Internal Dosimetry Laboratory

The risk of contamination with some radioactive material inside the body may be due to the handling of open sources or simply being present in potentially contaminated environments. The possible types of contamination are: by ingestion, inhalation or absorption (in the case of contact of this material with wounds on the body). Direct measurement of the body or a specific organ provides a quick and convenient estimate of the activity present inside the body. These measurements, possibly combined with the results of the excretion analysis, allow the assessment of the effective dose committed and its attribution as a result of internal contamination.

In the Internal Dosimetry Laboratory (LDI) of the CDTN, people who work in nuclear facilities, in the TRIGA Reactor and in the Radiopharmaceutical Research and Production Unit (UPPR) are monitored to investigate possible internal contamination. Workers from other industries or hospitals may also be monitored in this laboratory.

In the event of an accident, it is important to have calibrated and prepared direct measurement methods to verify whether or not contamination has occurred, since these measurements will help to assess whether any medical treatment will be necessary.

The CDTN LDI performs measurements of internal contamination using three different counting systems: the Whole Body Counter (CCI), Thyroid Counting System and Skull Counting System.

Whole Body Counter

The Whole Body Detection System is used for routine monitoring of Occupationally Exposed Individuals (OEIs) at the TRIGA IPR-R1/CDTN research reactor and for the general public whenever there is a risk of accidental exposure. The Whole Body Counter uses an 8"x4" NaI(Tl) detector covering an energy range of 300 keV to 2000 keV, with a Minimum Detectable Activity (MDA) of 75 Bq for 137Cs and 60Co, in a measurement time of 30 minutes.

Skull Counting System

The Skull Counting System consists of a 3"x3" NaI(Tl) detector, with a Minimum Detectable Activity (MDA) of 40 Bq for the radionuclide 18F, in a measurement time of 15 minutes. It is used to monitor professionals involved in the handling of unsealed sources such as 18F-FDG, produced by UPPR/CDTN workers.

Thyroid Counting System

Thyroid Counting Geometry is used to measure internal contamination of professionals involved in handling unsealed sources such as 124I in research activities. This counting system can also be used in research and in cases of accidents involving the community and/or nuclear medicine services of regional hospitals that use iodine radioisotopes.

Contact: 

Bruno Melo Mendes - bmm@cdtn.br - Tel.: +55 31 34399674