Design and prototyping of a human brain PET scanner based on monolithic scintillators

Mendes, P. Rato; Alberdi, J.; Canadas, M.; Acilu, P. Garcia de; Navarrete, J.; Núñez, Luis A.; Pérez, J. M.; Romero, L.; Sarasola, I.; Willmott, C.

doi:10.1109/nssmic.2010.5874302

Cited by 9 publications

(5 citation statements)

References 9 publications

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“…The final BrainPET scanner will be a cylindrical insert for an existing MRI system. It will consist of 52 cassettes of four detector blocks each, arranged in four rings of 400 mm diameter [2]. A detector block is made of two radially stacked trapezoidal monolithic LYSO:Ce crystals, with 10 mm thickness and surfaces of 18.5 × 21.4/22.4 mm and 18.5 × 22.5/23.5 mm respectively (figure 1, left).…”

Section: Monolithic Scintillator Blocks In Petmentioning

confidence: 99%

“…The proposed BrainPET scanner is based on gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce), coupled to commercial arrays of avalanche silicon photodiodes (APDs) [2]. The introduction of monolithic crystals instead of the most usual pixelated ones has a number of potential advantages, such as higher sensitivity, better energy resolution, continuous coordinates and intrinsic depth of interaction (DOI) correction [3].…”

Section: Introductionmentioning

confidence: 99%

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Study and optimization of positioning algorithms for monolithic PET detectors blocks

Acilu¹,

Sarasola²,

Canadas³

et al. 2012

J. Inst.

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We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. The proposed scanner is based on annihilation gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) coupled to magnetically-compatible avalanche photodiodes (APD) matrices. The light distribution generated on the LYSO:Ce block provides the impinging position of the 511 keV photons by means of a positioning algorithm. Several positioning methods, from the simplest Anger Logic to more sophisticate supervised-learning Neural Networks (NN), can be implemented to extract the incidence position of gammas directly from the APD signals. Finally, an optimal method based on a two-step Feed-Forward Neural Network has been selected. It allows us to reach a resolution at detector level of 2 mm, and acquire images of point sources using a first BrainPET prototype consisting of two monolithic blocks working in coincidence. Neural networks provide a straightforward positioning of the acquired data once they have been trained, however the training process is usually time-consuming. In order to obtain an efficient positioning method for the complete scanner it was necessary to find a training procedure that reduces the data acquisition and processing time without introducing a noticeable degradation of the spatial resolution. A grouping process and posterior selection of the training data have been done regarding the similitude of the light distribution of events which have one common incident coordinate (transversal or longitudinal). By doing this, the amount of training data can be reduced to about 5% of the initial number with a degradation of spatial resolution lower than 10%.

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Section: Monolithic Scintillator Blocks In Petmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study and optimization of positioning algorithms for monolithic PET detectors blocks

Acilu¹,

Sarasola²,

Canadas³

et al. 2012

J. Inst.

Self Cite

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show abstract

“…Nevertheless, a dedicated brain PET offers a superior solution for human brain imaging as it has the potential to achieve better sensitivity, spatial resolution, and image quality than the 76 cm diameter PET cameras [4]. However, only cylinder or similar cylinder systems with smaller ring structure were fabricated for brain PET imaging [5][6][7][8][9]. Furthermore, a spherical PET (S-PET) can achieve an even higher geometrical sensitivity and a lower parallax error than conventional cylindrical ring PET scanners, thus making it a good candidate for high performance dedicated brain imaging [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Design study of dedicated brain PET with polyhedron geometry

Han

et al. 2015

THC

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Abstract. BACKGROUND: Despite being the conventional choice, whole body PET cameras with a 76 cm diameter ring are not the optimal means of human brain imaging. OBJECTIVE: In fact, a dedicated brain PET with a better geometrical structure has the potential to achieve a higher sensitivity, a higher signal-to-noise ratio, and a better imaging performance. METHODS: In this study, a polyhedron geometrical dedicated brain PET (a dodecahedron design) is compared to three other candidates via their geometrical efficiencies by calculating the Solid Angle Fractions (SAF); the three other candidates include a spherical cap design, a cylindrical design, and the conventional whole body PET. RESULTS: The spherical cap and the dodecahedron have an identical SAF that is 58.4% higher than that of a 30 cm diameter cylinder and 5.44 times higher than that of a 76 cm diameter cylinder. The conceptual polygon-shape detectors (including pentagon and hexagon detectors based on the PMT-light-sharing scheme instead of the conventional square-shaped block detector module) are presented for the polyhedron PET design. Monte Carlo simulations are performed in order to validate the detector decoding. CONCLUSIONS:The results show that crystals in a pentagon-shape detector can be successfully decoded by Anger Logic. The new detector designs support the polyhedron PET investigation.

