Search

Abstract: The thermal stability of nanocomposite metals (a nanostructured copper matrix embedding niobium nanotubes) is investigated via time-resolved in situ annealing under synchrotron high-energy X-rays. The diffraction peak profile analysis demonstrates that internal-stress relaxation begins in the Nb nanotubes at a temperature far below the bulk recrystallization temperature and follows size-specific regimes originating from a proximity effect with the nanostructured Cu matrix: the increased Cu–Nb interface surface disrupts internal-stress relaxation processes, confirming the larger thermal resistance of nanostructured materials. [ABSTRACT FROM AUTHOR]

Ni-based superalloys are composed of a matrix with an austenitic face-centered cubic (FCC) crystal structure (γ phase) which is generally strengthened by the presence of a high fraction of ordered FCC precipitates γ′ (Ni3(Ti,Al) type) and/or γ″ (Ni3Nb type). Plasma assisted nitriding of various Ni-based superalloys, either polycrystals (Haynes®230, Inconel®718, Udimet®720Li, N18) or single crystals (MC2 and MC-NG), presenting from 100vol.% to 30vol.% of γ phase, has been performed at moderate temperature (400°C) to shed light on the specific responses of the different (δ, γ′, γ″) precipitates under nitriding. Characterizations by glow discharge optical emission spectroscopy and scanning electron microscopy have evidenced the formation of nitrided layers with thicknesses varying from ~1μm to ~8μm depending on alloys and treatment duration. In all alloys, X-ray diffraction on nitrided samples confirms that the γ phase is nitrided, as in austenitic stainless steels, to form the expanded austenitic FCC phase γN, a nitrogen insertion solid solution, with a mean concentration of ~25at.% N. CrN nitrides were also identified. The incorporation of nitrogen within the precipitates appeared to depend on the alloy microstructure: for polycrystals, regardless of their proportion, the δ, γ′ or γ″ precipitates seem nitrided in similar proportion than the matrix γ although the exact nature (nitrides or expanded δ, γ′, γ″ phases) of the obtained nitrided phases was not confirmed. On the contrary, in the single crystal MC2, the γ′ precipitates accommodate a much lower nitrogen amount, in the range 3–5at.%. Whatever the materials, the surface swelling induced by the nitrogen uptake is only relative to the total incorporated nitrogen quantity and is roughly independent on the nature of the nitrided phases. [ABSTRACT FROM AUTHOR]

Combining radiation and hormone therapy has become common clinical practice in recent years for locally advanced prostate cancer. The use of such concomitant therapy in the treatment of breast disease has been very infrequently reported in the literature, but such an application seems justified given the common hormonal dependence of breast cancer and the potential synergetic effect of these two treatment modalities. As adjuvant therapy, tamoxifen is the key drug in the hormonal treatment arsenal, providing a significant improvement in both local control and global survival rates. Aromatase inhibitors are currently being evaluated in this setting, and initial results are promising. In vitro, tamoxifen does not seem to offer a protective effect against radiation. In clinical use, the few available published studies confirm the superiority of the association of radiation with tamoxifen as opposed to radiation therapy alone in decreasing local recurrences of surgically removed breast tumors. Toxicity associated with such concomitant therapy includes mainly subcutaneous and pulmonary fibroses. However, subcutaneous fibrosis and its cosmetic impact on the treated breast are frequently described side effects of radiation therapy, and their incidence may actually be reduced when tamoxifen is associated. The evidence is less controversial for pulmonary fibrosis, which is more common with the concomitant therapy. The association of radiation and aromatase inhibitors has as of yet rarely been reported. Letrozole (Femara®) has a radiosensitizing effect on breast-cancer cell lines transfected with the aromatase gene. Clinical data assessing this effect in vivo are not available. The FEMTABIG study (letrozole vs. tamoxifen vs. sequential treatment) did not specify the sequence of radiation and hormonal therapy. The ATAC study comparing the adjuvant use of anastrozole (Arimidex®) and tamoxifen does not provide any information on the number of patients receiving radiation concomitant with the hormonal treatment, and in addition also does not specify the sequence of radiation and hormonal treatment. The TEAM study compared exemestane (Aromasine®) and tamoxifen, but specified that hormonal treatment follow the completion of radiation therapy. [Copyright &y& Elsevier]

