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Refereed/Peer-reviewed Introduction: Training, educating, and fostering of young professionals are key requisites for the progress of any profession. The young medical physicists (MPs) of today are the medical physics professionals and leaders of tomorrow. It is, therefore, essential that they learn to work collectively and in a coordinated manner at both national and European levels at an early stage in their career. In view of this, EFOMP is planning to create a special interest group (SIG) encompassing early career MPs from across Europe. Methods: A survey was developed by EFOMP and circulated to all National Member Organisations (NMOs) to gather information on the status of early career groups in their respective societies and on the interest to partake in such group within the Federation. Results: Of the 36 NMOs that are part of EFOMP, 32 responded to the survey. Only 9 NMOs have established early career MPs groups within their NMOs, while the remaining countries are either considering setting up young MPs groups in the future (15 NMOs) or do not show such interest (8 NMOs). Of all responders, 59% expressed interest in the creation of the EFOMP SIG, 34% remained neutral towards this issue by not answering the question and for two NMOs the SIG idea had no appeal. Conclusion: Most NMOs showed interest in the creation of an early career MPs group within EFOMP and offered constructive feedbacks on the roles they envisage for the group. EFOMP will use and implement this information when establishing the special interest group.

This document provides a description of the baseline services provided by SLICES to experimenters based on their various demands and needs as well on access modes and types. It starts with an overview of Slices mainly based on Deliverable D2.1. Then, it analyzes user requirements for SLICES services based on Deliverable D1.1 results. It also introduces three examples of usages of the platform in the field of cloud/edge, IoT, and wireless/wired networking. Then, the document presents the access modes and types of SLICES.

Subject motion in positron emission tomography (PET) is a key factor that degrades image resolution and quality, limiting its potential capabilities. Correcting for it is complicated due to the lack of sufficient measured PET data from each position. This poses a significant barrier in calculating the amount of motion occurring during a scan. Motion correction can be implemented at different stages of data processing either during or after image reconstruction, and once applied accurately can substantially improve image quality and information accuracy. With the development of integrated PET-MRI (magnetic resonance imaging) scanners, internal organ motion can be measured concurrently with both PET and MRI. In this review paper, we explore the synergistic use of PET and MRI data to correct for any motion that affects the PET images. Different types of motion that can occur during PET-MRI acquisitions are presented and the associated motion detection, estimation and correction methods are reviewed. Finally, some highlights from recent literature in selected human and animal imaging applications are presented and the importance of motion correction for accurate kinetic modelling in dynamic PET-MRI is emphasized. This article is part of the theme issue ‘Synergistic tomographic image reconstruction: part 2’.

Background According to the Ministry of Health in Cyprus, since 2009, every year more than 3.000 new incidents with neoplasm are diagnosed. The National Health System (NHS) of Cyprus aims to offer adequate health services, comparing them with European Union standards. However, it is lacking a Positron Emission Tomography-Computed Tomography (PET/CT) unit. The present study aims to examine whether an investment by the Cyprus NHS of a PET/CT unit can be financially sustainable. Methods A financial analysis of the operating revenues and expenses of a departmental PET/CT with F18-FDG was performed taking into consideration all related parameters. A detailed estimation of the unit's operation expenses (PET/CT unit supply, overheads, salaries, etc.) and incomes was produced for a 15-year period. This initial scenario was not financially viable and therefore two alternatives are also examined. Results After performing a detailed analysis and projection for the evaluation of the feasibility study in the initial scenario, the overall outcome is estimated negative deriving to a €2,2 million losses in the cumulative results by 2035. The second scenario concluded that the required number of incidents to reach a neutral cash flow after a 15-year period should increase from 8.971 to 23.430. The third scenario reached the conclusion that a parallel investment to the purchase of the PET/CT unit by installing a cyclotron unit in the Cypriot NHS provides cumulative results positive of €1,7 million for the PET/CT, in the same period, that can finance the largest part of the €2,5 million required for the installation of the cyclotron unit. Conclusions Our findings show that an investment of a sole PET/CT unit is not a financially viable. Alternative possibilities such as usage of a PET/CT operated by the private sector or supporting patients to travel to another country are within the economic terms recommended. Key messages From a financial viewpoint, the scenario of investing in a PET/CT unit by the Cyprus NHS is not viable. Examining alternative options for patients in need of a PET/CT unit, where the initial investment cost for the state is not financially viable.

