A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

Surgical Myocardial Revascularization with a Composite T-graft from the Left Internal Mammary Artery-Comparison of the Great Saphenous Vein with the Radial Artery.

BACKGROUND: Composite T-grafts between left internal mammary artery (LIMA) and radial artery (RA) are a common concept in complete arterial myocardial revascularization. The aim of the present study was to investigate whether the use of the great saphenous vein (SV) instead of RA leads to comparably good results in terms of outcome in this context. METHODS: Patients who underwent myocardial revascularization with a T-graft using RA or a segment of SV to the right coronary artery or circumflex artery between the beginning of 2014 and the end of 2019 at the Department of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Campus Kiel were included. To minimize surgical variation, only patients were observed by a single senior surgeon in the department. Exclusion criteria were previous cardiac surgery, preoperative extracorporeal circulatory support, off-pump surgery, additional aortocoronary bypasses, and cardiac combination procedures. RESULTS: A total of 115 patients were studied. In 55 patients, the T-graft was placed between the LIMA and SV, and in 60 patients, the T-graft was placed between the LIMA and RA. Patients in the SV group were older (70.6 ± 7.8 vs. 58.5 ± 10.0 years; p < 0.001), suffered more frequently from non-ST elevation myocardial infarction (12.7 vs. 1.7%; p = 0.027), arterial hypertension (83.6 vs. 61.7%; p = 0.009), and atrial fibrillation (18.2 vs. 1.7%; p = 0.003). They were less likely to be active smokers (16.4 vs. 38.3%; p = 0.009) and less likely to have a history of variceal surgery (0 vs. 15.0%; p = 0.003). Calcification of the ascending aorta was also found more frequently in the saphenous group (18.2 vs. 3.3%, p = 0.009). Operative times and number of distal anastomoses did not differ significantly between the two groups. Postoperative deliriums (16.7 vs. 5.0%; p = 0.043) were observed more frequently in venous patients. Wound healing disorders of the leg (11.1 vs. 0%; p = 0.011) did only occur in SV group and wound infections of the arm only in the RA group. Complete follow-up was achieved in 74.8% of cases. Median follow-up was 60.3 (39.6; 73.2) months. Serious adverse cardiac-cerebral events (19.0 vs. 22.7%; p = 0.675) and mortality (14.5 vs. 6.7%; p = 0.167) did not differ significantly between the groups at follow-up. Myocardial infarction (0 vs. 2.5%; p = 1.000) and stroke (0 vs. 7.5%; p = 0.245) were observed exclusively in RA group. Percutaneous coronary intervention was required in single patients of RA group (0 vs. 15.0%; p = 0.028). No patient from either group underwent repeat coronary artery bypass grafting (CABG). The patients of SV group had angiographically competent grafts and open anastomoses. Graft failure was noted in a single patient in RA group, in which case both grafts and native coronary vessels were stented. Kaplan-Meier analysis revealed no significant survival disadvantage for SV group compared with RA group. CONCLUSION: CABG with a composite T-graft between LIMA and a segment of SV may be comparable to bypass surgery with a composite T-graft between LIMA and RA. This might be true in terms of morbidity and mortality over an intermediate-term observation period. The results of our studies give rise to the hypothesis that the decision not to perform aortic bypass anastomosis may be more important than the choice of graft material.

SELNET clinical practice guidelines for bone sarcoma.

Bone sarcoma are infrequent diseases, representing < 0.2% of all adult neoplasms. A multidisciplinary management within reference centers for sarcoma, with discussion of the diagnostic and therapeutic strategies within an expert multidisciplinary tumour board, is essential for these patients, given its heterogeneity and low frequency. This approach leads to an improvement in patient's outcome, as demonstrated in several studies. The Sarcoma European Latin-American Network (SELNET), aims to improve clinical outcome in sarcoma care, with a special focus in Latin-American countries. These Clinical Practice Guidelines (CPG) have been developed and agreed by a multidisciplinary expert group (including medical and radiation oncologist, surgical oncologist, orthopaedic surgeons, radiologist, pathologist, molecular biologist and representatives of patients advocacy groups) of the SELNET consortium, and are conceived to provide the standard approach to diagnosis, treatment and follow-up of bone sarcoma patients in the Latin-American context.

Evaluation of a proficiency test of 131I, 134Cs and 137Cs in maize powder.

