WO2010027636A1

WO2010027636A1 - Medical fluid injector calibration apparatus

Info

Publication number: WO2010027636A1
Application number: PCT/US2009/053970
Authority: WO
Inventors: Charles S. Neer
Original assignee: Mallinckrodt Inc.
Priority date: 2008-08-25
Filing date: 2009-08-17
Publication date: 2010-03-11

Abstract

An injector calibration apparatus (110) is disclosed operable to be interconnected to, and impart a predeterminable force on, a ram (74) of a power injector (10). The injector calibration apparatus (110) may include a ram (118) operable to interface with the ram (74) of the power injector (10). A force gauge (122) may be disposed to measure the amount of force imparted on the ram (74) by the ram (118) of the injector calibration apparatus (110). In one embodiment, the output of the force gauge (122) may be amplified and fed into the power injector (10). The power injector (10) may be operable to control the level of force imparted on the ram (74) by the injector calibration apparatus (110) such that a series of powerhead motor (58) current levels for a variety of powerhead ram (74) speed and force combinations may be measured and recorded in a calibration look up table.

Description

MEDICAL FLUID INJECTOR CALIBRATION APPARATUS

RELATED APPLICATIONS This application claims priority to US Provisional Patent Application No. 61/091,509 filed on 25 August

2008 entitled "INJECTOR CALIBRATION APPARATUS".

FIELD OF THE INVENTION

The present invention generally relates to powered medical fluid injectors and, more particularly to calibrating a powered medical fluid injector.

BACKGROUND

Various medical procedures require that one or more medical fluids be injected into the patient. Medical imaging procedures oftentimes involve the injection of a contrast media into the patient, possibly along with saline or other fluids. Other medical procedures involve injecting one or more fluids into a patient for therapeutic purposes. Power injectors may be used for these types of applications.

A powered medical fluid injector (or power injector) generally includes what is commonly referred to as a powerhead. One or more syringes may be mounted to the powerhead in various manners (e.g., detachably; rear- loading; front-loading; side-loading). Each syringe typically includes what may be characterized as a syringe plunger, piston, or the like. Each such syringe plunger is designed to interface with (e.g., contact and/or temporarily interconnect with) an appropriate syringe plunger driver that is incorporated into the powerhead, such that operation of the syringe plunger driver axtally advances the associated syringe plunger inside and relative to a barrel of the syringe. One typical syringe plunger driver is in the form of a ram that is mounted on a threaded lead or drive screw. Rotation of the drive screw in one rotational direction advances the associated ram in one axial direction, while rotation of the drive screw in the opposite rotational direction advances the associated ram in the opposite axial direction.

It is generally desirable to calibrate a power injector in order to correlate a parameter of the syringe plunger driver, such as motor current, to pressure output of the powerhead. For instance, such a calibration may compensate for powerhead-to-powerhead variations in, inter alia, the motor, a gear train coupling the motor to the drive screw, the drive screw-to-ram interface, and a ram-to-bushing interface.

SUMMARY

The present invention at least generally relates to calibrating a powered medical fluid injector. This calibration may relate to monitoring pressure during operation of the injector, In one embodiment, a motor current of the injector is monitored and is used to determine a pressure associated with the operation of the injector. Calibration may be undertaken in relation to monitoring this motor current for pressure monitoring purposes. Various aspects of the present invention will now be described. Although each of the following aspects may relate or be applicable to the foregoing, the content of this introduction is not a requirement for any of these aspects unless otherwise noted.

First and second aspects of the present invention are each embodied by a medical fluid injector calibration apparatus. The medical fluid injector calibration apparatus may include a frame and an injector ram 5 interface member. The injector ram interface member may be operable to interface with an injector ram of the medical fluid injector and may be movable relative to the injector calibration apparatus frame. in the case of the first aspect, the injector calibration apparatus may further include a frame interface member operable to interconnect to a mounting member of the injector being calibrated such that the injector calibration apparatus frame is maintained in a fixed position relative to the injector. In this regard, the injector l O calibration apparatus may be operable to mount or attach to the injector being calibrated in a manner similar to how a syringe, a faceplate, or a syringe adapter may be mounted or attached to the injector, although the injector calibration apparatus may be mounted on or attached to the injector in any appropriate manner. The injector calibration apparatus may further include a motor operable to drive the injector ram interface member.

In the case of the second aspect, the injector calibration apparatus may further include a sensor, such as

15 for example a force gauge, operable to measure a level of force between the injector ram interface member and the injector ram. For example, the force gauge may be disposed between the injector ram interface member and the injector ram in such a manner as to be able to measure the force between these two components. The force gauge may be of any appropriate type and/or configuration operable to measure the force between the injector ram interface member and the injector ram. Furthermore, the force gauge may be positioned in any appropriate 0 location such that it is capable of measuring the force on the injector ram.

A number of feature refinements and additional features are separately applicable to each of the first and second aspects of the present invention. These feature refinements and additional features may be used individually or in any combination. The following discussion is separately applicable to each of the first and second aspects, up to the start of the discussion of a third aspect of the present invention. 5 In an embodiment of the first aspect, the injector calibration apparatus may further include a force level measuring member operable to measure a level of force between the injector ram interface member and the injector ram. In an embodiment of the second aspect, the injector calibration apparatus may further include a frame interface member that may be operable to interconnect to a mounting member of the injector.

The injector calibration apparatus may further include an injector calibration apparatus ram. The injector 0 ram interface member may be operable to mechanically couple the injector calibration apparatus ram to the injector ram for tandem movement of the injector calibration apparatus ram and the injector ram. The tandem movement may occur during extension and retraction of the injector ram. One end of the injector ram interface member may be fixedly attached to the injector calibration apparatus ram, while another of its ends may be configured to removably attach to the injector ram. In this regard, the injector ram interface member may be5 configured similarly to a head of a syringe plunger coupler, thereby interconnecting to the injector ram in a manner similar to how syringe plungers are interconnected to the injector ram. In an embodiment, the injector calibration apparatus frame and injector calibration apparatus ram may be configured similarly to the frame and ram of the injector to be calibrated, tn this regard, portions of the injector calibration apparatus may be constructed from parts used in the injector. For example, one possible construction of an injector calibration apparatus may include reconfiguring an injector to function as an injector calibration apparatus. Any appropriate structural configuration may be used for the injector calibration apparatus. The injector ram interface member may be characterized as an end portion of the above-noted injector calibration apparatus ram. Although the injector calibration apparatus ram may be coupled (e.g., mechanically) with the injector ram, the injector calibration apparatus ram and the injector ram could simply be placed in abutting relation. As the injector calibration apparatus ram may be characterized as a resistive source for calibrating the injector, the interface between the injector calibration apparatus and the injector may be characterized as being fluid-free.

The injector calibration apparatus may include an injector calibration apparatus motor interconnected to the injector ram interface member. The motor may be of any appropriate configuration operable to drive the injector ram interface member. The injector calibration apparatus motor may be operable to control (e.g., selectively) the level of force between the injector ram interface member and the injector ram. In an embodiment, the injector calibration apparatus motor may be configured similarly to the motor of the injector to be calibrated. For example, one possible construction of an injector calibration apparatus may include incorporating a motor from an injector to function as the injector calibration apparatus motor. The injector calibration apparatus motor may be coupled to an injector calibration apparatus ram that is interconnected to the injector ram interface member. For example, the injector calibration apparatus motor may be operatively interconnected to the injector calibration apparatus ram through a gear train and/or a drive screw. The drive screw may convert a rotational output of the injector calibration apparatus motor into a linear movement of the injector calibration apparatus ram. The injector calibration apparatus ram may be interconnected to a rotary encoder.

The injector calibration apparatus may include a force gauge output operable to be interconnected to the injector. For example, a force gauge of the injector calibration apparatus may be interconnectable to the injector being calibrated via the force gauge output. Through such a connection, the injector calibration apparatus may be able to monitor the level of force present on the injector ram. The force gauge output may be accessible through an electrical connector, The force gauge output may be conditioned to generate an appropriate output. For example, the force gauge output may be generated by a force gauge interconnected to an amplifier circuit. The amplifier circuit may produce a voltage output from, for example, 0 to 5 V that is representative of the level of force measured by the force gauge. The force gauge output may be configured to generate any appropriate output type and range.

The injector calibration apparatus may include control circuitry operable to control (e.g., selectively) the level of force between the injector ram interface member and the injector ram based at least in part on an output from the injector. For example, the injector calibration apparatus may contain control circuitry operable to drive an injector calibration apparatus motor such that the injector calibration apparatus motor imparts a controlled level of force on the ram of the injector being calibrated. The level of force may be based on an input to the control circuitry from the injector. The input to the control circuitry may, for example, be in the form of a putse width modulated signal.

In an embodiment of the injector calibration apparatus, the level of feree between the injector ram interface member and the injector ram may be adjustable. The adjustability may at least partially be dependent on an output signal from the injector being calibrated. The adjustability may be operable to be set by an operator of the injector calibration apparatus. In an embodiment of the injector calibration apparatus, the level of force may be adjustable independently of a position of the injector ram.

In an embodiment of the injector calibration apparatus, the level of force may be adjustable during movement of the injector ram. In this regard, the force level may be adjusted upward or downward while the injector ram is moving at a fixed or variable speed. In the case of varying the force level for a fixed speed of movement of the injector ram, varying the force level while maintaining a selected ram speed may enable calibration of the injector at a plurality of distinct force levels for the selected ram speed. The various selected force levels between the injector ram interface member and the injector ram may be chosen to simulate pressure levels that may correspond to expected pressure levels for the injector when injecting fluids in normal use and/or pressure levels reflective of the operating capabilities of the injector.

The injector calibration apparatus may be operable to be installed on and removed from the injector, and which may be done in any appropriate manner. The injector calibration apparatus may be configured such that installation on, and removal from, the injector may be accomplished by an operator without the use of tools. In one embodiment, the injector calibration apparatus is detachably interconnectable with the injector. Third and fourth aspects of the present invention are each embodied by a method of calibrating an injector that may be used to inject fluid into a patient. The method may include interconnecting an injector calibration apparatus to the injector to be calibrated and driving a motor of the injector after it has been interconnected to the injector calibration apparatus to move an injector ram. A drive signal may be provided to the injector motor that is associated with providing a certain speed for the injector ram. In any case, the method may further include recording a level of the current drawn by the motor while the injector ram is moving.

In the case of the third aspect, the interconnecting of the injector calibration apparatus to the injector may include interconnecting the injector calibration apparatus to a mounting member of the injector. The mounting member of the injector may be in the form of a structure on which a faceplate may be detachably mounted. In this regard, the injector calibration apparatus may be configured to mount to the injector in at least generally the same manner as a faceplate. However, the mounting member of the injector may be of any appropriate size, shape, configuration, and/or type. Generally, the injector calibration apparatus may be mounted to the injector in any appropriate manner.

