Quality-of-life measurement in patients undergoing radiation therapy for head and neck cancer: a Hong Kong experience

The aims of this study are (1) to establish a reliable and valid quality-of-life (QOL) questionnaire for Chinese patients with head and neck (H&N) cancer who are treated with radiation therapy and (2) to evaluate the impact of the immediate side effects of treatment on the QOL of these patients. The 39-item "Quality of Life Radiation Therapy Instrument with Head and Neck Companion Module" (QOL-RTI/H&N) was translated into Chinese. In the reliability evaluation phase (study module 1), the questionnaire was administered twice to 56 H&N cancer patients, 7 days apart, during the second and third week of radiation therapy. In the validity evaluation phase (study module 2), 138 patients completed the QOL-RTI/H&N before starting and at the end of radiation therapy. Sixty-nine of these 138 patients also completed the QOL-RTI/H&N during the second week of their radiation therapy, at the same time as completing the Functional Assessment of Cancer Therapy-Head and Neck (FACT-H&N) questionnaire. Cronbach alpha coefficients were 0.88 for the general-tool QOL-RTI and 0.90 for the H&N subscale. Test-retest reliability was satisfactory with intraclass correlation coefficients of 0.89 for the general-tool QOL-RTI and 0.75 for the H&N subscale. The instrument can discriminate between patients with stage I or II disease and those with stage III or IV disease (P < .05). Concurrent validity was established by the good agreement with the FACT-H&N (r = 0.86, P < .001). A highly significant deterioration was in the QOL from the baseline to the end of treatment (mean difference for general tool = 1.95, P < .001; mean difference for H&N subscale = 4.85, P < .001). The Chinese QOL-RTI/H&N is a reliable and valid tool for determining the QOL in H&N cancer patients receiving radiation therapy. The immediate side effects of treatment had a significantly negative impact on the patients' QOL. The impact was relatively large for the functional and treatment-site aspects.

Intelligent line segment perception with cortex-like mechanisms

This paper proposes a novel general framework for line segment perception, which is motivated by a biological visual cortex, and requires no parameter tuning. In this framework, we design a model to approximate receptive fields of simple cells. More importantly, the structure of biological orientation columns is imitated by organizing artificial complex and hypercomplex cells with the same orientation into independent arrays. Besides, an interaction mechanism is implemented by a set of self-organization rules. Enlightened by the visual topological theory, the outputs of these artificial cells are integrated to generate line segments that can describe nonlocal structural information of images. Each line segment is evaluated quantitatively by its significance. The computation complexity is also analyzed. The proposed method is tested and compared to state-of-the-art algorithms on real images with complex scenes and strong noises. The experiments demonstrate that our method outperforms the existing methods in the balance between conciseness and completeness.

On the fundamental mechanisms of active screen plasma nitriding

The nitriding mechanisms of conventional DC plasma treatments have been extensively studied and discussed, but no general agreement has been reached thus far. The sputtering and redeposition theory is among the most accepted ones but, even though this mechanism is feasible, its contribution to the nitriding effect is under question. Furthermore, the novel active screen plasma nitriding technique has been successful in treating samples left at floating potential, where sputtering can not be considered to play a major role. Therefore, it has been proposed that the material sputtered from the cathodic mesh of the active screen furnace (auxiliary cathode) and deposited onto the treated specimens is involved in the mass transfer of nitrogen. The contribution made by this transferred material is the focus of attention of the present study. The hardening effect on the treated specimens showed considerable correlation with the deposition layer, and the XRD analysis of this deposited material yielded possible FeN and FexN peaks. This finding supports the deposition of iron nitrides and their subsequent decomposition on the treated substrate as a mechanism of significance to the plasma nitriding treatments conducted in active screen experimental settings.