In this study, the properties of the reconstruction algorithm Iterative in comparison with the FORE-Iterative using

Hyper-responsive mobile applications}, such as augmented reality and online games, require ultra-low latency access to back-end services and data at runtime. While fog computing tries to meet such latency requirements by placing corresponding back-end services and data closer to clients, for e.g., within an access network, assuming a fixed back-end server throughout execution is problematic due to user mobility. A more flexible approach is thus required to allow for adapting to changes in network conditions when users roam, by relocating back-end services and data to closer available infrastructure. Support for real-time migration of software services exists, however, migrating associated disk state remains a bottleneck. This paper presents FOGFS, a fog file system that employs intelligent snapshotting, migration and synchronization mechanisms to speed up the migration of an application‘s disk state between different edge locations at runtime. The experimental evaluation of our prototype implementation reveals that the attainable speed-up is as much as 3. 3 x compared to conventional migration approaches.

Today there is a high demand for computing programmers, and at the same time a shortage of skilled professionals. This has triggered the creation of many initiatives in the past few years, with the aim of reversing the phenomenon. To achieve this, such events are designed to promote a more appealing image for programming, both as a profession and as a skill. This paper describes one such initiative, which uses a unique blend of differently themed, parallel workshops to motivate high school students to learn programming. With the use of questionnaires, we survey the participants and present our findings concerning the effectiveness of these workshops to engage the participants, to promote the value of coding, and to encourage the participants to consider a career in the field. We evaluate our results both at a general level, as well as by comparison among five individually themed workshops.

The investigation of the performance of different positron emission tomography (PET) reconstruction and motion compensation methods requires accurate and realistic representation of the anatomy and motion trajectories as observed in real subjects during acquisitions. The generation of well-controlled clinical datasets is difficult due to the many different clinical protocols, scanner specifications, patient sizes, and physiological variations. Alternatively, computational phantoms can be used to generate large data sets for different disease states, providing a ground truth. Several studies use registration of dynamic images to derive voxel deformations to create moving computational phantoms. These phantoms together with simulation software generate raw data. This paper proposes a method for the synthesis of dynamic PET data using a fast analytic method. This is achieved by incorporating realistic models of respiratory motion into a numerical phantom to generate datasets with continuous and variable motion with magnetic resonance imaging (MRI)-derived motion modeling and high resolution MRI images. In this paper, data sets for two different clinical traces are presented, 18F-FDG and 68Ga-PSMA. This approach incorporates realistic models of respiratory motion to generate temporally and spatially correlated MRI and PET data sets, as those expected to be obtained from simultaneous PET–MRI acquisitions.

The impact of respiratory motion correction on quantitative accuracy in PET imaging is evaluated using simulations for variable patient specific characteristics such as tumor uptake and respiratory pattern. Respiratory patterns from real patients were acquired, with long quiescent motion periods (type-1) as commonly observed in most patients and with long-term amplitude variability as is expected under conditions of difficult breathing (type-2). The respiratory patterns were combined with an MR-derived motion model to simulate real-time 4-D PET-MR datasets. Lung and liver tumors were simulated with diameters of 10 and 12 mm and tumor-to-background ratio ranging from 3:1 to 6:1. Projection data for 6- and 3-mm PET resolution were generated for the Philips Gemini scanner and reconstructed without and with motion correction using OSEM (2 iterations, 23 subsets). Motion correction was incorporated into the reconstruction process based on MR-derived motion fields. Tumor peak standardized uptake values (SUVpeak) were calculated from 30 noise realizations. Respiratory motion correction improves the quantitative performance with the greatest benefit observed for patients of breathing type-2. For breathing type-1 after applying motion correction, SUVpeak of 12-mm liver tumor with 6:1 contrast was increased by 46% for a current PET resolution (i.e., 6 mm) and by 47% for a higher PET resolution (i.e., 3 mm). Furthermore, the results of this study indicate that the benefit of higher scanner resolution is small unless motion correction is applied. In particular, for large liver tumor (12 mm) with low contrast (3:1) after motion correction, the SUVpeak was increased by 34% for 6-mm resolution and by 50% for a higher PET resolution (i.e., 3-mm resolution. This investigation indicates that there is a high impact of respiratory motion correction on tumor quantitative accuracy and that motion correction is important in order to benefit from the increased resolution of future PET scanners.