The third aspect may include connecting an injector ram interface member of the injector calibration apparatus to an injector ram of the medical fluid injector. The injector ram interface member may be configured to connect to the injector ram of the injector in a manner similar to how a syringe plunger coupler interconnects to the injector ram of the injector during normal injector operation. In any case, the third aspect may further include driving a motor of the injector calibration apparatus (e.g., to provide a resistive force) while the motor of the injector is also being driven.

In the case of the fourth aspect of the present invention, the interconnecting of the injector calibration apparatus to the medical fluid injector may include disposing a force gauge (e.g., of the injector calibration apparatus) relative to an injector ram of the injector such that the force gauge is operable to measure a force of the injector calibration apparatus on the injector ram. The method may further include adjusting, as the injector ram is being driven, the injector calibration apparatus such that a first level of force is measured by the force gauge. A level of current that is being drawn by the injector motor (while the injector ram is being driven by a signal associated with providing a first speed for the injector ram, and also while the resistive force provide by the injector calibration apparatus is at the first level of force and as measured by the force gauge) may be recorded.

A number of feature refinements and additional features are separately applicable to each of the third and fourth aspects of the present invention, These feature refinements and additional features may be used individually or in any combination. The following discussion is separately applicable to each of the third and fourth aspects, up to the start of the discussion of a fifth aspect of the present invention. In an embodiment of the third aspect, the connecting step may include disposing a force gauge (e.g., of the injector calibration apparatus) relative to the injector ram such that the force gauge is operable to measure a first level of force of the injector calibration apparatus on the injector ram.

The methods of the third and fourth aspects may include providing the injector free from a syringe interconnected to the injector ram prior to the interconnecting step. Indeed, the methods may be performed without any fluid being used to exert a resistive force on the injector ram. In this regard, the injector calibration apparatus may interface directly with the injector ram, obviating the need for a fluid medium to be used to provide a resistive force to the motion of the injector ram and thereby also the need for a fluid pressure measuring device.

The adjusting steps that may be employed in relation to each of the third and fourth aspects may include varying a signal supplied to a motor of the injector calibration apparatus. During performance of any such an adjusting step, the motor of the injector calibration apparatus may be interconnected to an injector calibration apparatus ram and the force gauge may be interposed between the injector calibration apparatus ram and the injector ram. The signal supplied to the motor of the injector calibration apparatus may be at least partially based on an output signal of the force gauge. In this regard, the output signal of the force gauge may be amplified and fed directly to a drive circuit for the injector calibration apparatus motor, and thus the injector calibration apparatus may be operable to maintain a preset force level and which may be measured by the force gauge. In an embodiment, the output signal of the force gauge may be amplified and fed into the injector being calibrated. In such an embodiment, the injector being calibrated may generate an output signal directed to the drive circuit of the injector calibration apparatus motor, and thus the injector may be operable to monitor and/or control the level of force between the injector ram and the injector calibration apparatus ram. The force achievable by the injector calibration apparatus on the injector ram may be independent of the position of the injector. The force of the injector calibration apparatus on the injector ram may be operable to be varied independent of the position of the injector ram. The methods of the third and fourth aspects may further include providing a signal to the motor of the injector that is associated with moving the injector ram at a second speed. During this driving of the injector motor, the injector calibration apparatus may be adjusted (e.g., by adjusting the signal to the motor of the injector calibration apparatus) such that the first level of force between the injector calibration apparatus ram and the injector ram is maintained. The level of the current drawn by the injector motor (while the injector ram is being driven at the second speed and furthermore while the injector calibration apparatus ram imparts the first level of force on the injector ram) may be measured by the force gauge and recorded. In this regard, the level of force between the injector ram and the injector calibration apparatus ram may be maintained at a particular level while the injector ram is moved at a plurality of different speeds, thus generating calibration values for the injector motor for a particular pressure at a variety of different injector ram speeds.

The methods of the third and fourth aspects may further include adjusting the injector calibration apparatus (e.g., by adjusting the signal being provided to the motor of the injector calibration apparatus) such that a second fevel of force between the injector calibration apparatus ram and the injector ram is achieved or realized. The level of the current drawn by the injector motor (while the injector motor is being driven by a signal associated with providing the first speed for the injector ram, and furthermore while the second level of force exists between the injector ram and the injector calibration apparatus ram) may be measured by the force gauge and recorded. In this regard, the speed of the injector ram may be maintained at a particular level while the force between the injector ram and the injector calibration apparatus ram is varied, thus generating calibration values for the injector motor for a particular speed at a variety of different force levels. The methods of the third and fourth aspects may be performed at a plurality of injector ram speeds and a plurality of levels of force. The methods may further include creating a table of values containing a recorded level of current drawn by the motor of the injector for each performed combination of level of force and injector ram speed.

A fifth aspect of the present invention is embodied in a powered medical fluid injector that includes a motor, a ram operatively interconnected to the motor, and a memory storage device containing a lookup table. The lookup table may include pressure values corresponding to combinations of various ram speeds and motor currents.

A number of feature refinements and additional features are applicable to the fifth aspect of the present invention. These feature refinements and additional features may be used individually or in any combination. The following discussion is separately applicable to the fifth aspect, up to the start of the discussion of a sixth aspect of the present invention.

Each unique combination of ram speed and motor current and a corresponding pressure value may constitute a data group. The lookup table may contain a sufficient number of data groups such that the power injector may rely solely on the lookup table to determine a present pressure. In this regard, no interpolation or other calibration-related calculations may need to be performed to determine the present pressure. The lookup table may contain all combinations of ram speed and motor current that the power injector could reasonably expect to encounter during an injection procedure. In one embodiment, the lookup table may contain at least five hundred pressure values corresponding to unique combinations of ram speed and motor current. In another embodiment, the lookup tabfe may contain a thousand or more pressure values corresponding to unique combinations of ram speed and motor current.

A sixth aspect of the present invention is embodied in a power injector assembly that includes a powered medical fluid injector, which in turn inciudes a syringe plunger driver having a motorized drive source. The powered medical fluid injector also includes an injector ram that may be operatively interconnected with the motorized drive source. The power injector assembly further includes an injector calibration apparatus, which in turn includes a movable calibration ram disposed in opposing relation to the injector ram. The calibration ram may be operable to exert a resistive force on the injector ram. A magnitude of this resistive force may be controllable independ ent of a position of the cali bration ram .

A number of feature refinements and additional features are applicable to the sixth aspect of the present invention. These feature refinements and additional features may be used individually or in any combination. The following discussion is separately applicable to the sixth aspect, up to the start of the discussion of a seventh aspect of the present invention. In an embodiment of the power injector assembly, the injector ram may be both extendable and retractable through operation of the motorized drive source. The injector ram may be coupled with a syringe plunger when the injector calibration apparatus is disassociated with the power injector.

In an embodiment, the injector calibration apparatus may be mounted (e.g., detachably) to the power injector in any appropriate manner. The injector calibration apparatus may be characterized as being maintained in a fixed position relative to the power injector (e.g., without being mounted to the power injector). For example, both the injector calibration apparatus and the power injector may be placed into a fixture where their positions are fixed relative to each other.

In an embodiment, the injector ram and the calibration ram may be axially aligned. The calibration ram may be both extendable and retractable. The calibration ram may be disposed such that it may be operable to exert a resistive force on the injector ram during extension of the injector ram. The calibration ram may also be operable to exert a resistive force on the injector ram during a forced retraction of the calibration ram. The resistive force may include the injector ram back-driving the calibration ram.

In an embodiment, the injector calibration apparatus may further include a calibration motor. In such an embodiment, the resistive force may be provided by the injector ram back-driving the calibration motor. The resistive force may be provided by the injector calibration apparatus when the calibration motor is driving the calibration ram in the same direction as movement of the injector ram.

In an embodiment the injector calibration apparatus may further include a calibration motor and the power injector assembly may further include a sensor and calibration logic. The sensor may be operable to monitor a magnitude of a resistive force imparted on the injector ram and the calibration logic may be operatively interconnected with each of the calibration motor and the sensor. The power injector assembly may include a data structure that is operatively interconnected with the calibration logic. The data structure may include a plurality of data groups that each includes a pressure, an associated injector ram speed, and an associated monitored current. The calibration logic of the power injector assembly may be operatively interconnected with and control operation of the injector calibration apparatus and the motorized drive source of the power injector during a calibration procedure. This data structure may be populated in any appropriate manner, including in accordance with an eighth aspect of the present invention that is addressed below.

5 A seventh aspect of the present invention is embodied in a powered medical fluid injector that includes calibration logic {e.g., to control operation of an injector calibration apparatus). The calibration logic may be operable to run a calibration procedure, for instance in accordance with the eighth aspect that will now be discussed (e.g., the calibration logic may be operable to direct the injector calibration apparatus to impart a predetermined level of resistance to movement of an injector ram of the powered medical fluid injector). i o An eighth aspect of the present invention is embodied in a method for calibrating a powered medical fluid injector, where the powered medical fluid injector includes an injector ram and a pressure monitoring protocol. The method includes advancing the injector ram while in an uncoupled state in relation to any power injector syringe. The method further includes inputting and providing a predetermined resistance for this advancement of the injector ram and calibrating the pressure monitoring protocol based at least in part on the noted advancement and

15 the provision of a predetermined resistance.

A number of feature refinements and additional features are applicable to the eighth aspect of the present invention. These feature refinements and additional features may be used individually or in any combination. The following discussion is applicable to the eighth aspect, unless otherwise noted.

In an embodiment, the advancement of the injector ram may include extending the injector ram. The 0 provision of the predetermined resistance may be in the form of exerting a mechanical force on the injector ram. The mechanical force may be transmitted between the injector ram and a calibration ram. The calibration ram may be biased in a direction of the injector ram. The calibration ram may be driven in a direction opposite from the injector ram.

In an embodiment, the advancement of the injector ram may include moving the injector ram in a first 5 direction and the provision of a predetermined resistance may include attempting to move a calibration ram in a second direction that is opposite of the first direction. In such an embodiment, a force may be transmitted between the injector ram and the calibration ram.

The calibration of the pressure monitoring protocol may include populating a lookup table of the power injector. This calibration may include associating a current of a motor operatively interconnected with the injector0 ram, with a speed that the injector ram is being advanced and a magnitude of the predetermined resistance being exerted on the injector ram. The lookup table may include a plurality of unique combinations of speed of the injector and magnitude of resistance. Each of the unique combinations may be placed into a data group along with an associated motor current to form the lookup table. This lookup table may be populated in any appropriate manner. !n one embodiment, the injector ram is driven by a signal associated with a certain ram speed or flow5 rate, and a number of different predetermined resistances are exerted on the injector ram. This may be repeated for each of a number of desired ram speeds. In another embodiment, a predetermined resistance is exerted on the injector ram while the injector ram is advanced at a number of different speeds. This may be repeated at a number for each of a number of predetermined resistances.

