Abstract: A system for use during a medical or surgical procedure on a body. The system modifies a reference image data set according to a density image of a body element during a procedure, generates a displaced image data set representing the position and geometry of the body element during the procedure, and compares the density image of the body element during the procedure to the reference image of the body element. The system also includes a display utilizing the displaced image data set generated by the processor to illustrate the position and geometry of the body element during the procedure. Methods relating to the system are also disclosed.

Abstract: Various embodiments of the invention include systems and methods for adapting a movement model based on an image captured during radiation treatment of a patient. The movement model may, for example, be used in radiotherapy to treat lung cancer. The movement model is typically based on a series of images of a patient captured over a period of time. The movement model and/or one or images included therein may be used to generate a reference image of the patient. The reference image is compared with an image of the patient optionally captured during treatment. The result of this comparison is used to adapt the movement model to conditions during the treatment.

Abstract: A system to allow registration of a patient to image space is disclosed. The registration can be performed without touching a plurality of fiducial points on the patient or in the image data. The registration process can eliminate manual steps of image to patient registration and image to image registration.

Abstract: An apparatus and a method for guiding the placement of an object to a desired location based on an image generated by an image intensifier where the apparatus includes a first coupling mechanism that is configured to be releasably attachable to one of the transmitter and receiver of the image intensifier and a second coupling mechanism that is coupled to the first coupling mechanism and includes an object holding mechanism, the object holding mechanism is configured to releasably hold the object and where at least a portion of the second coupling mechanism is visible in the image generated by the image intensifier when the apparatus is attached to the image intensifier.

Abstract: An improved marker system, components and method for use with a medical navigation system, wherein the marker system includes interchangeable tracking marker holders and fastener bases for attaching the marker holders to instruments or body parts that are to be tracked during a medical procedure. A reference star (the marker holder and tracking marker(s)) and fastener base are removably attached to one another. This enables different reference stars to be interchangeably attached to a given fastener base, or vice versa, thereby to provide the best combination of reference star and fastener base for a given application. This preferably is accomplished by a standard interface between the fastener base and the holder for the tracking markers, e.g., reflective markers. In addition, surgical instruments may have integrally formed therein the standard interface, thereby eliminating the need for a fastener base.

Abstract: A system and method for creating a cavity to receive an acetabulum in a pelvic bone with the aid of a navigated tool are provided. A tear-drop point on a pelvic bone is located by means of a scanning instrument. A tear-drop plane is determined from position data of the tear-drop point and the plane of the pelvic inlet. The tear-drop plane lies perpendicular to the plane of the pelvic inlet, extends parallel to a line connecting the two anterior superior iliac spines, and runs through the tear-drop point. A reference point is determined which is at a defined height above the tear-drop plane, in a defined position in an anterior-posterior direction, and at a defined spacing from an outer surface of the pelvic bone in a lateral-medial direction. A tool is worked into the pelvic bone in a desired direction relative to the reference point.

Abstract: Certain embodiments of the present invention provide for a system and method for modeling S-distortion in an image intensifier. In an embodiment, the method may include identifying a reference coordinate on an input screen of the image intensifier. The method also includes computing a set of charged particle velocity vectors. The method also includes computing a set of magnetic field vectors. The method also includes computing the force exerted on the charged particle in an image intensifier. Certain embodiments of the present invention include an iterative method for calibrating an image acquisition system with an analytic S-distortion model. In an embodiment, the method may include comparing the difference between the measured fiducial shadow positions and the model fiducial positions with a threshold value. If the difference is less than the threshold value, the optical distortion parameters are used for linearizing the set of acquired images.

Abstract: A system for controlling a medical device in a patient. A display system displays an image of a volume of the patient in a virtual three-dimensional space. A stylus is controllable to actuate a virtual element in the virtual space. A navigation system controls the medical device in the patient volume based on a position of the actuated virtual element. This inherently three-dimensional interface allows a physician to actuate the medical device more intuitively than possible using a two-dimensional interface.

Abstract: This document discusses trajectory guides that include an instrument guide with at least one lumen angled with respect to an orthogonal or other through-axis. In one example, patterned lumens on the instrument guide provide a mirror image pattern of trajectory axes intersecting a target plane. In another example, height adjustment of the instrument guide extends these or other targeting techniques to a three-dimensional volume. This document also describes a method of manufacturing such an instrument guide, which is also applicable to manufacturing an instrument guide providing parallel lumens.

