A fluid injection system comprising: a fluid injector (610, 10); at least one fluid chamber (612, 26, 28, 1716) configured to contain fluid, the at least one fluid chamber (612, 26, 28, 1716) in fluid communication with the fluid injector (610, 10); one or more electromagnetic radiation or ultrasonic sensors (2000, 3000, 1484) positioned relative to the at least one fluid chamber (612, 26, 28, 1716) to detect a position of a meniscus at a liquid-gas interface of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716) by dithering a field of detection of the one or more, electromagnetic radiation or ultrasonic sensors; and at least one processor in communication with the one or more electromagnetic radiation or ultrasonic sensors (2000, 3000, 1484) and the fluid injector (610, 10), the at least one processor configured to: determine the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716); calculate the volume of fluid contained in the at least one fluid chamber (612, 26, 28, 1716) based on the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716), and at least one of: i) display on a display in communication with the at least one processor the volume of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716); ii) enable the fluid injector (610, 10) to perform an injector filling operation or an injection procedure; iii) inform a user of an insufficient volume and allow the user to install a fluid chamber (612, 26, 28, 1716) having a sufficient volume; iv) inform the user of the insufficient volume and allow the user to continue with a system-adjusted volume or a user-adjusted volume; and v) disable the fluid injector (610, 10) from performing the injector filling operation or an injection procedure. a fluid injector (610, 10); at least one fluid chamber (612, 26, 28, 1716) configured to contain fluid, the at least one fluid chamber (612, 26, 28, 1716) in fluid communication with the fluid injector (610, 10); one or more electromagnetic radiation or ultrasonic sensors (2000, 3000, 1484) positioned relative to the at least one fluid chamber (612, 26, 28, 1716) to detect a position of a meniscus at a liquid-gas interface of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716) by dithering a field of detection of the one or more, electromagnetic radiation or ultrasonic sensors; and at least one processor in communication with the one or more electromagnetic radiation or ultrasonic sensors (2000, 3000, 1484) and the fluid injector (610, 10), the at least one processor configured to: determine the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716); calculate the volume of fluid contained in the at least one fluid chamber (612, 26, 28, 1716) based on the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716), and at least one of: i) display on a display in communication with the at least one processor the volume of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716); ii) enable the fluid injector (610, 10) to perform an injector filling operation or an injection procedure; iii) inform a user of an insufficient volume and allow the user to install a fluid chamber (612, 26, 28, 1716) having a sufficient volume; iv) inform the user of the insufficient volume and allow the user to continue with a system-adjusted volume or a user-adjusted volume; and v) disable the fluid injector (610, 10) from performing the injector filling operation or an injection procedure. determine the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716); calculate the volume of fluid contained in the at least one fluid chamber (612, 26, 28, 1716) based on the position of the meniscus at the liquid-gas interface of the fluid in the at least one fluid chamber (612, 26, 28, 1716), and at least one of: i) display on a display in communication with the at least one processor the volume of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716); ii) enable the fluid injector (610, 10) to perform an injector filling operation or an injection procedure; iii) inform a user of an insufficient volume and allow the user to install a fluid chamber (612, 26, 28, 1716) having a sufficient volume; iv) inform the user of the insufficient volume and allow the user to continue with a system-adjusted volume or a user-adjusted volume; and v) disable the fluid injector (610, 10) from performing the injector filling operation or an injection procedure. i) display on a display in communication with the at least one processor the volume of the fluid contained in the at least one fluid chamber (612, 26, 28, 1716); ii) enable the fluid injector (610, 10) to perform an injector filling operation or an injection procedure; iii) inform a user of an insufficient volume and allow the user to install a fluid chamber (612, 26, 28, 1716) having a sufficient volume; iv) inform the user of the insufficient volume and allow the user to continue with a system-adjusted volume or a user-adjusted volume; and v) disable the fluid injector (610, 10) from performing the injector filling operation or an injection procedure.