A number of feature refinements and additional features are separately applicable to each of above-noted first, second, third, fourth, fifth, sixth, seventh, and eighth aspects of the present invention as well. These feature refinements and additional features may be used individually or in any combination in relation to each of the above-noted first, second, third, fourth, fifth, sixth, seventh, and eighth aspects. Initially, any feature of any other various aspects of the present invention that is intended to be limited to a "singular" context or the like will be clearly set forth herein by terms such as "only," "single," "limited to," or the like. Merely introducing a feature in accordance with commonly accepted antecedent basis practice does not limit the corresponding feature to the singular (e.g., indicating that a power injector includes "a syringe" alone does not mean that the power injector includes only a single syringe). Moreover, any failure to use phrases such as "at least one" or the like also does not limit the corresponding feature to the singular {e.g., indicating that a power injector includes "a syringe" versus "at least one syringe" alone does not mean that the syringe includes only a single syringe). Finally, use of the phrase "at least generally" or the like in relation to a particular feature encompasses the corresponding characteristic and insubstantial variations thereof (e.g., indicating that a syringe barrel is at least generally cylindrical encompasses the syringe barrel being cylindrical).

Any "logic" that may be utilized by any of the various aspects of the present invention may be implemented in any appropriate manner, including without limitation in any appropriate software, firmware, or hardware, using one or more platforms, using one or more processors, using memory of any appropriate type, using any single computer of any appropriate type or a multiple computers of any appropriate type and interconnected in any appropriate manner, or any combination thereof. This logic may be implemented at any single location or at multiple locations that are interconnected in any appropriate manner (e.g., via any type of network).

Any powered medical fluid injector that may be utilized to provide a fluid discharge may be of any appropriate size, shape, configuration, and/or type. Any such powered medical fluid injector may utilize one or more syringe plunger drivers of any appropriate size, shape, configuration, and/or type, where each such syringe plunger driver is capable of at least bi-directional movement (e.g., a movement in a first direction for discharging fluid; a movement in a second direction for accommodating a loading of fluid or so as to return to a position for a subsequent fluid discharge operation), and where each such syringe plunger driver may interact with its corresponding syringe plunger in any appropriate manner (e.g., by mechanical contact; by an appropriate coupling (mechanical or otherwise)) so as to be able to advance the syringe plunger in at least one direction (e.g., to discharge fluid). Each syringe plunger driver may utilize one or more drive sources of any appropriate size, shape, configuration, and/or type. Multiple drive source outputs may be combined in any appropriate manner to advance a single syringe plunger at a given time. One or more drive sources may be dedicated to a single syringe plunger driver, one or more drive sources may be associated with multiple syringe plunger drivers (e.g., incorporating a transmission of sorts to change the output from one syringe plunger to another syringe plunger), or a combination thereof. Representative drive source forms include a brushed or brushless electric motor, a hydraulic motor, a pneumatic motor, a piezoelectric motor, or a stepper motor.

Any such powered medical fluid injector may be used for any appropriate appiication where the delivery of one or more medical fluids is desired, including without limitation any appropriate medical application (e.g., computed tomography or CT imaging; magnetic resonance imaging or MRI; single photon emission computed tomography or SPECT imaging; positron emission tomography or PET imaging; X-ray imaging; angiographic imaging; optical imaging; ultrasound imaging). Any such powered medical fluid injector may be used in conjunction with any component or combination of components, such as an appropriate imaging system (e.g., a CT scanner). For instance, information could be conveyed between any such power injector and one or more other components (e.g., scan delay information, injection start signal, injection rate).

Any appropriate number of syringes may be utilized with any such powered medical fluid injector in any appropriate manner (e.g., detachably; front-loaded; rear-loaded; side-loaded), any appropriate medical fluid may be discharged from a given syringe of any such powered medical fluid injector (e.g., contrast media, a radiopharmaceutical, saline, and any combination thereof), and any appropriate fluid may be discharged from a multiple syringe power injector configuration in any appropriate manner (e.g., sequentially, simultaneously), or any combination thereof. In one embodiment, fluid discharged from a syringe by operation of the powered medical fluid injector is directed into a conduit (e.g., a medical tubing set), where this conduit is fluidly interconnected with the syringe in any appropriate manner and directs fluid to a desired location (e.g., to a catheter that is inserted into a patient, for instance for injection). Multiple syringes may discharge into a common conduit (e.g., for provision to a single injection site), or one syringe may discharge into one conduit (e.g., for provision to one injection site), while another syringe may discharge into a different conduit (e.g., for provision to a different injection site). In one embodiment, each syringe includes a syringe barrel and a plunger that is disposed within and movable relative to the syringe barrel. This plunger may interface with the power injector's syringe plunger drive assembly such that the syringe plunger drive assembly is able to advance the plunger in at least one direction, and possibly in two different, opposite directions.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic of one embodiment of a power injector.

Figure 2A is a perspective view of one embodiment of a portable stand-mounted, dual-head power injector.

Figure 2B is an enlarged, partially exploded, perspective view of a powerhead used by the power injector of Figure 2A.

Figure 2C is a schematic of one embodiment of a syringe plunger drive assembly used by the power injector of Figure 2A. Figure 3 is a schematic of one embodiment of an injector calibration apparatus interconnected to the syringe plunger drive assembly of Figure 2C.

Figure 4 is a block diagram of the injector calibration apparatus of Figure 3. Figure 5 is a block diagram of logic structure for the power injector of Figure 2C. Figure 6 is a flowchart of one embodiment of a method of calibrating the power injector of Figure 2C using the injector calibration apparatus of Figures 3-4.

Figure 7 is a flowchart of a calibration protocol for calibrating the power injector of Figure 2C using the 5 injector calibration apparatus of Figures 3-4.

DETAILED DESCRIPTION

Figure 1 presents a schematic of one embodiment of a power injector 10 having a powerhead 12. One or more graphical user interfaces or GUIs 11 may be associated with the powerhead 12. Each GU1 11 : 1) may be of i O any appropriate size, shape, configuration, and/or type; 2) may be operatively interconnected with the powerhead 12 in any appropriate manner; 3) may be disposed at any appropriate location; 4) may be configured to provide one or any combination of the following functions: controlling one or more aspects of the operation of the power injector 10; inputting/editing one or more parameters associated with the operation of the power injector 10; and displaying appropriate information (e.g., associated with the operation of the power injector 10); or 5) any

15 combination of the foregoing. Any appropriate number of GUIs 11 may be utilized. In one embodiment, the power injector 10 includes a GU1 11 that is incorporated by a console that is separate from but which communicates with the powerhead 12. In another embodiment, the power injector 10 includes a GU1 11 that is part of the powerhead 12. In yet another embodiment, the power injector 10 utilizes one GU1 11 on a separate console that communicates with the powerhead 12, and also utilizes another GU1 11 that is on the powerhead 12. Each GU1 11 0 could provide the same functionality or set of functionalities, or the GU!s 11 may differ in at least some respect in relation to their respective functionalities.

A syringe 28 may be installed on this powerhead 12 and, when installed, may be considered to be part of the power injector 10. Some injection procedures may result in a relatively high pressure being generated within the syringe 28. In this regard, it may be desirable to dispose the syringe 28 within a pressure jacket 26. The 5 pressure jacket 26 is typically associated with the powerhead 12 in a manner that allows the syringe 28 to be disposed therein as a part of or after installing the syringe 28 on the powerhead 12. The same pressure jacket 26 will typically remain associated with the powerhead 12, as various syringes 28 are positioned within and removed from the pressure jacket 26 for multiple injection procedures. The power injector 10 may eliminate the pressure jacket 26 if the power injector 10 is configured/utilized for low-pressure injections and/or if the syringe(s) 28 to be0 utilized with the power injector 10 is (are) of sufficient durability to withstand high-pressure injections without the additional support provided by a pressure jacket 26. In any case, fluid discharged from the syringe 28 may be directed into a conduit 38 of any appropriate size, shape, configuration, and/or type, which may be fluidly interconnected with the syringe 28 in any appropriate manner, and which may direct fluid to any appropriate location (e.g., to a patient). 5 The powerfiead 12 includes a syringe plunger drive assembly or syringe plunger driver 14 that interacts

(e.g., interfaces) with the syringe 28 (e.g., a plunger 32 thereof) to discharge fluid from the syringe 28. This syringe plunger drive assembly 14 includes a drive source 16 (e.g., a motor of any appropriate size, shape, configuration, and/or type, optional gearing, and the like) that powers a drive output 18 (e.g., a rotatable drive screw). A ram 20 may be advanced along an appropriate path (e.g., axial) by the drive output 18. The ram 20 may include a coupler 22 for interacting or interfacing with a corresponding portion of the syringe 28 in a manner that wiEI be discussed below. The syringe 28 includes the plunger or piston 32 that is movably disposed within a syringe barrel 30 (e.g., for axial reciprocation along an axis coinciding with the double-headed arrow B). The plunger 32 may include a coupler 34. This syringe plunger coupler 34 may interact or interface with the ram coupler 22 to allow the syringe plunger drive assembly 14 to retract the syringe plunger 32 within the syringe barrel 30. The syringe plunger coupler 34 may be in the form of a shaft 36a that extends from a body of the syringe plunger 32, together with a head or button 36b. However, the syringe plunger coupler 34 may be of any appropriate size, shape, configuration, and/or type.

Generally, the syringe plunger drive assembly 14 of the power injector 10 may interact with the syringe plunger 32 of the syringe 28 in any appropriate manner (e.g., by mechanical contact; by an appropriate coupling {mechanical or otherwise)) so as to be able to move or advance the syringe plunger 32 (relative to the syringe barrel 30) in at least one direction (e.g., to discharge fluid from the corresponding syringe 28). That is, although the syringe plunger drive assembly 14 may be capable of bi-directional motion (e.g., via operation of the same drive source 16), the power injector 10 may be configured such that the operation of the syringe plunger drive assembly 14 actually only moves each syringe plunger 32 being used by the power injector 10 in only one direction. However, the syringe plunger drive assembly 14 may be configured to interact with each syringe plunger 32 being used by the power injector 10 so as to be able to move each such syringe plunger 32 in each of two different directions (e.g. in different directions along a common axial path).

Retraction of the syringe plunger 32 may be utilized to accommodate a loading of fluid into the syringe barrel 30 for a subsequent injection or discharge, may be utilized to actually draw fluid into the syringe barrel 30 for a subsequent injection or discharge, or for any other appropriate purpose. Certain configurations may not require that the syringe plunger drive assembly 14 be able to retract the syringe plunger 32, in which case the ram coupler 22 and syringe plunger coupler 34 may not be desired. In this case, the syringe plunger drive assembly 14 may be retracted for purposes of executing another fluid delivery operation (e.g., after another pre-filled syringe 28 has been installed). Even when a ram coupler 22 and syringe plunger coupler 34 are utilized, it may such that these components may or may not be coupled when the ram 20 advances the syringe plunger 32 to discharge fluid from the syringe 28 (e.g., the ram 20 may simply "push on" the syringe plunger coupler 34 or on a proximal end of the syringe plunger 32). Any single motion or combination of motions in any appropriate dimension or combination of dimensions may be utilized to dispose the ram coupler 22 and syringe plunger coupler 34 in a coupled state or condition, to dispose the ram coupler 22 and syringe plunger coupler 34 in an un-coupied state or condition, or both. The syringe 28 may be installed on the powerhead 12 in any appropriate manner. For instance, the syringe 28 could be configured to be installed directly on the powerhead 12. In the illustrated embodiment, a housing 24 is appropriately mounted on the powerhead 12 to provide an interface between the syringe 28 and the powerhead 12. This housing 24 may be in the form of an adapter to which one or more configurations of syringes 28 may be installed, and where at least one configuration for a syringe 28 could be installed directly on the powerhead 12 without using any such adapter. The housing 24 may also be in the form of a faceplate to which one or more configurations of syringes 28 may be installed. In this case, it may be such that a faceplate is required to install a syringe 28 on the powerhead 12 - the syringe 28 could not be installed on the powerhead 12 without the faceplate. When a pressure jacket 26 is being used, it may be installed on the powerhead 12 in the various manners discussed herein in relation to the syringe 28, and the syringe 28 will then thereafter be installed in the pressure jacket 26.

