Abstract:
A training aid for of a medical procedure where a substance is injected under the skin is disclosed that provides a user with the sensation of “pushing” the substance under the skin to smooth out raised areas. The training apparatus includes an artificial skin area with a raised feature protruding there from that is provided by cam-driven lifters positioned under the artificial skin area. The raised feature simulates the injected substance and may be touched and manipulated by the user.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to medical simulation systems, and more particularly to a medical simulation apparatus that allows palpation of a simulated wheal under simulated skin and provides haptic feedback. 
     BACKGROUND OF THE INVENTION 
     Dermal fillers are being used more and more to help reverse the changes associated with aging. The goal of dermal fillers is to return the dermis, particularly on the face, to its original youthful state. As such, dermal fillers are being used to reduce or eliminate wrinkles, raise scar depressions, enhance lips, and replace soft-tissue volume loss. Dermal fillers are injected under the skin of a patient and correct placement is crucial to avoid undesirable results. For instance, dermal fillers that are injected too superficially may result in the patient seeing the filler product through the epidermis, whereas dermal fillers injected too deeply may result in the filler product not producing the desired cosmetic correction. In addition, some palpation and/or manipulation of the injected dermal filler may be necessary to achieve/assure optimal results. 
     As with most medical procedures, training is important to obtain an acceptable level of proficiency and to avoid unintended consequences. Training via seminars with and without live or video observation is currently a primary means for a practitioner to gain experience but is less than optimal. “Hands-on” training may be more desirable, yet is likely impractical for a great percentage of practitioners due to consent and liability issues pertaining thereto. Consequently, a medical simulation for simulating a dermal filler injection procedure where the practitioner can simulate the injection of the substance under a patient&#39;s skin while palpating a simulated wheal created by the injected substance would be a useful training aid. 
     BRIEF SUMMARY OF THE INVENTION 
     Embodiments hereof are directed to an apparatus for training a medical procedure where a substance is to be injected under the skin. The apparatus provides a user with the sensation of “pushing” the substance under the skin to smooth out raised areas. The apparatus includes an outer flexible membrane that simulates skin having a palpation region to be palpated. A cam palpator having a set of lifters operably contacting a set of cams rotated by a cam shaft is disposed under the palpation region of the outer membrane such that the lifters are used to create a raised feature in the palpation region to be touched by the user. A motor is operably coupled to the cam shaft and has a position sensor operably coupled thereto that is configured to send a signal based on a rotational position of a drive shaft of the motor to a simulation. In response to a user interaction, such as a simulated injection, a region of interest is raised in the palpation region by the cam palpator mechanism, wherein a signal from the position sensor coupled with commands from the simulation cause the region of interest in the palpatable region to be presented to the user. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing and other features and advantages of the invention will be apparent from the following description of embodiments thereof as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The drawings are not to scale. 
         FIG. 1  shows a block diagram of a training system having a palpation region in accordance with an embodiment hereof. 
         FIG. 2  illustrates a perspective view of a housing configured to simulate a patient&#39;s face in accordance with an embodiment hereof. 
         FIG. 3  illustrates a cam palpator in accordance with an embodiment hereof with all lifters in an even, planar configuration. 
         FIG. 4  illustrates the cam palpator of  FIG. 3  with a portion of the lifters in a raised configuration to simulate a wheal of injected substance. 
         FIGS. 5 and 5A  illustrate a cam palpator in accordance with another embodiment hereof. 
         FIG. 6  illustrates a top perspective view of a cam palpator in accordance with another embodiment hereof. 
         FIG. 6A  illustrates a perspective side view of a cam palpator in accordance with another embodiment hereof. 
         FIG. 7  illustrates an exemplary display of a dermal filler injection training system in accordance with an embodiment hereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of embodiments hereof are in the context of a training apparatus for simulating the injection of a substance under the skin, the invention may also be adapted for use as a training aid for other medical procedures where it is deemed useful. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
       FIG. 1  shows a block diagram of a training system having a palpation region in accordance with an embodiment hereof. As shown in  FIG. 1 , training system  100  includes housing  110 , needle-pad device and feedback assembly  114 , injection simulator  120 , haptic feedback assembly  130 , sensors  140  and  150 , input/output interface  160 , processor  170  and visual display  180 . Housing  110  includes a palpation region  112 , which is felt by a user, haptic feedback assembly  130  includes a cam palpator  135  and display  180  includes virtual environment  185 . In this embodiment, needle-pad device and feedback assembly  114 , haptic feedback assembly  130 , sensors  140  and  150 , and input/output interface  160  are disposed within housing  110 . 