Proofs by induction are central to many computer science areas such as data structures, theory of computation, programming languages, program efficiency-time complexity, and program correctness. Proofs by induction can also improve students’ understanding and performance of computer science concepts such as programming languages, algorithm design, and recursion, as well as serve as a medium for teaching them. Even though students are exposed to proofs by induction in many courses of their curricula, they still have difficulties understanding and performing them. This impacts the whole course of their studies, since proofs by induction are omnipresent in computer science. Specifically, students do not gain conceptual understanding of induction early in the curriculum and as a result, they have difficulties applying it to more advanced areas later on in their studies. The goal of my dissertation is twofold: (1) identifying sources of computer science students’ difficulties with proofs by induction, and (2) developing a new approach to teaching proofs by induction by way of an interactive and multimodal electronic book (e-book). For the first goal, I undertook a study to identify possible sources of computer science students’ difficulties with proofs by induction. Its results suggest that there is a close correlation between students’ understanding of inductive definitions and their understanding and performance of proofs by induction. For designing and developing my e-book, I took into consideration the results of my study, as well as the drawbacks of the current methodologies of teaching proofs by induction for computer science. I designed my e-book to be used as a standalone and complete educational environment. I also conducted a study on the effectiveness of my e-book in the classroom. The results of my study suggest that, unlike the current methodologies of teaching proofs by induction for computer science, my e-book helped students overcome many of their difficulties and gain conceptual understanding of proofs induction.

Among the most fundamental concepts of computer science education is introductory programming, and, many effective approaches were proposed to teach programming to novice learners. Despite all efforts, students still show poor performance with course assessments, which can then lead to dropping out of their studies after their first experience with programming. In the last few years, a number of interventions were suggested, including the utilization of educational games that can motivate, stimulate and engage students far better than conventional approaches. In this paper, we present CodeAdventure, an educational adventure-like game that has been designed for learning and practicing introductory programming concepts. CodeAdventure adopts an integrated design approach that employs various mechanisms and techniques to achieve a truly immersive game learning experience while in parallel provides a fun way to practice and apply various programming concepts. CodeAdventure uses compelling graphics and incorporates different learning techniques that have been shown to be effective for students’ learning, such as providing hints and clues on how to solve puzzles, referencing instructional material, and immediate feedback on students’ performance .

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future PET scanners.

Purpose: Although there have been various proposed methods for positron emission tomography(PET) motion correction, there is not sufficient evidence to answer which method is better in practice. This investigation aims to characterize the behavior of the two main motion-correction approaches in terms of convergence and image properties. Methods: For the first method, reconstruct-transform-average(RTA),reconstructions of each gate are transformed to a reference gate and averaged. In the second method, motion-compensated image reconstruction (MCIR), motion information is incorporated within the reconstruction. Both techniques studied were based on the ordered subsets expectation maximization algorithm. Motion information was obtained from a dynamic MR acquisition performed on a human volunteer and concurrent PET data were simulated from the dynamic MR data. The two approaches were assessed statistically using multiple realizations to accurately define the noise properties of the reconstructed images. Results: MCIR successfully recovers the true values of all regions, whereas RTA has high bias due to the limited count-statistics and interpolation errors during the transformation step. In addition, RTAnoise is very small and stabilized, whereas in MCIR noise becomes progressively greater with the number of iterations and therefore MCIR outperforms RTA in terms of MSE only if noise is treated. For example, MCIR with postfiltering results in MSE up to 42% lower than RTA. Conclusions: This study indicates that MCIR may provide superior performance overall to RTA if noise is minimized. However, in applications where quantification is not the main objective RTA can be a practical and simple method to correct for motion.

