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Abstract Background The incorporation of magnetic resonance (MR) imaging in radiotherapy (RT) workflows improves contouring precision, yet it introduces geometrical uncertainties when registered with computed tomography (CT) scans. Synthetic CT (sCT) images could minimize these uncertainties and streamline the RT workflow. This study aims to compare the contouring capabilities of sCT images with conventional CT-based/MR-assisted RT workflows, with an emphasis on managing artefacts caused by surgical fixation devices (SFDs). Methods The study comprised a commissioning cohort of 100 patients with cranial tumors treated using a conventional CT-based/MR-assisted RT workflow and a validation cohort of 30 patients with grade IV glioblastomas treated using an MR-only workflow. A CE-marked artificial-intelligence-based sCT product was utilized. The delineation accuracy comparison was performed using dice similarity coefficient (DSC) and average Hausdorff distance (AHD). Artefacts within the commissioning cohort were visually inspected, classified and an estimation of thickness was derived using Hausdorff distance (HD). For the validation cohort, boolean operators were used to extract artefact volumes adjacent to the target and contrasted to the planning treatment volume. Results The combination of high DSC (0.94) and low AHD (0.04 mm) indicates equal target delineation capacity between sCT images and conventional CT scans. However, the results for organs at risk delineation were less consistent, likely because of voxel size differences between sCT images and CT scans and absence of standardized delineation routines. Artefacts observed in sCT images appeared as enhancements of cranial bone. When close to the target, they could affect its definition. Therefore, in the validation cohort the clinical target volume (CTV) was expanded towards the bone by 3.5 mm, as estimated by HD analysis. Subsequent analysis on cone-beam CT scans showed that the CTV adjustment was enough to provide acceptable target coverage. Conclusion The tested sCT product performed on par with conventional CT in terms of contouring capability. Additionally, this study provides both the first comprehensive classification of metal artefacts on a sCT product and a novel method to assess the clinical impact of artefacts caused by SFDs on target delineation. This methodology encourages similar analysis for other sCT products.

Background: The incorporation of magnetic resonance (MR) imaging in radiotherapy (RT) workflows improves contouring precision, yet it introduces geometrical uncertainties when registered with computed tomography (CT) scans. Synthetic CT (sCT) images could minimize these uncertainties and streamline the RT workflow. This study aims to compare the contouring capabilities of sCT images with conventional CT-based/MR-assisted RT workflows, with an emphasis on managing artefacts caused by surgical fixation devices (SFDs). Methods: The study comprised a commissioning cohort of 100 patients with cranial tumors treated using a conventional CT-based/MR-assisted RT workflow and a validation cohort of 30 patients with grade IV glioblastomas treated using an MR-only workflow. A CE-marked artificial-intelligence-based sCT product was utilized. The delineation accuracy comparison was performed using dice similarity coefficient (DSC) and average Hausdorff distance (AHD). Artefacts within the commissioning cohort were visually inspected, classified and an estimation of thickness was derived using Hausdorff distance (HD). For the validation cohort, boolean operators were used to extract artefact volumes adjacent to the target and contrasted to the planning treatment volume. Results: The combination of high DSC (0.94) and low AHD (0.04 mm) indicates equal target delineation capacity between sCT images and conventional CT scans. However, the results for organs at risk delineation were less consistent, likely because of voxel size differences between sCT images and CT scans and absence of standardized delineation routines. Artefacts observed in sCT images appeared as enhancements of cranial bone. When close to the target, they could affect its definition. Therefore, in the validation cohort the clinical target volume (CTV) was expanded towards the bone by 3.5 mm, as estimated by HD analysis. Subsequent analysis on cone-beam CT scans showed that the CTV adjustment was enough to provide acceptable target coverage. Conclusion: The tested sCT product performed on par with conventional CT in terms of contouring capability. Additionally, this study provides both the first comprehensive classification of metal artefacts on a sCT product and a novel method to assess the clinical impact of artefacts caused by SFDs on target delineation. This methodology encourages similar analysis for other sCT products. [ABSTRACT FROM AUTHOR]

Making metal objects by cold method is known as dovatgeri. Dovatgar artists used to make alchemy with delicate carvings on the bodies of silver and copper vessels and gave them a hundredfold value. Although the history of dovatgri in Shiraz goes back to the early days of this art, there are only a handful of workshops left in this city these days. This research, which is of a basic type and was carried out by a descriptive-analytical method; In addition to the introduction of this indigenous art-industry and its types, its history, formation process and its tools and materials from the perspective of location and use; We are looking to see what is its current position among handicrafts in Shiraz. The method of data collection in this research is in the field, combined with a library and visiting the workshops active in the city of Shiraz, and the preparation of interviews, photos and films of its artists. The findings of the research show that, unfortunately, the indigenous art-industry of davatgari in Shiraz is being forgotten or rather, it is doomed to be forgotten, and the number of davatgari does not exceed the fingers of one hand, and the difficulty...