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“…Utilizando las coordenadas de dichos píxeles se obtienen perfiles lineales a lo largo de los cilindros de la imagen original, siguiendo la dirección axial; finalmente, los valores medidos a lo largo de cada perfil, dividido por la concentración de actividad media obtenida en la zona uniforme, determinan los coeficientes de recuperación para cada tamaño de cilindro. El coeficiente de variación (%STD) asociado a los coeficientes de recuperación se calcula utilizando la siguiente expresión: (3)(4)(5)(6)(7)(8) donde el subíndice línea hace referencia a los perfiles lineales anteriormente indicados y fondo a la zona uniforme.…”

Section: Calidad De Imagenunclassified

“…El valor de SOR corresponde con el valor medio medido en cada VOI, dividido por el valor medio en la zona uniforme. El coeficiente de variación se calcula de la misma forma indicada en la expresión (3)(4)(5)(6)(7)(8), teniendo en cuenta que el subíndice línea hace ahora referencia a los valores de los píxeles en los respectivos VOI.…”

Section: Calidad De Imagenunclassified

Aspectos metodológicos para la evaluación de sistemas de tomografía por emisión de positrones empleando técnicas Montecarlo, protocolos estandarizados y diferentes trazadores

Castro¹

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This thesis analyzes the factors affecting the performance evaluation in positron emission tomography (PET) imaging, focusing on preclinical scanners. It explores the possibilities of standard protocols of assessment on the following aspects: their use as tools to validate Monte Carlo simulation programs, their usefulness as a method for comparing scanners and their validity in the study of the effect of alternative radioisotopes on image quality.Initially we study the methods of performance evaluation oriented to validate PET simulations. For this we present the GAMOS program as a simulation framework and show the results of its validation based on the standard NEMA NU 4-2008 for preclinical PET scanners. This has been accomplished by comparing simulated results against experimental acquisitions in the ClearPET scanner, describing the methodology for the evaluation and selection of NEMA parameters. This section also mentions the contributions developed in GAMOS for PET applications, such as the inclusion of tools for image reconstruction. Furthermore, the evaluation of the ClearPET scanner is used to compare its performance against another preclinical scanner, specifically the rPET-1 system. This is the first complete NEMA NU 4 based characterization study of both systems. At the same time we analyze how do the significant design differences of these two systems, especially the size of the axial field of view and the detectors configuration affect their performance characteristics. 68 Ga is one of the unconventional radioisotopes in PET imaging the use of which is currently significantly increasing; however, it presents the disadvantage of the long positron range (distance traveled by the emitted positron before annihilating with an electron). Besides the positron range, additional gamma photon emission is another physical property characteristic of PET radioisotopes that can affect the reconstructed image quality, as it happens to the isotope 48 V. In this thesis we assess these effects through studies of spatial resolution and image quality. Finally, we analyze the scope of the NEMA NU 4-2008 to carry out such studies, adapting it and proposing possible modifications.iii AgradecimientosMe gustaría dar las gracias en primer lugar a los dos directores que han posibilitado el desarrollo y conclusión de esta tesis. A Miguel Embid, por haber confiado en mi hace ya seis

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Design and prototyping of a human brain PET scanner based on monolithic scintillators

Cited by 9 publications

References 9 publications

Study and optimization of positioning algorithms for monolithic PET detectors blocks

Study and optimization of positioning algorithms for monolithic PET detectors blocks

Design study of dedicated brain PET with polyhedron geometry

Aspectos metodológicos para la evaluación de sistemas de tomografía por emisión de positrones empleando técnicas Montecarlo, protocolos estandarizados y diferentes trazadores

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