Abstract: The present invention provides new and useful features and mechanisms for the localization and transport of biopsy specimens. The invention having a specimen board, an absorbent material in operative engagement and in coplanar alignment with the specimen board, a compression sheet, radio opaque indicia located within the specimen board, and a flexible connection between the compression sheet and the specimen board, and an attachment device which provides for removable engagement of the specimen board and compression sheet. The apparatus further provides for a clear visualization window and operating instructions. The absorbent material is capable of adjustable movement between a first and second position, providing orthogonal positioning relative to the specimen board. As a result, the apparatus may be used to create three dimensional radiographic images allowing tissue analysis resulting in orthogonal views while maintaining original positional reference points.

Abstract: A method for performing computer-assisted orthopaedic surgery includes the steps of: (1) producing and displaying three-dimensional geometrical models of first and second bones, the first and second bones forming a joint; (2) identifying a zone of impingement between the first bone and the second bone on at least one of the bones; and (3) generating and displaying a color map of at least one surface of at least one bone, the at least one surface being within the zone of impingement, the color map including different colors representing different depths of bone to be removed in order to achieve an increased range of motion between the first and second bones.

Abstract: A method for restoring navigation failure information in a fluoroscopy-based imaging system is disclosed. The method includes obtaining a plurality of receiver navigation information using a calibration target rigidly attached to a supporting member of the imaging system. The calibration target may include a plurality of receivers providing navigation information and the supporting member may be a C-arm. The method identifies a navigation failure and corresponding to the navigation failure a calibrated receiver navigation information is generated. The calibrated receiver navigation information is generated using a calibration information and a C-arm imaging position obtained during navigation failure. A receiver navigation information corresponding to the navigation failure is estimated using the calibrated receiver navigation information, and a transmitter navigation information.

Abstract: A method for defining an antetorsion angle ? of a femur is provided. The antetorsion angle ? is defined by two angles ?? and ? that can be determined by means of two images of the femur, wherein the equation tan ?=tan ??/(cos ?·cos ?) can be used to calculate the antetorsion angle ?.

Abstract: A stereotactic navigation system for navigating an instrument to a target within a patient may include a stereotactic head frame, an imaging device, a tracking device, a controller and a display. The stereotactic head frame is coupled to the patient and is used to assist in guiding the instrument to the target. The imaging device captures image data of the patient and of the stereotactic head frame. The tracking device is used to track the position of the instrument relative to the stereotactic head frame. The controller receives the image data from the imaging device and identifies the stereotactic head frame in the image data and automatically registers the image data with navigable patient space upon identifying the stereotactic head frame, while the display displays the image data.

Abstract: An anatomical data registration device may include a dental device. The dental device may configurable to be subject-specific. A dental device may be positionable in a substantially fixed spatial relationship relative to a portion of the subject. An anatomical data registration device may include one or more radiopaque markers. At least one of the radiopaque markers may be positioned in the dental device. The radiopaque marker may be configured to facilitate alignment of two or more images of the portion of the subject. The data registration device may be positionable within a subject's mouth.

Abstract: Provided herein are devices and methods for supporting and positioning a tracking assembly for mounting variously configured medical devices for prostate imaging, biopsy, and other therapeutic applications. In one aspect, a support assembly provides multiple degrees of freedom for positioning a tracking assembly and mounted probe relative to a patient on a patient support structure such as an examination table or a gurney bed and/or maintaining a tracking assembly and mounted probe in a desired location throughout the rendering of imaging, biopsy, or other therapeutic procedures.

Abstract: An adapter can be easily used to assist a surgical navigation system to determine the effector axis or the effector plane of a surgical instrument. The adapter has a body with a geometrical feature, the geometrical feature has a known relation with a navigation tracker device that can be attached to the adapter. When the adapter is held against a surgical instrument in a non-fixed manner, the effector axis or the effector plane of the instrument can be tracked by the surgical navigation system. The method includes a calibration method to determine the known relation between the effector axis or the effector plane and the location of the navigation tracker.

Abstract: A method of registering an article having a surface to previously created scan data of the article includes the steps of providing a flexible substrate having multiple tracking points attached to the substrate, applying the substrate to the article to be registered, creating a model of the surface of the article from a location of each tracking point; and registering the model with the previously created scan data. A method of creating a model of a surface having a shape and an article to enable the creation of a model of a surface are also disclosed.