Teeth detection and tooth segmentation are essential for processing Cone Beam Computed Tomography (CBCT) images. The accuracy decides the credibility of the subsequent applications, such as diagnosis, treatment plans in clinical practice or other research that is dependent on automatic dental identification. The main problems are complex noises and metal artefacts which would affect the accuracy of teeth detection and segmentation with traditional algorithms. In this study, we proposed a teeth-detection method to avoid the problems above and to accelerate the operation speed. In our method, (1) a Convolutional Neural Network (CNN) was employed to classify layer classes; (2) images were chosen to perform Region of Interest (ROI) cropping; (3) in ROI regions, we used a YOLO v3 and multi-level combined teeth detection method to locate each tooth bounding box; (4) we obtained tooth bounding boxes on all layers. We compared our method with a Faster R-CNN method which was commonly used in previous studies. The training and prediction time were shortened by 80% and 62% in our method, respectively. The Object Inclusion Ratio (OIR) metric of our method was 96.27%, while for the Faster R-CNN method, it was 91.40%. When testing images with severe noise or with different missing teeth, our method promises a stable result. In conclusion, our method of teeth detection on dental CBCT is practical and reliable for its high prediction speed and robust detection. [ABSTRACT FROM AUTHOR]

Copyright of Archaeology & Science / Arheologija i Prirodne Nauke is the property of Institute of Archaeology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In contrast to other contemporaneous cultural groups, the Otomani Füzesabony cultural complex (OFCC) is conspicuous, inter alia, due to covering a relatively wide geographical area. Within it can be observed a high variability of source bases, which is conditioned by the differing emergence and adaptation backgrounds, as well as by a varying length of duration across different geographical regions. To make things worse, this diversity of archaeological sources is reflected also in the different use of terminology and in various absolute and relative chronological systems. When dealing with the chronological issues of the OFCC in the territory of Eastern Slovakia the fortified settlement in Spišský Štvrtok, deserves special consideration. Despite the absence of any absolute dates from the site, significantly represented material culture allows one to review its relative chronological framework. In this respect, the morpho typology of selected pottery and metal artefacts, together with their decorative motifs, provide useful information about its relative chronology. A formalised description of jugs, which represent the chronologically most sensitive group of pottery, allows for a partial use of statistical methods as well. As a result, we can obtain a relatively comprehensive view of the initial phase, the length of occupation, and the abandonment period of the fortified settlement. In combination with 14C dates this information might in future contribute to a more exact understanding of the chronological relations within a wider area of East Central Europe.

BackgroundTo determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of (18)F-fluorodeoxyglucose uptake in lesions near metallic prostheses.MethodsA custom hip prosthesis phantom with a lesion-sized cavity filled with 0.2 ml (18)F-FDG solution having an activity of 3.367 MBq adjacent to a prosthesis bore was imaged twice with a chrome-cobalt steel hip prosthesis and a plastic replica, respectively. Scanning was performed on a clinical hybrid PET/CT system equipped with an additional external (137)Cs transmission source. PET emission images were reconstructed from both phantom configurations with CT-based attenuation correction (CTAC) and with CT-based attenuation correction using MAR (MARCTAC). To compare results with the attenuation-correction method extant prior to the advent of PET/CT, we also carried out attenuation correction with (137)Cs transmission-based attenuation correction (TXAC). CTAC and MARCTAC images were scaled to attenuation coefficients at 511 keV using a trilinear function that mapped the highest CT values to the prosthesis alloy attenuation coefficient. Accuracy and spatial distribution of the lesion activity was compared between the three reconstruction schemes.ResultsCompared to the reference activity of 3.37 MBq, the estimated activity quantified from the PET image corrected by TXAC was 3.41 MBq. The activity estimated from PET images corrected by MARCTAC was similar in accuracy at 3.32 MBq. CTAC corrected PET images resulted in nearly 40 % overestimation of lesion activity at 4.70 MBq. Comparison of PET images obtained with the plastic and metal prostheses in place showed that CTAC resulted in a marked distortion of the (18)F-FDG distribution within the lesion, whereas application of MARCTAC and TXAC resulted in lesion distributions similar to those observed with the plastic replica.ConclusionsMAR combined with a trilinear CT number mapping for PET attenuation correction resulted in estimates of lesion activity comparable in accuracy to that obtained with (137)Cs transmission-based attenuation correction, and far superior to estimates made without attenuation correction or with a standard CT attenuation map. The ability to use CT images for attenuation correction is a potentially important development because it obviates the need for a (137)Cs transmission source, which entails extra scan time, logistical complexity and expense.

Teeth detection and tooth segmentation are essential for processing Cone Beam Computed Tomography (CBCT) images. The accuracy decides the credibility of the subsequent applications, such as diagnosis, treatment plans in clinical practice or other research that is dependent on automatic dental identification. The main problems are complex noises and metal artefacts which would affect the accuracy of teeth detection and segmentation with traditional algorithms. In this study, we proposed a teeth-detection method to avoid the problems above and to accelerate the operation speed. In our method, (1) a Convolutional Neural Network (CNN) was employed to classify layer classes; (2) images were chosen to perform Region of Interest (ROI) cropping; (3) in ROI regions, we used a YOLO v3 and multi-level combined teeth detection method to locate each tooth bounding box; (4) we obtained tooth bounding boxes on all layers. We compared our method with a Faster R-CNN method which was commonly used in previous studies. The training and prediction time were shortened by 80% and 62% in our method, respectively. The Object Inclusion Ratio (OIR) metric of our method was 96.27%, while for the Faster R-CNN method, it was 91.40%. When testing images with severe noise or with different missing teeth, our method promises a stable result. In conclusion, our method of teeth detection on dental CBCT is practical and reliable for its high prediction speed and robust detection.

