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The study aimed to implement realistic source models of a computed tomography (CT) scanner and Monte Carlo simulations to actual patient data and to calculate patient-specific organ and effective dose estimates for patients undergoing dynamic CT myocardial perfusion examinations. Source models including bowtie filter, tube output and x-ray spectra were determined for a dual-source Siemens Somatom Definition Flash scanner. Twenty CT angiography patient datasets were merged with a scaled International Commission on Radiological Protection (ICRP) 110 voxel phantom. Dose simulations were conducted with ImpactMC software. Effective dose estimates varied from 5.0 to 14.6 mSv for the 80 kV spectrum and from 8.9 to 24.7 mSv for the 100 kV spectrum. Significant differences in organ doses and effective doses between patients emphasise the need to use actual patient data merged with matched anthropomorphic anatomy in the dose simulations to achieve a reasonable level of accuracy in the dose estimation procedure. [ABSTRACT FROM AUTHOR]

The eye lens exposure among 16 technicians in two nuclear medicine departments at university hospitals in Finland was investigated by measuring the operational quantity Hp(3) using EYE-D dosemeters. For all workers, the annual mean Hp(3) was estimated to be 1.1 mSv (max. 3.9 mSv). The relation between Hp(3) to routinely monitored personal dose equivalent Hp(10) was clearly correlated. Considering individual dose measurement periods (2–4 weeks), the Hp(3)/Hp(10) ratio was 0.7 (Pearson's coefficient r  = 0.90, p  < 0.001, variation of ratio 0.1–2.3). The variation decreased considerably with increasing Hp(10) (σ 2 = 0.04 vs. 0.43 for Hp(10) > 0.1 mSv vs. < 0.1 mSv, respectively), i.e. higher Hp(10) predicts Hp(3) more reliably. Moreover, annual Hp(10) data from national dose register during 2009–2018 were used to derive the annual Hp(3) applying the Hp(3)/Hp(10) ratio. The data from Finnish nuclear medicine departments imply that routine measurements of Hp(3) among nuclear medicine technicians are not justified. [ABSTRACT FROM AUTHOR]

A pencil-type ionization chamber commonly used in computed tomography (CT) dosimetry is usually calibrated free in air, but used inside a PMMA CT phantom. Measurements and Monte Carlo simulations are used to investigate the validity of chamber calibration in this situation where the body phantom modifies the x-ray spectrum impinging on the chamber. The results for the PTW 30009 chamber indicate that the additional uncertainty in CT dose index (CTDIw) measurement introduced by the phantom is ~1% or less. The pencil chamber used in CTDIw measurements should have a flat energy response down to at least 30 keV photon energy to avoid excessive increase in measurement uncertainty. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the optimal use of XR-RV3 GafChromic® films to assess patient skin dose in interventional radiology while addressing the means to reduce uncertainties in dose assessment. Methods: XR-Type R GafChromic films have been shown to represent the most efficient and suitable solution to determine patient skin dose in interventional procedures. As film dosimetry can be associated with high uncertainty, this paper presents the EURADOS WG 12 initiative to carry out a comprehensive study of film characteristics with a multisite approach. The considered sources of uncertainties include scanner, film, and fitting-related errors. The work focused on studying film behavior with clinical high-dose-rate pulsed beams (previously unavailable in the literature) together with reference standard laboratory beams. Results: First, the performance analysis of six different scanner models has shown that scan uniformity perpendicular to the lamp motion axis and that long term stability are the main sources of scanner-related uncertainties. These could induce errors of up to 7% on the film readings unless regularly checked and corrected. Typically, scan uniformity correction matrices and reading normalization to the scanner-specific and daily background reading should be done. In addition, the analysis on multiple film batches has shown that XR-RV3 films have generally good uniformity within one batch (<1.5%), require 24 h to stabilize after the irradiation and their response is roughly independent of dose rate (<5%). However, XR-RV3 films showed large variations (up to 15%) with radiation quality both in standard laboratory and in clinical conditions. As such, and prior to conducting patient skin dose measurements, it is mandatory to choose the appropriate calibration beam quality depending on the characteristics of the x-ray systems that will be used clinically. In addition, yellow side film irradiations should be preferentially used since they showed a lower dependence on beam parameters compared to white side film irradiations. Finally, among the six different fit equations tested in this work, typically used third order polynomials and more rational and simplistic equations, of the form dose inversely proportional to pixel value, were both found to provide satisfactory results. Fitting-related uncertainty was clearly identified as a major contributor to the overall film dosimetry uncertainty with up to 40% error on the dose estimate. Conclusions: The overall uncertainty associated with the use of XR-RV3 films to determine skin dose in the interventional environment can realistically be estimated to be around 20% (k = 1). This uncertainty can be reduced to within 5% if carefully monitoring scanner, film, and fitting-related errors or it can easily increase to over 40% if minimal care is not taken. This work demonstrates the importance of appropriate calibration, reading, fitting, and other film-related and scan-related processes, which will help improve the accuracy of skin dose measurements in interventional procedures. [ABSTRACT FROM AUTHOR]

