39. Pulsed dose rate brachytherapy – describing of a method and a review of clinical applications

IntroductionPulsed Dose Rate (PDR) treatment is a new brachytherapy modality that combines physical adventages of high-dose-rate (HDR) technology (isodose optimization, radiation safety) with the radiobiological adventages of low-dose-rate (LDR) brachytherapy.Pulsed brachytherapy consists of using a stronger radiation source than for LDR brachytherapy and is giving a senes of short exposures of 10 to 30 minutes in every hour to approximately the same total dose in the same overall as with the LDR. Modern afterloading equipment offers some advantages over intersitial or intracavitary insertion of separate needles, tubes, seeds or wires. Isodose volumes in tissue can be created flexibly by a combination of careful placement of the catheter and adjustment of the dwell times of the computerized stepping source. Automatic removal of the radiation sources into a shielded safe eliminates radiation exposures to staff and visitors. Radiation exposure is also eliminated to the staff who formerly loaded and unloaded a multiplicity of radioactive sources into the catheters, ovoids, tubes etc.Material and methodsThis retrospective study based on summarized clinical investigations analyses the feasibility, differences between methods of brachytherapy and preliminary oncologic results of PDR brachytherapy.Since July 2000 15 patients were treated in Greatpoland Cancer Center using PDR brachytherapy. They were 10 patients with recurrent brain malignant glioma, 2 with recurrent nasopharyngeal cancer, and patients with lip cancer, recurrent breast cancer and recurrent salivary gland cancer. Only patient with lip cancer was treated radically. Nucletron PDR unit with 1 Ci source and PLATO planning system were used.ResultsShort time of observation doesn’t allow to draw a radical conclusions. On the ground of literature and preliminary own results it seems that PDR brachytherapy is save and efficient method of treatment. The most important complication was a local infection in place of implanted catheter. In some cases (for example in patients with recurrent malignant glioma after teletherapy) PDR brachytherapy perhaps could be a treatment of choice

Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes

<p>Abstract</p> <p>Background</p> <p>The present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters.</p> <p>Methods</p> <p>Holstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate.</p> <p>Results and Discussion</p> <p>Frequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.</p> <p>There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows.</p> <p>Conclusion</p> <p>The GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.</p

Deformation of Aluminium Bronze by HPT and ECAP Methods

Aluminium bronzes BA1032 having a multiphase microstructure, is low-deformable materials with strength close to that of high-strength steels. The influence of high-pressure torsion (HPT) and equal channel angular pressing (ECAP) on aluminium bronze structure was presented. The HPT method was found to be unsuitable for the processing of the investigated aluminium bronzes. The studies have indicated that it is possible to deform multiphase aluminium bronzes BA1032 in the ECAP process at a temperature of 400-500°C. The deformation of the bronzes at lower temperatures encounters some difficulties cracks appear which make repeated ECAP impossible

Numerical Modelling of Welding of Car Body Sheets Made of Selected Aluminium Alloys

In the paper, verification of welding process parameters of overlap joints of aluminium alloys EN AW-6082 and EN AW-7075, determined on the grounds of a numerical FEM model and a mathematical model, is presented. A model was prepared in order to determine the range of process parameters, for that the risk of hot crack occurrence during welding the material with limited weldability (EN AW-7075) would be minimum and the joints will meet the quality criteria. Results of metallographic and mechanical examinations of overlap welded joints are presented. Indicated are different destruction mechanisms of overlap and butt joints, as well as significant differences in their tensile strength: 110 to 135 MPa for overlap joints and 258 MPa on average for butt joints