On the one hand, the discovered isolated finds do not enable us to specify the chronological system of a particular type of object, on the other hand, the simple registration of these items can be useful in understanding their original distribution network as well as the settlement structure during a particular period. Publication of basic data is fundamental for further research on the Early Middle Ages in the south of Bohemia. It is not without interest that two of the published items (a strap-end made of brass and a spearhead with a facetted cross-section of the socket) represent likely imports from the Mediterranean and the Frankish Empire. [ABSTRACT FROM AUTHOR]

The Scythian necropolis of Sâncrai (Alba County) was investigated in 2016, which led to the discovery of 95 burials (inhumation and cremation). The study of the tombs revealed a rich funerary inventory, composed mainly of ceramic vessels of different shapes and sizes; weapons such as akinakes daggers, spearheads and arrowheads; ornaments including amber beads, kauri shells, kaolin, earrings, loop rings, saltaleoni type bracelets and clothing appliqués; and harness elements, including horsehair and quiver appliqués. The purpose of this paper is to describe the archaeometric analyses of metal pieces recovered from this site. A combination of non-invasive/micro-destructive analytical techniques (optical microscopy, scanning electron microscopy coupled with energy dispersive spectrometry, and Fourier-transform infrared spectroscopy) and statistical methods (cluster analysis, using SPSS Statistics) was used to obtain comprehensive information about the studied metal artefacts. In this respect, 16 metallic samples were investigated to establish the samples' defects as well as their elemental and molecular composition. Overall, the analytical and statistical analyses show us that the metallic samples can be split into three groups based on composition: iron, copper-tin/bronze and gold-silver. In these groups, samples present a strong correlation, suggesting that they were created using similar minerals. [ABSTRACT FROM AUTHOR]

In the last years, the re-examination of old finds, some casual discoveries and recent excavation works allowed us to update our knowledge on the latest phases of the Neolithic and Eneolithic in Friuli. The increasing data at our disposal do not allow to present an organic picture yet, but it depicts a vast occupation area characterised during the Late Neolithic by a Padan cultural influence, whilst during the Eneolithic significant signs of connections with the transalpine and especially the Balkan worlds have emerged.

odmoky (Příbram District) - a new La Tène Viereckschanze? The article presents the first results of the survey of the hitherto unknown La Tène period site of Podmoky (Příbram District). Metal detector prospecting yielded extraordinary finds of metal artefacts from the period LT B/C - LT D, including coins and militaria. However, the interpretation of this site remains open; it may be an elite settlement, a quadrangular enclosure or a ritual site. A link to the mining of local ores (gold, antimony ores) cannot be ruled out, as increased antimony contents were also noted in some bronze artefacts. [ABSTRACT FROM AUTHOR]

In contrast to other contemporaneous cultural groups, the Otomani-Füzesabony cultural complex (OFCC) is conspicuous, inter alia, due to covering a relatively wide geographical area. Within it can be observed a high variability of source bases, which is conditioned by the differing emergence and adaptation backgrounds, as well as by a varying length of duration across different geographical regions. To make things worse, this diversity of archaeological sources is reflected also in the different use of terminology and in various absolute and relative chronological systems. When dealing with the chronological issues of the OFCC in the territory of Eastern Slovakia the fortified settlement in Spišský Štvrtok, deserves special consideration. Despite the absence of any absolute dates from the site, significantly represented material culture allows one to review its relative chronological framework. In this respect, the morpho-typology of selected pottery and metal artefacts, together with their decorative motifs, provide useful information about its relative chronology. A formalised description of jugs, which represent the chronologically most sensitive group of pottery, allows for a partial use of statistical methods as well. As a result, we can obtain a relatively comprehensive view of the initial phase, the length of occupation, and the abandonment period of the fortified settlement. In combination with 14C dates this information might in future contribute to a more exact understanding of the chronological relations within a wider area of East-Central Europe. [ABSTRACT FROM AUTHOR]

