Definition of person data

 

For demonstration of incorporation monitoring for Th-227 a special dataset is created as shown on the left.

 

  • Occupational cetegory: activities in the medicine including medial research
  • Monitoring category: adult person with access to controlled areas
  • Begin of monitoring 01.01.2018

     

     

Definition of material handling data

 

For decision on the need of individual monitoring the potential dose due to unknown intakes has to be estimated. For this purpose the material handling has to be specified.

 

In this example material parameters are assumed to be as follows:

  • Absorption type M
  • Particle size 5 µm AMAD

The handling of this material is assumed to be as follows:

  • Handled activity: 5 MBq (typical activity applied in therapy with Th-227)
  • Release potential: low
  • Protection level: ventilation box
  • Duration of handling: 10 days (the activity of 5 MBq Th-227 is handled by that person on 10 days per year)

With these parameters the following potential exposure is calculated according to the German regulations (RiPhyKo):

  • potential intake: 500 Bq Th-227 per year
  • potential annual dose: 3,1 mSv

 

Decision on the need of individual monitoring

 

There is a need for individual monitoring if the annual dose due to potential intakes is more than1 mSv. In this example the potential dose is 3,1 mSv. So

  • there is a need for routine monitoring and thus
  • the person is allocated to monitoring category 1 (adult person with access to controlled areas; the age of the person is checked automatically

 

Definition of routine monitoring procedure

 

There are two general requirements for routine monitoring:

 

  • the monitoring interval should be not too long, i.e. the misinterpretation potential due to unknown time of intake should be less than factor 3 (misinterpretation criterion M)
  • the sensitivity of the measuring procedure should make sure that an exposure of 1 mSv per year can be detected in any case (i.e. the hypothetical measuring value at the end of any monitoring interval should be above the LLD of the measuring procedure for any intake scenario; sensitivity criterion S)

The monitoring procedure is defined by

  • Measurement technique
  • Monitoring interval (typically 7d, 14d, 30d, 60d, 90d, 120d, or 180d)
  • Detectable activity (i.e. the measured value at the end of the montoring interval for an annual exposure of 1 mSv)

 

IDEA System checks any reasonable monitoring procedure with respect to both criteria. If the procedure meets one of the two criteria, the respective line in the table (left) is indicated in yellow. So, for example, routine monitoring by urine measurements with the monitoring interval being 30d would meet the misinterpretation criterion, but it would not meet the sensitivity criterion because the detectable activity is 0,4 mBq, this being below the LLD of 1 mBq.

 

 

 

If the monitoring procedure meets both requirements, the respective line in the table is indicated in light green.

 

So, in the case of Th-227, routine monitoring by feces measurement with the monitoring interval being 30 d would meet both requirements.

 

...will be continued...