This study investigated the usefulness of the dose optimization strategy of increased tube voltage (kVp) and decreased tube current-exposure time product (mAs) (or high kVp-low mAs) by examining practitioners' assessments of perceived aesthetic and diagnostic quality of direct digital radiographs acquired using this strategy. Ninety-one practitioners (radiologists, radiology residents, radiographers, and radiography students) from eight clinical sites in Ontario examined three types of radiographs (''standard'' image, þ20 kVp image, and þ30 kVp image) for anthropomorphic pelvis, chest, skull, and hand phantoms and rated (on a five-point scale) each image in regard to its perceived aesthetic quality, perceived diagnostic quality, and visualization of anatomic structures. Our primary findings are that for the pelvis, skull, and hand-although not the chest-images acquired using standard technical factors were rated significantly higher in diagnostic and aesthetic quality than those acquired using the high kVp-low mAs strategy. Despite this, both standard and dose-optimized images of the pelvis, skull, and hand were rated to be of acceptable diagnostic quality for clinical use. In conclusion, for the pelvis, skull, and hand, an increase of 20 kVp was an effective strategy to reduce dose while still acquiring images of diagnostic quality. RESUM E Cette etude evalue l'utilit e de la strat egie d'optimisation de la dose fond ee sur l'augmentation de la tension du tube (kVp) et de la diminution du produit tube de courant/temps d'exposition (mAs) (ou kVp elev e-mAs faible) en examinant l' evaluation que font les praticiens de la qualit e esth etique et diagnostique perçue des radiographies num eriques directes prises a l'aide de cette strat egie. Quatre-vingt onze praticiens (radiologistes, r esidents en radiologie, radiographes et etudiants en radiographie) de huit sites cliniques en Ontario ont examin e trois types de radiographies (image « standard », image a þ20 kVp, image a þ30 kVp) de fantômes anthropomorphiques du pelvis, de la poitrine, du crâne et de la main et les ont cot ees (sur une echelle de 1 a 5) selon (a) qualit e esth etique perçue, (b) leur qualit e diagnostique perçue et (c) la visualisation des structures anatomiques. Nos constatations initiales montrent que, dans le cas des images du pelvis, du crâne et de la main, mais non celles de la poitrine, les images prises avec les facteurs techniques standard ont reçu une note significativement plus elev ee pour la qualit e esth etique et diagnostique que celles prises en utilisant la technique kVp elev e-mAs faible. Cependant, les images standard et a dose optimis ee du pelvis, du crâne et de la main ont et e jug ees de qualit e diagnostique acceptable pour un usage clinique. En conclusion, pour le pelvis, le crâne et la main, une augmentation de þ20 kVp est une strat egie efficace pour r eduire la dose tout en produisant quand même des images de qualit e diagnostique.

No abstract

We describe a simple fabrication technique - targeted towards non-specialists - that allows for the production of leak-proof polydimethylsiloxane (PDMS) microfluidic devices that are compatible with live-cell microscopy. Thin PDMS base membranes were spin-coated onto a glass-bottom cell culture dish and then partially cured via microwave irradiation. PDMS chips were generated using a replica molding technique, and then sealed to the PDMS base membrane by microwave irradiation. Once a mold was generated, devices could be rapidly fabricated within hours. Fibronectin pre-treatment of the PDMS improved cell attachment. Coupling the device to programmable pumps allowed application of precise fluid flow rates through the channels. The transparency and minimal thickness of the device enabled compatibility with inverted light microscopy techniques (e.g. phase-contrast, fluorescence imaging, etc.). The key benefits of this technique are the use of standard laboratory equipment during fabrication and ease of implementation, helping to extend applications in live-cell microfluidics for scientists outside the engineering and core microdevice communities.

The vasculature in ischemic muscle is rebuilt by the splitting of primordial vessels, led by VEGFR2-metastable endothelial cells.

Total joint replacements can be subject to the loss of polyethylene material due to wear, leading to osteolysis and decreased implant longevity. Micro-computed tomography (micro-CT) techniques have recently been developed to calculate 3D surface deviations in worn implant components. We describe a micro-CT technique to measure the volume of the surface deviations (volume of wear plus creep) within a specific region or compartment, and report its repeatability and reproducibility. Six worn polyethylene tibial inserts were scanned using a laboratory micro-CT scanner and subsequently reconstructed at 50 μm voxel spacing. A previously developed custom software application was used to quantify the 3D surface deviations between the worn tibial inserts and an unworn reference geometry. Three observers (two trained and one expert) used new custom software to manually outline the localized regions of surface deviation (three times for each of the worn inserts) and calculate the volume of the deviations. The overall intraobserver variability in the surface deviation volumes was 3.6% medially and 1.1% laterally. The overall interobserver variability was 4.8% medially and 1.7% laterally. Placement of points in outlining the region of deviation contributed the greatest variability to the measurements. Repeatability and reproducibility of the volume measurements are similar to measurements of total (nonregional) wear volume including a previous micro-CT technique (10%), fluid displacement (4.8%), and radiographic measurements (15.7%). The principles of this technique can likely be used to measure regional wear and creep volume in knee and hip joint replacement components from wear simulator, pin-on-disk, and retrieval studies.