Abstract: A probe for insertion into the body of a subject includes a sensor, a first microcircuit, which stores first calibration data with respect to the sensor, and a first connector at the proximal end of the probe. A probe adapter includes a second connector, which mates with the first connector, a signal processing circuit, which is processes the sensor signal, and a second microcircuit, which stores second calibration data with respect to the signal processing circuit. A microcontroller in the adapter receives the first and second calibration data and computes combined calibration data. The adapter includes a third connector, which mates with a fourth connector on a console. The console includes signal analysis circuitry, which analyzes the processed signal using the combined calibration data provided by the probe adapter.

Abstract: A method and apparatus for determining, calculating, and/or viewing a trajectory. The trajectory can be displayed on a display relative to image data of a patient. A user can use the system to determine relationships between two or more trajectories that have been determined. The relationships can be within two dimensional, three-dimensional, or four dimensional space. The relationships can include distance, angle, etc. The relationships can also be determined between real time trajectories and stored trajectories, or combinations thereof.

Abstract: A method and system is presented for treating moving target regions in a patient's anatomy by creating radiosurgical lesions. The method includes determining a pulsating motion of a patient separately from a determining of a respiratory motion, and directing a radiosurgical beam, from a radiosurgical beam source, to a target in the patient based on the determining of the pulsating motion. Directing the radiosurgical beam to the target may include creating a lesion in the heart to inhibit atrial fibrillation. The method may further include determining the respiratory motion of the patient, and compensating for movement of the target, due to the respiratory motion and the pulsating motion of the patient, in the directing of the radiosurgical beam based on the determining of the respiratory motion and the determining of the pulsating motion.

Abstract: A method for determining a three dimensional representation of a tubular organ, the method comprising the procedures of registering a three dimensional medical positioning system (MPS) coordinate system with a two dimensional coordinate system, acquiring a plurality of MPS points within the tubular organ, the MPS points are associated with the MPS coordinated system, each of the MPS point is acquired with a respective organ timing signal reading, acquiring at least one two dimensional image of the tubular organ, the at least one two dimensional image is associated with the two dimensional coordinate system, the at least one two dimensional image is acquired from at least one perspective, each of the at least one two dimensional image is further acquired with a respective organ timing signal reading, associated each of the MPS points with the at least one two dimensional image according to the organ timing signals thereof, determining a temporal three dimensional representation of a portion of the tubular orga

Abstract: A method and apparatus to perform a procedure that can include a processor assisted surgical procedure. During the procedure patient space and image space can be registered to allow for tracking of various tracking sensors. A dynamic reference frame can be used to maintain localization of the patient space with the image space. The dynamic reference frame can be fixedly interconnected with a bone portion of the anatomy.

Abstract: The invention relates to a system and a method for the investigation of a body volume (3), particularly for the diagnosis of breast cancer According to the method, a sequence of X-ray projections (P, P?) from different directions is produced by a rotatable X-ray source (1) and a stationary digital X-ray detector (5). From these projections (P, P?), a set of sectional images (a, b, c, d) is calculated by tomosynthesis. A physician may indicate a suspicious structure on a reference image (R) that is derived from one of the projections (P, P?) or sectional images (a, b, c, d) and displayed on a monitor (6). The computer (7) may then locate the structure on all sectional images (a, b, c, d) and calculate the similarity of a corresponding image feature. The sectional 10 image at which the similarity is strongest then indicates the depth (zo) at which the structure (4) is positioned in the body volume (3).

Abstract: A method of defining a biological target for treatment in which image detectable markers are placed at and correlated to the location or locations of tissue biopsy. By obtaining pathological analysis of the biopsy tissue specimens and correlating the analysis to the corresponding marker locations, the definitive pathological analysis of the target tissue at the marker locations can be correlated to corresponding locations on a functional image of the target tissue. The correlation of the marker locations and pathology to the corresponding locations on a functional image can then be used to prescribe and apply modulated therapy to the target tissue.

