Contouring cardiac substructures on average intensity projection 4D-CT for lung cancer radiotherapy: a proposal of a heart valve contouring atlas

BACKGROUND AND PURPOSE

A detailed contouring atlas of the heart valves is lacking. Existing heart contouring atlases have not been evaluated on average intensity projection four-dimensional non-contrast computed tomography (AVE-4D-CT) scans, routinely used for organ-at-risk delineation in lung cancer radiotherapy. We aimed to develop the heart valve contouring atlas and to assess inter-observer variation in delineation of the heart, its substructures, and coronary arteries on AVE-4D-CT scans, along with its impact on radiotherapy doses.

MATERIALS AND METHODS

A heart valve contouring atlas was developed. Five radiation oncologists and four cardiologists delineated the valves according to this atlas, and the remaining heart substructures according to the existing atlases, on AVE-4D-CT scans of ten patients who underwent radio(chemo)therapy for NSCLC. The observer contours were then compared to the collectively defined "reference" contours. Spatial variation was assessed using the Sørensen-Dice similarity coefficient (DSC), directed average Hausdorff distance (DAH), directed Hausdorff distance (HD), and the mean distance to agreement (MDA). The effect of spatial variation on radiotherapy doses was assessed using the patients' treatment plans.

RESULTS

Inter-observer contour overlap (mean DSC) was 0.68, 0.49, 0.45 and 0.45, and inter-observer contour separation (mean DAH) was 2.1, 3.4, 2.6 and 2.9 mm for the pulmonic (PV), aortic (AV), mitral (MV) and tricuspid valve (TV), respectively. Mean HD was higher for TV and MV (13.3 and 11.7mm) than for AV and PV (7.8 and 7mm). The highest mean MDA of 3.1mm was found for AV, and the lowest (1.9mm) for PV. Inter-observer agreement was the lowest for the coronary arteries, but statistically significant dose variation was found mainly in the left ventricular septal and anterior segments.

CONCLUSION

Our atlas enables reproducible delineation of the heart valves. Delineation of the heart and its substructures on AVE-4D-CT scans is feasible, with inter-observer variability similar to that reported on conventional non-contrast CT scans.

The SπRIT time projection chamber

The Superconducting Analyzer for MUlti-particles from RAdioIsotope (SAMURAI) Pion-Reconstruction and Ion-Tracker Time Projection Chamber (SπRIT TPC) was designed to enable measurements of heavy ion collisions with the SAMURAI spectrometer at the RIKEN radioactive isotope beam factory and provides constraints on the equation of state of neutron-rich nuclear matter. The SπRIT TPC has a 50.5 cm drift length and an 86.4 × 134.4 cm² pad plane with 12 096 pads that are equipped with the generic electronics for TPCs. The SπRIT TPC allows for an excellent reconstruction of particles and provides isotopic resolution for pions and other light charged particles across a wide range of energy losses and momenta. The details of the SπRIT TPC are presented, along with discussion of the TPC performance based on cosmic rays and charged particles emitted in heavy ion collisions.

Probing the Symmetry Energy with the Spectral Pion Ratio

Many neutron star properties, such as the proton fraction, reflect the symmetry energy contributions to the equation of state that dominate when neutron and proton densities differ strongly. To constrain these contributions at suprasaturation densities, we measure the spectra of charged pions produced by colliding rare isotope tin (Sn) beams with isotopically enriched Sn targets. Using ratios of the charged pion spectra measured at high transverse momenta, we deduce the slope of the symmetry energy to be 42<L<117  MeV. This value is slightly lower but consistent with the L values deduced from a recent measurement of the neutron skin thickness of ^{208}Pb.

Tuning of Classifiers to Speed-Up Detection of Pedestrians in Infrared Images

This paper presents an experimental evaluation of real-time pedestrian detection algorithms and their tuning using the proposed universal performance index. With this index, the precise choice of various parameters is possible. Moreover, we determined the best resolution of the analysis window, which is much lower than the initial window. By such means, we can speed-up the processing (i.e., reduce the classification time by 74%). There are cases in which we increased both the processing speed and the classification accuracy. We made experiments with various baseline detectors and datasets in order to confirm versatility of the proposed ideas. The analyzed classifiers are those typically applied to detection of pedestrians, namely: aggregated channel feature (ACF), deep convolutional neural network (CNN), and support vector machine (SVM). We used a suite of five precisely chosen night (and day) IR vision datasets.