In 2017, JRC-Geel organised a proficiency test for 120 participants on the massic activity determination of 131I, 134Cs and 137Cs in maize powder. The proficiency test reference material was produced by spiking blank maize powder. The material was characterised for its radioactive content using γ-ray spectrometry. The z scores of the reported massic activity were acceptable in 92% of the results for 131I, and in 94% for both 134Cs and 137Cs. The ζ scores were consistent with the reference value for 66% of the results for 131I, 56% for 134Cs and 68% for 137Cs.

Measurement of absolute γ-ray emission probabilities in the decay of 227Ac in equilibrium with its progeny.

The emission probabilities of γ rays produced in the 227Ac decay series were determined by high-resolution γ-ray spectrometry of sources with standardised activity. The sources were prepared quantitatively on glass discs by drop deposition of a solution with 227Ac in radioactive equilibrium with its daughter nuclides. Their activity was measured by a primary standardisation technique based on alpha-particle counting at a defined low solid angle. Four laboratories performed γ-ray spectrometry and derived absolute γ-ray intensities. Mean values were calculated and compared with literature data and the currently recommended evaluated data. New values on certain γ-ray emission probabilities are proposed.

A gamma-ray spectrometry analysis software environment.

At the JRC-Geel's RadioNuclide Metrology sector, a Monte Carlo code based on EGSnrc, and a general purpose calculation sheet implemented in Microsoft Excel®, have been developed to make the quantitative gamma-ray spectrometry analysis of samples simpler and more robust. The further aim is that the software can be used by non-experts in gamma-ray spectrometry e.g. external researchers using JRC-Geel's facilities through the EUFRAT transnational access scheme. This paper presents the developed Monte Carlo software and the functionality included in the calculation sheet.

Measurement of absolute γ-ray emission probabilities in the decay of 235U.

Accurate measurements were performed of the photon emission probabilities following the α decay of 235U to 231Th. Sources of highly enriched 235U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities. Four laboratories participated in this work and reported emission probabilities for 33 γ-ray lines. Most of them agree with previously published evaluated data. In addition, new values are proposed for γ-lines which have been measured only once in the past.

The BiPo-3 detector.

The BiPo-3 detector is a low radioactive detector dedicated to measuring ultra-low natural contaminations of 208Tl and 214Bi in thin materials, initially developed to measure the radiopurity of the double ß decay source foils of the SuperNEMO experiment at the µBq/kg level. The BiPo-3 technique consists in installing the foil of interest between two thin ultra-radiopure scintillators coupled to low radioactive photomultipliers. The design and performances of the detector are presented. In this paper, the final results of the 208Tl and 214Bi activity measurements of the first enriched 82Se foils are reported for the first time, showing the capability of the detector to reach sensitivities in the range of some µBq/kg.

Reference materials produced for a European metrological research project focussing on measurements of NORM.

Reliable measurement of Naturally Occurring Radioactive Materials is of significance in order to comply with environmental regulations and for radiological protection purposes. This paper discusses the standardisation of three reference materials, namely sand, tuff and TiO2 to serve as quality control materials for traceability, method validation and instrument calibration. The sample preparation, material characterization via γ, α and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the assignment of values for both the 4n (Thorium) and 4n+2 (Uranium) decay series are described.

A low-energy set-up for gamma-ray spectrometry of NORM tailored to the needs of a secondary smelting facility.

A measurement station dedicated for quantitative radiological characterisation of naturally occurring radionuclides in a metallurgical company and based on gamma-ray spectrometry was developed. The station is intended for performing quality control of final non-ferrous metal products and for radiological checks of incoming materials. A low-background point-contact HPGe-detector was used and the signal was split in two branches to enable collecting simultaneously spectra with high amplification (for gamma-ray energies below 250keV) and low amplification.

Search for Neutrinoless Quadruple-ß Decay of

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-ß decay of ^{150}Nd using a total exposure of 0.19 kg yr recorded with the NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T_{1/2}>(1.1-3.2)×10^{21} yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons.

Microstructured Nickel-Titanium Thin Film Leaflets for Hybrid Tissue Engineered Heart Valves Fabricated by Magnetron Sputter Deposition.

Heart valves are constantly exposed to high dynamic loading and are prone to degeneration. Therefore, it is a challenge to develop a durable heart valve substitute. A promising approach in heart valve engineering is the development of hybrid scaffolds which are composed of a mechanically strong inorganic mesh enclosed by valvular tissue. In order to engineer an efficient, durable and very thin heart valve for transcatheter implantations, we developed a fabrication process for microstructured heart valve leaflets made from a nickel-titanium (NiTi) thin film shape memory alloy. To examine the capability of microstructured NiTi thin film as a matrix scaffold for tissue engineered hybrid heart valves, leaflets were successfully seeded with smooth muscle cells (SMCs). In vitro pulsatile hydrodynamic testing of the NiTi thin film valve leaflets demonstrated that the SMC layer significantly improved the diastolic sufficiency of the microstructured leaflets, without affecting the systolic efficiency. Compared to an established porcine reference valve model, magnetron sputtered NiTi thin film material demonstrated its suitability for hybrid tissue engineered heart valves.

