土方开挖技术在园林工程施工中的探析

随着社会经济的高速发展,我国园林工程建设得到极大地提升,土方开挖技术作为园林工程建设中的重要施工技术,其技术水平的高低直接影响着园林工程的质量。本文主要对园林工程土方开挖施工的准备及技术应用进行了分析,以期为提高园林工程施工的质量提供一个可靠地依据。

Influences of Motion Artifacts on Three-Dimensional Reconstruction Volume and Conformal Radiotherapy Planning

Objective ：To investigate the influences of motion artifacts on three-dimensional （3D） reconstruction volume and conformal radiotherapy planning. Methods： A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeedl6 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy （3D- CRT） plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system （TPS）. Results：For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from - 18.4% to 20.5% for a larger one. Conclusion ：The motion artifacts have great effects on 3 D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.

Evaluation of conventional radiotherapy vs. conformal radiotherapy in the treatment of non-small-cell lung cancer after surgical resection

Objective： To compare the survival fractions and radiation-induced complications of conventional radiotherapy （CV） vs. conformal radiotherapy （CF） for non-small-cell lung cancer （NSCLC） after surgical resection. Methods： Between 1990 and 2002, 167 patients underwent post-radiotherapy either CV （n = 90） or CF （n = 77） for pathological IliA NSCLC at the University of Texas M.D. Anderson Cancer Center. Patients and tumor charactedstics were balanced in the two treatment groups. Surgical resection mainly consisted of Iobectomy and mediastinal lymph node dissection. In the CV group, postoperative radiotherapy was delivered to 54.3 Gy （range 22-69.6 Gy） in 27 fractions （range 11-58 f） for 5-6 weeks, while the CF group with RT to 53.9 Gy （range 50-63 Gy） in 26 fractions （range 25-33 f） for 5-6 weeks. Overall survival, disease-free survival, local control and distant metastasis-free survival were calculated using the Kaplan-Meier method. The complications of radiotherapy were also compared between the two groups. The median follow-up duration was 36 months in the CV group while 24 months in the CF group. Results： No statistically significant differences were found in terms of disease-free survival, local-regional control and distant metastasis-free survival in the two treatment groups. However, the overall survival was found statistically significant different in the two groups （P = 0.014）. Postoperative radiotherapy complications such as weight loss, skin reaction, dysphagia, and cardiac related complication were similar in the two groups although the lung fibrosis, cardiac complications and hematologic complications were significantly different, and 8 cases of death in the CV group associated with cardiac complications while none was observed in the CF group. Conclusion： The treatment of stage IliA NSCLC using either CV or CF postoperative radiotherapy resulted in similar outcomes in terms of local control, disease-free survival and most of complications. However, CF could achieve better overall survival and less complications such as lung fibrosis, cardiac complications and hematologic complications. The advantage is worth further observation.

In-situ production of ozone and ultraviolet light using a barrier discharge reactor for wastewater treatment

A dielectric barrier discharge (DBD) reactor consisting of water-filled dielectric tube electrodes was used for the treatment of wastewater. The inner dielectric tube, which acted as the discharging electrode, was filled with an aqueous electrolyte solution. The outer dielectric tube, which served as the other electrode, was in contact with the wastewater, which was grounded. The present reactor system was energy-efficient for the production of ozone, not only because the perfect contact between the aqueous electrode and the dielectric surface minimized the loss of the electrical energy, but also because the DBD reactor was cooled by the wastewater. In addition, the ultraviolet (UV) light produced in the DBD reactor was able to assist in the wastewater treatment since the quartz tube used as the dielectric material was UV-transparent. The performance of the present DBD system was evaluated using a synthetic wastewater formed from distilled water and an azo dye, amaranth. The experimental parameters were the concentration of the electrolyte in the aqueous electrode, the discharge power, the initial pH of the wastewater and the concentration of hydrogen peroxide added to the wastewater. The wastewater treatment system was found to be effective for achieving decomposition of the dye.