     Housing  110  can be any type of structure that supports a palpation region  112 . Housing  110  can also be configured such that several components of training system  100  are disposed outside housing  110 . Thus in alternate embodiments, needle-pad device and feedback assembly  114 , components of haptic feedback assembly  130 , sensors  140 ,  150 , and/or input/output interface  160  can be disposed outside of housing  110 . 
       FIG. 2  illustrates an embodiment of housing  110  configured to simulate a patient&#39;s face in accordance with an embodiment hereof. In other embodiments, the anatomical structure can simulate other body portions of a simulated patient, such as any other portion that would be desirably treated with dermal filler. Housing  110  includes a base portion  113 , a top portion  116 , and an anatomical structure  117  extending from top portion  116 . Anatomical structure  117  includes a flexible outer membrane or covering  115  with palpation region  112  that simulates tissue such as skin and provides a mock or fake skin surface to a user. In an embodiment, outer membrane  115  may be made of a flexible material such as a synthetic rubber, for e.g., neoprene, with or without a fabric-covering to simulate a patient&#39;s epidermis that overlays a thin foam layer to simulate a patient&#39;s dermis. Anatomical structure  117  may include an internal frame having solid portions that support outer membrane  115  and includes at least one opening  119  in outer membrane  115  through which a user can access needle-pad device and feedback assembly  114  with injection simulator  120  to provide the simulated injectable dermal filler. 
     In an embodiment, needle-pad device and feedback assembly  114  may be adapted from the Virtual IV product system manufactured by Immersion, Inc. of San Jose, Calif. A user selects an injection site in the system software and inserts the needle of injection simulator  120  into opening  119  where the needle enters needle pad device and feedback assembly  114 , which tracks an azimuth (yaw), elevation (pitch) and insert depth of the needle. Force feedback is provided to the user through needle pad device and feedback assembly  114  such that the user feels the pierce of the dermal layers and entry into the tissue. In another embodiment, the vascular access simulation system shown and described in U.S. Pat. No. 6,470,302 to Cunningham et al., which is incorporated by reference here in its entirety, may be adapted by one of ordinary skill in the art for use as a needle-pad device and feedback assembly in accordance with embodiments hereof. 
     Haptic feedback assembly  130  provides haptic feedback to palpation region  112 . Feedback assembly  130  includes a motor  137  for driving cam palpator  135 , as shown in  FIGS. 3 and 4 . Cam palpator  135  is situated within housing  110  under palpation region  112  to selectively provide a raised feature  121  in outer membrane  115 , as shown in  FIG. 4 . Raised feature  121 , which projects from anatomical structure  117 , is intended to simulate a wheal created by injected dermal filler and may be palpated and manipulated by a user. Raised feature  121  is created by a set of lifters  334  of cam palpator  135  that are in a raised configuration (as shown in  FIG. 4 ) by operation of a corresponding set of cams  336  on a cam shaft  338  of cam palpator  135 . Each lifter in the set of lifters  334  may be sequentially raised and lowered as cam shaft  338  is rotated, to thereby provide a variety of raised configurations. A drive end  339  of camshaft  338  is operably connected to a drive shaft of a motor  137 , such as, for e.g., a Maxon Motor model 111783 available from Maxon Motor, Ag of Switzerland. Motor  137  can be connected directly to cam shaft  338 , such as with a shaft coupler, for e.g., a McMaster-Carr shaft coupler model 9845T2 available from McMaster-Carr Supply Company of Elmhurst, Ill., or through a drive train or gearbox with a 1:1 ratio for back driveability. A position sensor  150  is operably coupled to motor  137  and is configured to send a signal based on a position of the motor&#39;s drive shaft to processor  170  via input/output interface  160 . In an embodiment, position sensor  150  may be an incremental rotary encoder, such as a two piece optical encoder having a codewheel and a reader available from US Digital of Vancouver, Wash. In various other embodiments, position sensor  150  may be a potentiometer, an accelerometer, resolver or an inclinometer. Motor  137  is back-drivable such that, along with the back-drivability of cams  336  of cam palpator  135 , a user applying an external force in palpation region  112  is permitted to move or manipulate raised feature  121 , i.e., lifters  334 , to simulate pushing dermal filler under the simulated skin and thereby return lifters  334  to a planar configuration, as shown  FIG. 3 . 