Purpose. – To report our experience on treatment planning and acute toxicity in 16 patients suffering from clinically localized prostate cancer treated with high-dose intensity-modulated radiation therapy (IMRT).Patients and methods. – Between March 2001 and October 2002, 16 patients with clinically localized prostate cancer were treated with IMRT. Treatment planning included an inverse-planning approach, and the desired beam intensity profiles were delivered by dynamic multileaf collimation. All patients received the entire treatment course with IMRT to a prescribed dose of 78 Gy. All IMRT treatment plans were compared with a theoretical conventional three-dimensional conformal radiation therapy (3D-CRT). Acute lower gastro-intestinal (GI) and genito-urinary (GU) toxicity was evaluated in all patients and graded according to the Common Toxicity Criteria for Adverse Events version 3.0 (CTCAE v. 3.0). A relationship between dose volume and clinical toxicity was evaluated.Results. – Ninety-five percent of the PTV2 received more than 76 Gy using IMRT or 3D-CRT with no difference between both methods. The dose–volume histogram mean obtained for the PTV2 was not different between IMRT and 3D-CRT. IMRT improved homogeneity of the delivered dose to the PTV2 as compared with 3D-CRT (7.5 vs 9%, respectively). Ninety-five percent of the PTV1 received 5 Gy more using IMRT with protection of the bladder and the rectum walls. The benefit was considered below 75 and 70 Gy for the wall of the bladder and the rectum, respectively. Grade 2 GI and GU toxicity was observed in four (25%) and five (31%) patients, respectively. No grade 3 toxicity was observed. There was a trend towards a relationship between the mean rectal dose and acute rectal toxicity but without statistical significant difference (P =0.09).Conclusion. – Dose escalation with IMRT is feasible with no grade 3 or higher acute GI or GU toxicity. Examination of a larger cohort and longer-term follow-up are warranted in the future. [Copyright &y& Elsevier]

Objectives: We analysed the acute toxicity observed in the European Organisation for Research and Treatment of Cancer (EORTC) randomised trial 22863 comparing conventional external irradiation with or without an agonist analogue of gonadotropin-releasing hormone in high-risk prostate cancer patients.Methods: Four hundred five patients that received a dose of at least 30 Gy were considered evaluable for acute toxicity assessment. Toxicity was grouped in a few categories: general, genito-urinary, and lower gastro-intestinal. Univariate and multivariate analyses were performed using the World Health Organisation (WHO) toxicity score and grouping together toxicity scores in different bimodal and trimodal groups.Results: Overall, our data show that age, previous surgery and irradiation dose are important predictive factors for acute toxicity, but not the use of combined hormone therapy. Fifteen percent of patients suffered of moderate to severe acute toxicity (WHO G3–G4). Life threatening toxicity was observed in six cases (1.5%).Conclusions: The assessment of toxicity combining in different groups the original five scores scale produced conflicting results similar to those commonly reported in literature. Interpretation of the role of pre-treatment factors with uneven distribution in the study requires careful evaluation. These data obtained with conventional curative irradiation of high-risk prostate cancer patients are proposed for comparison with results achieved using modern state-of-the-art irradiation techniques. [ABSTRACT FROM AUTHOR]

Abstract: Cancers of the paranasal sinuses are rare tumors, with treatment based on a multidisciplinary approach. Surgery and radiation therapy, possibly associated with chemotherapy are used to obtain 5 years specific survival rate of 60–70 %. Advances in radiotherapy, including the use of imaging for 3D conformal approach require precise knowledge of the radioanatomy for this type of tumor to determine the different volumes of interest. Purpose of this study was to specify radioanatomy and conformal radiation modalities for cancers of the sinuses, and is illustrated by a case report. [ABSTRACT FROM AUTHOR]