Issues in radiation dose measurement using electronic personal dosimeters during disaster relief activities

Area of Science:

• Medical physics
• Disaster medicine
• Radiation safety

Background:

• The Noto Peninsula earthquake necessitated medical relief efforts by the Japanese Red Cross Society (JRCS).
• Accurate radiation exposure monitoring is crucial for personnel operating in disaster zones, especially during potential nuclear incidents.

Purpose of the Study:

• To measure radiation exposure of JRCS medical relief team members during the Noto Peninsula earthquake.
• To investigate the occurrence of electromagnetic interference (EMI) events causing abnormally high dose readings on electronic personal dosimeters (EPDs).

Main Methods:

• Six JRCS medical relief team members were equipped with EPDs to monitor radiation exposure.
• A background radiation dosimeter was deployed on-site to record ambient radiation levels.
• Data collected over 2.5 days of relief activities were analyzed.

Main Results:

• Background radiation levels were minimal (3.0 ± 3.0 μSv).
• One nurse recorded an exceptionally high dose of 2075.0 ± 207.5 μSv, significantly exceeding the average dose of 40.0 ± 39.5 μSv for other team members.
• Abnormally high dose readings were observed without evidence of radioactive material dispersion.

Conclusions:

• Electromagnetic interference (EMI) from digital devices is strongly suspected as the cause of the anomalous high radiation dose readings.
• Three out of four individuals with high readings were operating digital devices, supporting the EMI hypothesis.
• Implementing countermeasures against EMI is essential for effective radiation dose management using EPDs during nuclear disaster relief operations.