A father has called the legal system "ridiculous" after the doctor responsible for the injection which killed his son walked free from jail.
Wayne Jowett died a month after the mistake
Dr Feda Mulhem was sentenced to eight months after admitting unlawfully killing cancer patient Wayne Jowett and a further 10 months on five unrelated assault charges.
But having already served 11 months on remand - more than half his sentence - Mulhem, of Stanley Road, Leicester, was released from custody.
Mr Jowett, 18, died after a toxic cancer drug was wrongly injected into his spine at Nottingham's Queen's Medical Centre in 2001.
The teenager was undergoing treatment for a form of leukaemia when the mistake happened - and was actually in remission from the disease.
Mr Jowett's father, also called Wayne, said: "Eight months for the killing of my son is absolutely ridiculous.
"It leaves a sour taste in my mouth."
Delivering the sentence, Mr Justice Poole told Mulhem: "No sentence I impose can possibly compensate Wayne's family for their loss."
Mulhem apologised to the family.
In a statement issued after the sentence, he said: "I would like to give my deepest and heartfelt apologies to the family of Wayne Jowett who have suffered so much because of his death."
Mulhem had ordered a junior doctor to administer the drug into the spine, even though neither had been formally trained in giving chemotherapy.
The drug he was given to complete his treatment, Vincristine, is safe if injected into a vein, but highly toxic if given "intrathecally" - into the spine.
An independent report later criticised staff and procedures at the hospital and highlighted design faults in syringes and drug packaging.
The design of Vincristine phials is being changed so that they can no longer be fitted to spinal injection kits.
The court heard that Mulhem failed to note what was written on the patient's haematology chart and failed to see which drug should have been administered.
The doctor, who came to work in Britain in 1998 after qualifying in Syria, later told police that he got it into his head he was administering a completely different drug.
He also failed to check the route of administration and the syringe, which would have stated that the drug was Vincristine and would have told him that the drug should have been injected into a vein.
The error only came to light when another junior doctor queried what had happened.
Although desperate attempts to reverse the treatment's effects were made once the mistake was realised, it was too late.
Wayne gradually became paralysed and died almost a month later when his breathing machine was turned off.
The two doctors were immediately suspended as Queen's Medical Centre set up an inquiry into the death.
The hospital subsequently admitted liability for the error and a "substantial" settlement was reached with Mr Jowett's family.
The mistake happened because of a mix-up between two chemotherapy drugs which should never have been given to the patient at the same time.
The other drug, Cytosine, was supposed to be given as a spinal injection.
Exactly the same mistake has been made in UK hospitals on 13 occasions over the last 15 years, with mostly fatal consequences.
The Department of Health set up a committee to come up with ways of reducing the number of medical mistakes within the NHS.
Its report in June 2000 urged the government to examine ways of completely wiping out deaths and disability caused by "wrongly administered spinal injections" by the year 2001.