Iterative reconstruction as a method for optimisation of computed tomography procedures

Background: Computed tomography (CT) is still commonly regarded as a method that causes a high radiation exposure. For that reason, producers intensively try to find new solutions for dose reduction while maintaining a high diagnostic value of images. One of the recent strategies focuses on CT image reconstruction. Iterative reconstruction (IR) is an alternative for filtered back projection (FBP) that is commonly used today. The aim of the article is to demonstrate and compare the effects of two IR algorithms on dose value and image details. Material/Methods: Investigations were performed on two 128 multi-detector (MDCT) CT scanners: - iCT (Philips Healthcare with iDose4); - Definitions AS+ (Siemens Medical Solutions with SAFIRE system). The measurements involved: - image quality indicators for the CATPHAN 600 phantom; - dosimetric indicators of exposure (DLP i CTDIvol). Results: The signal-to-noise ratios (SNR) in the images reconstructed with IR and FBP were analysed, and the SNR(IR)/SNR(FBP) ratios were calculated and correlated with CTDIvol values. The effects of IR and FBP algorithms on low-contrast resolution were also compared in relation to CTDIvol values. The smallest diameter of supra-slice objects in the Catphan phantom were taken into consideration. Conclusions: Both iterative algorithms definitely improved the visibility of low-contrast objects in comparison to a standard algorithm (FBP) with similar exposure parameters. These algorithms allow an 80% reduction of the CTDIvol value while maintaining an acceptable visibility of low-contrast objects. However, the results obtained with each of the studied iterative algorithms differ

Impact of Allura Clarity technology on radiation dose exposure during left atrial appendage closure

Background: To evaluate the impact of the Clarity IQ technology on reducing radiation risk in patients undergoing cardiac interventional radiology (IR) procedures. Material/Methods: Phantom studies were performed with two angiographic systems, FD10 Allura Xper and FD10 Allura Clarity. In the study, we performed left atrial appendage closure. Dosimetric measurements were performed with thermoluminescent dosimeters (TLD) placed inside a CIRS anthropomorphic phantom. Radiation risk was estimated based on the TLD readings and expressed as the dose absorbed by particular organs. The Mann-Whitney U test was carried out to test for significance of differences in the absorbed radiation doses between the techniques. Results: During left atrial appendage closure, the estimated dose absorbed by particular organs was lower in the case of the FD10 Allura Clarity system in comparison to the Allura Xper. In this procedure, dose reduction for particular organs ranged between 49-86%. Conclusions: Application of the FD10 Allura Clarity system resulted in a significant dose reduction, thereby leading to a significant decrease in radiation risk for patients undergoing IR procedures

Dose and noise in abdominal computed tomography examinations

Background: Dose reduction in computed tomography (CT) examinations was an idea of the Co-rdinated Research Project (CRP) "Dose Reduction in Computed Tomography (CT) while maintaining Diagnostic Confidence", supported by the International Agency of Atomic Energy (IAEA) in the years 2003-2005. Participation in the CRP inspired the authors' attempts to elaborate a method for optimization of CT abdominal procedures allowing reduce a dose to patient with saving diagnostically satisfying image quality. The paper presents the algorithm together with clinical verification of the results of the study. Material/Methods: Two types of single-slice CT scanners were used for the investigations. The images recorded for patients undergoing routine abdomen examinations and then these obtained with modified exposure parameters were analyzed. The influence of the changed tube outputs on image quality was checked using Catphan 424 phantom. Results: As the result no statistically significant difference between the measured noise in clinical images for patients examined at routine and modified settings (within the same weight category) was observed. Conclusions: The conclusion was that at routine (screening) abdomen examinations, the dose may be reduced up to 50% with saving diagnostically satisfying image quality

Certification of the crude Protein, Fat, Lactose and Ash Content of whole Milk Powder and the crude Protein and Fat Content of Skim Milk Powder, BCR-380R & BCR-685

This report describes the preparation of two milk powder reference materials and the measurement exercises that led to the certification of the content (mass fraction) of the crude protein (Kjeldahl-N x 6.38), fat, lactose and ash in whole milk powder (BCR-380R) and crude protein (Kjeldahl-N x 6.38) and fat in skim milk powder (BCR-685).JRC.D.2-Reference material

The Certification of the Mass Fractions of Proximates and Essential Elements in Rye Flour and Wheat Flour -- Certified Reference Materials ERM®-BC381 and ERM®-BC382

This report describes the preparation of the rye flour matrix reference materials ERM®BC381 and ERM®-BC382, respectively, and the certification of the contents (mass fractions) of four proximates and four essential elements. All results are expressed as a mass fraction on a dry mass basis. The preparation and processing of the materials, homogeneity studies, stability studies and characterisation are described hereafter and the results are discussed. Uncertainties were calculated in compliance with Guide to the expression of Uncertainty in Measurement (GUM) and include uncertainties due to possible heterogeneity, instability and from characterisation.JRC.DDG.D.2-Reference material

Stat3 is required to maintain the full differentiation potential of mammary stem cells and the proliferative potential of mammary luminal progenitors.

Stat3 has a defined role in mammary gland where it is a critical mediator of cell death during post-lactational regression. On the other hand, Stat3 is required for the self-renewal of embryonic stem cells and is sufficient for the induction of a naïve pluripotent state in epiblast stem cells. Mammary stem cells (MaSCs) have a high capacity for self-renewal and can grow robustly in transplantation experiments in vivo. However, a role for Stat3 in MaSCs has not been investigated. Here we show that depletion of Stat3 from basal cells results in reduced primary transplantation efficiency and diminishes the potential to generate ductal, but not alveolar, outgrowths. In addition, Stat3 is required for maximal proliferation of luminal progenitors