Clear-PEM: A PET imaging system dedicated to breast cancer diagnostics

The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A specialized gantry allows to perform exams of the breast and of the axilla. In this paper we present results of the measurement of detector modules that integrate the system under construction as well as the imaging performance estimated from Monte Carlo simulated data.http://www.sciencedirect.com/science/article/B6TJM-4M942B5-D/1/e8aea93baa1aeae3538ea200a5a5466

A Four-Dimensional Image Reconstruction Framework for PET under Arbitrary Geometries

Positron Emission Tomography (PET) is a functional imaging modality with applications ranging from the treatment of cancer, studying neurological diseases and disease models. Virtual-Pinhole PET technology improves the image quality in terms of resolution and contrast recovery. The technology calls for having a detector with smaller crystals placed near a region of interest in a conventional whole-body PET scanner. The improvement is from the higher spatial sampling of the imaging area near the detector. A prototype half-ring PET insert built to study head-and-neck cancer imaging was extended to breast cancer imaging. We have built a prototype half-ring PET insert for head-and-neck cancer imaging applications. In the first half of this work, we extend the use of the insert to breast imaging and show that such a system provides high resolution images of breast and axillary lymph nodes while maintaining the full imaging field of view capability of a clinical PET scanner. We are focused on designing unconventional PET geometries for specific applications. A general purpose 4D PET reconstruction framework was created to estimate the radionuclide uptake in the subject. Quantitative estimation in PET requires precise modeling of PET physics. Data acquired in a PET scanner is well modeled as a Poisson counting process. Reconstruction given the forward model is implemented using MAP-OSEM. The framework is capable of reconstructing PET data under arbitrary position of the detector elements and different crystal sizes. A novel symmetry finding algorithm is created to reduce the system matrix size, without loss of resolution. The framework motivates investigation into different PET system geometries for different applications, as well as optimizing the design of PET systems. A generalized normalization procedure was developed to model unknown components. The programs are parallelized using OpenMP and MPI to run on small workstations as well as super-computing clusters. The performance of our reconstruction framework is presented through four novel and unconventional PET systems, each designed specifically for a different geometry. The Virtual-Pinhole half-ring system is a half-ring insert integrated into a Siemens Biograph-40, for head and neck imaging. The Flat-panel system is a modular insert system integrated into the Biograph-40, designed for breast cancer imaging. The MicroInsert II is the second generation full ring insert device, integrated into the MicroPET scanner to improve the resolution and contrast recovery of the MicroPET scanner. The Plant PET system is a PET system designed to image plants vertically, and integrated into a plant growth chamber. The improvement in speed/memory from symmetry finding is as high as a factor of 50 in some cases. Further improvements to the framework and state of the field are also discussed

Sensitivity correction of images obtained with the prototype Clear-PEM in pre-clinical environment

Dissertation presented at Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa to obtain a Master Degree in Biomedical EngineeringNuclear medicine has, when compared to anatomical imaging techniques, the great advantage of identifying the metabolic activity of the cells, hence becoming a great option for tumour identification. A new technology in this area is Positron Emission Mammography (PEM) that follows the same physical basics of Positron Emission Tomography (PET). The Clear-PEM project, a Portuguese research project, uses this technology and, in alternative to the whole-body exam, only the breast is examined, using two detector plates that rotate around the breast to detect radiation. The prototype has the ability to perform a complementary exam of the axillary region. This scanner is designed to detect small lesions or tumours in early stages, with high resolution and high sensitivity. After the acquisition, the data undergoes a process of reconstruction and corrections. It is our job to study which parameters should be adjusted in order to get the best contrast between lesions and the breast background, as well as meeting the high resolution standards we set to achieve. This work consisted in the correction of some characteristics that might influence image quality. The first correction made was the elimination of the presence of the gaps between the detector crystals’ effects, resulting in the enhancement of the image Signal-to-Noise Ratio (SNR). By varying the energy window of the image acquisitions, it was possible to minimize the effect of scattered photons, and varying the timing window minimized the effect of random coincidences

Mammography Techniques and Review

Mammography remains at the backbone of medical tools to examine the human breast. The early detection of breast cancer typically uses adjunct tests to mammogram such as ultrasound, positron emission mammography, electrical impedance, Computer-aided detection systems and others. In the present digital era it is even more important to use the best new techniques and systems available to improve the correct diagnosis and to prevent mortality from breast cancer. The first part of this book deals with the electrical impedance mammographic scheme, ultrasound axillary imaging, position emission mammography and digital mammogram enhancement. A detailed consideration of CBR CAD System and the availability of mammographs in Brazil forms the second part of this book. With the up-to-date papers from world experts, this book will be invaluable to anyone who studies the field of mammography

Organ-Dedicated Molecular Imaging Systems

[EN] In this review, we will cover both clinical and technical aspects of the advantages and disadvantages of organ specific (dedicated) molecular imaging (MI) systems, namely positron emission tomography (PET) and single photon emission computed tomography, including gamma cameras. This review will start with the introduction to the organ-dedicated MI systems. Thereafter, we will describe the differences and their advantages/disadvantages when compared with the standard large size scanners. We will review time evolution of dedicated systems, from first attempts to current scanners, and the ones that ended in clinical use. We will review later the state of the art of these systems for different organs, namely: breast, brain, heart, and prostate. We will also present the advantages offered by these systems as a function of the special application or field, such as in surgery, therapy assistance and assessment, etc. Their technological evolution will be introduced for each organ-based imager. Some of the advantages of dedicated devices are: higher sensitivity by placing the detectors closer to the organ, improved spatial resolution, better image contrast recovery (by reducing the noise from other organs), and also lower cost. Designing a complete ring-shaped dedicated PET scanner is sometimes difficult and limited angle tomography systems are preferable as they have more flexibility in placing the detectors around the body/organ. Examples of these geometries will be presented for breast, prostate and heart imaging. Recently achievable excellent time of flight capabilities below 300-ps full width at half of the maximum reduce significantly the impact of missing angles on the reconstructed images.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, in part by the EU through the FP7 Program under Grant 603002, and in part by the Spanish Ministerio de Economia, Industria y Competitividad through PROSPET (DTS15/00152) funded by the Ministerio de Economia y Competitividad under Grant TEC2016-79884-C2-1-R.González Martínez, AJ.; Sánchez, F.; Benlloch Baviera, JM. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences. 2(5):388-403. https://doi.org/10.1109/TRPMS.2018.2846745S3884032