Details

Autor(en) / Beteiligte

• NISHIZAWA, Kunihide
• MAEKOSHI, Hisashi

Titel

Thyroidal 125I Monitoring System Using a Survey Meter for 125I

Ist Teil von

• RADIOISOTOPES, 1989/04/15, Vol.38(4), pp.203-208

Ort / Verlag

Japan: Japan Radioisotope Association

Erscheinungsjahr

1989

Quelle

MEDLINE

Beschreibungen/Notizen

• This paper describes the counting efficiency and detection limit of a thyroidal 125I monitoring system. Two systems were used: (1) M 1 was composed of only a survey meter for 124I (SM) having a NaI (Tl) crystal of 2inφ×5mmt and (2) M 2 was composed of the SM having an output terminal for spectroscopy and a multichannel pulse height analyzer. The counting efficiency was determined by using an anthropomorphic neck phantom embedded four simulated thyroids of 17, 20. 5, 31 and 40 ml including 125I solution. The couting efficiency between 0°and 45°to the direction from the center of the thyroid to the front of the neck coincided within -4%. The efficiency of M1 ranged from 7.9 to 1.8% as the distance between the probe and the neck increased from 0 to 5 cm. Similarly the efficiency of M2 ranged from 8.3 to 2.2%. The detection limit of M 1 ranged from 7 to 34 Bq, and the limit of M2 ranged from 1 to 5.1 Bq. M2 system was applied to monitoring a worker performing iodization with Na125I of 74 MBq. Both monitoring systems proved to sensitively detect thyroidal 125I within the uncertainty ±10%.