The housing 24 may be mounted on and remain in a fixed position relative to the powerhead 12 when installing a syringe 28. Another option is to movably interconnect the housing 24 and the powerhead 12 to accommodate installing a syringe 28. For instance, the housing 24 may move within a plane that contains the double-headed arrow A to provide one or more of coupled state or condition and an un-coupled state or condition between the ram coupler 22 and the syringe plunger coupler 34.

One particular power injector configuration is illustrated in Figure 2A, is identified by a reference numeral 40, and is at least generally in accordance with the power injector 10 of Figure 1. The power injector 40 includes a powerhead 50 that is mounted on a portable stand 48. A pair of syringes 86a, 86b for the power injector 40 is mounted on the powerhead 50. Fluid may be discharged from the syringes 86a, 86b during operation of the power injector 40.

The portable stand 48 may be of any appropriate size, shape, configuration, and/or type. Wheels, rollers, casters, or the like may be utilized to make the stand 48 portable. The powerhead 50 could be maintained in a fixed position relative to the portable stand 48. However, it may be desirable to allow the position of the powerhead 50 to be adjustable relative to the portable stand 48 in at least some manner. For instance, it may be desirable to have the powerhead 50 in one position relative to the portable stand 48 when loading fluid into one or more of the syringes 86a, 86b, and to have the powerhead 50 in a different position relative to the portable stand 48 for performance of an injection procedure. In this regard, the powerhead 50 may be movably interconnected with the portable stand 48 in any appropriate manner (e.g., such that the powerhead 50 may be pivoted through at least a certain range of motion, and thereafter maintained in the desired position).

It should be appreciated that the powerhead 50 could be supported in any appropriate manner for providing fluid. For instance, instead of being mounted on a portable structure, the powerhead 50 could be interconnected with a support assembly, that in turn is mounted to an appropriate structure (e.g., ceiling, wall, floor). Any support assembly for the powerhead 50 may be positionally adjustable in at least some respect (e.g., by having one or more support sections that may be repositioned relative to one more other support sections), or may be maintained in a fixed position. Moreover, the powerhead 50 may be integrated with any such support assembly so as to either be maintained in a fixed position or so as to be adjustable relative the support assembly. The powerhead 50 includes a graphical user interface or GUI 52. This GUI 52 may be configured to provide one or any combination of the following functions: controlling one or more aspects of the operation of the power injector 40; inputting/editing one or more parameters associated with the operation of the power injector 40; and displaying appropriate information (e.g., associated with the operation of the power injector 40). The power injector 40 may also include a console 42 and powerpack 46 that each may be in communication with the powerhead 50 in any appropriate manner (e.g., via one or more cables), that may be placed on a table or mounted on an electronics rack in an examination room or at any other appropriate location, or both. The powerpack 46 5 may include one or more of the following and in any appropriate combination: a power supply for the injector 40; interface circuitry for providing communication between the console 42 and powerhead 50; circuitry for permitting connection of the power injector 40 to remote units such as remote consoles, remote hand or foot control switches, or other original equipment manufacturer (OEM) remote control connections (e.g., to allow for the operation of power injector 40 to be synchronized with the x-ray exposure of an imaging system); and any other appropriate i o componentry. The console 42 may include a touch screen display 44, which in turn may provide one or more of the following functions and in any appropriate combination: allowing an operator to remotely control one or more aspects of the operation of the power injector 40; allowing an operator to enter/edit one or more parameters associated with the operation of the power injector 40; allowing an operator to specify and store programs for automated operation of the power injector 40 (which can later be automatically executed by the power injector 40

15 upon initiation by the operator); and displaying any appropriate information relation to the power injector 40 and including any aspect of its operation.

Various details regarding the integration of the syringes 86a, 86b with the powerhead 50 are presented in Figure 2B. Each of the syringes 86a, 86b includes the same general components. The syringe 86a includes plunger or piston 90a that is movably disposed within a syringe barrel 88a. Movement of the plunger 90a along an 0 axis 100a (Figure 2A) via operation of the powerhead 50 will discharge fluid from within a syringe barrel 88a through a nozzle 89a of the syringe 86a. An appropriate conduit (not shown) will typically be fluidly interconnected with the nozzle 89a in any appropriate manner to direct fluid to a desired location (e.g., a patient). Similarly, the syringe 86b includes plunger or piston 90b that is movably disposed within a syringe barrel 88b. Movement of the plunger 90b along an axis 100b (Figure 2A) via operation of the powerhead 50 will discharge fluid from within the 5 syringe barrel 88b through a nozzle 89b of the syringe 86b. An appropriate conduit (not shown) will typically be fluidly interconnected with the nozzle 89b in any appropriate manner to direct fluid to a desired location (e.g., a patient).

The syringe 86a is interconnected with the powerhead 50 via an intermediate faceplate 102a. This faceplate 102a includes a cradle 104 that supports at least part of the syringe barrel 88a, and which may 0 provide/accommodate any additional functionality or combination of functionalities. A mounting 82a is disposed on and is fixed relative to the powerhead 50 for interfacing with the faceplate 102a. A ram coupler 76 of a ram 74 (Figure 2C), which are each part of a syringe plunger drive assembly or syringe plunger driver 56 (Figure 2C) for the syringe 86a, is positioned in proximity to the faceplate 102a when mounted on the powerhead 50. Details regarding the syringe plunger drive assembly 56 will be discussed in more detail below in relation to Figure 2C.5 Generally, the ram coupler 76 may be coupled with the syringe plunger 90a of the syringe 86a, and the ram coupler 76 and ram 74 (Figure 2C) may then be moved relative to the powerhead 50 to move the syringe plunger 90a along the axis 100a (Figure 2A). It may be such that the ram coupler 76 is engaged with, but not actually coupled to, the syringe plunger 90a when moving the syringe plunger 90a to discharge fluid through the nozzle 89a of the syringe 86a.

The faceplate 102a may be moved at least generally within a plane that is orthogonal to the axes 100a, 100b (associated with movement of the syringe plungers 90a, 90b, respectively, and illustrated in Figure 2A), both to mount the faceplate 102a on and remove the faceplate 102a from its mounting 82a on the powerhead 50. The faceplate 102a may be used to couple the syringe plunger 90a with its corresponding ram coupler 76 on the powerhead 50. In this regard, the faceplate 102a includes a pair of handles 106a. Generally and with the syringe 86a being initially positioned within the faceplate 102a, the handles 106a may be moved to in turn move/translate the syringe 86a at least generally within a plane that is orthogonal to the axes 100a, 100b {associated with movement of the syringe plungers 90a, 90b, respectively, and illustrated in Figure 2A). Moving the handles 106a to one position moves/translates the syringe 86a (relative to the faceplate 102a) in an at least generally downward direction to couple its syringe plunger 90a with its corresponding ram coupler 76. Moving the handles 106a to another position moves/translates the syringe 86a (relative to the faceplate 102a) in an at least generally upward direction to uncouple its syringe plunger 90a from its corresponding ram coupler 76. The syringe 86b is interconnected with the powerhead 50 via an intermediate faceplate 102b. A mounting

82b is disposed on and is fixed relative to the powerhead 50 for interfacing with the faceplate 102b. A ram coupler 76 of a ram 74 (Figure 2C), which are each part of a syringe plunger drive assembly 56 for the syringe 86b, is positioned in proximity to the faceplate 102b when mounted to the powerhead 50. Details regarding the syringe plunger drive assembly 56 again will be discussed in more detail below in relation to Figure 2C. Generally, the ram coupler 76 may be coupled with the syringe plunger 90b of the syringe 86b, and the ram coupler 76 and ram 74 (Figure 2C) may be moved relative to the powerhead 50 to move the syringe plunger 90b along the axis 100b (Figure 2A). It may be such that the ram coupler 76 is engaged with, but not actually coupled to, the syringe plunger 90b when moving the syringe plunger 90b to discharge fluid through the nozzle 89b of the syringe 86b. The faceplate 102b may be moved at least generally within a plane that is orthogonal to the axes 100a, 100b (associated with movement of the syringe plungers 9Oa₁ 90b, respectively, and illustrated in Figure 2A), both to mount the faceplate 102b on and remove the faceplate 102b from its mounting 82b on the powerhead 50. The faceplate 102b also may be used to couple the syringe plunger 90b with its corresponding ram coupler 76 on the powerhead 50. In this regard, the faceplate 102b may include a handle 106b. Generally and with the syringe 86b being initially positioned within the faceplate 102b, the syringe 86b may be rotated along its long axis 100b (Figure 2A) and relative to the faceplate 102b. This rotation may be realized by moving the handle 106b, by grasping and turning the syringe 86b, or both. In any case, this rotation moves/translates both the syringe 86b and the faceplate 102b at least generally within a plane that is orthogonal to the axes 100a, 100b (associated with movement of the syringe plungers 90a, 9Ob₁ respectively, and illustrated in Figure 2A). Rotating the syringe 86b in one direction moves/translates the syringe 86b and faceplate 102b in an at least generally downward direction to couple the syringe plunger 90b with its corresponding ram coupler 76. Rotating the syringe 86b in the opposite direction moves/translates the syringe 86b and faceplate 102b in an at least generally upward direction to uncouple its syringe plunger 90b from its corresponding ram coupler 76. As illustrated in Figure 2B, the syringe plunger 90b includes a plunger body 92 and a syringe plunger coupler 94. This syringe plunger coupler 94 includes a shaft 98 that extends from the plunger body 92, along with a head 96 that is spaced from the plunger body 92. Each of the ram couplers 76 includes a larger slot that is positioned behind a smaller slot on the face of the ram coupler 76. The head 96 of the syringe plunger coupler 94 may be positioned within the larger slot of the ram coupler 76, and the shaft 98 of the syringe plunger coupler 94 may extend through the smaller siot on the face of the ram coupler 76 when the syringe plunger 90b and its corresponding ram coupler 76 are in a coupled state or condition. The syringe plunger 90a may include a similar syringe plunger coupler 94 for interfacing with its corresponding ram coupler 76.

