damping characteristics, (6) methods of assembling a plurality of disc-shaped thin members, such as lamination or mechanical compression, to form a fluid interface, and (7) electrical interconnection of one or more disc-shaped thin members with other stimulator components and/or other components of adaptive lithotripsy systems (see, e.g., FIGS. 4 and 5).

[0139] Hence, FIG. 3 schematically illustrates certain construction features of an example adaptive stimulator of class 699 which are not limited to a specific embodiment. The example comprises a hollow cylindrical housing 690 having a longitudinal axis, a first end 692, and a second end 694. First end 692 is closed by a fluid interface for transmitting and receiving vibration. In general, fluid interfaces of stimulators of class 699 each comprise one or more disc-shaped thin members which are analogous-in-part to disc-shaped thin member 621, disc-shaped thin member 622 and/or disc-shaped thin member 623. The illustrated fluid interface embodiment 621/622/623 comprises the three illustrated disc-shaped thin members in a compact (e.g., laminated) subassembly for purposes of description only, but alternate fluid interface embodiments of the invention may contain more or fewer disc-shaped thin members. At least one disc-shaped thin member within fluid interface 621/622/623 comprises ferromagnetic amorphous alloy, the effective elastic modulus of which is magnetostrictively-responsive to a time-varying longitudinal magnetic field created by electrical current in peripheral coil 682 which is schematically shown as enclosed in coil form 680. The longitudinal magnetic field influences the effective hardness of, and thus the resonant frequencies of: (1) at least one disc-shaped thin member 621, 622 and/or 623 and (2) the fluid interface 621/622/623 as a whole. Further, at least one disc-shaped thin member within fluid interface 621/622/623 comprises a vibration detector for generating a vibration electrical signals representing both vibration transmitted and characteristic backscatter vibration received via fluid interface 621/622/623.

[0140] Continuing with a description of FIG. 3, second end 694 of hollow cylindrical housing 690 is closed by electromagnetic hammer driver 660 (comprising a field emission structure which itself comprises electromagnetic controller 662 within electromagnetic hammer driver 660). Hammer (or movable mass) 640 is longitudinally movable within housing 690 between electromagnetic hammer driver 660 and fluid interface 621/622/623. In some embodiments, hammer 640 may itself be a field emission structure consisting of a permanent magnet (or consisting of a plurality of permanent magnets). Polarity of any such permanent magnets is not specified because it would be assigned in light of field emission from the electromagnetic controller 662. Alternatively, hammer 640 may be analogous in part to the armature of a linear electric motor, as in a railgun. (See, e.g., the '205 and '877 patents noted above).

[0141] Note that the longitudinal magnetic field is operative on hammer 640 (to alter reflex cycle time), and on each of the magnetostrictive disc-shaped thin members of fluid interface 621/622/623 (to alter their effective elastic modulus and thus alter their resonant frequencies).

[0142] Note also that the above vibration electrical signals representing vibration transmitted and/or received via fluid interface 621/622/623 may be augmented by sensorless control means (e.g., controlling operating parameters of electromagnetic controller 662 such as magnetic field strength and polarity) in free piston embodiments of adaptive stimulators of class 699.

[0143] FIG. 4 schematically illustrates a 2-dimensional view of major components and interconnections of adaptive lithotripsy system 798, together with brief explanatory labels and comments on component functions. As aids to orientation, a schematic lithotripsy target (i.e. material to be stimulated) is shown. Stimulation vibration and backscatter vibration (hydraulic) pathways are schematically illustrated for transmitting broad-spectrum vibration to, and receiving band-limited backscatter vibration from, material to be stimulated (e.g., renal calculi).

[0144] Adaptive lithotripsy system 798 schematically illustrated in FIG. 4 is relatively sophisticated, employing several structures, functions and interactions that appear in different invention embodiments. For example, closed-loop feedback-control of fluid interface resonant frequency is graphically indicated as a function of the stimulator controller. Analogously, closed-loop feedback-control of reflex cycle time is also graphically indicated as a function of the stimulator controller. Adjustment of either (1) fluid interface resonant frequency or (2) reflex cycle time (or both) may be implemented via the stimulator controller to up-shift or down-shift transmitted vibration PSD. Shifting PSD effectively narrows the relatively broad spectrum of transmitted vibration by causing vibration power to be relatively concentrated in predetermined (effectively narrowed) portions of the transmitted frequency spectrum.

[0145] Note that FIG. 4 necessarily represents an application of adaptive stimulators of class 699 because such stimulators feature PSD shifting by adjustments of reflex cycle time and/or fluid interface resonant frequency. In contrast, PSD shifting in an adaptive lithotripsy system featuring adaptive stimulators of class 599 is a function of reflex cycle time.

[0146] Note further that the labeling of an adaptive stimulator of class 699 in FIG. 4, comprising a tunable vibration generator combined with a vibration detector, emphasizes that the vibration detector is co-located with the vibration generator. One embodiment demonstrating such co-location of tunable vibration generator and vibration detector is that shown in FIG. 3, where one or more disc-shaped thin members function as vibration detectors while the fluid interface as a whole transmits stimulating vibration (and receives backscatter vibration). An alternative embodiment featuring co-location of vibration generator and vibration detector is that of the adaptive stimulator of class 599 in FIGS. 1 and 2, where an accelerometer (i.e., a vibration detector) is mounted directly on a fluid interface which transmits and receives vibration.

