Young Victorian ice user Kieron Thomas thought he'd "killed the lady" after he ran a red light at 110km/h and smashed into the woman's car in Ballarat.

Fearing jail, the learner driver then fled and hid in a garden, leaving Sherridan Rizzoli with a brain injury, fractures to her lower back, a broken pelvis, two broken vertebrae, a large hernia and severed nerves in her right arm on February 16 last year.

Kieron Thomas has been jailed for more than three years.

On Tuesday Thomas was sent to prison after pleading guilty to negligently causing serious injury to the 42-year-old Ballarat mother and hospital worker as he evaded police at high speed.

The 20-year-old from Clunes, who was driving an unregistered car, injected himself with methylamphetamine between 2am and 3am before asking his 25-year-old friend "if he wanted to go for a spin".