A methodology for auto-monitoring of internal contamination by 131I in nuclear medicine workers

Abstract

The manipulation of 131I in Nuclear Medicine involves significant risks of internal contamination of the staff. In the event of an accidental contamination, or when the Radiological Protection Program includes routine individual monitoring of internal contamination, it is necessary to implement internal dose estimation through in vivo and in vitro bioassay techniques. Due to the huge extension of the Brazilian country, this type of monitoring becomes unfeasible if all measurements have to be performed at the institutes of the CNEN. Thus, if the Nuclear Medicine Centres (NMC) become able to conduct the monitoring of their employees, this skill would be of great significance. The methodology proposed in this work consists in a simple and inexpensive protocol for auto-monitoring the internal contamination by 131I, using the resources available at the NMC. In order to verify the influence of the phantom in the calibration factor for the measurement of 131I in thyroid, it was performed a comparison among a variety of phantoms commercially available, including the Neck-Thyroid Phantom developed in IRD. A protocol for performing in vivo and in vitro measurements by the NMC was established. The applicability of the individual monitoring techniques was also evaluated by comparing the detection limits with the derived limits associated with the annual dose limits for workers.

Necessity of Internal Monitoring for Nuclear Medicine Staff in a Large Specialized Chinese Hospital

“…Compared with the external individual monitoring, the method of internal individual monitoring is diversified, and the result is easily influenced by many factors. The published literature reports [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] regarding internal exposure in the field of nuclear medicine mainly did research on commonly used nuclides 131 I, 99m Tc and 18 F, and among them, internal exposure induced by 131 I were most studied and reported.…”

“…Research in this area is divided into two parts: the first part is the study of the committed effective dose resulting from intake of radionuclides. A series of studies have been carried out on the internal exposure of nuclear medical staff by air sampling [ 9 , 10 , 11 , 12 , 13 ], direct measurement [ 14 , 15 , 16 , 17 , 18 ] or biological materials sample analysis [ 17 , 19 , 20 ]. The second part is the study of the necessity of internal monitoring for nuclear medicine staff.…”

Internal exposure in nuclear medicine: application of IAEA criteria to determine the need for internal monitoring

“…A comparative approach based on the exposure scenarios and safety conditions adopted in this work indicates that the use of 131 I presents the higher risk of intake by workers. However, due to costs associated with transporting workers or bioassay samples to laboratories for analysis, it is suggested that the nuclear medicine centers use their own diagnostic devices to perform the monitoring of the workers Vidal, 2007;. Since the occupationally exposed group with higher risk of intake are most likely professionals who work in the radiopharmacy laboratories of the nuclear medicine centers (Freitas, 1991), they should be the first group evaluated for implementing an internal monitoring plan.…”

Simulação de uma gama-câmara para medidas de atividade de 99mTc com o código monte carlo gate

“…Diversos trabalhos desenvolvidos na Suíça [9,10,11], Brasil [12,13,14] e Polônia [15] levaram a cabo pesquisas de medições realizadas nos SMN, usando instrumentos de laboratório comumente disponíveis e que, portanto, não requerem equipamentos complexos e caros para análises quantitativas precisas, como contadores de corpo inteiro.…”