Copyright of Archaeologia Historica is the property of Masaryk University, Faculty of Arts and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• High tube voltage combined with a high VMI reduced metal artefacts. • PCD-CT images was better than or as good as DECT − 0.3 images. • PCD-CT images show promising results for metal artefact reduction. To find the optimal imaging parameters for a photon-counting detector CT (PCD-CT) and to compare it to an energy-integrating detector CT (EID-CT) in terms of image quality and metal artefact severity using a metal-containing bovine knee specimen. A bovine knee with a stainless-steel plate and screws was imaged in a whole-body research PCD-CT at 120 kV and 140 kV and in an EID dual-source CT (DSCT) at Sn150 kV and 80/Sn150 kV. PCD-CT virtual monoenergetic 72 and 150 keV images and EID-CT images processed with and without metal artefact reduction algorithms (iMAR) were compared. Four radiologists rated the visualisation of bony structures and metal artefact severity. The Friedman test and Wilcoxon signed-rank test with Bonferroni's correction were used. P-values of ≤ 0.0001 were considered statistically significant. Distributions of HU values of regions of interest (ROIs) in artefact-affected areas were analysed. PCD-CT 140 kV 150 keV images received the highest scores and were significantly better than EID-CT Sn150 kV images. PCD-CT 72 keV images were rated significantly lower than all the others. HU-value variation was larger in the 120 kV and the 72 keV images. The ROI analysis revealed no large difference between scanners regarding artefact severity. PCD-CT 140 kV 150 keV images of a metal-containing bovine knee specimen provided the best image quality. They were superior to, or as good as, the best EID-CT images; even without the presumed advantage of tin filter and metal artefact reduction algorithms. PCD-CT is a promising method for reducing metal artefacts. [ABSTRACT FROM AUTHOR]

The paper summarizes all papers published by Bulgarian scientists in the field of archaeometry, issued in the last decade. The archaeometric investigations in Bulgaria cover the analyses of chemical composition of bronze, gold, silver, lead, glass, glaze, pottery, mortar, amber, resin and other archaeological objects. For their characterization many instrumental techniques such as AAS, ED-XRF, ICP-AES, INAA, LA-ICP-MS, SEM-EDS, etc. are used. These techniques, together with geophysical methods, archaeomagnetic investigations, dendrochronology and the various dating methods are all covered by the umbrella term ‘archaeometry’. MA programme in archaeometry has been offered in Sofia University ‘St. Kl. Ohridski’ in the last 10 years, whose graduates have been joining archaeological investigations professionally. In this way, archaeology is enriched with new understanding of the role of physics, chemistry, biology and geology.

External fixation is a common tool in the treatment of complex fractures, correction of limb deformity, and salvage arthrodesis. These devices typically incorporate radio-opaque metal rods/struts connected at varying distances and orientations between rings. Whilst the predominant imaging modality is plain film radiology, computed tomography (CT) may be performed in order for the surgeon to make a more confident clinical decision (e.g. timing of frame removal, assessment of degree of arthrodesis). We used a fractured sheep leg to systematically assess CT imaging performance with a Discovery CT750 HD CT scanner (GE Healthcare) to show how rod coupling in both traditional Ilizarov and hexapod frames distorts images. We also investigated the role of dual-energy CT (DECT) and metal artefact reduction software (MARS) on the visualisation of the fractured leg. Whilst mechanical reasons predominantly dictate the rod/strut configurations when building a circular frame, rod coupling in CT can be minimised. Firstly, ideally, all or all but one rod can be removed during imaging resulting in no rod coupling. If this is not possible, strategies for configuring the rods to minimise the effect of the rod coupling on the region of interest are demonstrated, e.g., in the case of a four-rod construct, switching the two anterior rods to a more central single one will achieve this goal without particularly jeopardising mechanical strength for a short period. It is also shown that the addition of DECT and MARS results in a reduction of artefacts, but also affects tissue and bone differentiation. [ABSTRACT FROM AUTHOR]

Introduction: To evaluate the clinical potential of dual layer computed tomography (DLCT) for posterior fusions of the thoracic and lumbar spine and determine the optimal keV-settings for an improved overall image quality and effective reduction of metal artefacts affecting the implant inheriting vertebral body, the spinal canal, the paravertebral muscle and aorta.Methods and Materials: Twenty patients with posterior thoracic and lumbar spinal fusion, who underwent a 120kVp- DLCT scan were included in this study. Two independent readers evaluated axial 0.9 mm slides with soft tissue and bone window settings. Image quality of the conventional scan was compared to virtual monoenergetic images (VMI) at 40, 60, 80, 100,120, 140, 160, 180 and 200 keV. Diagnostic image quality was assessed on a four point Likert-scale overall, as well as specifically for the implant inheriting bone, paravertebral muscle, spinal canal or aorta. The Hounsfield Units (HU) of the area with the most pronounced streak artefact as well as HU of a reference area containing fat and muscle were documented for each keV-setting and compared to the conventional image. SNR and CNR were calculated for each of the four anatomic areas. Statistical analysis was conducted for the total collective and separately for the thoracic and lumbar spine level.Results: Starting from 80 keV qualitative analysis revealed significant improvement of overall image quality and benefit for each tissue separately compared to the conventional images (CI) (p-values in the range from <0.001 to 0.005). 180 keV was considered the optimal monoenergetic setting regarding the overall image quality. For the assessment of the implant inheriting bone, the spinal canal, paravertebral muscle and aorta 200, 180, 160 and 180 keV were rated to be the most sufficient. Our results reveal high inter-reader agreement for qualitative evaluations (intra-class correlation coefficients >0.927; p < 0.05). HU values within the most pronounced streak artefact increased significantly with higher keV (p < 0.001), while there was no significant alteration of HU within the reference area. A decrease in SNR and CNR for higher VMI was revealed by our results.Conclusion: VMIs of higher energies provide significant reduction of metallic artefacts from posterior spinal fusions. Dedicated keV settings to evaluate either the implant inheriting bone, the spinal canal,adjacent muscle or aorta - structures, which are frequently of particular interest after posterior spinal fusion - are recommended. In addition, an optimal keV for an improved overall image quality is proposed. [ABSTRACT FROM AUTHOR]