Abstract: A method and system for producing tomosynthetic images of a patient's breast. An x-ray source that delivers x-rays through a breast immobilized and compressed between a compression paddle and a breast platform and form an image at a digital x-ray receptor panel. Multiple x-ray images are taken as the x-ray source and the receptor move relative to the immobilized breast. In one preferred embodiment, the x-ray source travels from ?15° to +15°. The source can travel in an arc around the breast while the receptor travels linearly while remaining parallel and at the same distance from the breast platform. The sets of x-ray image data taken at different angles are combined to form tomosynthetic images that can be viewed in different formats, alone or as an adjunct to conventional mammograms.

Abstract: A system and method are provided for control of a navigation system for deploying a medical device within a subject, and for enhancement of a display image of anatomical features for viewing the projected location and movement of medical devices, and projected locations of a variety of anatomical features and other spatial markers in the operating region. The display of the X-ray imaging system information is augmented in a manner such that a physician can more easily become oriented in three dimensions with the use of a single-plane X-ray display. The projection of points and geometrical shapes within the subject body onto a known imaging plane can be obtained using associated imaging parameters and projective geometry.

Abstract: A method and apparatus for cross checking points palpated with a localization device. Points corresponding to the palpated points are obtained from a preoperative image of an object such as an X-Ray of a tibia bone. During a surgical procedure, the accuracy of palpated points are determined based on the palpated points and corresponding points obtained from the preoperative image. If a palpated point is inaccurate, an indicator is generated to indicate the inaccuracy of the palpated point.

Abstract: A localization mechanism, or fixture, is used in conjunction with a breast coil for breast compression and for guiding a core biopsy instrument during prone stereotactic biopsy procedures in both open and closed Magnetic Resonance Imaging (MRI) machines. The localization fixture includes a fiducial marker and three-dimensional Cartesian positionable guide for supporting and orienting an MRI-compatible biopsy instrument with detachable probe/thumb wheel probe to the biopsy site of suspicious tissues or lesions.

Abstract: A therapy delivery system for the intermittent delivery of biologics, chemicals, or pharmaceuticals into tissues involves a chronically implantable guide tube having a guide cannula with a proximal and a distal end, an access port mounted on the proximal end of the guide cannula and adapted for chronic implantation into a patient, a first stop mounted near the distal end of the guide cannula and a delivery cannula insertable into the lumen of the guide cannula through the access port. The delivery cannula mechanically interacts with the first stop and is designed to prevent the delivery cannula from extending beyond a predetermined distance from the distal end of the guide cannula. A tissue-piercing tip may be attached to the distal end of the delivery cannula. A stylet may be used to occupy the lumen of the guide cannula when the delivery cannula is not in use.

Abstract: A portable orthovoltage radiotherapy system is described that is configured to deliver a therapeutic dose of radiation to a target structure in a patient. In some embodiments, inflammatory ocular disorders are treated, specifically macular degeneration. In some embodiments, the ocular structures are placed in a global coordinate system based on ocular imaging. In some embodiments, the ocular structures inside the global coordinate system lead to direction of an automated positioning system that is directed based on the ocular structures within the coordinate system.

Abstract: A system and method for providing computer assistance for performing a medical procedure provides a graphical user interface to guide and/or assist a user, for example a surgeon, performing the medical procedure, whether surgical or non-surgical. The computer-assisted system comprises a software application that may be used for a medical procedure.

Abstract: A method for planning minimally invasive direct coronary artery bypass (MIDCAB) for a patient includes obtaining acquisition data from a medical imaging system, and generating a 3D model of the coronary arteries and one or more cardiac chambers of interest. One or more anatomical landmarks are identified on the 3D model, and saved views of the 3D model are registered on an interventional system. One or more of the registered saved views are visualized with the interventional system.

Abstract: A method for calibrating a medical system capable of generating a magnetic field for tracking a position of a medical device has various steps such as defining a mapping volume within the generated magnetic field and placing a metallic object within the mapping volume. A sensor is aligned at a first point within the mapping volume and the magnetic field at the first point is measured with the sensor to establish a first coordinate position (Xi, Yi, Zi). An interpolation technique in one embodiment and an extrapolation technique in another embodiment are used in the calibration method.

Abstract: A device and method for automatically verifying, calibrating and surveying a navigable surgical instrument, wherein by means of a scanning device, the geometry of the instrument, in particular the shape of the functional elements (e.g., tips) and their spatial position with respect to an attachable reference system, are detected. By means of a data processing unit, a three-dimensional model of the instrument is calculated from the detected information concerning the geometry of the instrument including the reference system, wherein verification, calibration or surveying is performed with the aid of the ascertained information concerning the geometry of the instrument.