In 3D PET, scatter of the gamma photons is one of the most significant physical factors which degrades not only image quality but also quantification. The currently most used scatter estimation method is the analytic single scatter simulation (SSS) which usually accommodates for multiple scattering by scaling the single scatter estimation. However, it has not been clear yet how accurate this approximation is for cases where multiple scatter is significant, raising the question: “How important is correction for multiple scattered photons, and how accurately do we need to simulate all scattered events by appropriate scaling?” This study answers these questions and evaluates the accuracy of SSS implementation in the open-source library STIR. Different scatter orders approximations are evaluated including different levels of scattering and different scaling approaches using Monte Carlo (i.e. SimSET) data. SimSET simulations of a large anthropomorphic phantom were reconstructed with iterative reconstruction algorithms. Images reconstructed with 3D filtered back-projection reprojection algorithm have been compared quantitatively in order to clarify the errors due to different scatter order approximations. Quantification in regions has improved by scatter correction. For example, in the heart the ideal value was 3, whereas before scatter correction the standard uptake value (SUV) was 4.0, after single scatter correction was 3.3 and after single and double scatter correction was 3.0. After correction by scaling single scatter with tail-fit, the SUV was 3.1, whereas with total-fit it was 3.0. Similarly, for the SSS correction methodology implemented in STIR using tail-fit the heart SUV was 3.1 whereas using total-fit it was 3.0. The results demonstrate that correction for double scatter improves image contrast and therefore it is required for the accurate estimation of activity distribution in PET imaging. However, it has been also shown that scaling the single scatter distribution is a reasonable approximation to compensate for total scatter. Finally, scatter correction with STIR has shown excellent agreement with Monte Carlo simulations.

Most K–12 outreach programs worldwide within materials science and beyond rely on scientists visiting K–12 classrooms and assisting teachers with instruction and development of classroom materials, as well as developing on-site professional development workshops. Due to the limited time materials scientists and teachers have available for participating in K–12 outreach programs, more creative approaches are necessary to accommodate the needs of a broader spectrum of teachers and students. Incorporating technology into K–12 outreach programs is one approach that can be used to overcome some of the obstacles currently faced. This article discusses different manners in which technology can be included in K–12 materials science outreach programs, such as K–12 educational software and tools as well as online professional development programs. This article also draws on broader educational technology research to identify known challenges of incorporating technology into outreach programs and possible ways to overcome such challenges.

Purpose In an oncology nuclear medicine department, radioisotopes are not only used for tumor detecting, staging, evaluation of therapy response but also for therapeutic purposes. This study documents the radiation exposure of departmental staff, related to cyclotron operation and service during the production and injection of 18F radiopharmaceuticals for PET/CT examination. In addition, it investigates exposure in a multiple holding tank system used for the storage of 131I waste generated from patients undergoing thyroid therapy, in order to optimize environmental protection procedures. Methods Measurements for the dose rates of neutrons and photons in the room of ABT-BG-75 self-shielded mini-cyclotron were recorded during bombardment for 18F-FDG production using a neutron detector and a scintillation dosimeter. The correlation between the duration of bombardment and required time to reach a dose rate equal to background level was investigated. An electronic dosimeter was used to record staff exposure for 18F production, dispensing, administration and imaging using PET-CT. Finally, the decay rate of 131I waste was measured using a dose rate meter positioned in the decay tank system of the radioactive iodine isolation ward. Results The time required for the cyclotron room to reach background level following completion of bombardment (3 × 50 min each) was approximately 2 h. The dose rate from neutrons was found to be negligible and from photons was less than 7.5 μ Sv/h. Therefore, personnel can safely enter the room during bombardment. The staff mean whole-body dose per 18F-administered patient was 1–2 μ Sv, depending on patient condition. The values obtained from the 131I radioactive waste stored in a delay tank system were comparable with theoretical values. Conclusion This study is useful for optimizing radiation exposure in an oncology nuclear medicine department. It is shown that during 18F production exposure is mostly attributed to photons. The level of the dose permits staff entry into the cyclotron room. Staff responsible for administration received 1–2 μ Sv per 18F-patient, considered to be on the lower end of the acceptable limit for a radiation worker. The study also documents the decay rate of 131I waste over the period which the suggested activity level for release in the environment is reached.