     Processor  170  includes a simulation program that is provided a signal from sensor  140  after injection simulator  120  is used to administer a simulated injection of dermal filler to needle pad device and feedback assembly  114 . In response thereto, processor  170  generates an output that directs motor  137  to rotate cam shaft  338  to a predetermined position that orients the set of lifters  334  to produce a raised feature or simulated wheal  121 . Once raised feature  121  is produced, motor  137  holds the predetermined position of cam shaft  338  thereby keeping lifters  334 , and thus raised feature  121 , stationary under palpation region  112 . In the simulation program, one or more signals from position sensor  150  relate to a rotational position of motor  137  that is correlated to one or more predetermined rotational positions of cam shaft  338  with corresponding orientation(s) of lifters  334 . If processor  170  receives a signal from position sensor  150  that is generated due to reverse motion on cam shaft  338 , and in turn the drive shaft of motor  137 , sensed by position sensor  150 , the simulation program assumes that a user is applying an external force, i.e., is pushing on simulated wheal  121  one way or another, and in response thereto processor  170  generates an output that directs motor  137  based on the rules in the simulation to provide haptic feedback through simulated wheal  121  of haptic feedback assembly  130  permitting manipulation thereof or not, and/or by allowing the manipulation to proceed quickly or slowly. The simulation program includes visual rendering of the anatomy, such as visual rendering of the anatomy proximate an injection site, physical rendering of the underlying anatomy including the physical properties related to skin, cartilage, bone, muscle, and other tissue, reading data received from the position sensor of the cam palpator, and outputting data for controlling the cam palpator. In addition, the simulation program includes parameters related to, but not limited to, the amount of dermal filler material injected, the anatomical features around the injection site, the physical properties of the dermal filler material such as viscosity, and the rate of injection. These parameters are inputs to model that control the behavior of the feedback assemblies  114 ,  130 . As such, the simulation program may provide the user the feel, e.g., greater resistance to smoothing out of the simulated wheal at a simulated injection site over bone or cartilage or due to a thicker and/or greater amount of dermal filler being injected requiring the user to exert more of a force against the palpation region to “smooth out” the simulated wheal. 
     A simulation program as described in U.S. Pat. No. 7,289,106 to Bailey et al, which is incorporated by reference here in its entirety, may be adapted by one of ordinary skill in the art for use in accordance with embodiments hereof. 
     In another embodiment shown in  FIGS. 5 and 5A , a cam palpator  535  includes a bracket  547  that holds lifters  534 . Lifter bracket  547  may be raised or lowered to control the engagement of cams  536  with their respective lifters  534 . Lifter bracket  547  is raised or lowered by an actuation mechanism (not shown) that includes two inclined planes and a screw such that when the screw is tightened or loosened the planes ride against each other causing the distance between cams  536  and lifter bracket  547  to change. In an embodiment, the screw of the actuation mechanism may be attached to a motor and sensor such that the simulation program may be used to control the actuation mechanism by computer. In  FIG. 5 , lifter bracket  547  is lowered, or closer to the cam shaft, to thereby permit lifters  534  to engage more fully with cams  536  and to be raised higher relative to lifter bracket  547  to thereby display a larger raised feature or simulated wheal. In  FIG. 5A , lifter bracket  547  is raised, or moved away from the cam shaft, to thereby limit engagement of lifters  534  with cams  536  such that lifters  534  are only slightly raised relative to lifter bracket  547  to thereby display a smaller, more subtle raised feature or simulated wheal. In the embodiment of  FIGS. 5 and 5A , a servo-motor may be operably coupled to cam palpator  535  to actuate cams  536 . 
       FIG. 6  illustrates a top perspective view of a cam palpator  635  for use as a haptic feedback assembly in accordance with another embodiment hereof. Cam palpator  635  includes an array of pinpoint-like lifters  634  arranged in separately controlled rows, each row being connected to a motor (not shown) and a sensor or optical encoder (not shown). In such an embodiment, two dimensional manipulation of wheal  621  may be simulated by a user.  FIG. 6A  is a perspective side view of a cam palpator  635 ′ having square or pin-like lifters  634 ′ that may be used in the array of  FIG. 6  or in another haptic feedback assembly. 
     Processor  170  includes a memory component (not shown in  FIG. 1 ). The memory component may include one or more types of memory. For example, the memory component may include a read only memory (ROM) component and a random access memory (RAM) component. The memory component may also include other types of memory that are suitable for storing data or software in a form retrievable by processor  170 . For example, electronically programmable read only memory (EPROM), erasable electronically programmable read only memory (EEPROM), flash memory, as well as other suitable forms of memory may be included within the memory component. Processor  170  may also include a variety of other components, such as for example, co-processors, graphics processors, etc., depending upon the desired functionality of the device. 
     Training system  100  is configured such that a user (e.g., a medical practitioner or clinician) uses injection simulator  120  and palpates palpation region  112  in conjunction with viewing the virtual environment  185  on visual display  180 . In other words, the user receives haptic output at palpation region  112  while also viewing the virtual environment  185 , which is provided in coordination with the haptic output.  FIG. 7  illustrates an exemplary visual display of a dermal filler injection training system in accordance with an embodiment hereof. 
     While various embodiments according to the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.