An injection system for the independent administration of imaging-guided injections utilizing the hand-on-needle technique including a pressure-sensitive pump and a switch assembly is provided. The switch assembly is adjustably mounted to a probe with a releasable mount, and includes a displaceable lever that can be displaced from a neutral position to a first position to initiate an aspiration event at the needle and from a neutral position to a second position to initiate an injection event at the needle. The displaceable lever and the pressure-sensitive pump are in electronic communication with a control module, which includes programmable logic executed by a processor to send and receive electronic communication(s) from the pump and switch, including when to continue and/or terminate aspiration and injection events at the needle.
