Incorporation monitoring

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The incorporation monitoring is a system for the detection of radioactive substances in the human body. It is routinely used for people who work with unsealed radioactive substances (powders, liquids, gases and the like) and, if necessary, also for other people after accidents in which radioactive substances were released. Quantitative objective is the determination of the activity supply, ie the type that at a time or during a period by inhalation ( inhalation ), swallowed ( ingestion has passed), absorption through the intact skin or wound absorbed into the body of the person. From this, the radiation dose to the person can be calculated as a model.

Methods

Direct measurement (in vivo method)

Direct measurements are carried out in whole-body counters and partial-body counters . Whole body counters are measuring devices whose detectors determine the activity of radioactive substances in the entire body. Partial body counters are measuring devices whose detectors measure the activity of radioactive substances in certain organs or body parts, especially in the thyroid gland , in the bones (on the knee or on the skull ) or in the lungs . This method is only used for radionuclides whose radiation outside the body can be measured and identified. In routine use, these are radionuclides that emit gamma radiation or positron radiation. In the experimental application, radionuclides can also be determined, which emit high-energy beta radiation and neutron radiation. The aim of the direct measurement is to determine the body activity, i.e. the activity of the radioactive substances in the human body at the time of the measurement. Using model-based data on the time course of body activity after a supply of radioactive substances ( retention ), the activity supply can be calculated from this.

Excretion analysis (in vitro method)

Excretion analysis is the determination of radioactive substances in urine or stool . For this purpose, urine or stool samples, which for most applications have to be collected over a period of 24 hours, are processed in the chemical laboratory in such a way that the activity of radioactive substances can then be determined using suitable measuring methods ( alpha spectrometry , liquid scintillation counting , mass spectrometry with inductively coupled plasma ) can. This method is suitable for radionuclides that do not emit any radiation that can be detected outside the body. The aim of the excretion analysis is to determine the activity of the radioactive substances in the excretions at the time of sampling. Using modeled calculated data on the time course of the activity in the excretions after a supply of radioactive substances, the activity supply can be calculated from this.

Indoor air measurement

Indoor air measurement is the determination of airborne radioactive substances directly at the workplace. For this purpose, stationary or person-carried suspended matter collectors , which take samples of the suspended matter at the workplace during work, are used. In some cases, the activity of the samples is determined directly in the suspended matter collector or, following sampling, in a suitable measuring device. The aim of indoor air measurement is to determine the activity concentration of radioactive substances in the air at the time of sampling. The activity intake can be calculated from the values ​​of the respiratory rate assumed as a model and with the length of stay of the exposed person at the respective workplace.

Situation in Germany

In Germany there are about 30 incorporation measuring points which are determined by the radiation protection authorities of the federal states to measure occupationally exposed persons by means of direct measurement or excretion analysis. The companies in which radioactive substances are handled are responsible for monitoring indoor air. The measuring points work on the basis of the guideline for physical radiation protection control to determine body doses, Part 2: Determination of body dose for internal radiation exposure (incorporation monitoring), which is published by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety . The control center for incorporation monitoring at the Federal Office for Radiation Protection coordinates the work of the measuring points and ensures their quality. The measuring centers report the measurements carried out and the body doses determined from the measurement results to the radiation protection register , which is also located at the Federal Office for Radiation Protection.

National standards in the field of incorporation monitoring are drawn up by Working Committee NA 080-00-03 AA Nuclear Medicine in the DIN Standards Committee Radiology (NAR).

International bodies

Working group 7 Internal dosimetry of the European Radiation Dosimetry Group ( EURADOS ) deals with practical issues relating to the implementation of incorporation monitoring . In particular, she has created the guideline Technical Recommendations for Monitoring Individuals for Occupational Intakes of Radionuclides ("Technical Recommendations for the Monitoring of Persons for Occupational Intakes of Radionuclides").

International standards in the field of incorporation monitoring are established by the working group ISO / TC 85 / SC 2 / WG 13 Monitoring and dosimetry for internal exposure in the subcommittee ISO / TC 85 / SC 2 Radiological protection of the technical committee ISO / TC 85 Nuclear energy, nuclear technologies , and radiological protection of the International Organization for Standardization .

Individual evidence

  1. ↑ a b c d Technical recommendations for monitoring individuals for occupational intakes of radionuclides. Website of the Publications Office of the European Union (accessed 16 January 2020). ISBN 978-92-79-86302-8 .
  2. ↑ Officially determined measuring points. Website of the Federal Office for Radiation Protection (accessed on January 16, 2020).
  3. ↑ a b Implementation of the incorporation monitoring. Website of the Federal Office for Radiation Protection (accessed on January 16, 2020).
  4. ↑ Guideline for physical radiation protection controls to determine body doses, Part 2: Determination of body dose in the event of internal radiation exposure (incorporation monitoring) (Sections 40, 41 and 42 StrlSchV) .
  5. ↑ Control center for incorporation monitoring of the BfS. Website of the Federal Office for Radiation Protection (accessed on January 16, 2020).
  6. ^ DIN standards committee for radiology (NAR). Website of the German Institute for Standardization (accessed on January 16, 2020).
  7. ↑ EURADOS Working Group 7 Internal Dosimetry (PDF document). Website of the European Radiation Dosimetry Group eV (accessed on January 16, 2020).
  8. ↑ ISO / TC 85 / SC 2 Radiological protection. International Organization for Standardization website (accessed January 16, 2020).