Condori Alvarado, Alejandro E. (2019) Caracterización de eficiencia de detección de sistemas de espectrometría gamma con detector CZT compacto para uso en medicina nuclear y PET, por medio de modelado montecarlo. / Efficiency characterization of gamma spectrometry system with compact CZT detector for use in nuclear medicine and PET through Monte Carlo. Maestría en Física Médica, Universidad Nacional de Cuyo, Instituto Balseiro.
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Resumen en español
El estado de arte actual requiere que un laboratorio de control de calidad de Radiofarmacia -PET cuente con un sistema de espectrometría gamma con alta resolución energética. Los sistemas basados en detectores semiconductores de HPGe son idóneos dada su alta resolución y elevada sensibilidad. Sin embargo, son equipos costosos, voluminosos y cuya operación y mantenimiento requiere condiciones especiales. Los detectores basados en semiconductores CZT representan una potencial alternativa, son mas económicos y poseen una resolución intermedia entre detectores centelladores y HPGe. El presente trabajo trata sobre la validación del código de simulación Montecarlo FLUKA para la caracterización de la eciencia de detección de un sistema espectrométrico basado en detector CZT Kromek GR1+. Se diseña y ajusta el modelo del sistema espectrométrico con código FLUKA, contrastando los resultados de eciencia simulada respecto a mediciones experimentales con fuente de referencia Tipo-M de ¹⁵²Eu en posición estándar y no estándar. Al analizar el proceso iterativo de ajuste se obtiene para los valores de eciencia simulada una sobre- estimación respecto a los experimentales de 2;5% respecto a la mediana en el rango de energías del ¹⁵²Eu. Los errores por sobre-estimación se minimizan al aplicar universalmente un factor de corrección multiplicativo de 0,975. Finalmente el modelo FLUKA corregido ha sido vericado, calculando la actividad para distintas fuentes fabricadas in-situ con una variedad de geometrías distintas a la fuente de referencia Tipo-M de ¹⁵²Eu. En paralelo se desarrollo para cada caso el equivalente modelo de Montecarlo: Eppendorf (10 y 20 µL), en vial de 10 mL y en filtros de carbono activado para muestreo de contaminación radioactiva de aire, cargados con actividades conocidas de ¹⁸F y ¹¹C. Los espectros experimentales obtenidos con Kromek son procesados con el software Genie 2000, el calculo de actividad se logra aplicando los correspondientes factores de sensibilidad obtenidos en la simulación FLUKA. El resultado se compara con la medición sobre activímetro. Los errores obtenidos se encuentran en el rango de ≈±5;6 %.
Resumen en inglés
In a modern PET radiopharmaceutical QC Laboratory, a Gamma-Ray spectrometer system with a high energy resolution is a desirable characteristic. HPGe based systems have a very high energy resolution with a suitable sensitivity. However, they are expensive, bulky systems and their maintenance is cumbersome. CZT gamma-ray spectrometers are potentially a cheaper alternative. This work deals with the characterization and calibration of a CZT Kromek GR1+ based spectrometer. For this end, the entire system has been modelled and simulated with Montecarlo FLUKA code throughout multiple test. Experimental measurements had been performed with a ¹⁵²Eu standard M-type disc source. Standard and nonstandard source positioning inside the spectrometer shielding were used for most comprehensive detector response characterization and simulated efficiency values. Dead layers thickness optimization on the detector model resulted in a 2:5% median value overestimation. In order to minimize errors, a 0.975 correction factor was successfully implemented. For verication purposes, other source geometries, and isotopes were elaborated locally, including Eppendorf tubes with 10 and 20 µL filling volume and 10 mL vial, intended for routine practice. Also, to aid radiation protection survey procedures, air sampling charcoal lters had been loaded with ¹⁸F and ¹¹C known activities. For every source their respective measurement had been performed on Kromek and their efficiency obtained from Fluka simulation. The so achieved activity estimations were compared to the known amounts. The error was ≈±5:6%.
| Tipo de objeto: | Tesis (Maestría en Física Médica) |
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| Palabras Clave: | Gamma spectrometry; Espectrometría gamma; Nuclear medicine; Medicina nuclear; [Monte carlo simulation; Simulación Monte carlo; FLUKA code; Código FLUKA; CZT detector; Detector CZT] |
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| Materias: | Medicina > Espectrometría gamma |
| Divisiones: | FUESMEN |
| Código ID: | 891 |
| Depositado Por: | Tamara Cárcamo |
| Depositado En: | 12 Abr 2021 11:04 |
| Última Modificación: | 12 Abr 2021 11:04 |
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