Method For Controlling Fluid Accuracy And Backflow Compensation

Abstract

A method for controlling fluid ratio accuracy during a dual flow injection with a powered injection system is described. The method includes predicting a first capacitance volume of a first syringe comprising a first medical fluid and a second capacitance volume of a second syringe comprising a second medical fluid with a first capacitance correction factor and a second capacitance correction factor, respectively, selecting a ratio of the first medical fluid and the second medical fluid to be administered to a patient in the dual flow injection, determining a relative acceleration ratio of a first piston of the first syringe and a second piston of a second syringe based on the predicted first capacitance volume and the predicted second capacitance volume, wherein the relative acceleration ratio is selected to maintain the selected ratio of the first medical fluid and the second medical fluid during the dual flow injection, and injecting a mixture of a first medical fluid and a second medical fluid having the selected ratio with the powered injection system.

1 - 20 . (canceled) 
     
     
         21 . A method for controlling fluid ratio accuracy during a dual flow injection with a fluid delivery system including a powered fluid injector, the method comprising:
 selecting, using a fluid control module operatively associated with the powered fluid injector, a fluid ratio of a first medical fluid and a second medical fluid to be administered to a patient in the dual flow injection;   determining, using the fluid control module operatively associated with the powered fluid injector, a relative acceleration ratio of a first piston for injecting the first medical fluid and a second piston for injecting the second medical fluid, wherein the relative acceleration ratio is selected to compensate for capacitance of the fluid delivery system while maintaining the selected fluid ratio during the dual flow injection; and   injecting a mixture of the first medical fluid and the second medical fluid having the selected fluid ratio with the fluid delivery system.   
     
     
         22 . The method of  claim 21 , wherein the acceleration ratio of the first piston relative to the second piston is less than 1:1. 
     
     
         23 . The method of  claim 21 , further comprising:
 initially during injection of the mixture, accelerating the first piston to a first steady state velocity over a longer time period than a time period for accelerating the second piston to a second steady state velocity.   
     
     
         24 . The method of  claim 23 , further comprising:
 after the first piston reaches the first steady velocity, maintaining the first steady state velocity during the injection of the mixture, and   after the second piston reaches the second steady velocity, maintaining the second steady state velocity during the injection of the mixture.   
     
     
         25 . The method of  claim 23 , wherein the first steady state velocity is higher than the second steady state velocity. 
     
     
         26 . The method of  claim 21 , further comprising:
 initially during injection of the mixture, accelerating the second piston at a maximum acceleration that the second piston can achieve.   
     
     
         27 . The method of  claim 21 , further comprising:
 initially during injection of the mixture, accelerating the second piston to minimize the amount of time required for the second piston to reach a steady state velocity.   
     
     
         28 . The method of  claim 21 , further comprising:
 initially during injection of the mixture, accelerating the second piston to reach a steady state velocity in less than 0.5 seconds.   
     
     
         29 . The method of  claim 21 , wherein the first piston is accelerated at an acceleration value A 1 , where the acceleration value A 1  is determined by equation (1),
     A   1   =A   2 /( c ·( V   1   /V   2 ))  (1)
   wherein A 2  is an acceleration value for the second piston, c is a scalar correction factor selected to compensate for the capacitance of the fluid delivery system, V 1  is a velocity of the first piston, and V 2  is a velocity of the second piston.   
     
     
         30 . The method of  claim 29 , further comprising:
 selecting the scalar correction factor using the fluid control module operatively associated with the powered fluid injector.   
     
     
         31 . The method of  claim 21 , wherein the capacitance of the fluid delivery system comprises at least one of:
 capacitance of a first syringe containing the first medical fluid;   capacitance of a second syringe containing the second medical fluid;   capacitance of a tubing set connected to the first syringe; and   capacitance of a tubing set connected to the second syringe.   
     
     
         32 . The method of claim of  claim 31 , further comprising:
 predicting, using the fluid control module operatively associated with the powered fluid injector, at least one of: a capacitance volume of the first syringe and a capacitance volume of the second syringe.   
     
     
         33 . The method of  claim 21 , wherein the first medical fluid has a different viscosity than the second medical fluid. 
     
     
         34 . The method of  claim 21 , wherein the first medical fluid has a higher viscosity than the second medical fluid. 
     
     
         35 . The method of  claim 21 , wherein the first medical fluid is an imaging contrast agent and the second medical fluid is saline. 
     
     
         35 . The method of  claim 35 , wherein the fluid ratio of the first medical fluid to the second medical fluid ranges from 10:90 to 90:10 imaging contrast agent to saline. 
     
     
         36 . The method of  claim 21 , wherein the fluid delivery system further comprises a first tubing set connected to a distal end of a first syringe containing the first medical fluid and a second tubing set connected to a distal end of a second syringe containing the second medical fluid. 
     
     
         37 . The method of  claim 28 , wherein a backflow volume of the first medical fluid into the second tubing set is less than 0.5 mL.