The powerhead 50 is utilized to discharge fluid from the syringes 86a, 86b in the case of the power injector 40. That is, the powerhead 50 provides the motive force to discharge fluid from each of the syringes 86a, 86b. One embodiment of what may be characterized as a syringe plunger drive assembly or syringe plunger driver is illustrated in Figure 2C, is identified by reference numeral 56, and may be utilized by the powerhead 50 to discharge fluid from each of the syringes 86a, 86b. A separate syringe plunger drive assembly 56 may be incorporated into the powerhead 50 for each of the syringes 86a, 86b. Sn this regard and referring back to Figures 2A-B, the powerhead 50 may include hand-operated knobs 80a and 80b for use in separately controlling each of the syringe plunger drive assemblies 56.

Initially and in relation to the syringe plunger drive assembly 56 of Figure 2C, each of its individual components may be of any appropriate size, shape, configuration and/or type. The syringe plunger drive assembly 56 includes a motor 58, which has an output shaft 60. A drive gear 62 is mounted on and rotates with the output shaft 60 of the motor 58. The drive gear 62 is engaged or is at least engageable with a driven gear 64. This driven gear 64 is mounted on and rotates with a drive screw or shaft 66. The axis about which the drive screw 66 rotates is identified by reference numeral 68. One or more bearings 72 appropriately support the drive screw 66.

A carriage or ram 74 is movably mounted on the drive screw 66. Generally, rotation of the drive screw 66 in one direction axially advances the ram 74 along the drive screw 66 (and thereby along axis 68) in the direction of the corresponding syringe 86a/b, while rotation of the drive screw 66 in the opposite direction axially advances the ram 74 along the drive screw 66 (and thereby along axis 68) away from the corresponding syringe 86a/b. In this regard, the perimeter of at least part of the drive screw 66 includes helical threads 70 that interface with at least part of the ram 74. The ram 74 is also movably mounted within an appropriate bushing 78 that does not allow the ram 74 to rotate during a rotation of the drive screw 66. Therefore, the rotation of the drive screw 66 provides for an axial movement of the ram 74 in a direction determined by the rotational direction of the drive screw 66.

The ram 74 includes a coupler 76 that that may be detachably coupled with a syringe plunger coupler 94 of the syringe plunger 90a/b of the corresponding syringe 86a/b. When the ram coupler 76 and syringe plunger coupler 94 are appropriately coupled, the syringe plunger 90a/b moves along with ram 74. Figure 2C illustrates a configuration where the syringe QGsIb may be moved along its corresponding axis 100a/b without being coupled to the ram 74. When the syringe 86a/b is moved along its corresponding axis 100a/b such that the head 96 of its syringe plunger 90a/b is aligned with the ram coupler 76, but with the axes 68 still in the offset configuration of Figure 2C, the syringe 86a/b may be translated within a plane that is orthogonal to the axis 68 along which the ram 74 moves. This establishes a coupled engagement between the ram coupler 76 and the syringe plunger coupler 96 in the above-noted manner. The power injectors 10, 40 of Figures 1 and 2A-C each may be used for any appropriate application, including without limitation for medical imaging applications where fluid is injected into a subject (e.g., a patient). Representative medical imaging applications for the power injectors 10, 40 include without limitation computed tomography or CT imaging, magnetic resonance imaging or MRI, single photon emission computed tomography or SPECT imaging, positron emission tomography or PET imaging, X-ray imaging, angiographic imaging, optical imaging, and ultrasound imaging. The power injectors 10, 40 each could be used alone or in combination with one or more other components. The power injectors 10, 40 each may be operatively interconnected with one or more components, for instance so that information may be conveyed between the power injector 10, 40 and one or more other components (e.g., scan delay information, injection start signal, injection rate).

Any number of syringes may be utilized by each of the power injectors 10, 40, including without limitation single-head configurations (for a single syringe) and dual-head configurations (for two syringes). In the case of a multiple syringe configuration, each power injector 10, 40 may discharge fluid from the various syringes in any appropriate manner and according to any timing sequence (e.g., sequential discharges from two or more syringes, simultaneous discharges from two or more syringes, or any combination thereof). Multiple syringes may discharge into a common conduit (e.g., for provision to a single injection site), or one syringe may discharge into one conduit (e.g., for provision to one injection site), while another syringe may discharge into a different conduit (e.g., for provision to a different injection site). Each such syringe utilized by each of the power injectors 10, 40 may include any appropriate fluid (e.g., a medical fluid), for instance contrast media, a radiopharmaceutical, saline, and any combination thereof. Each such syringe utilized by each of the power injectors 10, 40 may be installed in any appropriate manner (e.g., rear-loading configurations may be utilized; front-loading configurations may be utilized; side-loading configurations may be utilized).

Figure 3 schematically illustrates the powerhead 50 of Figure 2C interconnected to one embodiment of an injector calibration apparatus 110. The injector calibration apparatus 110 may be used in the calibration of the power injector 10 that includes the powerhead 50. For example, after initial manufacture of the powerhead 50, the injector calibration apparatus 110 may be interconnected to the powerhead 50 and a calibration routine may be performed. The calibration routine may calibrate the injector 10 that includes the powerhead 50 such that for a given injection flow rate and motor current (i.e., motor 58 (Figure 2C)), the pressure in the syringe may be determined (e.g., from a monitored motor current).

Calibration may be desirable to compensate for variations in the manufacture and assembly of various components of the powerhead 50. For example, the conversion of input current to output torque by the motor 58 (Figure 2C) may vary from part to part, lot to lot, or by motor manufacturer. In addition, the gear train coupling the motor output to the drive screw 66 may introduce variations. The conversion of the rotational motion of the drive screw 66 to the linear motion of the ram 74 may also introduce variability. The mechanical components such as bearings and bushings may be another source of variability in the relationship between current to the motor 58 (Figure 2C) and the output pressure of the powerhead 50. Furthermore, these variations may vary as a function of output pressure and/orflow rate (e.g., desired ram 74 speed).

One known calibration system uses a liquid-filled syringe interconnected to the injector to be calibrated to 5 perform calibration. In such a system, generally a pressure transducer is connected to the output of the syringe to sense the fluid pressure generated by the injector. However, such a system may introduce unwanted variations into the calibration process. These unwanted variations may be due to, for example, contaminated fluid, inaccurate pressure orifices (e.g., due to clogging), and/or syringe body-to-piston variations. The injector calibration apparatus 110 avoids these potential variations by eliminating the need for fluid in the calibration i o process and not requiring the use of a syringe and piston in the calibration process.

To calibrate the injector 10 without the use of fluid and/or syringes, the injector calibration apparatus 110 interfaces with the ram 74 of the powerhead 50 and applies a selectable and controlied level of force on the ram 74. In such a system, the output force exerted on the ram 74 may be converted into an expected pressure output of the injector 10 when a syringe filled with fluid is interconnected to the powerhead 50. The conversion may

15 include an accommodation for syringe body to piston friction. In this regard, a standard value that best represents the expected syringe body to piston friction may be used in the conversion. Thus, as opposed to typical existing calibration systems, no syringe body-to-plunger variations (introduced by the syringe used in calibration) are introduced during calibration.

Calibrating the injector 10 by directly coupling to the ram 74, as opposed to using a syringe and fluid 0 medium to measure a pressure output, may result in improved calibration time or greater calibration accuracy for an equivalent calibration time. For example, directly coupling to the ram 74 may result in faster response times between motor 58 (Figure 2C) input and force output. In systems using fluids to calibrate an injector output, there may be a delay in reaching the desired pressure due to compressibility of the fluid {e.g., if there are bubbles present) and/or expansion of the various fluid-holding components (syringe, tubing, etc.). These delays are not 5 present in the injector calibration apparatus 110 that directly measures the output force of the ram 74. Additionally, when the ram 74 of the powerhead 50 reaches its fully extended position during the calibration procedure using the injector calibration apparatus 110, the ram 74 is simply retracted and the calibration process may continue. In systems using fluid to calibrate the injector, it may be necessary to replace the syringe with a new fluid filled syringe before the calibration process can continue. In this regard, the injector calibration apparatus 110 enables0 rapid calibration of the injector 10 at a variety of ram 74 speeds and output pressures. For example, in a known process of calibrating the injector 10 using interconnected syringes, a pressure transducer and fluid, a calibration routine may take on the order of thirty minutes to fully complete. An equivalent calibration process using the injector calibration apparatus 110 and methods taught herein may take on the order of five minutes.

The injector calibration apparatus 110 may, for example, be similar in configuration to the powerhead 50.5 In this regard, since the powerhead 50, as described earlier, includes a ram 74 coupled to a motor 58 (Figure 2C), an efficient way of constructing the injector calibration apparatus 110 may be to use many of the parts of the powerhead 50. Accordingly, the injector calibration apparatus 110 may be configured as a modified powerhead 50 with custom parts added to enable it to interconnect to and interact with the powerhead 50. However, the injector calibration apparatus 110 may be of any appropriate configuration.

The injector calibration apparatus 110 may include an injector calibration apparatus frame 112. The injector calibration apparatus frame 112 may house an injector calibration apparatus ram drive screw 116. An injector calibration apparatus motor 114 may be operable to cause the injector calibration apparatus ram drive screw 116 to rotate when a signal (e.g., a pulse width modulated (PWM) voltage) is applied to the injector calibration apparatus motor 114, An injector calibration apparatus ram 118 may be operatively interconnected to the injector calibration apparatus ram drive screw 116 such that when the injector calibration apparatus ram drive screw 116 is rotated, the injector calibration apparatus ram 118 may move linearly, either extending or retracting. The injector calibration apparatus frame 112, the injector calibration apparatus motor 114, the injector calibration apparatus ram drive screw 116, and the injector calibration apparatus ram 118 may be parts configured similarly to corresponding parts of the powerhead 50. Alternatively, some or all of these parts may be modified powerhead 50 parts or custom constructed parts made specifically for use in the injector calibration apparatus 110. The injector calibration apparatus motor 114 may include an encoder operable to measure the rotation of the motor 114. Such measured rotation may then be correlated to the position and/or speed of the injector calibration apparatus ram 118. Other appropriate injector calibration apparatus ram 118 movement measurement systems (e.g., a linear encoder) may be used to determine injector calibration apparatus ram 118 movement and/or position.

A mount or adapter 120 may be used to interconnect the injector calibration apparatus frame 112 to the injector 10 to be calibrated. Where the injector calibration apparatus 110 utilizes components from, or similar to, standard powerhead 50 components, the adapter 120 may be sized such that the injector caiibration apparatus frame 112 is disposed away from the powerhead 50 a distance that is comparable to a stroke length of the ram 74 of the powerhead 50. Such an offset may allow the interconnection illustrated in Figure 3, where a retracted ram 74 position corresponds to an extended injector calibration apparatus ram 118 position, in this regard, as the ram 74 is extended during the calibration process, that extension may be accompanied by a corresponding retraction of the injector calibration apparatus ram 118. The adapter 120 may be operable to interconnect the injector calibration apparatus 110 to the powerhead 50 in a manner similar to how the faceplates 102a, 102b may be mounted to the powerhead 50. However, the injector calibration apparatus 110 may be mounted to the powerhead 50 in any appropriate manner.

