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.
•A Monte Carlo code has been developed and validated using EGSnrc.•A radionuclide decay generator has been written and validated.•Detection efficiency can be calculated for High Purity Germanium detector.•A flexible and user friendly analysis software using MS Excel® has been developed.•Functionalities and performances of the software are presented.
Abstract
A search for double-beta decay of
$$^{190}$$
190
Pt and
$$^{198}$$
198
Pt with emission of
$$\gamma $$
γ
-ray quanta was realized at the HADES underground laboratory with a 148 g platinum ...sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of
$$^{190}$$
190
Pt relative to different channels and modes of the decays were set on the level of
$$\lim T_{1/2}\sim 10^{14}$$
lim
T
1
/
2
∼
10
14
–
$$10^{16}$$
10
16
year. A possible exact resonant
$$0\nu KN$$
0
ν
K
N
transition to the 1,2 1326.9 keV level of
$$^{190}$$
190
Os is limited for the first time as
$$T_{1/2} \ge 2.5 \times 10^{16}$$
T
1
/
2
≥
2.5
×
10
16
year. A new lower limit on the double-beta decay of
$$^{198}$$
198
Pt to the first excited level of
$$^{198}$$
198
Hg was set as
$$T_{1/2} \ge 3.2\times 10^{19}$$
T
1
/
2
≥
3.2
×
10
19
year, one order of magnitude higher than the limit obtained in the previous experiment.
•Transcatheter aortic valve replacement (TAVR) reduces mitral regurgitation (MR) mostly (63.5 %) in patients with prior higher-grade MR (MR grade > 2).•Reduction in MR occurs concomitantly with ...reduction in cardiac and echocardiographic markers (NT-proBNP and systolic pulmonary artery pressure). Whereas there is no improvement in those factors in patients with worsening or unchanged MR status after TAVR.•There is no difference in survival for patients with relevant (r-MR) or clinically non relevant MR (nr-MR) at baseline.•There is no difference in survival for patients which underwent TAVR and whose MR status improved.
To investigate the change in severity of mitral regurgitation (MR) after transcatheter aortic valve replacement (TAVR) and its effect on 5-year mortality.
There is inconsistency in literature on pre-existing MR influencing long-term survival in patients who undergo TAVR.
Patients who underwent TAVR at the University Hospital Schleswig-Holstein (USKH) Campus Kiel between March 2009 and February 2018 have been enrolled. Echocardiography determined the degree of MR before and within 7 days after TAVR. Patients were divided into two groups according to their MR at baseline: MR-grade ≤ 2 (non-relevant MR, nr-MR) and baseline MR-grade > 2 (relevant MR, r-MR). Primary endpoint was a composite of MR baseline influence on mortality and MR reduction and its’ impact on mortality.
A total of 820 patients (642 nr-MR and 178 in r-MR) were included in this study. Of these, 167 patients showed an improvement in MR-grade. Thereof 106 (63.5 %) referred to r-MR with a significant decrease in mean MR-grade (p < 0.01). Systolic pulmonary artery pressure (sPAP) (p < 0.01) and NT-proBNP (p = 0.03) decreased in patients who had an improvement. There was no significant difference in 5-year mortality for MR at baseline (p = 0.35) or reduction in mortality for r-MR patients with an MR improvement compared to patients with worsening or equal MR status (p = 0.80).
In patients undergoing TAVR, 63.5 % of patients with MR-grade ≥ 2 at baseline showed an improvement of grade of MR after TAVR with reduction of their sPAP and NT-proBNP values but there was no significant difference in mortality.
A search for double-beta decay of
190
Pt and
198
Pt with emission of
γ
-ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background ...HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of
190
Pt relative to different channels and modes of the decays were set on the level of
lim
T
1
/
2
∼
10
14
–
10
16
year. A possible exact resonant
0
ν
K
N
transition to the 1,2 1326.9 keV level of
190
Os is limited for the first time as
T
1
/
2
≥
2.5
×
10
16
year. A new lower limit on the double-beta decay of
198
Pt to the first excited level of
198
Hg was set as
T
1
/
2
≥
3.2
×
10
19
year, one order of magnitude higher than the limit obtained in the previous experiment.
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.
•Proficiency test reference material prepared by spiking.•120 European laboratories participated in the PT.•More than 90% of satisfactory results according to z score evaluation.•Improvement of uncertainty estimation needed in around one third of submitted results.
The first ever search for
α
decays to the first excited state in Yb was performed for six isotopes of hafnium (174, 176, 177, 178, 179, 180) using a high purity Hf sample of natural isotopic ...abundance with a mass of 179.8 g. For
179
Hf, also
α
decay to the ground state of
175
Yb was searched for thanks to the
β
-instability of the daughter nuclide
175
Yb. The measurements were conducted using an ultra-low-background HPGe-detector system located 225 m underground. After 75 days of data taking no decays were detected but lower bounds for the half-lives of the decays were derived on the level of
lim
T
1
/
2
∼
10
15
-
10
18
a. The decay with the shortest half-life based on theoretical calculation is the decay of
174
Hf to the first
2
+
84.3 keV excited level of
170
Yb. The experimental lower bound was found to be
T
1
/
2
≥
3.3
×
10
15
a.
The dead-layer uniformity of the top surface of two high purity germanium detectors has been studied using a novel automated scanning set-up that allows a fine-grained topography of a detector's top ...and lateral surfaces. Comparisons between measurements and Monte Carlo simulations allowed implementation of a dead-layer variation into the detector model, which reproduces the measurements results. The effect of the non-uniform dead-layer on activity determinations based on low-energy γ-rays (i.e. below ~100keV) has been determined to be of the order of 10% or more.
•We performed a top dead-layer topography of two HPGe detectors.•We identified a non-uniform dead-layer thickness along the surface of one of them.•We built a Monte Carlo model able to reproduce the measurements results.•We estimated an effect on the activity calculation for low energy γ-ray emitters of ~50%.
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.
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.
Zusammenfassung
Die schweren Mitralklappeninsuffizienzen nehmen zu und können bei 30 % der meist älteren Patienten mit schwersten Nebenerkrankungen nicht mit dem Goldstandard der minimal-invasiven ...Operation, einer Rekonstruktion oder einem Klappenersatz versorgt werden. Aufgrund dieser Tatsache werden Transkathetertechniken entwickelt, die als Alternative zum chirurgischen Standard diese klinische Versorgung sicherstellen. Ziel ist es dabei, die Mitralinsuffizienz aufzuheben. Neben der erfolgreichen MitraClip-Therapie werden alternative Transkatheterrekonstruktionstechnologien entwickelt. Wie bei den TAVI-Prozeduren werden darüber hinaus auch Klappenstents für die Mitralposition entwickelt, die hauptsächlich transapikal und „off-pump“ auch schon am Patienten eingesetzt werden.
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