Modulation of lymphocyte subsets and humoral immune response by florfenicol administered to sheep red blood cell-immunized broiler chickens

Florfenicol is a broad-spectrum bacteriostatic antibiotic commonly used for the treatment of systemic infections in farm animals. The aim of this study was to determine the effect of florfenicol on the percentage of T lymphocytes (CD3+, CD4+, CD8+, TCRgd+ cells) and B lymphocytes (Bu-1+ cells) and on total serum anti - sheep red blood cell (SRBC) haemagglutinin titer in the peripheral blood of SRBC-immunized broiler chickens. The study included three groups of broiler chickens differentiated by weight (0.5, 1.2, 2.4 kg). Florfenicol was administered orally at a dose of 30 mg/kg. The drug was administered eight times at 24 h intervals. The chickens were immunized with SRBC 24 h after administration of the third dose of florfenicol. Florfenicol increased the percentage of CD3+ blood lymphocytes with a corresponding decrease in the percentage of B lymphocytes in birds weighing 0.5 and 2.4 kg. Florfenicol reduced the production of total anti SRBC-haemagglutinins on day 5 after antigen injection in all three body weight groups of the broiler chickens. In conclusion, florfenicol exerted a modulating effect on the immune response of the birds and this should be taken into consideration when using this antibiotic for certain indications.

Alleviating Effect of α-Lipoic Acid and Magnesium on Cadmium-Induced Inflammatory Processes, Oxidative Stress and Bone Metabolism Disorders in Wistar Rats

Cadmium exposure contributes to internal organ dysfunction and the development of chronic diseases. The aim of the study was to assess the alleviating effect of α-lipoic acid and/or magnesium on cadmium-induced oxidative stress and disorders in bone metabolism, kidney and liver function, and hematological and biochemical parameters changes. Male rats were exposed to cadmium (30 mg Cd/kg of feed) for three months. Some animals exposed to Cd were supplemented with magnesium (150 mg Mg/kg of feed) and/or with α-lipoic acid (100 mg/kg body weight, four times a week). Cd intake inhibited body weight gain and lowered hemoglobin concentration, whereas it increased the activities of liver enzymes, as well as the level of oxidative stress, CTX-1 (C-terminal telopeptide of type I collagen, bone resorption marker), and CRP (C-reactive protein, marker of inflammation); it decreased vitamin D3, GSH (reduced glutathione), and the serum urea nitrogen/creatinine index. Mg and/or α-lipoic acid supplementation increased the antioxidant potential, and partially normalized the studied biochemical parameters. The obtained results show that both magnesium and α-lipoic acid decrease oxidative stress and the level of inflammatory marker, as well as normalize bone metabolism and liver and kidney function. Combined intake of α-lipoic acid and magnesium results in reinforcement of the protective effect; especially, it increases antioxidant defense.

Influence of physical training on markers of bone turnover, mechanical properties, morphological alterations, density and mineral contents in the femur of rats exposed to cadmium and/or alcohol

The aim of the study was to investigate the effect of physical training on bone parameters of rats exposed to alcohol (Al) and/or cadmium (Cd). Young female rats were divided into one control group and six groups exposed to Cd and/or Al. Al (36% calories of diet) and Cd (20 mg Cd/kg feed) were administered with liquid diet. Half of the rats from the treated groups were subjected to treadmill training (20 m/min for 0.5 h, 4 days a week). The experiment was carried out for 5 months. Al decreased the concentration of calcium (Ca) and iron (Fe) in the femur, whereas Cd and Cd + Al intake reduced the contents of Ca, Fe and zinc. Al and/or Cd caused an increase in both C-terminal telopeptide of type I collagen (CTX1; bone resorption marker) and osteocalcin (OC; formation indicator) and enhanced the degree of porosity and flexural strength of the femur. Al partially prevented the loss of Fe from the bone caused by Cd, but intensified the inhibition of growth of body weight in comparison with separate exposure to Cd. In rats co-exposed to Cd + Al, the levels of CTX1 were greater compared with those treated with Al or Cd separately, and the density was less than that in rats exposed to Al separately. The training caused increases of magnesium and Ca contents, decreases in CTX1, as well as increases in OC and bone density, decreasing their porosity. The effect of training on the bone status, however, was limited (especially in rats co-exposed to Cd and Al) because of the increase in their mineralization, stimulated by exercises, was insufficient in relation to collagen production intensity. In conclusion, training had favourable effects on some bone parameters, but did not compensate for the negative effects of Al and/or Cd exposure on the poor mineralization and histopathological and morphological changes in the femur.

