Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151

Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist is responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography

Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems

Purpose: To develop an experimental method for measuring the effective detective quantum efficiency (eDQE) of digital radiographic imaging systems and evaluate its use in select imaging systems

Structure-activity relationship studies on the macrolide exotoxin mycolactone of Mycobacterium ulcerans

BACKGROUND: Mycolactones are a family of polyketide-derived macrolide exotoxins produced by Mycobacterium ulcerans, the causative agent of the chronic necrotizing skin disease Buruli ulcer. The toxin is synthesized by polyketide synthases encoded by the virulence plasmid pMUM. The apoptotic, necrotic and immunosuppressive properties of mycolactones play a central role in the pathogenesis of M. ulcerans. METHODOLOGYPRINCIPAL FINDINGS: We have synthesized and tested a series of mycolactone derivatives to conduct structure-activity relationship studies. Flow cytometry, fluorescence microscopy and Alamar Blue-based metabolic assays were used to assess activities of mycolactones on the murine L929 fibroblast cell line. Modifications of the C-linked upper side chain (comprising C12-C20) caused less pronounced changes in cytotoxicity than modifications in the lower C5-O-linked polyunsaturated acyl side chain. A derivative with a truncated lower side chain was unique in having strong inhibitory effects on fibroblast metabolism and cell proliferation at non-cytotoxic concentrations. We also tested whether mycolactones have antimicrobial activity and found no activity against representatives of Gram-positive (Streptococcus pneumoniae) or Gram-negative bacteria (Neisseria meningitis and Escherichia coli), the fungus Saccharomyces cerevisae or the amoeba Dictyostelium discoideum. CONCLUSION: Highly defined synthetic compounds allowed to unambiguously compare biological activities of mycolactones expressed by different M. ulcerans lineages and may help identifying target structures and triggering pathways

A technique optimization protocol and the potential for dose reduction in digital mammography

Digital mammography requires revisiting techniques that have been optimized for prior screen∕film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potential for dose reduction in comparison to the clinically established techniques based on screen- film. An objective figure of merit (FOM) was employed to evaluate a direct-conversion amorphous selenium (a-Se) FFDM system (Siemens Mammomat NovationDR, Siemens AG Medical Solutions, Erlangen, Germany) and was derived from the quotient of the squared signal-difference-to-noise ratio to mean glandular dose, for various combinations of technique factors and breast phantom configurations including kilovoltage settings (23–35 kVp), target∕filter combinations (Mo–Mo and W–Rh), breast-equivalent plastic in various thicknesses (2–8 cm) and densities (100% adipose, 50% adipose∕50% glandular, and 100% glandular), and simulated mass and calcification lesions. When using a W–Rh spectrum, the optimized FOM results for the simulated mass and calcification lesions showed highly consistent trends with kVp for each combination of breast density and thickness. The optimized kVp ranged from 26 kVp for 2 cm 100% adipose breasts to 30 kVp for 8 cm 100% glandular breasts. The use of the optimized W–Rh technique compared to standard Mo–Mo techniques provided dose savings ranging from 9% for 2 cm thick, 100% adipose breasts, to 63% for 6 cm thick, 100% glandular breasts, and for breasts with a 50% adipose∕50% glandular composition, from 12% for 2 cm thick breasts up to 57% for 8 cm thick breasts

MCL-1 is a stress sensor that regulates autophagy in a developmentally regulated manner

The short-lived antiapoptotic BCL-2 homologue MCL-1 exerts an inhibitory effect on apoptosis and autophagy. The functional outcome of stress-induced MCL-1 degradation depends on the nature of stimulus and the cellular context, such as the differentiation state of neurons

Cardiac anomalies in individuals with the 18q deletion syndrome; report of a child with Ebstein anomaly and review of the literature

Item does not contain fulltextIndividuals with the 18q deletion syndrome are presented with various clinical characteristics, including cardiac anomalies in 24-36% of the reported cases. Nonetheless, genotype-phenotype correlations for cardiac anomalies in the 18q deletion syndrome have rarely been reported. We report on two girls with a terminal 18q deletion, one in whom an Ebstein anomaly and Wolff-Parkinson-White syndrome were detected and the other with multiple valve stenosis and a ventricular septal defect. The genotype and cardiac abnormalities of these girls and 17 other individuals with a de novo 18qter deletion reported in the literature are reviewed. All 19 individuals shared a small overlapping deletion region between 18q22.3q23. The most common cardiac defects detected were pulmonary valve anomalies and atrial septal defects. Ebstein anomaly, a rare cardiac malformation, was diagnosed in two individuals. Additional molecularly based genotype-phenotype studies are needed in order to pinpoint candidate genes within this region that contribute to normal cardiac development. A careful cardiac evaluation consisting of physical examination, ECG and ultrasound examination should be performed in all individuals diagnosed with the 18q deletion syndrome