Tracing radioactivity from Fukushima in the Northern Pacific Ocean.

Following the accident at the Fukushima Daiichi nuclear power plant, a campaign of sampling and measuring anthropogenic radionuclides in North Pacific seawater was set up. The main aim was to study natural processes using these radionuclides as tracers. Because of dilution, the activities of anthropogenic radionuclides at long range were very low and their measurement required advanced pre-concentration techniques and underground gamma-ray spectrometry. Data and metrological aspects of the measurements using HPGe-detectors are presented and discussed.

Cell adhesion on NiTi thin film sputter-deposited meshes.

Scaffolds for tissue engineering enable the possibility to fabricate and form biomedical implants in vitro, which fulfill special functionality in vivo. In this study, free-standing Nickel­Titanium(NiTi) thin film mesheswere produced by means of magnetron sputter deposition.Meshes contained precisely defined rhombic holes in the size of 440 to 1309 µm2 and a strut width ranging from 5.3 to 9.2 µm. The effective mechanical properties of the microstructured superelastic NiTi thin film were examined by tensile testing. These results will be adapted for the design of the holes in the film. The influence of hole and strut dimensions on the adhesion of sheep autologous cells (CD133+) was studied after 24 h and after seven days of incubation. Optical analysis using fluorescence microscopy and scanning electron microscopy showed that cell adhesion depends on the structural parameters of the mesh. After 7 days in cell culture a large part of the mesh was covered with aligned fibrous material. Cell adhesion is particularly facilitated on meshes with small rhombic holes of 440 µm2 and a strut width of 5.3 µm. Our results demonstrate that free-standing NiTi thin film meshes have a promising potential for applicationsin cardiovascular tissue engineering, particularly for the fabrication of heart valves.

Equivalence of computer codes for calculation of coincidence summing correction factors - Part II.

The aim of this study was to check for equivalence of computer codes that are capable of performing calculations of true coincidence summing (TCS) correction factors. All calculations were performed for a set of well-defined detector parameters, sample parameters and decay scheme data. The studied geometry was a point source of (133)Ba positioned directly on the detector window of a low-energy (n-type) detector. Good agreement was established between the TCS correction factors computed by the different codes.

[Interventional mitral valve replacement. Current status]. / Interventioneller Ersatz der Mitralklappe. Aktueller Stand.

Approximately 30 % of patients suffering from severe valvular heart disease, such as mitral valve regurgitation are non-compliant to the gold standard of minimally invasive surgery, reconstruction or valve replacement. The number of these mostly old patients with severe comorbidities is increasing; therefore, transcatheter interventions have been developed to address an unmet clinical need and may be an alternative therapeutic option to the reference standard. Apart from the successful MitraClip therapy, alternative transcatheter reconstruction technologies are being developed. As with transcatheter aortic valve implantation (TAVI) procedures, the off-pump implantation of a valved stent into the mitral position mainly via a transapical approach will be of great benefit. Recently, the feasibility of transcatheter mitral valved stent implantation in high-risk patients has already been reported.

In vivo quantification of the apical fixation forces of different mitral valved stent designs in the beating heart.

The aim of this study was the quantification of the apical fixation forces of mitral valved stents for the first time. A test set-up was developed to measure the forces acting on the apical fixation of mitral valved stents. Twenty pigs received a self-expanding valved stent in the mitral position via a transapical approach in an off-pump procedure. Following stent deployment in the beating heart, the apical fixation forces were recorded following a standardized protocol and normalized. The apical fixation force of two different valved stent designs (AP: sole apical fixation, n = 10; SA: additional sub-annular fixation, n = 10) was compared to quantify the impact of the design change. Force measurement was successfully conducted in 18 of 20 animals (design AP: n = 10; design SA: n = 8). Evaluation showed higher mean forces and amplitude in the group with sole apical fixation (p = 0.046; Table 1). The impact of the additional sub-annular fixation was shown by a significant reduction of the force acting upon the apex of the heart. Quantification of these in vivo forces provides important information about the impact of different stent designs and might provide an objective parameter for stent performance evaluation in clinical application.