bullet or bullets.
Another hostage, cafe manager Tori Johnson, was killed by a bullet to the head from gunman Man Haron Monis. His death prompted police to storm the Lindt Chocolate Cafe and kill Monis.
The inquest aims to establish whether deaths were avoidable and if it should have been treated as a terrorist event.
Eighteen people were taken hostage.
The stand-off at the cafe in Martin Place in Sydney's business district on 15 December led to a massive police operation and the shutdown of a large part of the city centre.
At the opening of the coroner's inquest in Sydney, Jeremy Gormly, the lawyer assisting the state coroner, said Ms Dawson was "struck by six fragments of a police bullet or bullets which ricocheted from hard surfaces into her body".
Australian media reports earlier this month had indicated that Ms Dawson, a 38-year-old barrister and mother of three young children, had died after being hit in the heart and shoulder by fragments from a police bullet.