Database of radiological incidents and related events--Johnston's Archive

San Jose radiotherapy accident, 1996

compiled by Wm. Robert Johnston
last modified 11 May 2005

Date: 22 August-27 September 1996

Location: San Jose, Costa Rica

Type of event: radiotherapy accident


An error in the calibration of a cobalt-60 radiotherapy unit in Costa Rica resulted in overdosages of about 60%. The equipment change that produced the error occurred on 22 August, with the first treatments administered on 26 August. Of 42 patients that died through 7 July 1997, 3 died probably as a direct result of radiation exposure and 4 more with radiation exposure a contributing cause. Another 22 died probably of their disease and not of radiation exposure. Of the surviving overexposed patients, 4 suffered "catastrophic" consequences, 16 more severe effects, 26 had lesser effects, and 22 had no effects. Some sources attribute 17 deaths to the misadministrations.

Consequences: 7 fatalities, 81 injuries.


© 2004, 2005 by Wm. Robert Johnston.
Last modified 11 May 2005.
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