Doctor Toby Russell was a Federation scientist specializing in neurogenetic research, posted to the Adelman Neurological Institute. She created a number of revolutionary medical technologies and drugs, most notably the genitronic replicator, although not all of her innovations were successful. She often risked the lives of her patients in the name of her research, not caring whether or not the patient survived, only if she gained data from the attempt.
Russell visited the USS Enterprise-D in 2368 at the request of Dr. Beverly Crusher, as a consult after Lieutenant Worf was paralyzed. She suggested using the untested genitronic replicator to repair Worf's spinal column and restore full mobility, but Crusher felt the technology was too risky and would endanger Worf's life even further. Crusher and Russell then presented a traditional treatment based on neural transducers to Worf, but he refused, as he would rather die than live a life without full mobility. Russell then suggested the genitronic replicator to Worf, angering Dr. Crusher.
The already tense situation was further inflamed when Russell assisted in triage of victims from the USS Denver. She used one of her experimental drugs, borathium, on a survivor rather than another proven treatment which may have saved his life. Russell felt justified in using borathium, as she was able to recover valuable data which would allow her to improve the drug's effectiveness. Dr. Crusher, still upset over Russell's behavior concerning Worf, relieved her of medical duty.
After conferring with Captain Picard, Dr. Crusher eventually decided to authorize the use of the genitronic replicator, and Russell participated in the groundbreaking surgery. Although the procedure was a success due to Worf's Klingon anatomy, Crusher still believed Russell practiced dangerous and inappropriate medicine- particularly since Worf had briefly died on the operating table, only being restored thanks to his neurological functions being 'backed up' along with most of his other vital organs-, and reminded her of that fact as she left the Enterprise-D. (TNG: "Ethics")
In the novel A Time for War, A Time for Peace, Toby Russell is part of a Starfleet team that is inspecting the USS Enterprise-E and during part of her sickbay inspection, Russell is once again confronted by Beverly Crusher about her reckless medical practices and Crusher also reminds Russell, to her irritation, that after the initial wave of articles about the successful genitronics procedure, which was only barely successful due to Worf's unique Klingon physiology, nothing else has ever been heard about genitronics.