Radiotherapy Accident- Costa Rica 1996

By To-Anh

  • Background

    Background
    • 3 hospital in the Capital devoted to treatment of cancer: The San Juan de Dios, the Mexico Hospital and the Dr. Rafael Angel
    • 2 hospital offer radiotherapy facilities: the San Juan and the Mexico
    • 1 have radiotherapist but no equipment available: Dr. Rafael Angel

  • Beam miscalibration

    Beam miscalibration
    • The source of the Alcyon teletherapy unit was exchanged and put into operation
    • The 60 Co radiation therapy was replaced at San Juan de Dios Hospital
    • A worker made a mistake in calculating the dose rate.
    • The error was not recognized and operation were resumed with cancer patients.

  • Unrecognized Dosage Deviation

    • Treatment continued with the miscalibrated beam
    • Medical staff administered radiation treatments assuming normal dosage.
    • Pt. began receiving radiation at higher than intended doses.
    • Lack of immediate detection or correction resulted in continued overexposure.

  • First alert

    First alert
    -The radiation oncologist at the Dr. Rafael Angel hospital had noticed the unusual severe effects in some patient treat with the Alcyon II unit.
    - The effects were related to the skin, low digestive tracts.
    - By then, 115 patients received treatment on the mis-calculated machine.

  • The error was realized

    The error was realized
    • The person in charge of dosimetry at the San Juan hospital contacted the physicist and requested him to measure the absorbed dose rate and compare to his own measurement.
    • 0.3 units equal to 0.3 min, or 18 s. The dosage rate has been determined using a value of 30seconds.
    • 66% overexposure.
    • Irreparable damage had already been caused by the machine by the time it was shut down.

  • Immediate Action

    Immediate Action
    • The person in charge of dosimetry contacted the Control of Ionizing Radiation of the Ministry of Health of Costa Rica
    • Discrepancy was found by expert about the dose rate and the value found on the certification given by the manufacturer.
    • The radiotherapy treatment stopped, the machine was closed down officially
    • Investigation started.

  • Effect on humans

    Effect on humans
    • Within 9 month of the accident, 42 patients had died ( 7 deaths primary due to overexposure, 22 died probably of their disease)
    • Experts from the Pan American Health Organization confirmed the occurrence of overexposures in radiotherapy treatments.
    • Irreversible radiation effects and complications resulting from the accident were anticipated to appear in patients over the coming years.

  • IAEA report

    IAEA report
    • A number of the patient examined will be at danger of brain necrosis or loss of hearing
    • At least 1 case blindness for year to come.
    • About 10% of the total number of patients are at very high risk of spinal cord effects, some are already paralyzed.
    • Radiation induced changes in heart have been reported in patients.

  • Counting continued...

    Counting continued...
    • 61 patients died -13 deaths due to overexposed, 4 related to overexposed, 9 insufficient data.

  • Penalty

    Penalty
    • The person in charge of dosimetry under investigate turn out was not a radiation physicist. He just attended only a number of training course and fellowship
    • He was charged with 16 culpable homicide and sentenced 6 years in prison