Abstract: A system and method for CT guided instrument targeting including a radiolucent instrument driver; a robot and a control box. The robot includes a robotic module that positions the radiolucent driver about two directions coincident a predetermined point. The control device is connected to the robot and the radiolucent instrument driver. The control driver sends a robot control signal to the robot that causes the robotic module to place the radiolucent instrument driver in a desired orientation with respect to the predetermined point. After the radiolucent instrument driver is in the desired orientation, the control device sends a driver control signal to the radiolucent instrument driver that causes the radiolucent driver to insert a medical instrument or device through the predetermined point to a location proximate a target point in a patient.

Abstract: In one embodiment, an adaptive medical image registration procedure includes a motion estimation procedure involving estimating or determining an amount of patient or tissue motion along a set of axes; an evaluation procedure involving evaluating an estimated amount of motion relative to a correction threshold; and a correction procedure involving performing a two dimensional image resampling, a three dimensional image resampling, or possibly avoiding an image resampling based upon a relationship between an estimated amount of motion and the correction threshold. Axes considered by a motion estimation procedure may include an axis of lowest image resolution, and the correction threshold may have a value given by a fraction of a lowest image resolution.

Abstract: The invention concerns a device for monitoring an imaging or radiotherapy unit (1) for treating members of the human body subject to displacements related to movements of the diaphragm. The invention is characterized in that said monitoring device is designed to enable, in a prior preparation phase, to store two values, called rest value and triggering value, respectively representing, for each patient, of his suspended ventilatory level and an inhalation or exhalation ventilatory level, triggering acquisition of images or irradiation, then, during the real monitoring of the unit (1), in commanding an image or irradiation acquisition, once the correspondence between the measured value of the suspended ventilatory level and the stored rest value has been established, and only when the correspondence between the measured respiratory value of the patient and the stored triggering value has been subsequently established.

Abstract: Method for delivering a stent coupled with a catheter, to a selected position within a lumen of the body of a patient, the method includes the procedures of: selecting a single image of the lumen, among a plurality of images of an image sequence of the lumen, receiving a position input associated with the selected image and respective of the selected position, the position input is defined in a coordinate system respective of a medical positioning system (MPS), detecting the current position of the stent in the coordinate system, according to position data acquired by an MPS sensor attached to the catheter in the vicinity of the stent, superimposing on at least one maneuvering associated image of the lumen, at least one stent representation respective of the current position, and at least one marking representation respective of the position input, according to a real-time organ timing signal of an inspected organ of the body, maneuvering the catheter through the lumen, toward the selected position, according

Abstract: Radiation treatment of the lung or surrounding tissue during continuous breathing is made possible by preparing a treatment plan linked to motion phase and then synchronizing the plan to motion phase as the patient follows a regular breathing schedule.

Abstract: A system and method for positioning a device at a desired location in a tubular organ such as an artery. A three-dimensional reconstruction of the organ is obtained, and the desired location is marked in the reconstruction. The device is inserted into the organ and an image is obtained of the device and organ. The reconstruction with the marked location is projected onto a plane from the perspective of the image and the projection and image are superimposed. If the device is not at the desired location, the device is repositioned in the organ and an additional image of the device is obtained. The reconstruction is then projected onto a plane from the perspective of the additional image and the additional image and the projection are superimposed. This process is repeated, as required, until the device is in the desired location.

Abstract: A magnetic navigation system for orienting a magnetically responsive device in an operating region in a subject has at least two magnet units and a support for mounting the at least two magnet units for movement relative to the subject, the support supporting the at least two magnet units adjacent the operating region in the subject at locations to apply a magnetic field to the operating region. Each magnet unit includes sing a magnet and a positioner for selectively changing the position of the magnet. The system also includes a control for operating the positioners of each magnet unit to selectively change the positions of the magnets to maintain the magnetic field direction applied to the operating region by the magnets as the locations of the magnet units relative to the operating region change.