To help operators acknowledge patient dose during interventional procedures, EURADOSWG-12 focused on measuring patient skin dose using XR-RV3 gafchromic films, thermoluminescent detector (TLD) pellets or 2D TL foils and on investigating possible correlation to the on-line dose indicators such as fluoroscopy time, Kerma-area product (KAP) and cumulative air Kerma at reference point (CK). The study aims at defining non-centre-specific European alert thresholds for skin dose in three interventional procedures: chemoembolization of the liver (CE), neuroembolization (NE) and percutaneous coronary interventions (PCI). Skin dose values of >3 Gy (ICRP threshold for skin injuries) were indeed measured in these procedures confirming the need for dose indicators that correlate with maximum skin dose (MSD). However, although MSD showed fairly good correlation with KAP and CK, several limitations were identified challenging the set-up of non-centre-specific European alert thresholds. This paper presents preliminary results of this wide European measurement campaign and focuses on the main challenges in the definition of European alert thresholds. [ABSTRACT FROM AUTHOR]

A Peltier-cooled silicon drift detector was successfully applied for conversion electron spectrometry. The energy resolution of the detector for 45 keV electrons was 0.50 keV (FWHM). The approximate thickness of the dead layer was determined to be 140 ± 20 nm Si equivalent. The relative efficiency of the detector was verified to be approximately constant in the energy range of 17-75 keV. This is concordant with the high transparency of the thin dead layer and the sufficient thickness of the detector (450 μm) to stop the electrons. The detector is suitable for use in plutonium analysis of chemically prepared samples. Moreover, it was demonstrated that conversion electron spectrometry is better than alpha spectrometry in preserving its capability to determine the Pu/Pu isotopic ratio as a function of sample thickness. The investigated measurement technique can be considered a promising new tool in safeguards, complementary to existing methods. [ABSTRACT FROM AUTHOR]

The current system of dose quantities in radiological protection is based, in addition to the absorbed dose, on the concepts of equivalent dose and effective dose. This system has been developed mainly with uniform whole-body exposures in mind. Conceptual and practical problems arise when the system is applied to more general exposure situations where the radiation quality is altered within the human body. In this article these problems are discussed, using proton beam radiotherapy as a specific example, and a proposition is made that dose equivalent quantities should be used instead of equivalent doses when organ doses are of interest. The calculations of out-of-field organ doses in proton therapy show that the International Commission on Radiological Protection-prescribed use of the proton weighting factor generally leads to an underestimation of the stochastic risks, while the use of neutron weighting factors in the way as practised in the literature leads to a significant overestimation of these risks. [ABSTRACT FROM PUBLISHER]

Linssi is a Structured Query Language (SQL) database for HPGe gamma-ray spectrometry. It covers the whole production chain from sample preparation to final analysis results. Static or mobile sampling and measurement and multiple sample types are supported. In addition, each sample can be split or combined any number of times. A sample may be measured multiple times and each measurement multiply analyzed as well. With Linssi, measurement setups with detectors, shields, attenuators and source geometries can be defined. Full control of calibrations, their histories and tracing of each calibration point back to its corresponding analysis and calibration measurement is supported. Linssi database and user scripts are available from . [ABSTRACT FROM AUTHOR]

The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra. [ABSTRACT FROM AUTHOR]

Conversion coefficients from fluence to ambient dose equivalent, from fluence to maximum dose equivalent and quality factors for slow negative muons are examined in detail. Negative muons, when stopped, produce energetic photons, electrons and a variety of high-LET particles. Contribution from each particle type to the dose equivalent is calculated. The results show that for the high-LET particles the details of energy spectra and decay yields are important for accurate dose estimates. For slow negative muons the ambient dose equivalent does not always yield a conservative estimate for the protection quantities. Especially, the skin equivalent dose is strongly underestimated if the radiation-weighting factor of unity for slow muons is used. Comparisons to earlier studies are presented. [ABSTRACT FROM AUTHOR]

