Radiological overexposure

["J. J. Rozental" <josrozen@netmedia.net.il>]

Dear Radsafers

	Probably almost Health Physicist and Regulators had learned about the
Radiological overexposure that occurred at the San Juan de Dios Hospital in
San Jose, Costa Rica, in August and September 1996, 115 patients  that were
treated for neoplasm by radiotherapy were affected; the  initiating event
occurred on 22 August 1996, when a Cobalt 60 radiation radiotherapy source
was replaced. When the new source was calibrated, an error was made in
calculating the dose rate and this  miscalculation resulted in the
administration to patients of higher radiation doses than dose prescribed.
The error was realized on 27 September (more than a month later) and
treatments were stopped, the radiotherapy machine was closed down on 3
October 1996. Almost one year later, among 7 and 11 July 1997 and expert
International team assessed the overexposure , and confirmed that the
exposure rate had been greater than assumed, by  about 50-60%.  This
accident was the most serious radiological accident that has occurred
considering  overexposure of patients. Its understanding and lessons needs
to be learned as part of all future training courses, specially for Health
Physicist
Now the IAEA published the complete report including the technical
information as result of the  meeting to assessed the event,  held at  the
IAEA Headquarters from 1 to 6 September 1997. This document was published as
Special publication Series STI/PUB/1027 in June 1998 and the title is
Accidental overexposure of Radiotherapy Patients in San Jose, Costa Rica. 

Examination and evaluation of  70 of the 73 patients who remained alive were
carried out, and: 

a) The following table  describes the findings from the direct examination
of patients (73)

4 severe or catastrophic effects
16 Marked effects, high risk of future effects
26 Radiation effects that were not severe at the time of examination: Some
risk of future effects
22 No definite effects of significance at the time of examination: Low risk
of future effects
2 Underexposed patients as therapy was discontinued (when the error was
discovered)
3 could not be seen: one possible at risk of future effects

b) The following table  describes the findings from the review of records of
deceased patients, total 42

3 exposure as the major factor in causing death
4 exposure as a substantial contributory factor
22 death related to a tumor or cause other than exposure
5 not enough to judge
8 data on patients nor reviewed by the expert team


Finally, Let's think a little more about responsibility:  Who is (are)
responsible?

 a)  The Radiation Protection Officer, who made the calibration  of the new
source?
 b)  The Organization, that has the responsibility to implementing measures
for ensuring radiation protection programmes?
 c)  The Physician that did not follow the RPO's  "procedures"?
 d)  The Regulatory Authority if does not make inspection during the source
changes and calibration?
  
  Finally:
  
 e)  What realistic should be a training course to workers,  many  so short.
Do you believe these two days training courses for workers or even two weeks
for Radiation Protection Officer,  provides adequate information, on the
basic principles of Radiation Protection and Safety?

	"The fact that accidents are uncommon should not, however, give grounds for
complacency. No radiological accident is acceptable"-- Dr. Hans Blix former
IAEA Director General, commentary made in 1987 about  the Radiological
Accident in Goiania.

J. J. Rozental
<josrozen@netmedia.net.il>
Israel 


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