6 MV和10 MVX线宫颈癌经典适形照射治疗计划比较分析

目的 研究不同身高、体质量宫颈癌术后患者不同能量6 MV和10 MVX线经典适形四野照射治疗计划的剂量分布,指导临床照射能量的选择.方法 选取21例患者,按体质指数(BMI)分为肥胖组和非肥胖组并进行6 MV和10 MV X线箱式照射治疗的计划设计,统计分析治疗计划相关的剂量学参数.结果 采用10 MV X线的治疗计划:①2组均能降低计划靶区(PTV)的最大剂量(Dmax)、最小剂量(Dmax)、提高适形指数(CI)和不均匀性指数(HI);不能降低平均剂量(Dmax);非肥胖组中位剂量(D50)有变化;肥胖组患者更能有效地降低Dmax和提高HI.②能降低靶区周围危及器官(OAR)的剂量.③更能有效地减少患者中低受量体积.④更能有效地减少机器跳数(MU).结论 对于肥胖宫颈癌患者,采用10 MV X线治疗计划具有优势.     

基于笔形束散射核的非均匀模体透射平面散射线分析

目的:利用蒙特卡罗方法分析透射平面上散射光子的物理性质以及非均匀模体厚度对散射核的影响,为基于电子射野影像设备（EPID）的在体剂量验证研究提供基础。方法:利用EGSnrc建立笔形束散射核模型,并模拟获得X射线穿过非均匀模体（水肺水/水骨水模体）以及相应等效厚度水模后30 cm处透射平面上的多种散射线能量注量分布,并分析水肺水/水骨水模体与其等效厚度水模体在散射线能量注量分布上的差异。结果:散射核中一阶康普顿散射线最大能量注量在1×10-4 MeV·cm-2数量级,当离轴距离为8~12 cm时下降至最大值的一半,而散射核中其它散射线能量注量最大值在1×10-5 MeV·cm-2数量级附近或以下。对于水肺水/水骨水模体,散射核能量注量相对偏差变化为±1.2%~±11.5%,且随模体非均匀层厚度增大而增大。结论:散射核中一阶康普顿散射线占比最大,同时也贡献了大部分能量注量相对偏差,在通过散射核来重建非均匀模体后EPID平面上的射线分布时,应着重考虑一阶康普顿散射线对重建结果的影响,并对其进行有效的修正。     

Determination of emission probabilities of gamma photons in the decay of Co

The emission probabilities of gamma photons in the decay of ⁵⁶Co were determined at Czech Metrology Institute (CMI) by means of an HPGe detector. This detector was calibrated experimentally and by MCNP-computation in the energy range from 40 to 2754 keV for a point source geometry and source-to-detector distance of 25 cm. Experimental and computed peak and total efficiencies were compared and calibration curves were determined. Full-peak efficiencies were calculated for all ⁵⁶Co γ-ray energies, and were used to calculate the emission probabilities. A set of point sources was prepared from a ⁵⁶Co solution. The solution was standardized using the 4πβ–γ coincidence method, and an ampoule was sent to international reference system for activity measurement of γ-ray emitting radionuclides (SIR). Each point source was measured with the HPGe detector at a source-to-detector distance of 25 cm. Coincidence emission probabilities of all the gamma photons were calculated and used to determine the summing correction factors.     

Sum rules and determination of exciton coupling using absorption and circular dichroism spectra of biological polymers

Optical spectra of biological polymers contain important information about their structure and function in living organisms. This information can be accessed by extracting an optical interaction of monomers, i.e., their exciton coupling, from experimental data. This coupling is sensitive to molecular structure, geometry, and conformation and can be used to characterize them. However, the accurate determination of exciton coupling in important biological molecules is difficult because inhomogeneous broadening smears out the monomer interaction. We suggest a way to overcome this problem by applying exact sum rules. These sum rules are derived by establishing a straightforward relationship between integral characteristics of absorption and circular dicroism spectra, and exciton coupling. Exciton coupling between AT pairs in native DNA conformation is estimated by applying these sum rules to DNA hairpin optical spectra as V₀ ~ 0.035 eV in agreement with the earlier numerical calculations.     

