|Fig. 1: Location of Fleurus, Belgium. (Source: Wikipedia Commons)|
In 2006, a level 4 nuclear incident occurred in Fleurus, Belgium after a facility worker suffered severe health effects as a result of high doses of radiation.  The nuclear incident in Fleurus, located in central Belgium as seen in Fig. 1, occurred in a Sterigenics medical device sterilization facility. [2,3] The International Atomic Energy Agency (IAEA) uses the International Nuclear and Radiological Event Scale as an assessment tool for damage done by nuclear accidents.  The scale ranges from 0-7, with a score of 0 indicating a "below scale" event with no safety significance, and a 7 indicating a major accident. The level 4 Fleurus nuclear incident signifies an accident with local consequences. 
On March 11, 2006, an alarm went off in the facility, and an operator entered the irradiation room to close the open cell door.  He turned off the alarm, and then decided to close the access door to the irradiator.  Following safety protocol, the cell had to be checked for the absence of personnel before closing the door, so the operator had to enter the cell to validate the reset contact switch.  The cell included a bunker, in which the irradiation material was placed in baskets located on both sides of the source, and a 6-m deep pool underneath the concrete slab.  The source moves back and forth from bunker to pool through a concrete slab.  At that time, the Co-60 sources were partly out of the security position, most likely in an intermediate position between the high position used for irradiation phases and the low storage position. [2,3] As a result, the whole body of the operator was exposed to the radiation for approximately 22 seconds.  A few hours later, he experienced nausea and vomiting but did not think it was related to the irradiation.  Eighteen days after the incident, the victim consulted a physician because of persistent nausea, as well as intermittent diarrhea, headache and hair loss. 
Since a possible accidental exposure was suspected, the patient was placed in the hematology department of Percy Hospital in France.  The possibility of multi-organ failure (MOF) was considered initially at the Hospital, but quickly ruled out after it was determined the patient suffered exclusively from a hematological syndrome.  The patient experienced a 26% drop in hemoglobin levels, and had blood poisoning eight days after hospitalization.  Severe hematopoietic syndrome (grade 4) was diagnosed, and treatment with Neulasta was initiated as soon as possible after the diagnosis - 28 days after exposure.  The patient was also treated with Erythropoietin, and given platelet transfusions.  This cytokine treatment had an incredibly positive effect and the blood cell counts of the patient recovered quickly.  Forty-three days after exposure, the hematopoietic syndrome was completely resolved. 
Physical dosimetry is a detection method for radiation exposure, and serves to estimate the dose received and its distribution throughout the body of the victim.  This is so doctors may fine tune their diagnosis, and be more precise in their treatment.  It is an addition to data produced by clinical and biological investigations.  Physical dosimetry was reconstructed on site of the Sterigenics facility following the incident and the numerical simulations indicated a dose gradient between the pelvis and the skull.  It was estimated that the patient had received a mean dose of 4.2 - 4.8 Gy.  The results clearly showed the irradiation was heterogeneous, which was crucial to developing a treatment strategy.  This means that some areas of bone marrow were under-exposed relative to others. Given the dose levels, this suggested spontaneous secondary resumption of bone marrow activity in the affected areas.  These results supported the diagnosis of residual hematopoiesis, and thus provided crucial information that helped to determine the medical treatment of the patient. 
© Daniel Lowet. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 T. Miller, "Rating Nuclear Accidents and Incidents: Which Were the Worst?" PBS News Hour, 18 Mar 11
 P. Gourmelon et al., "European Consensus on the Medical Management of Acute Radiation Syndrome and Analysis of the Radiation Accidents in Belgium and Senegal," Health Phys. 98, 825 (2010).
 C. Huet et al., "Physical Dosimetric Reconstruction of a Radiological Accident at Fleurus (Belgium) on 11 March 2006," Radiat. Meas. 43, 845 (2008).