The injector calibration apparatus frame 112 may be maintained in a fixed position relative to the powerhead 50 by the injector calibration apparatus 110 being mounted to the powerhead 50. However, this "fixed positional relationship" may be realized in any appropriate manner (e.g., by disposing one or both of the powerhead 50 and/or the injector calibration apparatus 110 in one or more fixtures). In any case, the arrangement of the injector calibration apparatus 110 and powerhead 50 is subject to a number of characterizations, that apply individually and in any combination. The injector calibration apparatus ram 118 may be disposed in opposing relation to the injector ram 74. The injector calibration apparatus ram 118 may be disposed such that it is axially aligned with the injector ram 74. A force gauge 122, or any other appropriate sensor operable to determine a level of force, may be disposed between the ram 74 and the injector calibration apparatus ram 118. Although this force gauge 122 may be characterized as being part of the injector calibration apparatus 110, such may not be required. In any case, the force gauge 122 may be operable to measure the force (e.g., a force imparted on the ram 74 by the injector calibration apparatus ram 118 that is resistive to the movement of the ram 74) on the ram 74 from the injector calibration apparatus 110. Alternatively, the force gauge 122 may be disposed in any appropriate location where it would be able to measure the force output of the ram 74. The force gauge 122 may be calibrated to provide consistent and repeatable results during calibration sequences. The force gauge 122 may be calibrated such that the output voltage of an amplifier 140 (Figure 6) interconnected to the force gauge 122 may be representative of the force measured by the force gauge 122. For example, the force gauge 122 may be calibrated such that the force measured by the force gauge 122 may be determined by multiplying the value of the voltage output from the amplifier 140 (Figure 6) by 100 or any other appropriate value (e.g., 1.5 V equals 150 PSI force).

An injector ram interface member 124 may be interconnected to the injector calibration apparatus ram 118. The injector ram interface member 124 may be configured to be removably interconnectable to the ram coupler 76 of the ram 74. In this regard, the injector calibration apparatus 110 may be operable to be interconnected to the powerhead 50 at the faceplate interface and ram coupler 76 interface in a manner similar to the faceplates 102a, 102b and syringes 86a, 86b described above. In this regard, the injector calibration apparatus 110 may be operable to quick connect and disconnect (e.g., connect and disconnect without the need for tools) from the powerhead 50, thus helping to reduce overall calibration time. In such a configuration, the ram 74 and the injector calibration apparatus ram 118 may be interconnected for tandem movement. Alternatively, the ram 74 may simply butt up against the injector ram interface member 124, or the force gauge 122 itself. In such a configuration, the force gauge 122 may only be operable to measure the force at the ram 74 generated by the powerhead 50 during the extension stroke of the ram 74. In such a configuration, the force gauge 122 may be incapable of measuring the force at the ram 74 generated by the powerhead 50 during retraction of the ram 74. The injector ram interface member 124 may be a unique part interconnectable to the injector calibration apparatus ram 118 or the injector ram interface member 124 may be a part of the injector calibration apparatus ram 118.

Figure 4 is a block diagram illustrating interconnections between an injector calibration apparatus 110 and the power injector 10 to be calibrated. The injector calibration apparatus 110 may mechanically interact or interface with the power injector 10 through a force gauge 122. The force gauge 122 may be attached to an injector calibration apparatus ram 118 or may be disposed in any other appropriate position. Movement of the injector calibration apparatus ram 118 may be at least partially controlled by an injector calibration apparatus motor 114. An output of the force gauge 122 (e.g., a calibrated voltage output) may be fed through an electrical interconnection into the amplifier 140 and an amplified force gauge output signal may be delivered to the power injector 10. The amplifier 140 may be operable to amplify the output of the force gauge 122 differently depending on the model ofthe power injector 10 being calibrated. Forexampfe, for one model of power injector 10, the amplifier 140 may modify the signal coming from the force gauge 122 such that the pressure range from 0 to 1200 PSI corresponds to a voltage range of 0 to 5 V. For another model of power injector 10, the amplifier 140 may, for example, modify the signal coming from the force gauge 122 such that the pressure range from O to 300 PSI corresponds to an output voltage of the amplifier 140 from 0 to 5 V. The power injector 10 may be electrically interconnected to a drive circuit 142 of the injector calibration apparatus 110. The drive circuit 142 may be capable of controlling the injector calibration apparatus motor 114 based on a signal received from the power injector 10. The signal from the power injector 10 may, for example, be a PWM signal. The drive circuit 142 may use the PWM signal to control the injector calibration apparatus motor 114.

To calibrate the power injector 10 at a particular desired pressure and flow rate combination, the power injector 10 may drive the motor 58 such that the ram 74 of the power injector 10 is moving at a preset speed. This preset speed may correspond to a desired preset flow rate. As the ram 74 of the power injector 10 is moving at the preset speed, the injector calibration apparatus 110 may impart a preset force on the ram 74 of power injector 10 that corresponds to the desired pressure of the pressure and flow rate combination to be calibrated. This may be achieved in the following manner.

As the ram 74 of the power injector 10 is moving at the preset rate, the force on the ram 74 of the power injector 10 is measured by the force gauge 122. The signal from the force gauge 122 is then fed into the amplifier 140 and the amplified signal is fed back into the power injector 10. In this regard, the amount of force present on the ram 74 of the power injector 10 is fed back to the power injector 10 in the form of the level of the signal coming from the amplifier 140. The power injector 10 may adjust the level of force present on the ram 74 of the power injector 10 by controlling the injector calibration apparatus motor 114. Control of the injector calibration apparatus motor 114 may be achieved by adjusting an electrical signal from the power injector 10 to the drive circuit 142. In short, for a given speed of the ram of the power injector 10, the power injector 10 can use the injector calibration apparatus 110 to control the level of feree on the ram 74 of the power injector 10. The level of current drawn by the motor 58 of the power injector 10 at the desired ram speed and at the desired pressure can be measured and this value can be stored as part of the calibration process.

The level of force imparted on the ram 74 by the injector calibration apparatus ram 118 may be independent of the position of the injector calibration apparatus ram 118, may be set or established at any desired level in any appropriate manner and at any appropriate time, or any combination thereof. Furthermore, the injector calibration apparatus 110 may be operable to impart a resistive force on the ram 74 when the ram 74 is extending or when the ram 74 is retracting. During the imparting of the resistive force on the ram 74 by the injector calibration apparatus 110, the injector calibration apparatus motor 114 may be back-driven by the ram 74. As used herein, "back-driving" refers to the condition where power is being applied to the injector calibration apparatus motor 144 that would, in the absence of a connection to the ram 74, drive the injector calibration apparatus ram 118 in a first direction. However, the ram 74 forces the injector calibration apparatus ram 118 to move in a direction opposite to the first direction, thus driving the injector calibration apparatus ram 118 back against the first direction. For example, as the ram 74 is extending, a signal may be applied to the injector calibration apparatus motor 114 that would normally extend the injector calibration apparatus ram 118 in the absence of the connection to the ram 74. However, the ram 74 may back-drive the injector calibration apparatus ram 118, causing the injector calibration apparatus ram 118 to retract. In some circumstances, the injector calibration apparatus motor 114 may remain unpowered or may assist in the movement of the injector calibration apparatus ram 118. For example, when no power is being delivered to the injector calibration apparatus motor 114, there will still be a friction-only level of resistance to the movement of the ram 74 when the ram 74 is extending against the injector calibration apparatus ram 118. This is because the ram 74 will have to overcome frictional resistance of the drive train of the injector calibration apparatus ram 118 (e.g., the injector calibration apparatus ram drive screw 116, gears, bearings, the injector calibration apparatus motor 114). In circumstances where the desired force on the ram 74 is below the friction- only level of resistance, the injector calibration apparatus motor 114 may drive the injector calibration apparatus ram 118 in the same direction as the movement of the ram 74, thereby reducing the level of force imparted on the ram 74 to a level below the friction-only level of resistance.

The resistive forces imparted on the ram 74 by the injector calibration apparatus ram 118 may be imparted on the ram 74 during both extension and retraction of the ram 74. For example, as the ram 74 is being retracted, the injector calibration apparatus 110 may impart a force on the ram 74 resistive to the retraction. This force may be controllable by the power injector 10, the injector calibration apparatus 110, or by any other appropriate means. The level of force imparted may be independent of the position of the injector calibration apparatus ram 118.

Figure 5 is a block diagram of logic structure for a power injector (e.g., the power injector 10 of Figure 2C). Hereafter this logic 130 will be described with regard to the power injector 10. The overall functionality of the power injector 10 may be controlled by a power injector control logic or module 130. The power injector control logic 130 may interact with other logic/modules to facilitate various functions of the power injector 10.

An injection procedure logic or module 132 may be configured to execute one or more injection protocols. Each injection protocol may utilize one or more fluids of any appropriate type (e.g., contrast media, saline), may include one or more phases, or both. Each phase may be defined as a delivery {e.g., for injection) of a predefined quantity of a predefined fluid in a predefined manner (e.g., one or more fixed flow rates, one or more variable flow rates, or a combination thereof). During the execution of such an injection protocol, the pressure to which the ram 74 is exposed may be monitored by a pressure monitoring logic or module 134. For example, the pressure exerted on the ram 74 may be monitored to ensure that a maximum pressure value is not exceeded during administration of fluids to a patient.

The pressure monitoring logic 134 may interface with a data structure 138 to determine a pressure exerted on the ram 74. This data structure 138 may be of any appropriate configuration in reiation to the storage of data. The data structure 138 may include a plurality of data groups. Each data group may contain a unique combination of ram 74 speed and motor 58 current values and furthermore, a pressure value may be included for each unique combination. In this regard, during normal operating conditions, the pressure monitoring logic 134 may measure and/or determine ram 74 speed and motor 58 current and look up the combination of ram 74 speed and motor 58 current in the data structure 138 to acquire the corresponding pressure value. The pressure value may then be communicated to the power injector control logic module 130 and/or the injection procedure logic 132. The power injector 10 may also include a calibration logic or module 136 that may be used to initially populate the data structure 138 by way of a calibration procedure. In this regard, the calibration logic 136 may contain instructions to control the injector calibration apparatus 110 to impart specific levels of force on the ram 74 as the ram 74 is moved at a plurality of known speeds. The calibration logic module 136 may further be operable to determine the level of current drawn by the motor 58 at a particular combination of ram 74 speed and level of force on the ram 74. The calibration logic module 136 may populate the data structure 138 with the particular combination. This process may be repeated for every desired combination of ram 74 speed and level of force on the ram 74.