BACKGROUND: The aim of this study was to determine the impact of respiratory motion correction on SPECT MPI and on defect detection using a phantom assembly.METHODS: SPECT/CT data were acquired using an anthropomorphic phantom with inflatable lungs and with an ECG beating and moving cardiac compartment. The heart motion followed the respiratory pattern in the cranio-caudal direction to simulate normal or deep breathing. Small or large transmural defects were inserted into the myocardial wall of the left ventricle. SPECT/CT images were acquired for each of the four respiratory phases, from exhale to inhale. A respiratory motion correction was applied using an image-based method with transformation parameters derived from the SPECT data by a non-rigid registration algorithm. A report on defect detection from two physicians and a quantitative analysis on MPI data were performed before and after applying motion correction.RESULTS: Respiratory motion correction eliminated artifacts present in the images, resulting in a uniform uptake and reduction of motion blurring, especially in the inferior and anterior regions of the LV myocardial walls. The physicians' report after motion correction showed that images were corrected for motion.CONCLUSIONS: A combination of motion correction with attenuation correction reduces artifacts in SPECT MPI. AC-SPECT images with and without motion correction should be simultaneously inspected to report on small defects.

Background Respiratory motion in positron emission tomography (PET) is an unavoidable source of error in the measurement of tracer uptake, lesion position and lesion size. The introduction of PET-MR dual modality scanners opens a new avenue for addressing this issue. Motion models offer a way to estimate motion using a reduced number of parameters. This can be beneficial for estimating motion from PET, which can otherwise be difficult due to the high level of noise of the data. Method We propose a novel technique that makes use of a respiratory motion model, formed from initial MR scan data. The motion model is used to constrain PET-PET registrations between a reference PET gate and the gates to be corrected. For evaluation, PET with added FDG-avid lesions was simulated from real, segmented, ultrashort echo time MR data obtained from four volunteers. Respiratory motion was included in the simulations using motion fields derived from real dynamic 3D MR volumes obtained from the same volunteers. Results Performance was compared to an MR-derived motion model driven method (which requires constant use of the MR scanner) and to unconstrained PET-PET registration of the PET gates. Without motion correction, a median drop in uncorrected lesion \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm {SUV}}_{\mathrm {peak}}$$\end{document}SUVpeak intensity to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$78.4 \pm 18.6 \,\,\%$$\end{document}78.4±18.6% and an increase in median head-foot lesion width, specified by a minimum bounding box, to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$179 \pm 63.7\,\, \%$$\end{document}179±63.7% was observed relative to the corresponding measures in motion-free simulations. The proposed method corrected these values to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$86.9 \pm 13.6\,\, \%$$\end{document}86.9±13.6% (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p

This study aims to investigate the impact of respiratory motion correction on the diagnostic accuracy in myocardial perfusion SPECT. SPECT/CT data were acquired using an anthropomorphic phantom. The lungs were given an exponential sine-wave respiratory pattern resulting in heart motion of 1.5cm and 2.7cm in the cranio-caudal direction at the level of the diaphragm for the simulation of normal and deep breathing respectively. Defects were inserted into the myocardial wall. Motion correction was applied using an image based method with transformation parameters derived by a non-rigid registration algorithm. Images were evaluated by nuclear medicine physician. Respiratory motion correction eliminated artifactual defects present in the images, resulting in uniform uptake and reduction of motion blurring especially in the inferior and anterior walls. Increased defect contrast and thinner appearance of the heart wall were observed. The extent of improvement depended on the amplitude of the motion displacement; Although the impact of motion correction on the detection task was not as apparent for 1.5cm as with 2.7cm motion, in both cases correction recovered the correct defect size and contrast while rectifying the artifactual decrease of uptake. Finally, a combination of motion correction with attenuation correction enhanced these findings. Respiratory motion correction reduces motion artefacts in SPECT images resulting in improved defect detectability in myocardial perfusion imaging.