X-ray Computed Tomography (XCT) has become an important tool for industrial measurement and quality control through its ability to measure internal structures and volumetric defects. Segmentation of constituent materials in the volume acquired through XCT is one of the most critical factors that influence its robustness and repeatability. Highly attenuating materials such as steel can introduce artefacts in CT images that adversely affect the segmentation process, and results in large errors during quantification. This paper presents a Markov Random Field (MRF) segmentation method as a suitable approach for industrial samples with metal artefacts. The advantages of employing the MRF segmentation method are shown in comparison with Otsu thresholding on CT data from two industrial objects. [ABSTRACT FROM AUTHOR]

Background The rate of retear after rotator cuff surgery is 17%. Magnetic resonance imaging (MRI) scans are used for confirmative diagnosis of retear. However, because of the presence of titanium suture anchors, metal artefacts on the MRI are common. The present study evaluated the diagnostic value of MRI after rotator cuff tendon surgery with respect to assessing the integrity as well as the degeneration and atrophy of the rotator cuff tendons when titanium anchors are in place. Methods Twenty patients who underwent revision surgery of the rotator cuff as a result of a clinically suspected retear between 2013 and 2015 were included. The MRI scans of these patients were retrospectively analyzed by four specialized shoulder surgeons and compared with intra-operative findings (gold standard). Sensitivity and interobserver agreement among the surgeons in assessing retears as well as the Goutallier and Warner classification were examined. Results In 36% (range 15% to 50%) of the pre-operative MRI scans, the observers could not review the rotator cuff tendons. When the rotator cuff tendons were assessable, a diagnostic accuracy with a mean sensitivity of 0.84 (0.70 to 1.0) across the surgeons was found, with poor interobserver agreement (kappa = 0.12). Conclusions Metal artefacts prevented accurate diagnosis from MRI scans of rotator cuff retear in 36% of the patients studied. [ABSTRACT FROM AUTHOR]

The paper deals with analysis of iron and metal artefacts recovered under the supervision of the author during a metal detector survey in 2011 and assemblages handed over by an amateur 'treasure hunter' originating from two deserted medieval villages, Prochod and Žďár, in the Velechvín forest district. The objects were evaluated with regard to their typological and functional classification into relevant groups. Compared to assemblages of iron and metal artefacts from systematically investigated DMVs in Bohemia and Moravia and other sites in South Bohemia, the issue of chronology and the way of using objects in contemporary living culture are addressed. The question of distribution and the context of the objects are also dealt with, in context of relief formations documented through geodetic-topographic survey. [ABSTRACT FROM AUTHOR]

Purpose: To quantify the impact of prosthesis material and design on the reduction of metal artefacts in total hip arthroplasties using virtual monochromatic dual-layer detector Spectral CT imaging.Methods: The water-filled total hip arthroplasty phantom was scanned on a novel 128-slice Philips IQon dual-layer detector Spectral CT scanner at 120-kVp and 140-kVp at a standard computed tomography dose index of 20.0mGy. Several unilateral and bilateral hip prostheses consisting of different metal alloys were inserted and combined which were surrounded by 18 hydroxyapatite calcium carbonate pellets representing bone. Images were reconstructed with iterative reconstruction and analysed at monochromatic energies ranging from 40 to 200keV. CT numbers in Hounsfield Units (HU), noise measured as the standard deviation in HU, signal-to-noise-ratios (SNRs) and contrast-to-noise-ratios (CNRs) were analysed within fixed regions-of-interests placed in and around the pellets.Results: In 70 and 74keV virtual monochromatic images the CT numbers of the pellets were similar to 120-kVp and 140-kVp polychromatic results, therefore serving as reference. A separation into three categories of metal artefacts was made (no, mild/moderate and severe) where pellets were categorized based on HU deviations. At high keV values overall image contrast was reduced. For mild/moderate artefacts, the highest average CNRs were attained with virtual monochromatic 130keV images, acquired at 140-kVp. Severe metal artefacts were not reduced. In 130keV images, only mild/moderate metal artefacts were significantly reduced compared to 70 and 74keV images. Deviations in CT numbers, noise, SNRs and CNRs due to metal artefacts were decreased with respectively 64%, 57%, 62% and 63% (p<0.001) compared to unaffected pellets. Optimal keVs, based on CNRs, for different unilateral and bilateral metal hip prostheses consisting of different metal alloys varied from 74 to 150keV. The Titanium alloy resulted in less severe artefacts and were reduced more effectively compared to the Cobalt alloy.Conclusions: Virtual monochromatic dual-layer Spectral CT imaging results in a significant reduction of streak artefacts produced by beam-hardening in mild and moderate artefacts by improving CT number accuracy, SNRs and CNRs, while decreasing noise values in a total hip arthroplasty phantom. An optimal monochromatic energy of 130keV was found ranging from 74keV to 150keV for different unilateral and bilateral hip prostheses consisting of different metal alloys. [ABSTRACT FROM AUTHOR]

