Effect of using different U/S probe Standoff materials in image geometry for interventional procedures : the example of prostate

PURPOSE: This study investigates the distortion of geometry of catheters and anatomy in acquired U/S images, caused by utilizing various stand-off materials for covering a transrectal bi-planar ultrasound probe in HDR and LDR prostate brachytherapy, biopsy and other interventional procedures. Furthermore, an evaluation of currently established water-bath based quality assurance (QA) procedures is presented. MATERIAL AND METHODS: Image acquisitions of an ultrasound QA setup were carried out at 5 MHz and 7 MHz. The U/S probe was covered by EA 4015 Silicone Standoff kit, or UA0059 Endocavity balloon filled either with water or one of the following: 40 ml of Endosgel(®), Instillagel(®), Ultraschall gel or Space OAR™ gel. The differences between images were recorded. Consequently, the dosimetric impact of the observed image distortion was investigated, using a tissue equivalent ultrasound prostate phantom - Model number 053 (CIRS Inc., Norfolk, VA, USA). RESULTS: By using the EA 4015 Silicone Standoff kit in normal water with sound speed of 1525 m/s, a 3 mm needle shift was observed. The expansion of objects appeared in radial direction. The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose. On the other hand, Instillagel(®) and Space OAR™ "shrinks" objects in an ultrasound image for 0.65 mm and 0.40 mm, respectively. CONCLUSIONS: The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy. Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging

Hydroxyl-platelet-activating factor exists in blood of healthy volunteers and periodontal patients.

Periodontal diseases are localized chronic inflammatory conditions of the gingival and underlying bone and connective tissue. Platelet-activating factor (PAF), a potent inflammatory phospholipid mediator that has been previously detected in elevated levels in inflamed gingival tissues, in gingival crevicular fluid and in saliva, is implicated in periodontal disease. Our results from previous studies showed that the biologically active phospholipid detected in gingival crevicular fluid is a hydroxyl-PAF analogue. In this study, hydroxyl-PAF analogue was detected for the first time in human blood derived from patients with chronic periodontitis as well as from periodontally healthy volunteers. The hydroxyl-PAF analogue was purified by high-performance liquid chromatography, detected by biological assays and identified by electrospray analysis. In addition, the quantitative determination of PAF and hydroxyl-PAF analogue (expressed as PAF-like activity) showed a statistically significant increase in the ratio of hydroxyl-PAF analogue levels to PAF levels in periodontal patients, suggesting that this bioactive lipid may play a role in oral inflammation

Liquidity creation through efficient M&As: A viable solution for vulnerable banking systems? Evidence from a stress test under a panel VAR methodology

According to the “cost efficiency - liquidity creation” hypothesis (CELCH), introduced in this paper, a rise in a bank’s cost efficiency level increases its liquidity creation. By employing a novel stress test scenario under a panel VAR methodology, the CELCH and the direction of causality between liquidity creation and cost efficiency are tested. Moreover, using new measures of liquidity creation (Berger and Bouwman, 2009), the question of whether potential bank mergers and acquisitions (M&As) can enhance liquidity creation and generate additional credit channels in the economy is addressed. The robustness of potential consolidation scenarios are evaluated and compared through the use of new “half-life” measures (Chortareas and Kapetanios, 2013). In line with CELCH, the positive impact of cost efficiency on liquidity creation is shown. The empirical evidence further suggests that potential consolidation activity can enhance the flow of credit in the economy. Bank shocks seem to have the most persistent effect on both liquidity creation and cost efficiency. Finally, doubts are cast on the strategies followed by policy authorities regarding the recent wave of M&As in the banking sector

An applied analysis of brand demand structure

The demand literature is concerned with the optimal allocation of expenditure at varied but usually high levels of commodity aggregation. Much less aggregation however is required for business applications. In applied business settings, interest centres upon the different brands of the same commodity because policy formulation takes place at the level of the individual brand. This paper considers application of formal demand analysis to brand demand data. A theoretically plausible demand system is invoked to describe inter-brand allocation of expenditure, test restrictions imposed by economic theory and yield empirically determined insights into brand demand structure.