The impact of respiratory motion correction on quantitative accuracy in PET imaging is evaluated using real-time simulations for variable patient specific characteristics such as tumor malignancy and respiratory pattern. Respiratory patterns from real patients were acquired, with long quiescent motion periods (type-1) as commonly observed in most of the patients and with long term amplitude variability as it is expected under conditions of difficult breathing (type-2). The respiratory patterns were combined with an MR-derived motion model to simulate real-time 4D PET/MR datasets. Lung and liver tumors were simulated with diameters ranging of 10 and 12 mm and tumor to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET resolution were generated for Philips Gemini scanner and reconstructed without and with motion correction using OSEM (2 iterations, 23 subsets). Motion correction was incorporated into the reconstruction process based on MR-derived motion fields. Tumors peak standardized uptake values (SUVpeak) were calculated from thirty noise realizations. Respiratory motion correction improves the quantitative performance with the greatest benefit observed for patients of breathing type-2. For breathing type-1 after applying motion correction SUVpeak of 12 mm liver tumor with 6:1 contrast was increased by 46% for a current PET resolution (i.e. 6 mm) and 47% for a higher PET resolution (i.e. 3 mm). Furthermore, the benefit of higher scanner resolution is small for torso imaging unless motion correction is applied. In particular, for large liver tumor (12 mm) with low contrast (3:1) after motion correction the SUVpeak was 34% increased for 6 mm resolution and 50% increased for a higher PET resolution (i.e. 3 mm resolution. This investigation indicates high impact of respiratory motion correction on tumor quantitative accuracy and its importance in order to benefit from the increased resolution of future PET scanners.

Respiratory motion can degrade PET image quality and various correction approaches have been investigated. A novel method, applicable to simultaneous PET-MR is to measure the motion with the MR and correct the PET data with the known motion fields. This study investigates the effectiveness of motion correction for PET-MR acquisition with phantom studies. It incorporates the improved motion estimation or a simultaneously acquired MR with the realism of a respiratory driven motion and the deformability of the PVA cryogel phantom. PVA cryogel has been used for motion modeling because of its elastic properties. Motion is transferred with a hydraulic system to the MR room, inside the PET insert. The MR-compatible PET insert uses silicon photomultiplier photodetectors and acquisition is capable of being synchronized with the MRI. Spatial registration between PET and MR is essential for accurate motion correction using MRI derived motion fields. We have performed simultaneous PET and MR acquisition of a non-rigid continuously deformable phantom PET and MR visible phantom. Calibration procedures were used to ensure that PET and MR acquisitions were accurately aligned both spatially and temporally. The final step of this study is the motion correction by using known techniques such as Motion Compensated Image Reconstruction (MCIR) and Reconstruct-Transform-Average (RTA). We have demonstrated that the temporally and spatially correlated PET and MR datasels can be used to motion correct the PET acquisition

Dynamic image acquisition protocols are increasingly used in emission tomography, for drug development and clinical research. As such, there is a need for computational phantoms accurately describing both the spatial as well as temporal distribution of the radiotracer, taking into account periodic and non-periodic physiological processes during the course of the acquisition, such as tracer kinetics and respiratory motion. To this end, we developed a new 5D anthropomorphic digital phantom for accurate parametric imaging simulation studies in emission tomography. The proposed phantom is comprised of 3 spatial and 2 temporal dimensions and is based on high spatial and temporal information derived from 4D MR data. The envisaged applications of this digital phantom include development and evaluation of motion correction and image reconstruction algorithms in PET and SPECT, development of protocols and methods for tracer and drug development and new kinetic parameter estimation algorithms amongst others. Example applications are shown in parametric [18F]FDG and [15O]H 2 O PET imaging.