Figure 6 is a flowchart of one embodiment of a method of calibrating the power injector 10 using the above-discussed calibration method. The calibration encompassed by Figure 6 is applicable to any appropriate power injector. The first step 150 in calibrating the power injector 10 may be to mechanically connect the injector calibration apparatus 110 to the power injector 10. This may be achieved in a manner similar to the process used to interconnect the faceplate 102a to the powerhead 50. An injector ram interface member 124 of the injector calibration apparatus 110 may then be mechanically interconnected to a ram coupler 76 of the power injector 10. The mounting of the injector calibration apparatus 110 to the powerhead 50 and the interconnection of the injector ram interface member 124 with the ram coupler 76 may occur simultaneously, sequentially in any order, or in at least partially overlapping relation.

The next step 152 may be to electrically interconnect the injector calibration apparatus 110 to the power injector 10. This may be achieved by connecting a single multi-connector cable between the injector calibration apparatus 110 and the power injector 10 or by connecting a plurality of cables between the injector calibration apparatus 110 and the power injector 10. The electrical interconnections may connect the amplifier circuit 140 and the drive circuit 142 of the injector calibration apparatus 110 to the power injector 10.

The next step 154 may be to set a pressure level to be calibrated during movement of the ram 74 of the power injector 10. The set pressure level may be converted to a corresponding force level to be measured by the force gauge 122 disposed between the ram 74 of the power injector 10 and the injector calibration apparatus ram 118. The next step 156 may be to move the ram 74 of the power injector 10 at a set speed while maintaining the set level of pressure on the ram 74 of the power injector 10. The set level of pressure may be maintained using the control method described above with reference to Figures 3 and 4.

The next step 158 may be to populate a table with the current level drawn by the motor 58 of the power injector 10 to maintain the set pressure level at the set speed. Once the power injector 10 has populated the table with the current level drawn by the motor to maintain the set pressure level, the next step 160 in the calibration process may be to determine if a calibration value has been determined for each desired speed for the current pressure level. If the calibration routine has not been completed for each desired speed, the process may proceed to step 162, which is to increment the speed to a new value and return to step 156 to calibrate the power injector 10 at the new speed. This loop may continue until power injector 10 calibration values have been determined for all desired speeds for the current pressure level. Once calibration values have been determined for all desired speeds for the current pressure level, the process may exit the speed increment loop (i.e., steps 156, 158, 160 and 162) and move to step 164.

At step 164, the process may be to determine if the injector calibration routine has determined calibration values for all desired pressures. If calibration values have not been determined for ali desired pressures, the next step 166 may be to increment the pressure value and returned to step 154. Calibration values may then be determined for each desired speed at the newly incremented pressure. In short, a pressure is selected, calibration values are determined for various injector speeds at that pressure, the pressure is then incremented and the process is repeated until calibration values have been determined at all desired speeds and all desired pressures. Once all desired calibration values have been determined, the next step 168 may be to disconnect the injector calibration apparatus 110 from the power injector 10.

!t should be appreciated that during the calibration process of Figure 6, the ram 74 of the power injector 10 may reach a fully extended position. The injector may then retract the ram 74 of the power injector 10 and immediately continue the calibration process.

The process illustrated in Figure 6 consists of first setting a pressure, then incrementing speeds to fully populate the calibration table for that particular pressure. The pressure is then incremented and the process continues until all speed/pressure combinations have been achieved. Alternatively, the process may include first setting a speed, then incrementing pressures to fully populate the calibration table for the particular speed (e.g., Figure 7). After the calibration table for the first speed has been fully populated, the speed may be incremented and then the pressure may be incremented to fully populate the calibration table for the new speed. This process may continue until all desired pressure/speed combinations have been achieved. A combination of the process of Figure 6 and this alternative method may be used.

The calibration methodologies described herein may be partially or fully automatic. In an automated calibration system, the operator may attach the injector calibration apparatus 110 to the power injector 10 and interconnect the injector calibration apparatus ram 118 to the ram 74 of the power injector 10. Next, the operator may electrically interconnect the power injector 10 to the amplifier 140 and drive circuit 142 of the injector calibration apparatus 110. Using a GUI of the power injector 10, the operator may initiate the calibration sequence and the process may begin. The sequence may thereafter proceed in a fully automated fashion. After completion of the calibration process, the operator may disconnect the injector calibration apparatus 110 from the power injector 10. In an alternate configuration and corresponding alternate calibration routine, the injector calibration apparatus 110 of Figure 4 may not include the electrical interconnections between the power injector 10 and the amplifier 140 and drive circuit 142 of the injector calibration apparatus 110. in such a system, an operator may set a particular resistance level on the injector calibration apparatus 110, and the injector calibration apparatus 110 may then proceed to maintain that preset resistance level between the injector calibration apparatus ram 118 and a ram 74 of the power injector 10. In such an injector calibration apparatus 110, the output from the force gauge 122 may be fed through the amplifier 140 and into the drive circuit 142 to provide a feedback loop such that the injector calibration apparatus 110 may then be capable of maintaining a preset level of force, as measured by the force gauge 122 between the injector calibration apparatus 118 and the ram 74 of the power injector 10. The power injector 10 may then be directed to run through a series of different ram 74 speeds (representing a series of different flow rates) with the injector calibration apparatus 110 providing a fixed resistance force. Once calibration values have been determined for all desired speeds for the given resistance force, the operator may then direct the injector calibration apparatus 110 to provide a new resistance level. The power injector 10 may then be directed to run through a series of different ram 74 speeds to calibrate the power injector 10 at the new resistance level. This procedure may be repeated until calibration levels have been determined for all desired combinations of speed and resistance levels.

In an exemplary calibration routine, the speed of the ram of the power injector 10 may be varied from a speed corresponding to a 0.1 milliliter per second {mL/s} flow rate to a speed corresponding to a 10 mL/s flow rate in .1 mL/s steps, thereby producing 100 calibration points fora particular pressure level. Furthermore in the present example, the speed variation may be repeated for 10 different pressures thereby producing a total of 1 ,000 calibration points (100 different ram speeds at each of 10 different pressures). Calibration information for special circumstances may also be recorded. For example calibration values for stall situations may be recorded. A stall situation may be where the motor of the power injector 10 is incapable of moving the ram 74. For example, calibration values for no load and/or very low load situations may be determined.

The apparatuses and calibration routine methodologies described herein may be operable produce lookup tables specific to the power injector 10 and powerhead 50 being calibrated. The lookup tables may be a particularly efficient method of calibrating the power injector 10. in this regard, the lookup tables provide a variety of speed and motor current combinations such that during normal operation, to retrieve a calibrated pressure value for a particular ram 74 speed and motor 58 current, the power injector 10 merely need to look up the particular combination. This is in contrast to other systems that may calibrate at fewer speed and motor current combinations and rely on calculations to determine calibrated pressure values that correspond to the speed and motor current combinations that do not correspond with a particular calibrated value. Retrieving a particular value from a table may require fewer processing resources than performing a calculation.

After calibration, and during regular usage, when a desired speed and pressure combination are programmed into the injector, the injector may use the motor current levels recorded during the calibration process to determine the proper operating parameters.

Figure 7 is a flowchart of a calibration protocol 170 for calibrating the power injector 10. The calibration protocol 170 may be utilized by the calibration logic 136 of Figure 5. Once the calibration protocol 170 is initiated, step 172 may be executed and is directed to loading an injector ram speed set. The injector ram speed set may include a plurality of speeds at which the injector is to be calibrated. The next step 174 may be to load a pressure/resistance set. The pressure/resistance set may include a plurality of pressures/resistances that are to be applied for each unique injector ram speed. The pressure/resistance set may contain values related to the level of resistance to be imparted on the injector ram during the performance of the calibration protocoi 170. These values may be converted to pressure values that may be achieved within a syringe interconnected to the power injector 10 during normal operations. Alternatively to steps 172 and 174, a single set of data containing a plurality of injector ram speed and resistance combinations may be loaded. This may be desired where, for example, it is not necessary to calibrate the power injector 10 at every potential pressure/resistance value for every potential injector ram speed. Steps 172 and 174 may be executed in any order and in any manner.

After the injector ram speed and pressure/resistance data has been loaded into the power injector 10, the 5 next step 176 may be to input the injector ram speed. This may be followed by the step 178 of inputting pressure/resistance. The next step 180 may be to advance the injector ram at the inputted injector ram speed. While the injector ram is moving at the inputted injector ram speed, the next step 182 may be to apply the inputted pressure/resistance. While the injector ram is moving at the inputted speed and the inputted pressure/resistance is being applied to the injector ram, the next step 184 may be to measure injector motor current. i o The next step 186 may be to record a data group in a data structure. The data group may comprise the injector ram speed from step 180, the pressure/resistance from step 182, and the measured injector motor current from 184. The data structure may be in the form of a lookup table containing a plurality of data groups. In this regard, during the execution of an injection protocol, the power injector 10 may be operable to determine a pressure within an attached syringe by looking in the data structure for a data group that contains the currently

15 measured ram speed (or a value close to the currently measured ram speed) and the currently measured motor current (or a value close to the currently measured motor current) and reading the associated pressure.

The next step 188 may be to determine if the injector ram has been extended beyond a predetermined amount. If the injector ram has been extended beyond the predetermined amount, such as an amount where not enough of the extension stroke remains to record another data group, the next step 190 may be to retract the 0 injector ram. If the injector ram has not been extended beyond the predetermined amount or if the injector ram has been retracted, the next step 192 may be to determine if the pressure/resistance set has been completed. If the pressure/resistance set has not been completed, the next step 194 may be to update the inputted pressure/resistance and return to step 180 and continue the process to record another data group using the updated input pressure/resistance value. If the determination of step 192 shows that the pressure/resistance that 5 has been completed, the next step 196 may be to determine if the injector ram speed set has been completed. If the injector ram speed set has not been completed, the next step 198 may be to update the inputted injector ram speed. After step 198, the process may return to step 178 and a plurality of data groups may be recorded for the updated injector ram speed and a plurality of pressures/resistances. If the determination in step 196 is that the injector ram speed set has been completed, the next step 200 may be to end the calibration process. Thus, 0 following the calibration protocol 170 may result in the formation of a populated data structure {e.g., a lookup table). It should be appreciated that the calibration protocol 170 could be configured to populate the data structure (step 186) by "looping" through a plurality of different injector ram speeds at a certain pressure/resistance, and then repeating the same for one or more additional pressures/resistances (e.g., in the manner of the Figure 6 embodiment). 5 The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

Claims

What is claimed:

1. An injector calibration apparatus for a medical fluid injector comprising: an injector calibration apparatus frame; an injector ram interface member operable to interface with an injector ram of a medical fluid injector, 5 wherein said injector ram interface member is movable relative to said calibration apparatus frame; a frame interface member operable to interconnect to a mounting member of the injector such that said injector calibration apparatus frame is fixed relative to said mounting member of the injector; and an injector calibration apparatus motor operable to drive said injector ram interface member.

2. The injector calibration apparatus of claim 1 , further comprising a force level measuring i O member operable to measure a level of force between said injector ram interface member and the injector ram .

3. An injector calibration apparatus for a medical fluid injector comprising: an injector calibration apparatus frame; an injector ram interface member operable to interface with an injector ram of a medical fluid injector, wherein said injector ram interface is movable relative to said injector calibration apparatus frame; and 15 a force gauge operable to measure a level of force between said injector ram interface member and the injector ram.