The paper provides a description of metal objects found in the surroundings of the Třísov oppidum in 2013-2016. Although the number of finds is not large, they substantially augment the spectrum of earlier finds from the oppidum. The relatively frequent occurrence of bronze artefacts that are probably not of local origin (a Nauheim-type fibula with decoration typical of southern France, a segment of a Němčice-type chain belt originating from the Middle Danube area and a foot from a North Italian vessel) is of some interest. This fact confirms the importance of the Třísov oppidum within the settlement network and long-distance contacts in the late La Tène period. [ABSTRACT FROM AUTHOR]

New isolated finds of bronze, copper and gold artefacts are published in this paper. They have been found in the southern part of Bohemia mostly in the last four years. Out of a total of 122 finds, 29 can be dated to the time interval from the Early Bronze Age to the beginning of the Middle Bronze Age (Br A-A2/B1), 22 to the Middle Bronze Age (Br B-C), 35 to the Urnfield period (Br D-Ha B) and 36 can only generally be dated to the Bronze Age. The paper includes typological-chronological and settlement-topographic analysis as well as XRF analysis of selected artefacts. [ABSTRACT FROM AUTHOR]

Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose due to different metal artefacts. The O-MAR algorithm deploys an iterative loop where the metal sinogram is identified, extracted, and subsequently serves as a mask to correct the measured sinogram. Main goal of this study is to quantify the ability of the O-MAR technique to correct deviation in medullary bone attenuation caused by streak artefacts from the large-head MoM THA embedded in a phantom. Secondary goal is to evaluate the influence of O-MAR on CNR. Methods: The phantom was designed as a Perspex box (PMMA) containing water and a supplementary MOM THA surrounded by Perspex columns comprising calibrated calcium pellets. Each column contains 200 mg of hydroxyapatite/calcium carbonate to simulate healthy bone tissue. Scans were obtained with and without a MoM THA at different dose levels. Different reconstructions were made with filter A, iDose level 5 and with and without O-MAR. The scans without the prosthesis were used as the baseline. Information about the attenuation in Hounsfield units, image noise in standard deviation within the ROI's were extracted and the CNR was calculated. Results: Pellet L0 and R0 (proximal of the MoM THA) were defined as reference, lacking any disturbance by metal artefacts; L5, L6 and L8 were respectively visually categorized as 'light' 'medium' and 'heavy disturbance'. Significant improvements in attenuation deviation caused by metal artefact were 43, 68 and 32 %, for respectively pellet L5, L6 and L8 (p < 0.001). Significant CNR improvements were present for L5 and L6 and were respectively 72 and 52 % (p < 0.001). O-MAR showed no improvement on CNR for L8. Conclusion: This phantom study significantly increases image quality by the use of O-MAR in the presence of metal artefacts by significantly reducing metal artefacts subsequently and increasing CNR on a 64 slice CT system in light and medium disturbance of the image. [ABSTRACT FROM AUTHOR]

The paper summarizes all papers published by Bulgarian scientists in the field of archaeometry, issued in the last decade. The archaeometric investigations in Bulgaria cover the analyses of chemical composition of bronze, gold, silver, lead, glass, glaze, pottery, mortar, amber, resin and other archaeological objects. For their characterization many instrumental techniques such as AAS, ED-XRF, ICP-AES, INAA, LA-ICP-MS, SEM-EDS, etc. are used. These techniques, together with geophysical methods, archaeomagnetic investigations, dendrochronology and the various dating methods are all covered by the umbrella term 'archaeometry'. MA programme in archaeometry has been offered in Sofia University 'St. Kl. Ohridski' in the last 10 years, whose graduates have been joining archaeological investigations professionally. In this way, archaeology is enriched with new understanding of the role of physics, chemistry, biology and geology. [ABSTRACT FROM AUTHOR]

We report a case of exuberant artefacts on the magnetic resonance imaging scan of the elbow produced by invisible metal debris secondary to previous surgery. [ABSTRACT FROM AUTHOR]

Purpose: Post-surgical evaluation of osteosynthesis material and adjacent tissue can be challenging in both radiography and cross-sectional imaging. This study investigates the performance of a multi-purpose X-ray scanner with cone-beam CT (CBCT) function and iterative metal artefact reduction capabilities in patients after osteoplasty of the appendicular skeleton.Method: Eighty individuals who underwent both conventional X-ray imaging and CBCT after osteoplasty of the hand/wrist (48), elbow (14), or ankle/foot (18) with the gantry-free twin robotic system were retrospectively enrolled. Radiological reports from clinical routine for both imaging modalities were retrospectively analyzed and compared with consensus expert reading by two musculoskeletal specialists serving as the standard of reference. Findings of screw dislocation or implant loosening, fragment displacement, and delayed healing were compared between X-ray and CBCT reports using the McNemar test.Results: The median dose-area-product of CBCT and X-ray scans amounted to 27.98 and 0.2 dGy*cm2, respectively. Diagnostic accuracy for screw dislocation was superior in CBCT compared to standard radiograms (98.8 % vs 83.8 %; p = 0.002). Implant loosening (98.8 % vs 86.3 %; p = 0.006), fragment displacement (98.8 % vs 85.0 %; p < 0.001), and delayed healing (97.5 % vs 88.8 %; p = 0.016) were also more reliably detected in CBCT. Employing CBCT, postoperative complications were detected with a sensitivity and specificity of at least 95.8 % and 98.1 %, compared to 33.3 % and 92.86 % in radiography.Conclusions: With superior accuracy for various osteoplasty-related complications, the CBCT scan mode of a gantry-free twin robotic X-ray system with iterative metal artefact reduction aids post-surgical assessment in the appendicular skeleton. [ABSTRACT FROM AUTHOR]

