Avaliação do impacto do avental de chumbo na dosimetria de IOE em instalações de medicina nuclear
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Data
2020-02-21
Autores
Cavallari, Heloisa Helena
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Universidade Estadual Paulista (Unesp)
Resumo
Existe uma crença histórica, decorrente da eficiência da proteção dos aventais plumbíferos nos serviços de Radiodiagnóstico, de que seja equivalente para serviços de Medicina Nuclear (MN). Porém, a melhora no entendimento da interação da radiação com a matéria permite compreender que em casos de manipulação de materiais com feixes largos de energia, esse interfere na radiação espalhada pelo meio absorvedor, podendo, inclusive aumentar a dose de exposição para os indivíduos ocupacionalmentes expostos (IOEs), diminuindo a eficácia de blindagens menos espessas. Além disso, o uso de avental plumbífero é considerado desconfortável ergonomicamente, devido ao peso e aumento da temperatura corporal pelos IOEs. O objetivo desse estudo foi verificar se o avental de chumbo utilizado por IOEs em instalações de MN é eficaz na proteção da radiação ionizante. Trata-se de um estudo transversal, observacional, descritivo, com coleta retrospectiva de leitura mensal da dose efetiva de dois dosímetros de tórax posicionados simultaneamente por baixo e por cima do avental de chumbo de 0,5 mm em 17 IOEs de cinco serviços, no período de setembro de 2016 a setembro de 2018, durante a rotina de serviços de MN convencional (113 leituras). Esse estudo foi aprovado pelo Comitê de Ética em Pesquisa (CEP). Foram realizadas estatísticas descritivas e inferenciais das variáveis dose efetiva mensal do dois dosímetros (abaixo e acima do avental – amostra pareada), considerando nível de significância de p <0,01 e intervalo de confiança de 99%. A média da leitura da dose efetiva dos dosímetros dos IOEs localizados abaixo do avental foi discretamente maior (0,881± 0,613) que a média dos dosímetros localizados acima do avental de chumbo (0,802±0,499), porém sem significância estatística (p=0,148). Em conclusão, o uso de avental plumbífero na prática das atividades de instalações de MN não reduz a dosimetria dos IOEs.
The use of lead aprons in the Nuclear Medicine (NM) setting is a practice based on the widespread adoption of the lead apron in Radiology, assuming equivalence in it's effectiveness in both activities. However, a better understanding of radiation-matter interaction raises the concern that when broad, non-collimated radiation beams are utilized, the interaction with thin shields such as the lead apron causes scattered radiation to possibly augmentate the dosis absorbed by occupationaly exposed individuals (OEI). There's also disadvantages concerning ergomics: extended use of a lead apron burdens OEI with its weight and thermal discomfort. The objective of this research was to verify whether lead aprons worn by OEI are effective as shielding against ionizing radiation in NM facilities. Consists of a cross sectional, observational, descriptive study, with retrospective data collection from two dosimeters per individual (17 OEI in five NM facilities, monthly readings) on the chest region, both superficial and deep to a 0.5mm lead apron. Data analyzed was gathered between September 2016 and September 2018, during routine work, totaling 113 readings. The study was approved by Research Ethics Committee (REC), The effective monthly dosis per dosimeter was subject to descriptive and inferential statistics, (superficial and deep to the lead apron - paired samples), considering significance level if p<0.01 and 99% confidence interval. The mean reading for deep-to-the-apron dosimeters was (0.881 ± 0.613) mSv, slightly above the mean reading for superficial-to-the-apron (0,802 ± 0,499) mSv, without statistical significance (p=0.148). In conclusion, the use of a lead apron by OEI working at NM facilities did not reduce dosimetry as measured.
The use of lead aprons in the Nuclear Medicine (NM) setting is a practice based on the widespread adoption of the lead apron in Radiology, assuming equivalence in it's effectiveness in both activities. However, a better understanding of radiation-matter interaction raises the concern that when broad, non-collimated radiation beams are utilized, the interaction with thin shields such as the lead apron causes scattered radiation to possibly augmentate the dosis absorbed by occupationaly exposed individuals (OEI). There's also disadvantages concerning ergomics: extended use of a lead apron burdens OEI with its weight and thermal discomfort. The objective of this research was to verify whether lead aprons worn by OEI are effective as shielding against ionizing radiation in NM facilities. Consists of a cross sectional, observational, descriptive study, with retrospective data collection from two dosimeters per individual (17 OEI in five NM facilities, monthly readings) on the chest region, both superficial and deep to a 0.5mm lead apron. Data analyzed was gathered between September 2016 and September 2018, during routine work, totaling 113 readings. The study was approved by Research Ethics Committee (REC), The effective monthly dosis per dosimeter was subject to descriptive and inferential statistics, (superficial and deep to the lead apron - paired samples), considering significance level if p<0.01 and 99% confidence interval. The mean reading for deep-to-the-apron dosimeters was (0.881 ± 0.613) mSv, slightly above the mean reading for superficial-to-the-apron (0,802 ± 0,499) mSv, without statistical significance (p=0.148). In conclusion, the use of a lead apron by OEI working at NM facilities did not reduce dosimetry as measured.
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Palavras-chave
Radioproteção, Radiação Ionizante, Ergonomia, Medicina Nuclear, Dosimetria de radiação, Radiation protection, Ionizing radiation, Ergonomics, Nuclear medicine, Radiometry