Linux System for Spectral Information (LINSSI1) is a SQL database and established under Linux. Currently it is compatible with HPGe gammaspectra analysis software UniSampo, Shaman and Aatami. Based on this database and software, an automated analysis pipeline has been setup for Canadian CTBT radiological monitoring networks. This paper has investigated the performance of this pipeline in its capabilities and reliabilities of rapid small peak search, nuclide identification, and radionuclide activity concentration evaluation. Up to now, more than 80 thousand daily monitoring gamma-spectra have been automatically received and processed, the results have been stored in database. The pipeline nuclide detection limits is satisfied for environmental radiation monitoring and nuclear emergency preparedness. [ABSTRACT FROM AUTHOR]

The transition matrix elements for coherent and incoherent channels of the neutrinoless μ− ν e− conversion are investigated. The results refer to the 27Al nucleus which has recently been chosen as a target in the MECO experiment at Brookhaven aiming to search for μ-e conversion events with a sensitivity 10-17. These results are compared to those obtained previously for 48Ti and 208Pb targets. We focus on the contributions to the branching ratio ℛμe− originating from scalar, vector and axial vector interactions resulting in conventional extentions of the standard model and minimal supersymmetric models with and without ℛ-parity violation. With our calculations we extract very severe constraints for the flavor violation parameters. [ABSTRACT FROM AUTHOR]

The β-decay of the Tz = - 2 nucleus 36Ca was studied at the LISE3 magnetic spectrometer at GANIL. Two new proton-emitting states have been detected and the other nine known βp and βγ transitions have been remeasured with improved resolution. A simulation with the GEANT code has been applied to this experimental setup. A comparison with shell model calculations is given. [ABSTRACT FROM AUTHOR]

Recently many shell-model calculations have been performed in order to extract the value of the ratio C[sup P]/C[sup A] in light nuclei. Most of these calculations fail to reproduce the value given by the partially conserved axial vector hypothesis, roughly 7. We show that, with the effective transition operators, calculated by the perturbative techniques, this discrepancy can be, at least partly, solved. New angular correlation data for [sup 28]Si are used for the extraction of C[sup P]/C[sup A]. In the case of [sup 20]Ne, the capture rate data are used for the extraction. [ABSTRACT FROM AUTHOR]

Recently many shell-model calculations have been performed in order to extract the value of the ratio CP/ CA in light nuclei. Most of these calculations fail to reproduce the value given by the partially conserved axial vector hypothesis, roughly 7. We show, that by using the effective transition operators, calculated by the perturbative techniques, this discrepancy can be, at least partly, solved. New angular correlation data for 28Si is used for the extraction of CP/ CA. In the case of 20Ne, the capture rate data is used for extraction. [ABSTRACT FROM AUTHOR]

Beta-decays ofAl andTi have been studied by applying ion guide techniques, gamma detection and a gas-Si telescope for charged-particle detection. The experimental beta-decay strength ofTi was found to be quenched by a factor of q = 0.64 compared to our shell model calculations below 8 MeV excitation energy inSc. This result is in line with the generally accepted value of q = 0.77. The isobaric analogue state of theTi ground state was measured to contain 10(8)% isospin impurity. This relatively high value could be well reproduced by the shell model calculation in the sdfp space. Gamma-decay of the T = 3/2 isobaric analogue state inMg was observed together with its decay by proton emission. The resonance strength from the ground state ofNa to the isobaric analogue state inMg was determined as 5.4(17) meV. The experimental proton width, 13(4) meV, agrees with the calculated value of 21 meV. [ABSTRACT FROM AUTHOR]

In interventional radiology, occupational radiation doses can be high. Therefore, many authors have established conversion coefficients from the dose-area product data or from the personal dosemeter reading to the effective dose of the radiologist. These conversion coefficients are studied also in this work, with an emphasis on sensitivity of the results to changes in exposure conditions. Comparison to earlier works indicates that, for the exposure conditions examined in this work, all previous models discussed in this work overestimate the effective dose of the radiologist when a lead apron and a thyroid shield are used. Without the thyroid shield, underestimation may occur with some models. [ABSTRACT FROM AUTHOR]