Breast Radiotherapy with Mixed Energy Photons; a Model for Optimal Beam Weighting

Utilization of high energy photons (>10MV) with an optimal weight using a mixed energy technique is a practical way to generate a homogenous dose distribution while maintaining adequate target coverage in intact breast radiotherapy. This study represents a model for estimation of this optimal weight for day to day clinical usage. For this purpose, treatment planning computed tomography scans of thirty-three consecutive early stage breast cancer patients following breast conservation surgery were analyzed. After delineation of the breast clinical target volume (CTV) and placing opposed wedge paired isocenteric tangential portals, dosimeteric calculations were conducted and dose volume histograms (DVHs) were generated, first with pure 6MV photons and then these calculations were repeated ten times with incorporating 18MV photons (ten percent increase in weight per step) in each individual patient. For each calculation two indexes including maximum dose in the breast CTV (Dmax) and the volume of CTV which covered with 95% Isodose line (VCTV, 95%IDL) were measured according to the DVH data and then normalized values were plotted in a graph. The optimal weight of 18MV photons was defined as the intersection point of Dmax and VCTV, 95%IDL graphs. For creating a model to predict this optimal weight multiple linear regression analysis was used based on some of the breast and tangential field parameters.The best fitting model for prediction of 18MV photons optimal weight in breast radiotherapy using mixed energy technique, incorporated chest wall separation plus central lung distance (Adjusted R2=0.776). In conclusion, this study represents a model for the estimation of optimal beam weighting in breast radiotherapy using mixed photon energy technique for routine day to day clinical usage.     

Effect of Gibberellic Acid on the Radiation-stunted Seedlings of Maize

Summary

Maize seeds of the single cross WF 9 × 38?11 were irradiated with pile neutrons with doses ranging from 1 × 10¹² Np to 5 × 10¹⁴ Np and then treated with gibberellic acid (GA). In one set of experiments the seeds were soaked in GA for 24 hours and raised in sand. In another set they were sprouted in water, and seedlings with a 2–3 cm root-length were from then grown on in GA solution. It was evident from both these experiments that GA can reverse the stunting of seedlings caused by radiation.     

长脉冲1 064nm激光联合高硫型水化硫铝酸钙540nm光子治疗面部毛细血管扩张症

目的探讨应用长脉冲1064nm激光联合高硫型水化硫铝酸钙（AFT）540nm光子治疗面部毛细血管扩张症。观察治疗效果。方法采用“飞顿I号”复合血管治疗仪,根据皮肤分型及治疗反应,选择不同能量密度和脉宽进行治疗。结果60例患者经4～6次治疗,均有疗效;无1例出现瘢痕、色素变化,总有效率达100％。结论长脉冲1064nm激光联合AFT 540nm光子治疗面部毛细血管扩张症效果明显,是一种安全、有效的治疗方法。     

Modulation of human neutrophil oxidative metabolism and degranulation by extract of Tamarindus indica L. fruit pulp

The tamarind (Tamarindus indica L.) is indigenous to Asian countries and widely cultivated in the American continents. The tamarind fruit pulp extract (ExT), traditionally used in spices, food components and juices, is rich in polyphenols that have demonstrated anti-atherosclerotic, antioxidant and immunomodulatory activities. This study evaluated the modulator effect of a crude hydroalcoholic ExT on some peripheral human neutrophil functions. The neutrophil reactive oxygen species generation, triggered by opsonized zymosan (OZ), n-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate (PMA), and assessed by luminol- and lucigenin-enhanced chemiluminescence (LumCL and LucCL, respectively), was inhibited by ExT in a concentration-dependent manner. ExT was a more effective inhibitor of the PMA-stimulated neutrophil function [IC₅₀ (in μg/10⁶cells) = 115.7 ± 9.7 (LumCL) and 174.5 ± 25.9 (LucCL)], than the OZ- [IC₅₀ = 248.5 ± 23.1 (LumCL) and 324.1 ± 34.6 (LucCL)] or fMLP-stimulated cells [IC₅₀ = 178.5 ± 12.2 (LumCL)]. The ExT also inhibited neutrophil NADPH oxidase activity (evaluated by O₂ consumption), degranulation and elastase activity (evaluated by spectrophotometric methods) at concentrations higher than 200 μg/10⁶ cells, without being toxic to the cells, under the conditions assessed. Together, these results indicate the potential of ExT as a source of compounds that can modulate the neutrophil-mediated inflammatory diseases.     

快中子放射治疗软组织肉瘤55例

[目的]观察快中子加光子混合射线放射治疗软组织肉瘤的临床疗效。[方法]19例软组织肉瘤患者接受快中子及光子根治性放射治疗（根治放疗组），36例为术后放疗（术后放疔组）。光子照射剂量为40～50Gy，快中子照射剂量为8～12Gv。[结果]放疗结束后根治性放疗组3年、5年、8年生存率分别为47．4％，36．8％及26．3％；术后放疗组分别为86．1％、69．6％及27．3％。放疗后所有患者均未出现严重并发症。[结论]快中子术后放疗是治疗软组织肉瘤的有效手段。