Epid cine acquisition mode for in vivo dosimetry in dynamic arc radiation therapy

In this paper the cine acquisition mode of an electronic portal imaging device (EPID) has been calibrated and tested to determine the in vivo dose for dynamic conformal arc radiation therapy (DCAT). The EPID cine acquisition mode, that allows a frame acquisition rate of one image every 1.66 s, was studied with a monitor unit rate equal to 100 UM/min. In these conditions good signal stability, ±1% (2SD) evaluated during three months, signal reproducibility within ±0.8% (2SD) and linearity with dose and dose rate within ±1% (2SD) were obtained.The transit signal, S_t, (due to the transmitted beam below the phantom) measured by the EPID cine acquisition mode was used to determine, (i) a set of correlation functions, F(w,L), defined as the ratio between S_t and the dose at half thickness, D_m, measured in solid water phantoms of different thicknesses, w and with square fields of side L, (ii) a set of factors, f(d,L), that take into account the different X-ray scatter contribution from the phantom to the S_t signal as a function of the variation, d, of the air gap between the phantom and the EPID. The reconstruction of the isocenter dose, D_iso, for DCAT was obtained convolving the transit signal values, obtained at different gantry angles, with the respective reconstruction factors determined by a house-made software. The method was tested with cylindrical and anthropomorphic phantoms and the results show that the reconstructed D_iso values can be obtained with an accuracy within ±2.5% in cylindrical phantom and within ±3.4% for anthropomorphic phantom.In conclusion, the transit dosimetry by EPID was assessed to be adequate to perform DCAT in vivo dosimetry, that is not realizable with the other traditional techniques. Moreover, the method proposed here could be implemented to supply in vivo dose values in real time.     

Predictive (un)distortion model and 3-D reconstruction by biplane snakes

This paper is concerned with the three-dimensional (3-D) reconstruction of coronary vessel centerlines and with how distortion of X-ray angiographic images affects it. Angiographies suffer from pincushion and other geometrical distortions, caused by the peripheral concavity of the image intensifier (II) and the nonlinearity of electronic acquisition devices. In routine clinical practice, where a field-of-view (FOV) of 17-23 cm is commonly used for the acquisition of coronary vessels, this distortion introduces a positional error of up to 7 pixels for an image matrix size of 512 x 512 and an FOV of 17 cm. This error increases with the size of the FOV. Geometrical distortions have a significant effect on the validity of the 3-D reconstruction of vessels from these images. We show how this effect can be reduced by integrating a predictive model of (un)distortion into the biplane snakes formulation for 3-D reconstruction. First, we prove that the distortion can be accurately modeled using a polynomial for each view. Also, we show that the estimated polynomial is independent of focal length, but not of changes in anatomical angles, as the II is influenced by the earth's magnetic field. Thus, we decompose the polynomial into two components: the steady and the orientation-dependent component. We determine the optimal polynomial degree for each component, which is empirically determined to be five for the steady component and three for the orientation-dependent component. This fact simplifies the prediction of the orientation-dependent polynomial, since the number of polynomial coefficients to be predicted is lower. The integration of this model into the biplane snakes formulation enables us to avoid image unwarping, which deteriorates image quality and therefore complicates vessel centerline feature extraction. Moreover, we improve the biplane snake behavior when dealing with wavy vessels, by means of using generalized gradient vector flow. Our experiments show that the proposed methods in this paper decrease up to 88% the reconstruction error obtained when geometrical distortion effects are ignored. Tests on imaged phantoms and real cardiac images are presented as well.     

Which variable of stenosis severity best describes the significance of an isolated left anterior descending coronary artery lesion? Correlation between quantitative coronary angiography, intracoronary Doppler measurements and high dose dipyridamole echocardiography

Herein is a procedure described using a semipermeable membrane (SPM) for enrichment of organic chemicals from lipid-containing samples. Dialysis with SPMs in an organic solvent can separate organochlorine contaminants such as non-, mono-, and di-o-PCBs, PCDDs, PCDFs, PCDTs, PCNs, pesticides, and PAHs from lipids. The method is nondestructive and more than 20 g of lipid can be dialyzed in a single membrane with acceptable recoveries of the internal standards, nearly independent of amount and type of lipid dialyzed. The lipid removal process shows good consistency between subsamples, and the lipid content can be reduced by 90-99%, depending on species and amount lipid. Neither triglycerides nor phospholipids were obtained in the dialysate fraction. The utility and reliability of the method is displayed by good precision for 72 PCBs and 27 organochlorine pesticides in the concentration range 0.05-50 micrograms/sample for triplicate subsamples, by the consistency in PCDD/F levels compared to a classic analytical procedure, and by the analysis of the above listed chemicals in approximately 200 biological samples of a wide variety of types. This technique can also be used as an enrichment device for contaminants when huge amounts of lipids are extracted for toxicological studies. Moreover, it is possible to use SPM to cleanup other samples from molecules with relatively high masses, e.g. sediments, soil, compost, and tar materials.     

