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