This paper considers the early copper and copper-alloy metallurgy of the entire Alpine region. It introduces a new approach to the interpretation of chemical composition data sets, which has been applied to a comprehensive regional database for the first time. The Alpine Chalcolithic and Early Bronze Age each have distinctive patterns of metal use, which can be interpreted through changes in mining, social choice, and major landscape features such as watersheds and river systems. Interestingly, the Alpine range does not act as a north-south barrier, as major differences in composition tend to appear on an east-west axis. Central among these is the prevalence of tin-bronze in the western Alps compared to the east. This 'tin-line' is discussed in terms of metal flow through the region and evidence for a deeply rooted geographical division that runs through much of Alpine prehistory. [ABSTRACT FROM AUTHOR]

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Various analytical techniques markedly contribute to the authentification of metal antiquities when visual judgments no more suffice to detect fakes, forgeries or extensive restorations. A careful analysis of the property of the materials from which the artefacts were made is often able to demonstrate an anachronism. In this paper, we evidenced three typical researches capable of supporting historians of art and curators opinions.

Copyright of Archeologické Rozhledy is the property of Academy of Sciences of the Czech Republic, Institute of Archaeology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over- or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron emission tomography (PET) images. Since this degrades the diagnostic quality of the images, metal artefact reduction (MAR) prior to attenuation correction is required. Methods: The proposed MAR method, referred to as virtual sinogram-based technique, replaces the projection bins of the sinogram that are influenced by metallic implants by a 2-D Clough-Tocher cubic interpolation scheme performed in an irregular grid, called Delaunay triangulated grid. To assess the performance of the proposed method, a physical phantom and 30 clinical PET/CT studies including hip prostheses were used. The results were compared to the method implemented on the Siemens Biograph mCT PET/CT scanner. Results: Both phantom and clinical studies revealed that the proposed method performs equally well as the Siemens MAR method in the regions corresponding to bright streaking artefacts and the artefact-free regions. However, in regions corresponding to dark streaking artefacts, the Siemens method does not seem to appropriately correct the tracer uptake while the proposed method consistently increased the uptake in the underestimated regions, thus bringing it to the expected level. This observation is corroborated by the experimental phantom study which demonstrates that the proposed method approaches the true activity concentration more closely. Conclusion: The proposed MAR method allows more accurate CT-based attenuation correction of PET images and prevents misinterpretation of tracer uptake, which might be biased owing to the propagation of bright and dark streaking artefacts from CT images to the PET data following the attenuation correction procedure. [ABSTRACT FROM AUTHOR]

In the literature, the ability to transform metal compounds into metal oxalates has been reported for different species of fungi. This could be an innovative conservation method for archaeological and artistic metal artefacts. In fact, with a high degree of insolubility and chemical stability even in acid atmospheres (pH 3), metal oxalates provide the surface with good protection. Within the framework of the EU-ARTECH project, different fungal strains have been used to transform existing corrosion patinas on outdoor bronze monuments into copper oxalates, while preserving the physical appearance of these artefacts. Given the promising results obtained with this first attempt, the same approach is now applied within the BAHAMAS (Marie Curie Intra European Fellowship action) project, but extended to other metal substrates, for example iron and silver, which are frequently found in cultural heritage artworks and also encounter several problems of active corrosion. The research is investigating the formation mechanisms and adhesion properties of the newly formed metal oxalates by means of complementary analytical techniques (X-ray diffraction (XRD), FTIR microscopy, Raman microscopy, scanning electron microscopy (SEM-EDS), electrochemical impedance spectroscopy (EIS), colorimetry). For each metal substrate, the most appropriate fungal strain is going to be identified and applied to corroded sheets and the novel fungal treatment compared with those used so far. Treated metal sheets will be monitored during 1-year exposure to different cycles of artificial ageing, to evaluate the corrosion resistance of the fungal patinas obtained. The objective of this contribution is to present the first results achieved so far on naturally corroded bronze sheets during the EU-ARTECH project and the analytical procedure used for the testing of the proposed treatment performances during the BAHAMAS project. [ABSTRACT FROM AUTHOR]

