A female driver was repeatedly using her mobile phone before she hit and a killed a cyclist on Kings Park Road in West Perth, a court has been told.

Joanne Leigh Lawrence, 42, pleaded guilty to dangerous driving causing the death of retired professor Paola Ferroni in November 2014.

A sentencing hearing in the District Court was on Friday told Lawrence was driving from her Bullsbrook home to an appointment in Claremont when she failed to see Ms Ferroni, who was cycling to a gym.

Prosecutor Brad Hollingsworth said mobile telephone records showed Lawrence had made and received about a dozen telephone calls and text messages during the 50-minute journey.

The court heard Lawrence had been arguing with family members, and some of the calls and texts were in the six minutes before the collision.

The last text message she is recorded as receiving was 16 seconds before Saint John Ambulance received a triple-0 call to attend the scene.

Mr Hollingsworth it appeared Lawrence was in a "highly charged emotional state" and her "preoccupation" with her mobile phone meant she failed to see Ms Ferroni.

Lawrence 'looking at flowers', not texting

Lawrence's lawyer, Gary Massey, said his client accepted she had used her mobile phone while driving, but maintained at the time of the collision she had been looking at rosebushes on the median strip and not reading a text message.

"We concede she was inattentive while driving from Bullsbrook to the crash site ... but we say the State can't prove she was looking at a message at the time of the collision," he said.

"We say at the relevant time she was looking at the flowers"

Mr Massey said at the time Lawrence was suffering from undiagnosed mental health problems, which affected her ability to concentrate.

He also submitted she was extremely remorseful and accepted that her actions "had caused irreparable harm" to Ms Ferroni's family and friends.

Judge Richard Keen did not accept Lawrence's claim she was looking at a rose garden on the median strip at the time of the crash.

He said he believed she was trying to minimise her culpability.

Judge Keen added Lawrence must have realised she had psychiatric conditions that impaired her concentration and ability to drive, and she should have thought carefully about getting behind the wheel.

Lawrence has been sentenced to three years' jail, and will have to serve 18 months before she can be released on parole.

Outside court, Ms Ferroni's partner Rosemary Coates said victims had no voice in the justice system.

"It's all about the rights of the offender," she said.

She also took aim at the medical profession.

"The offender had been under medical treatment long before the crash, and the medical profession has some culpability in not recommending the suspension of her licence if she was so medicated and so mentally impaired," Ms Coates said.