Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator

Abstract A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber component to detect the multi-MeV Compton scattered photons, together with a stack of 6 double-sided silicon strip detectors (DSSSD) acting as scatterer component. Key ingredient of the γ-source reconstruction is the determination of the γ-ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5o for the photon source reconstruction can be expected for the energy range around 3 – 5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the γ-ray energy. Intense, tightly collimated 137Cs and 60Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the "k-Nearest-Neighbors" algorithm developed at TU Delft [2] (together with its variant "Categorical Average Pattern", CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance

Rationale and Design of a Multi-National Study of Physicians' Opinions, Attitudes, and Practices Regarding Influenza Vaccination in Patients with Cardiovascular Diseases: A Mixed Methods Designs. The FLUence Project

Infections, particularly those involving the respiratory tract, are associated with an increased incidence of cardiovascular events, both de novo and as exacerbations of pre-existing cardiovascular diseases. Influenza vaccination has consistently been shown to reduce the incidence of cardiovascular events. Nonetheless, vaccination rates among adults remain suboptimal, both in the general population and among high-risk individuals. Multiple barriers hinder achieving adequate vaccination rates, with physicians’ beliefs and attitudes towards these interventions being crucial. The FLUence project was developed within the framework of the World Heart Federation’s Emerging Leaders program, to address this issue. This project has two phases: a global quantitative survey to assess the perceptions, opinions, and attitudes and challenges of physicians worldwide regarding the safety and efficacy of the influenza vaccination use, and a qualitative survey to further investigate the barriers and facilitators of recommending and using this vaccination. The quantitative survey was created and disseminated in five languages (English, Spanish, French, Italian, and Portuguese) to physicians of all specialties who care for adults, with a particular focus on patients with cardiovascular disease. The survey included eight domains with a total of 36 questions with closed options; a Likert scale with five possible answers was used to gauge participants’ opinions. To gain deeper insights into the complexities behind the low vaccination rates in adults, the second part of the project comprises a qualitative survey, conducted in the two lower-middle- and upper-middle-income countries: India and Argentina, respectively. These countries were selected because patients with cardiovascular diseases have access to free influenza vaccination in Argentina, whereas patients must pay for the vaccine out of pocket in India. Thus, the FLUence study will provide valuable information to better understand the perceptions and barriers to improving influenza vaccination rates from the perspective of physicians. It is imperative to actively engage all healthcare providers to improve influenza vaccination rates

Sub-millimeter precise photon interaction position determination in large monolithic scintillators via convolutional neural network algorithms

In this work, we present the development and application of a convolutional neural network (CNN)-based algorithm to precisely determine the interaction position ofγ-quanta in large monolithic scintillators. Those are used as an absorber component of a Compton camera (CC) system under development for ion beam range verification via prompt-gamma imaging. We examined two scintillation crystals: LaBr3:Ce and CeBr3. Each crystal had dimensions of 50.8 mm × 50.8 mm × 30 mm and was coupled to a 64-fold segmented multi-anode photomultiplier tube (PMT) with an 8 × 8 pixel arrangement. We determined the spatial resolution for three photon energies of 662, 1.17 and 1.33 MeV obtained from 2D detector scans with tightly collimated137Cs and60Co photon sources. With the new algorithm we achieved a spatial resolution for the CeBr3 crystal below 1.11(8) mm and below 0.98(7) mm for the LaBr3:Ce detector for all investigated energies between 662 keV and 1.33 MeV. We thereby improved the performance by more than a factor of 2.5 compared to the previously used categorical average pattern algorithm, which is a variation of the well-established k-nearest neighbor algorithm. The trained CNN has a low memory footprint and enables the reconstruction of up to 104events per second with only one GPU. Those improvements are crucial on the way to future clinicalin vivoapplicability of the CC for ion beam range verification.This work was supported by the DFG Cluster of Excellence MAP (Munich-Centre forAdvanced Photonics)

Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator

Abstract A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber component to detect the multi-MeV Compton scattered photons, together with a stack of 6 double-sided silicon strip detectors (DSSSD) acting as scatterer component. Key ingredient of the γ-source reconstruction is the determination of the γ-ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5o for the photon source reconstruction can be expected for the energy range around 3 – 5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the γ-ray energy. Intense, tightly collimated 137Cs and 60Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the "k-Nearest-Neighbors" algorithm developed at TU Delft [2] (together with its variant "Categorical Average Pattern", CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance

A Compton camera prototype for prompt gamma medical imaging

Compton camera prototype for a position-sensitive detection of prompt γ rays from proton-induced nuclear reactions is being developed in Garching. The detector system allows to track the Comptonscattered electrons. The camera consists of a monolithic LaBr3:Ce scintillation absorber crystal, read out by a multi-anode PMT, preceded by a stacked array of 6 double-sided silicon strip detectors acting as scatterers. The LaBr3:Ce crystal has been characterized with radioactive sources. Online commissioning measurements were performed with a pulsed deuteron beam at the Garching Tandem accelerator and with a clinical proton beam at the OncoRay facility in Dresden. The determination of the interaction point of the photons in the monolithic crystal was investigated

The attitudes of physicians toward guideline recommendations for the management of dyslipidemia in clinical practice - The VIPFARMA ISCP Project

Guideline recommendations for the management of dyslipidemia, based on current trial evidence and/or expert consensus, aim at improving atherosclerotic cardiovascular disease progression and clinical outcomes. The degree to which physicians accept and implement these recommendations, however, varies markedly depending on a number of factors. To explore the different attitudes of physicians regarding international recommendations for the management of dyslipidaemia in routine medical practice, the International Society of Cardiovascular Pharmacotherapy carried out a survey among physicians taking part in the Surveillance of Prescription Drugs in the Real World Project (VIPFARMA - ISCP Project). Methods. Seven clusters of questions were designed to characterize demographics, institutional profile, medical education, clinical practice profile, knowledge and attitudes regarding the use of statins, PCSK9 inhibitors, and triglyceride lowering agents. Results. The survey was completed by 898 Argentine physicians, of whom 68.3% were cardiologists and 40.0% had specialties related to cardiovascular prevention. Contrary to the recommendations of the Guidelines, 29.6% of physicians supported LDL goals above 70 mg/dl in secondary prevention. Acceptance of values lower than 70 mg/dl was associated with greater levels of continuing education (OR 0.64, 95% CI 0.45-0.91; p=0.014), specialization in preventive cardiology (OR 0.49, 95% CI 0.28-0.88; p=0.017) or diabetology (OR 0.48, 95% CI 0.24-0.98; p=0.043). A less aggressive attitude toward the achievement of guideline goals, such as rejection of the use of statins in diabetics (OR 2.83, 95% CI 1.30-6.18; p=0.009), reduction in statin dose (OR 2.87, 95% CI 2.02-4.10; p=<0.001) or discontinuation when LDL values less than 35 mg/dl are reached (OR 4.32, 95% CI 1.81-10.29; p=0.001) were observed in physicians who considered LDL values higher than 70 mg/dl as the goal in secondary prevention. Conclusions. One third of physicians in the survey do not follow goals recommended by international guidelines for secondary prevention. Lower levels of continuing medical education and incomplete knowledge of the recommended treatment goals appear to be important reasons for not implementing guideline recommendations in clinical practice