Following continuous improvement in PET spatial resolution, respiratory motion correction has become an important task. Two of the most common approaches that utilize all detected PET events to motion-correct PET data are the reconstruct-transform-average method (RTA) and motion-compensated image reconstruction (MCIR). In RTA, separate images are reconstructed for each respiratory frame, subsequently transformed to one reference frame and finally averaged to produce a motion-corrected image. In MCIR, the projection data from all frames are reconstructed by including motion information in the system matrix so that a motion-corrected image is reconstructed directly. Previous theoretical analyses have explained why MCIR is expected to outperform RTA. It has been suggested that MCIR creates less noise than RTA because the images for each separate respiratory frame will be severely affected by noise. However, recent investigations have shown that in the unregularized case RTA images can have fewer noise artefacts, while MCIR images are more quantitatively accurate but have the common salt-and-pepper noise. In this paper, we perform a realistic numerical 4D simulation study to compare the advantages gained by including regularization within reconstruction for RTA and MCIR, in particular using the median-root-prior incorporated in the ordered subsets maximum a posteriori one-step-late algorithm. In this investigation we have demonstrated that MCIR with proper regularization parameters reconstructs lesions with less bias and root mean square error and similar CNR and standard deviation to regularized RTA. This finding is reproducible for a variety of noise levels (25, 50, 100 million counts), lesion sizes (8 mm, 14 mm diameter) and iterations. Nevertheless, regularized RTA can also be a practical solution for motion compensation as a proper level of regularization reduces both bias and mean square error.

The matching problem in bipartite graphs is the basis for many applications that have become especially prominent with the advent of online markets that connect two entities (e.g., job-seekers and employers). Its algorithmic basis is the max-flow problem in networks, a topic that is often covered in introductory algorithms texts and courses.Separately, the Computer Science education literature is abundant with examples which indicate that the quality of the experience in the implementation of programming tasks is enhanced when done in groups.In this paper, we describe the application of a network-flow-based matching algorithm in bipartite graphs to form project groups in the algorithms course at the Colorado School of Mines (CSM). This activity simultaneously provides students with an immersive experience in a bipartite matching application. We present a small exploratory study on the effectiveness of the activity.

As percentages of women in computing jobs and university programs decline, recruiting and retaining women in the field of Computer Science (CS) becomes increasingly important. Undergraduate CS programs, and more specifically, introductory-level CS courses, offer an opportunity to introduce women to CS studies. Furthermore, learning experiences in introductory CS courses can be pivotal in shaping female students' perceptions of CS. Collaborative learning, in various forms, is an instructional construct that has been shown to be effective in recruiting and retaining women in undergraduate CS programs. In this paper we present an exploratory study on formal learning groups and their potential to attract and maintain female students' interest in CS studies.

Although there have been various proposed methods for motion correction in PET, there is not sufficient evidence to answer which method is better in terms of image quality and quantification. This study aims to characterize the behavior of the two main motion correction methods in terms of convergence and image properties. During the first method, reconstruct-transform-average (RTA), independent reconstructions of each gate are transformed to a reference gate and averaged. In the second method, motion-compensated image reconstruction (MCIR), all data are used with the motion information within a single reconstruction. The two methods are studied based on the OSEM algorithm. In this investigation motion fields were obtained from real dynamic MR acquisitions and concurrent PET data were simulated from the dynamic MR images. The two motion correction approaches were assessed statistically. Results indicate that MCIR is successful in the recovery of the true values of all regions, whereas RTA has high bias due to the non-negativity constraints and interpolation errors during transformation. It has been demonstrated that whilst at low iterations (i.e. 46 sub-iterations) the two methods have similar noise characteristics; at high iterations MCIR has increased noise. Finally, for low iterations the two methods have marginally similar coefficient of variation (CoV) whereas for large number of iterations RTA has clearly better CoV than MCIR. This study indicates that MCIR may provide superior performance overall to RTA providing the noise can be minimized.

In this paper, we present an approach to teaching induction that we call the "conceptual route" of teaching induction. Proofs by induction are central to the study of computer science and students come across them in many courses of their curricula. It is documented in the literature that in general students have difficulties with proofs by induction. Even though through the years some solutions were proposed to improve the situation, recent studies show that students are still having difficulties. Currently, proofs by induction take up too little of the computer science curriculum, and they are taught as a step-by-step procedure to be followed, which is not sufficient for students to gain conceptual understanding. In contrast, our approach aims at students' conceptual understanding by shifting their focus from the syntactic form of proofs by induction to their substance. The theoretical underpinning of our approach is an operationalization of the Induction Principle.