SIRIO-OTS 12 GHz orbital diversity experiment at Fucino

When rain occurs at a site, orbital diversity (OD) may be an alternative diversity scheme for future satellite communications above 10 GHz. The SIRIO-OTS OD attenuation measurements at 12 GHz with an aperture angle of 27.8° at Fucino show that the statistical gain obtainable is 20-25% of the OTS attenuation in decibels (if OTS is assumed as the satellite of the normal mode and SIRIO as OD resource, or spare link), or 30-40% of the SIRIO attenuation (if SIRIO is assumed as the satellite of normal mode, and OTS as OD resource). At 12 GHz these percentages represent a gain of a few decibels but at higher frequencies, such as 20/30 GHz, the gain may be multiplied by 2.5 to 5, giving noticeable power reductions. The instantaneous gain is also analyzed. The fundamental aspects of balancing an unbalanced diversity configuration are shown by applying the theory to the unbalanced SIRIO-OTS OD. Fade durations of the joint link show the same characteristics as the single-path ones: few long fades and many short fades. More important, the intervals of time in which the resource is used are long; this fact is favorable to the diversity configuration since switchover inefficiency is lowered     

Clinical and hormonal effects of the combination gonadotrophin-releasing hormone agonist plus oral contraceptive pills containing ethinyl-oestradiol (EE) and cyproterone acetate (CPA) versus the EE-CPA pill alone on polycystic ovarian disease-related hyperandrogenisms

This study examined how cyclophosphamide (CP)-induced cystitis related manifestations (bladder inflammation and behavioral impairment) differed in female and male Sprague-Dawley rats. Under transient halothane-O2-N2O gas anesthesia, a single dose of CP was injected (100 mg/kg i.p. in 1 ml saline) and the animal's behaviors analyzed for a period of 4 h using a protocol that permits quantitative analysis of behavioral impairment. The rats were then sacrificed and their bladders removed for histological quantification of inflammation. All CP-injected, but not control rats, exhibited a range of impairment behaviors that increased rapidly over a period of 2 h, gradually reaching plateau levels over the next 2 h. Female rats initially developed behavioral responses faster than male rats, but reached the same mean peak values overall as males. No sex differences were observed in CP-induced bladder inflammation. Influences of time-of-day and estrous stage were further examined in females. Time-of-day had no effect on the degree of bladder inflammation. Although there were also no significant time-of-day differences in behavioral impairments, impairment scores from 90 min after the injection consistently tended to be lower for rats injected 5 h versus 9 h after lights on. Overall, the effects of estrous stage were also insignificant. However, a subset of rats who were in the estrous stage of their cycle early in the morning of the experimental day developed the most severe degree of bladder inflammation, but failed to develop the severe behavioral impairments shown by all the other rats. These results show that there are seemingly only minor sex differences in the overall behavioral and inflammatory consequences of CP injections, as evidenced by similar final degrees of behavioral impairment and inflammation. These results also suggest, however, that there are sex differences in the etiology of the disease process. These differences are evidenced by the more rapid development of behavioral symptoms in females and the susceptibility of some of those having shown morning estrous smears to develop very severe bladder inflammation in absence of corresponding behavioral impairment. The multiple influences of sex and estrous condition on CP-induced cystitis related manifestations observed here underline the complexity of the etiological factors associated with the cystitis disease process.     

Analytical strategies in the structural characterization of elcatonin

Jaundice in critically ill patients may be difficult to explain. This study analyzes pathophysiologically relevant data, and discusses the prognostic value of hyperbilirubinemia. A total of 1275 patients were prospectively enrolled; 7.6% developed hyperbilirubinemia of at least 2 mg/dl. Mortality in icteric patients was significantly higher (29%) than in the non-icteric group. Sepsis, shock and the number of blood transfusions are very important in hyperbilirubinemia. Nevertheless, in critically ill patients, jaundice per se is not a sign of poor outcome; indeed it only reflects the underlying disease.     

Copolar and cochannel interference from adjacent satellites duringrain at 12 GHz

The authors report experimental results on copolar and cochannel interference from adjacent satellites during rain obtained by measuring simultaneous rain attenuations in the 12 GHz band in two convergent slant paths to receivers located in the Fucino plain (Italy) from the geostationary satellites SIRIO (15°W) and OTS (10°E) in 1978-1980. The results presented here are directly applicable to the design of actual TV satellite broadcasting systems and they can be extrapolated to higher frequencies to design future satellite communication systems