Abstract: A method for performing Magnetic Resonance Imaging (MRI) guided core biopsies is tendered more accurate and efficient by precisely positioning a disengaged probe assembly with respect to a localization fixture attached to a breast coil platform. The precise position is defined by MRI stereotopic location of suspicious tissue with respect to a fiducial marker on the localization fixture. With the probe inserted, dual lumens in the probe assembly are used for drainage or insertion of fluids as well as inserting diagnostic and therapeutic tools. Core biopsies are performed by engaging a biopsy instrument handle containing a cutter, with the localization fixture providing support and position to the handle. Repeated MRI scans are facilitated by the ability to disengage the handle without risk of displacing the probe assembly from the biopsy site.

Abstract: Devices and processes for use in computer aided or computer navigated surgery include one or more fault interfaces interposed between an indicium and an item to be used during surgery such as a body part, tool, implant, trial or other structure or component. After the indicia have been registered into the system and surgery begun, it is sometimes the case that indicia can be inadvertently moved or dislodged in position and/or orientation relative to the body part. Fault interfaces according to various embodiments are designed to fail first, so that the indicia can be repositioned relative to the item without the need to reregister the indicia into the system relative to the item. The fault interfaces preferably include structure that allows the indicium to be repositioned relative to the item so that it does not need to be reregistered into the system. Frame attachments which can by easily manufactured at relatively low cost, are disposable, and which are manufactured for single use are disclosed.

Abstract: The present invention, in another aspect, relates to a microstereotactic table. In one embodiment, the microstereotactic table includes a plate member having a first surface, an opposite, second surface, a body portion defined therebetween, a plurality of leg members, each of them removably engaged with the plate member, respectively, and a passage is formed between the first surface and the opposite, second surface of the body portion of the plate member and along a longitudinal axis, wherein a step is formed within the passage, and wherein the step is formed such that the distance from the step to one of the first surface and the opposite, second surface along the longitudinal axis is a predetermined length.

Abstract: An image-guided radiosurgery method and system are presented that use 2D/3D image registration to keep the radiosurgical beams properly focused onto a treatment target. A pre-treatment 3D scan of the target is generated at or near treatment planning time. A set of 2D DRRs are generated, based on the pre-treatment 3D scan. At least one 2D x-ray image of the target is generated in near real time during treatment. The DRRs are registered with the x-ray images, by computing a set of 3D transformation parameters that represent the change in target position between the 3D scan and the x-ray images. The relative position of the radiosurgical beams and the target is continuously adjusted in near real time in accordance with the 3D transformation parameters. A hierarchical and iterative 2D/3D registration algorithm is used, in which the transformation parameters that are in-plane with respect to the image plane of the x-ray images are computed separately from the out-of-plane transformation parameters.

Abstract: In time-resolved contrast-enhanced magnetic resonance angiography, a measure quantifying image quality provides a basis for generating a linear filtered composite image by facilitating selection of a mask and an arterial phase image for subtraction. Filtering of individual pixels of a temporal series of images provides enhanced contrast in a single image by allowing the temporal behavior of the pixel intensity to denote representation as an artery, vein or background tissue. Motion artifacts are suppressed by re-registering sequential images, adjusting weighting before averaging and subtraction and filtering the Fourier data to eliminate data corrupted by motion or other phenomena.

Abstract: An image system, notably an X-ray system and an ultrasound system, is provided in which images or sequences of images are generated and used to automatically change or optimize the operational behavior of individual image system components. Measurement fields are defined in the images of an image sequence by means of a data processing unit. Information is extracted from the measurement fields in order to adapt the system components. More specifically, in the course of a sequence of images the measurement fields are adapted or shifted in conformity with the motion of objects.

Abstract: The invention relates to a digital system (1) for performing stereotaxic biopsies with a biopsy needle. The inventive system (1) comprises a series of devices which are used to: emit X-rays, detect and transform X-ray photons into electric signáis, position a tissue sample between the X-ray source and the detector, process the electric signáis, and genérate images. The system can also be equipped with a series of devices complementary to those mentioned above, as well as a means for positioning the aforementioned devices in two positions and obtaining images in two different orientations.

Abstract: A tele-medicine system that includes an input device which can control a medical system. The input device may be the handle of a surgeon console. The medical system may include a robotically controlled medical device. A transmitter may transmit information relating to each state of the input device over a communication network. The medical system receives the transmitted state information through a receiver. The medical system changes state in response to the received state information from the input device. The system sends information relating to an entire state of the input device over a sample period to insure that the medical system receives all commands, data, etc. necessary to operate the system.