A calibration error led to more than 300 patients receiving less than required dosages during radiation therapy for skin cancer between November 2004 and November 2007, according to the Ottawa Hospital Cancer Centre.
The radiation machine at the Civic Campus, used to treat the more common Basal Cell and Squamous Cell cancers, may have led to 326 patients being underdosed by less than 17 per cent the amount prescribed by their physicians. Patients treated for other cancers were not affected.
Dr. Chris Carruthers, chief of medical staff for the Ottawa Hospital, said both types are slow growing, local cancers and “it’s very rare that these types of cancer cause death.
“The question that would arise is if the cancer did not respond to treatment, was it because it was resistant or because it was underdosed?” he said.
The error occurred in 2004 when the radiation unit was moved to the Civic. The machine, which delivers a dozen different doses in different sized beams, was measured at one beam setting. The other sizes were set using a math formula, but were not tested.
In November 2007, a physician tested one of the other settings and noticed it emitted a lower dose than reported on the machine.
The hospital has asked Cancer Care Ontario to review the incident.
Dr. Carol Sawka the Vice President of Clinical Programs with the CCO, said they are reviewing the calibrating procedures, including whether or not the hospital should have tested the dose levels at other beam settings.
The 326 patients are being contacted to ensure there was a follow-up and to schedule appointments if there are any questions.
Concerned patients can contact the hospital at 613-739-6800.