4. The injector calibration apparatus of any one of claims 1-3, further comprising a calibration apparatus ram, wherein said injector ram interface member is operable to mechanically couple said injector calibration apparatus ram to the injector ram for tandem movement of said injector calibration apparatus 0 ram and the injector ram.

5. The injector calibration apparatus of claim 4, wherein said tandem movement occurs during extension and retraction of the injector ram.

6. The injector calibration apparatus of any one of claims 2-5, further comprising an injector calibration apparatus motor interconnected to said injector ram interface member, wherein said injector 5 calibration apparatus motor is operable to control said level of force between said injector ram interface member and the injector ram.

7. The injector calibration apparatus of claim 6, wherein said injector calibration apparatus motor is coupled to an injector calibration apparatus ram, wherein said injector calibration apparatus ram is coupled to said injector ram interface member. 0

8. The injector calibration apparatus of any one of claims 1 -7, further comprising a force gauge output communicated to the injector.

9. The injector calibration apparatus of any one of claims 2-8, further comprising control circuitry operable to control said level of force between said injector ram interface member and the injector ram based at least in part on an output from the injector. 5

10. The injector calibration apparatus of any one of claims 2-9, wherein said level of force is adjustable.

11. The injector calibration apparatus of any one of claims 2-10, wherein said level of force is adjustable independent of a position of the injector ram.

12. The injector calibration apparatus of any one of claims 2-11 , wherein said level of force is adjustable during movement of the injector ram.

13. The injector calibration apparatus of any one of claims 1-12, wherein said injector calibration apparatus is free of a fluid interface with the injector.

14. The injector calibration apparatus of any one of claims 2-13, wherein said level of force between said injector ram interface member and the injector ram is operable to simulate known pressure levels for the injector when injecting fluids.

15. The injector calibration apparatus of any one of claims 1-14, wherein said injector ram interface member includes a head operable to interface with a ram coupler of the injector.

16. The injector calibration apparatus of any one of claims 1-15, wherein said injector calibration apparatus is operable to be installed on and removed from the injector.

17. The injector calibration apparatus of any one of claims 3-16, further comprising a frame interface member, wherein said frame interface member is operable to interconnect to a mounting member of the injector such that said injector calibration apparatus frame is fixed relative to the injector.

18. The injector calibration apparatus of any one of claims 1 , 2 and 17, wherein said frame interface member is configured to be installed onto and removed from the injector by a user without the use of tools.

19. A method of calibrating a medical fluid injector comprising: interconnecting an injector calibration apparatus to a mounting member of said injector, wherein said interconnecting step comprises fixing a frame of said injector calibration apparatus relative to said mounting member of said injector; connecting an injector ram interface member of said injector calibration apparatus to an injector ram of said injector; driving a motor of said injector after said interconnecting and connecting steps to move said injector ram at a first speed; driving a motor of said injector calibration apparatus during said driving a motor of said injector step; and recording a level of current drawn by said motor while said injector ram is moving at said first speed.

20. The method of claim 19, wherein said connecting step comprises disposing a force gauge of said injector calibration apparatus relative to said injector ram such that said force gauge is operable to measure a first level of force of said injector calibration apparatus on said injector ram.

21. A method of calibrating a medical fluid injector, said method comprising: interconnecting an injector calibration apparatus to said injector, wherein said interconnecting step comprises disposing a force gauge of said injector calibration apparatus relative to an injector ram of said injector such that said force gauge is operable to measure a force of said injector calibration apparatus on said injector ram; driving a motor of said injector after said interconnecting step to move said injector ram at a first speed; adjusting, during said driving step, said injector calibration apparatus such that a first level of force is measured by said force gauge during at least a portion of said driving step; and recording a level of current drawn by said motor while said injector ram is moving at said first speed and said first level of force is measured by said force gauge.

22. The method of any one of claims 19-21, further comprising, prior to said interconnecting step, providing said injector free from a syringe interconnected to said injector ram.

23. The method of any one of claims 19-22, wherein said injector calibration apparatus is free of a fluid interface with said injector.

24. The method of any one of claims 20-23, wherein an adjusting step comprises controlling a motor of said injector calibration apparatus, wherein said motor of said injector calibration apparatus is interconnected to an injector calibration apparatus ram, and wherein said force gauge is interconnected to said injector calibration apparatus ram.

25. The method of claim 24, wherein said controlling step is at least partially based on an output signal of said force gauge.

26. The method of any one of claims 24-25, wherein said first level of force is achievable independent of a position of said injector ram.

27. The method of any one of claims 24-26, wherein said first level of force is operable to be varied independent of a position of said injector ram.

28. The method of any one of claims 20-27, further comprising: running said motor of said injector after said interconnecting step to move said injector ram at a second speed; adjusting, during said running step, said injector calibration apparatus such that said first level of feree is measured by said force gauge during at least a portion of said running step; and recording a level of current drawn by said motor while said injector ram is moving at said second speed and said first level of force is measured by said force gauge.

29. The method of any one of claims 20-28, further comprising: adjusting, during said driving step, said injector calibration apparatus such that a second level of force is measured by said force gauge during at least a portion of said driving step; and recording a level of current drawn by said motor while said injector ram is moving at said first speed and said second level of force is measured by said force gauge.

30. The method of any one of claims 21-29, further comprising repeating said driving, adjusting, and recording steps for a plurality of injector ram speeds and a plurality of levels of feree.

31. The method of claim 30, further comprising creating a table of values containing a recorded level of current drawn by said motor of said injector for each performed combination of level of force and injector ram speed.

32. A medical fluid injector comprising: a motor; a ram operatively interconnected to said motor; and a memory storage device containing a lookup table, wherein said lookup table comprises pressure values corresponding to combinations of ram speed and motor current.

33. The injector of claim 32, wherein said tabie includes at least five hundred pressure values corresponding to unique combinations of ram speed and motor current.

34. The injector of any one of claims 32 and 33, wherein for all expected combinations of ram speed and motor current, said injector is operable to determine a pressure value by looking up ram speed and motor current in said lookup table.

35. The injector of any one of claims 32-34, wherein for all expected combinations of ram speed and motor current, said injector is operable to determine a pressure value using a process free from interpolation.

36. A power injector assembly comprising: a medical fluid injector comprising a syringe plunger driver, that in turn comprises a motorized drive source and an injector ram that is operatively interconnected with said motorized drive source; and an injector calibration apparatus comprising a movabie calibration ram disposed in opposing relation to said injector ram, wherein said calibration ram exerts a resistive force on said injector ram, wherein a magnitude of said resistive force is controllable independent of a position of said calibration ram.

37. The power injector assembly of claim 36, wherein said injector ram is both extendable and retractable.

38. The power injector assembly of any one of claims 36-37, wherein said injector ram may be coupled with a syringe plunger when said injector calibration apparatus is disassociated with said injector.

39. The power injector assembly of any one of claims 36-38, wherein said injector calibration apparatus is mounted to said injector.

40. The power injector assembly of any one of claims 36-39, wherein said injector calibration apparatus is detachably mounted to said injector.

41. The power injector assembly of any one of claims 36-40, wherein said injector calibration apparatus is disposable in a fixed position relative to said injector.

42. The power injector assembly of any one of claims 36-41 , wherein said injector ram and said calibration ram are axially aligned.

43. The power injector assembly of any one of claims 36-42, wherein said calibration ram is both extendable and retractable.

44. The power injector assembly of any one of claims 36-43, wherein said calibration ram exerts said resistive force on said injector ram during an extension of said injector ram.

45. The power injector assembly of any one of claims 36-44, wherein said calibration ram exerts said resistive force on said injector ram during a forced retraction of said calibration ram.

46. The power injector assembly of any one of claims 36-45, wherein said resistive force comprises said injector ram back-driving said calibration ram.

47. The power injector assembly of any one of claims 36-46, wherein said injector calibration apparatus further comprises a calibration motor.

48. The power injector assembly of claim 47, wherein said resistive force is provided by said injector ram back-driving said calibration motor.

49. The power injector assembly of claim 47, wherein said resistive force is provided by said injector calibration apparatus when said calibration motor is driving said calibration ram in the same direction as said injector ram.

50. The power injector assembly of any one of claims 36-49, further comprising a force gauge disposed between said injector ram and said calibration ram.

51. The power injector assembly of any one of claims 36-50, wherein said injector calibration apparatus further comprises a calibration motor, and wherein said power injector assembly further comprises a sensor and calibration logic, wherein said sensor monitors said magnitude of said resistive force, and wherein said calibration logic is operatively interconnected with each of said calibration motor and said sensor.

52. The power injector assembly of claim 51 , wherein said injector further comprises a data structure that is operatively interconnected with said calibration logic.

53. The power injector assembly of claim 52, wherein said data structure comprises a plurality of data groups that each comprise a pressure, an associated injector ram speed, and an associated monitored current.

54. The power injector assembly of any one of claims 36-53, wherein said injector comprises calibration logic, wherein said calibration logic is operatively interconnected with and controls operation of said injector calibration apparatus and said motorized drive source of said power injector during a calibration procedure.

55. A method for calibrating a medical fluid injector comprising an injector ram and a pressure monitoring protocol, comprising: advancing said injector ram while in an uncoupled state in relation to any power injector syringe; inputting a predetermined resistance for said advancing step; providing said predetermined resistance for said advancing step; and calibrating said pressure monitoring protocol using each of said advancing and providing steps.

56. The method of Claim 55, wherein said advancing step comprises extending said injector ram.

57. The method of any one of claims 55-56, wherein said providing said predetermined resistance step comprises exerting a mechanical force on said injector ram.

58. The method of any one of claims 55-57, wherein said providing said predetermined resistance step comprises biasing a calibration ram in a direction of said injector ram, and wherein a force is transmitted between said injector ram and said calibration ram.

59. The method of any one of claims 55-58, wherein said providing said predetermined resistance step comprises back-driving a calibration motor, and wherein a force is transmitted between said injector ram and said calibration ram.

60. The method of any one of claims 55-58, wherein said providing said predetermined resistance step comprises driving a calibration ram in a direction opposite from said injector ram, and wherein a force is transmitted between said injector ram and said calibration ram.

61. The method of any one of claims 55-59, wherein said advancing step comprises moving said injector ram in a first direction, wherein said providing said predetermined resistance step comprises attempting to move a calibration ram in a second direction that is opposite of said first direction, and wherein a force is transmitted between said injector ram and said calibration ram.

62. The method of any one of claims 55-61 , wherein said calibrating step comprises populating a lookup table of said injector.

63. The method of any one of claims 55-62, wherein said advancing step comprises operating a motor operatively interconnected with said injector ram, and wherein said calibrating step comprises associating a current of said motor with a speed of said injector ram from said advancing step and a magnitude of said predetermined resistance from said providing step.

64. The method of any one of claims 55-63, further comprising: repeating said advancing step at a plurality of different speeds; and repeating said providing said predetermined resistance step for each of a plurality of different resistances.