Analysis of Residence Time, Effective Half-Life, and Internal Dosimetry Before Radioiodine Therapy.

Radioiodine therapy has been widely used for ablation of remnant tissue after surgical treatment of differentiated thyroid carcinoma (DTC). Internal dosimetry provides a new approach to choosing the administered activity-an approach that considers the distribution and retention of 131I individually per patient. This study used clinical techniques of internal dosimetry to assess the accumulated activity, internal bone marrow dosimetry, and effective half-life in patients undergoing treatment for DTC. Methods: This was a quantitative, retrospective study analyzing diagnostic documents and images. The internal dosimetry method calculated the dose absorbed by the bone marrow per administered activity of 131I. Calculation of the absorbed dose took into account the accumulated activity, which was obtained through measurements of whole-body images acquired at 4 intervals over 5 d. Results: The median dose absorbed by the bone marrow per administered activity was 0.117 mGy/MBq (range, 0.043-0.152 mGy/MBq). The median whole-body residence time was 22.0 h (range, 12.6-39.4 h). The median effective half-life was 15.6 h (range, 7.6-28.2 h). Conclusion: Internal dosimetry provides information relevant to safe dose limits for DTC radioiodine therapy, especially in advanced cases of the disease for which greater activities may be necessary.

Occupational exposure in the work process of radiology technologists with 68Ga-labeled radiopharmaceuticals.

The study identified occupational exposure in the work of radiology technologists with 68Ga radiopharmaceuticals, in a Nuclear Medicine service in southern Brazil, by means of observation and document analysis. The occupational exposure related the factors, distance, time and shielding. Thus, it was observed high times during handling of the material, small distances between sources and radiosensitive structures, such as the eye lens and the thyroid gland. It is recommended to reassess and standardize the work, once that critical moments should not be restricted only to dosimetric reading.

Optimization of OSEM parameters in myocardial perfusion imaging reconstruction as a function of body mass index: a clinical approach.

OBJECTIVE: The present study is aimed at contributing to identify the most appropriate OSEM parameters to generate myocardial perfusion imaging reconstructions with the best diagnostic quality, correlating them with patients' body mass index. MATERIALS AND METHODS: The present study included 28 adult patients submitted to myocardial perfusion imaging in a public hospital. The OSEM method was utilized in the images reconstruction with six different combinations of iterations and subsets numbers. The images were analyzed by nuclear cardiology specialists taking their diagnostic value into consideration and indicating the most appropriate images in terms of diagnostic quality. RESULTS: An overall scoring analysis demonstrated that the combination of four iterations and four subsets has generated the most appropriate images in terms of diagnostic quality for all the classes of body mass index; however, the role played by the combination of six iterations and four subsets is highlighted in relation to the higher body mass index classes. CONCLUSION: The use of optimized parameters seems to play a relevant role in the generation of images with better diagnostic quality, ensuring the diagnosis and consequential appropriate and effective treatment for the patient.

OBJETIVO: O presente trabalho visa contribuir para identificar quais os parâmetros OSEM que geram as reconstruções na cintilografia de perfusão do miocárdio com o maior valor clínico de diagnóstico, relacionando-os com as classificações de índice de massa corporal. MATERIAIS E MÉTODOS: Foram selecionados 28 pacientes adultos que realizaram cintilografia de perfusão do miocárdio em um hospital público. Cada paciente teve seu exame processado com o método OSEM em seis combinações diferentes de número de iterações e subsets. As imagens foram analisadas por especialistas em cardiologia nuclear, que consideraram o valor clínico de diagnóstico delas e indicaram quais as imagens que mais se adequavam à qualidade diagnóstica. RESULTADOS: Em análise global da pontuação conforme as avaliações médicas, o arranjo de quatro iterações e quatro subsets gerou as imagens com melhor qualidade diagnóstica em todas as classes de índice de massa corporal, porém o arranjo com seis iterações e quatro subsets se destacou nas classes de maiores índices de massa corporal. CONCLUSÃO: A utilização de parâmetros otimizados parece ter papel importante em proporcionar reconstruções de melhor qualidade diagnóstica, garantindo-se assim que o paciente tenha o seu diagnóstico e consequente terapêutica encaminhados de forma mais adequada e eficaz.

Optimization of OSEM parameters in myocardial perfusion imaging reconstruction as a function of body mass index: a clinical approach / Otimização de parâmetros OSEM na reconstrução de cintilografias de perfusão do miocárdio em função do índice de massa corporal: uma escolha clínica

AbstractObjective:The present study is aimed at contributing to identify the most appropriate OSEM parameters to generate myocardial perfusion imaging reconstructions with the best diagnostic quality, correlating them with patients' body mass index.Materials and Methods:The present study included 28 adult patients submitted to myocardial perfusion imaging in a public hospital. The OSEM method was utilized in the images reconstruction with six different combinations of iterations and subsets numbers. The images were analyzed by nuclear cardiology specialists taking their diagnostic value into consideration and indicating the most appropriate images in terms of diagnostic quality.Results:An overall scoring analysis demonstrated that the combination of four iterations and four subsets has generated the most appropriate images in terms of diagnostic quality for all the classes of body mass index; however, the role played by the combination of six iterations and four subsets is highlighted in relation to the higher body mass index classes.Conclusion:The use of optimized parameters seems to play a relevant role in the generation of images with better diagnostic quality, ensuring the diagnosis and consequential appropriate and effective treatment for the patient.

ResumoObjetivo:O presente trabalho visa contribuir para identificar quais os parâmetros OSEM que geram as reconstruções na cintilografia de perfusão do miocárdio com o maior valor clínico de diagnóstico, relacionando-os com as classificações de índice de massa corporal.Materiais e Métodos:Foram selecionados 28 pacientes adultos que realizaram cintilografia de perfusão do miocárdio em um hospital público. Cada paciente teve seu exame processado com o método OSEM em seis combinações diferentes de número de iterações e subsets. As imagens foram analisadas por especialistas em cardiologia nuclear, que consideraram o valor clínico de diagnóstico delas e indicaram quais as imagens que mais se adequavam à qualidade diagnóstica.Resultados:Em análise global da pontuação conforme as avaliações médicas, o arranjo de quatro iterações e quatro subsets gerou as imagens com melhor qualidade diagnóstica em todas as classes de índice de massa corporal, porém o arranjo com seis iterações e quatro subsets se destacou nas classes de maiores índices de massa corporal.Conclusão:A utilização de parâmetros otimizados parece ter papel importante em proporcionar reconstruções de melhor qualidade diagnóstica, garantindo-se assim que o paciente tenha o seu diagnóstico e consequente terapêutica encaminhados de forma mais adequada e eficaz.