Abstract: A method is presented to generate metal-artefact-free finite element (FE) models based on in vivo micro-CT images of bone–implant structures in the case of the Guinea Pig’s tibiae. A bone–implant composite FE model was constructed based on both pre- (just before implant insertion) and post-operative (4days after implant insertion) sets of micro-CT scans. Definition of bone geometry and attribution of material properties to the volumetric elements was based on pre-operative images while post-operative scans were mainly used for registration. Standard Triangulation Language (STL) representations of implant and bone were generated after segmentation of CT images in MIMICS® (Materialise). Registration was performed in 3-matic® (Materialise). By taking two sets of scans at a 4days interval, undisturbed bone geometry before implant insertion and implant position after insertion were recorded. After adequate validation, FE models constructed with this method can be used to study bone adaptive response to controlled mechanical loading. [Copyright &y& Elsevier]

Abstract: The capability of laser ablation to perform controlled cleaning of varnishes containing contaminants and paints used by restorers in artistic objects from brass samples while keeping unaltered the finish structure is demonstrated in this work. Adequate laser energy per pulse and number of laser shots required to perform a suitable cleaning by laser ablation have been optimized. The inspection of the samples before and after the cleaning process by optical microscopy and by Fourier transform infrared spectroscopy (FTIR) technique demonstrated that the finish structure of the surface was intact while the coatings were completely eliminated. Furthermore, a laser-induced plasma spectroscopy (LIBS)-based detection system was applied during the irradiation process for the analysis of the material removal and also for its monitoring. [Copyright &y& Elsevier]

Objective: To determine the limits of accuracy of fusion of optical three-dimensional (3D) imaging and computed tomography (CT) with and without metal artefacts in an experimental setting and to show the application of this hybrid system in 3D orthognathic surgery simulation. Methods: Ten plaster casts of dental arches were subjected to a CT scan and optical 3D surface imaging. Subsequently, the first molars in the plaster casts were supplied with metal restorations, bilaterally, and new CT scans and optical surface images were assessed. The registration of the surface data of the two imaging modalities of the study models without and with metal restorations was carried out. The mean distance between the two data sets was calculated. From a patient a CT scan of the skull as well as optical 3D images of plaster casts of the dental arches were acquired. Again the two imaging modalities were registered and virtual orthognathic surgery simulation was carried out. Results: The mean distance between the corresponding data points of CT and optical 3D surface images was 0.1262 ± 0.0301 mm and 0.2671 ± 0.0580 mm, respectively, for the plaster casts without and with metal restorations. The differences between these data were statistically significant (P < 0.0005). For the patient case a mean difference of 0.66 ± 0.49 mm and 0.56 ± 0.48 mm for mandible and maxilla, respectively, was calculated between CT and optical surface data. Conclusion: The accuracy of the fusion of 3D CT surface data and optical 3D imaging is significantly reduced by metal artefacts. However, it seems appropriate for virtual orthognathic surgery simulation, as post-operative orthodontics are performed frequently. [ABSTRACT FROM AUTHOR]

Background: Computed tomography (CT) is currently the imaging modality of choice for guiding pulmonary percutaneous procedures. The use of a tin filter allows low-energy photons to be absorbed which contribute little to image quality but increases the radiation dose that a patient receives. Iterative metal artefact reduction (iMAR) was developed to diminish metal artefacts. This study investigated the impact of using tin filtration combined with an iMAR algorithm on dose reduction and image quality in CT-guided lung biopsy., Methods: Ninety-nine consecutive patients undergoing CT-guided lung biopsy were randomly assigned to routine-dose CT protocols (groups A and B; without and with iMAR, respectively) or tin filter CT protocols (groups C and D; without or with iMAR, respectively). Subjective image quality was analysed using a 5-point Likert scale. Objective image quality was assessed, and the noise, contrast-to-noise ratio, and figure of merit were compared among the four groups. Metal artefacts were quantified using CT number reduction and metal diameter blurring. The radiation doses, diagnostic performance, and complication rates were also estimated., Results: The subjective image quality of the two scan types was compared. Images with iMAR reconstruction were superior to those without iMAR reconstruction (group A: 3.49±0.65 vs . group B: 4.63±0.57; P<0.001, and group C: 3.88±0.66 vs . group D: 4.82±0.39; P<0.001). Images taken with a tin filter were found to have a significantly higher figure-of-merit than those taken without a tin filter (group A: 14,041±7,230 vs . group C: 21,866±10,656; P=0.001, and group B: 13,836±6,849 vs . group D: 21,639±9,964; P=0.001). In terms of metal artefact reduction, tin filtration combined with iMAR showed the lowest CT number reduction (116.62±103.48 HU) and metal diameter blurring (0.85±0.30) among the protocols. The effective radiation dose in the tin filter groups was 73.2% lower than that in the routine-dose groups. The complication rate and diagnostic performance (sensitivity, specificity, and overall accuracy) did not differ significantly between the tin filter and routine-dose groups (all P>0.05)., Conclusions: Tin filtration combined with an iMAR algorithm may reduce the radiation dose compared to the routine-dose CT protocol, while maintaining comparable diagnostic accuracy and image quality and producing fewer metal artefacts., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/qims-21-555). The authors have no conflicts of interest to declare., (2022 Quantitative Imaging in Medicine and Surgery. All rights reserved.)