[0147] Another difference between adaptive stimulators of class 599 and those of class 699 is that in stimulators of the latter class, the fluid interface resonant frequency estimator and the reflex cycle time estimator, while functions of the (programmable) stimulator controller, rely on data from peripheral coil 682 (regarding longitudinal magnetic field strength). At least one disc-shaped thin member of the adaptive stimulator of FIG. 3 is subject to magnetostrictive effects on the effective elastic modulus of the thin member. So the longitudinal magnetic field is operative on (1) the hammer (to alter reflex cycle time), and on (2) each of the magnetostrictive disc-shaped thin members of the fluid interface (to alter their effective elastic modulus and thus alter their resonant frequencies).

[0148] Note that data from one or more of the disc-shaped thin members (electrical cables 601, 602 and/or 603), peripheral coil 682 (electrical cable 684) and electromagnetic controller 662 (electrical cable 614) are transmitted to the stimulator controller via combined electrical cable 696.

[0149] Notwithstanding the above differences, in adaptive stimulators of both class 599 and class 699, a field emission structure may be responsive to at least one control signal (e.g., timed stimulator transmission signals and/or stimulator shift signals). Such responsiveness to at least one control signal is achieved, e.g., by emitting one or more electric and/or magnetic fields which are functions of at least one control signal as sensed by the field emission structure through change in one or more field emission structure electrical parameters. Thus, vibration transmitted by an adaptive stimulator (either class 599 or 699) may have a predetermined PSD which is a function of its reflex cycle time. The reflex cycle time, in turn, is dependent-in-part on one or more field emission structures that are themselves responsive to at least one control signal (e.g., a stimulator shift signal). A stimulator shift signal, in turn, may be responsive to vibration electrical signals via power/data cable 516 in FIG. 2 (class 599) or electrical signals via electrical cable 614 (within combined electrical cable 696) in FIG. 3 (class 699).

[0150] FIG. 5 schematically illustrates an embodiment of an adaptive lithotripsy system 799 which differs from adaptive lithotripsy system embodiment 798 shown in FIG. 4. A portion of the 2-dimensional stimulation system view of FIG. 4 is reproduced in FIG. 5, but differences between FIGS. 4 and 5 include replacement of a single adaptive stimulator of class 699 (in FIG. 4) with a linear array comprising three analogous adaptive stimulators (699, 699 and 699) in FIG. 5. Descriptions of functional features of stimulators in FIG. 5 resemble (in-part) analogous descriptions of the stimulator in FIG. 4, but adaptive lithotripsy system 799 combines impulse-generated swept-frequency stimulation vibration with timed signals to provide adaptive stimulation via a directionally propagated array vibration wave front. Swept-frequency stimulation vibration arises from cyclical up-shifts and down-shifts of the PSD of impulse-generated stimulation vibration. The cyclical PSD shifts, in turn, are achieved via closed-loop feedback-control of the impulse-generated vibration produced by stimulator linear array 699/699/699. PSD's and fluid interface resonant frequencies of the array stimulators may be individually adjusted for resonance excitation, fracturing and subsequent fragmentation of renal calculi at varying distances from the array.

[0151] Stimulation linear array 699/699/699 may behave in-part in a manner analogous to that of a phased-array antenna. For example, elective discrete time delays among sequential transmission times for vibration bursts from each stimulator in array 699/699/699 are controlled via timed stimulator transmission signals from the (programmable) stimulator array controller so as to exert control over the propagation direction of the combined stimulation vibration wave front (i.e., control over the directionally propagated array vibration wave front). Timed stimulator transmission signals, in turn, may have a phase relation (e.g., in-phase) with (1) cyclically-varying fluid interface resonant frequencies and/or, (2) cyclically-varying hammer impact reflex cycle times and/or, (3) cyclically varying total transmitted vibration power.

[0152] Further, other timing issues affect vibration from each adaptive stimulator in linear array 699/699/699. For example, differences in individual reflex cycle times among the stimulators affect their individual PSD's. Adjustable reflex cycle times, in turn, may reflect changes in electrical parameters (e.g., current in peripheral coil 682, magnetic field polarity, magnetic field strength, and/or the phase relationship of the time-varying longitudinal magnetic field and/or the stimulator electromagnetic hammer driver polarity reversal to hammer strike). Variability in adjustable reflex cycle times (e.g., non-uniform reflex cycle times) may also be responsive to stimulator shift signals from the (programmable) stimulator array controller. Such variability may result in vibration interference among stimulators in a spatial array. Both constructive interference (i.e., increase in amplitude) at one or more frequencies and destructive interference (i.e., decrease in amplitude) at other frequencies are likely, thus electively providing higher stimulation vibration energy levels at a plurality of discrete frequencies within a vibration burst.