Nuclear multifragmentation time scale and fluctuations of the largest fragment size

Distributions of the largest fragment charge, Zmax, in multifragmentation reactions around the Fermi energy can be decomposed into a sum of a Gaussian and a Gumbel distribution, whereas at much higher or lower energies one or the other distribution is asymptotically dominant. We demonstrate the same generic behavior for the largest cluster size in critical aggregation models for small systems, in or out of equilibrium, around the critical point. By analogy with the time-dependent irreversible aggregation model, we infer that Zmax distributions are characteristic of the multifragmentation time scale, which is largely determined by the onset of radial expansion in this energy range.

Isotopic dependence of the nuclear caloric curve

The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of (124)Sn and radioactive beams of (124)La and (107)Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (DeltaT approximately 0.6 MeV) appear for residue production near the onset of multifragmentation.

Bioelectrorheological model of the cell. 8. Cellular deformation under prolonged and recurrent shear stress

The influence of a prolonged and recurrent shear stress created by a periodic electric field on the mechanical properties of Neurospora crassa cells was investigated. Conditions were found under which modifications of cellular structures responding to stress become irreversible, and plastic flow of the viscoelastic structural elements is observed. The symmetry of the response of the cell under stress application and relaxation was lost, when compared to the reference conditions. To interpret the results a general rheological model was proposed. As previously described (Pawłowski et al., 1997), the existence of the three hypothetical supramolecular regions of the membrane (F, S and O) was suggested. Rheological parameters for the above regions were calculated. Theoretical functions were satisfactorily fitted to the experimental results.

Bioelectrorheological model of the cell. 4. Analysis of the extensil deformation of cellular membrane in alternating electric field

Analysis of the angular distribution of extensil mechanical stress, sigma e, generated in cytoplasmic membranes by an external oscillating electric field, is presented. Theoretical considerations show that sigma e is directly proportional to the local relative increase in membrane area and/or to the local relative decrease in its thickness. The magnitude of this stress depends on the position of the analyzed point of the membrane in relation to field direction. The maximal value, sigma eo, is reached at the cell "poles." The magnitude of sigma eo depends on electric and geometric parameters (in particular on field frequency) of the system studied. The foregoing analysis can be applied to quantitatively describe the destabilizing effects of the electric field on the cellular membrane, leading to its poration, fusion, and destruction.

Bioelectrorheological model of the cell. 5. Electrodestruction of cellular membrane in alternating electric field

Recently proposed analysis of the extensil stress developed in a cellular membrane subjected to an alternating electric field (Pawłowski, P., and M. Fikus, 1993. Bioelectrorheological model of the cell. 4. Analysis of the extensil deformation of the membrane in an alternating field. Biophys. J. 65:535-540) was applied in calculations of extensil stress threshold values, sigma eo[d], producing experimentally observed electrodestruction of cells within the frequency range of 7 x 10(1) - 3 x 10(5) Hz. It was shown that the susceptibility (s[d] = 1/sigma eo[d]), of the membrane to this process varies with field frequency and depends on the type of cells. Electrodestruction is facilitated in the 10(5)-Hz field. A rheological hypothesis explaining the experimentally observed dependence of membrane stability on electric field frequency was proposed and successfully tested for two other phenomena: electroporation and electrofusion.

Bioelectrorheological model of the cell. 3. Viscoelastic shear deformation of the membrane

An analytical electromechanical model of a spherical cell exposed to an alternating electric field was used to calculate shear stress generated in the cellular membrane. Shape deformation of Neurospora crassa (slime) spheroplasts was measured. Statistical analysis permitted empirical evaluation of creep of the cellular membrane within the range of infinitesimal stress. Final results were discussed in terms of various rheological models.