射野方向优化技术在胸中上段食管癌调强放疗中的应用

目的：比较射野方向优化设野和均匀布野的胸上段和胸中段食管癌调强放疗计划的剂量学差异,探讨射野方向优化技术在食管癌放疗计划设计中的作用。方法：使用Varian Eclipse 8.6治疗计划系统,对7例胸上段食管癌和7例胸中段食管癌患者分别制定7野均分（EGA）和射野方向优化（BAO）的调强计划。根据剂量体积直方图（DVH）比较靶区、脊髓、双肺、心脏和正常组织的剂量体积参数,靶区适形度指数（CI）、均匀度指数（HI）以及总治疗跳数（MU）,利用SPSS软件进行配对t检验。结果：BAO计划的射野方向分布明显不同于EGA计划,并且患者间的射野方向分布也存在一定的差异。对于胸上段食管癌,BAO计划PTVD2%（-1.12%）、CI（2.42%）、HI（-11.88%）劣于EGA计划（P〈0.05）,BAO计划双肺MLD（3.77%）、V5（6.48%）、V10（6.16%）,Body-PTV的V5（7.30%）明显优于EGA计划（P〈0.05）。对于胸中段食管癌,BAO计划PTV D2%（0.88%）、Dmean（0.34%）,脊髓D1%（5.65%）,双肺MLD（9.10%）、V5（11.93%）、V10（8.65%）、V15（8.60%）,Body-PTV的Dmean（3.63%）、V5（8.65%）以及MU（17.26%）均明显优于EGA计划（P〈0.05）。结论：在胸中上段食管癌放疗中,使用BAO技术能够产生个体化的治疗方案。对于胸上段食管癌,BGO计划对靶区剂量的覆盖没有改善,但降低了肺剂量,减少了放射性肺炎发生的可能性;对于胸中段食管癌,BGO计划在不降低靶区剂量覆盖和较少MU的情况下,可以显著减少肺、脊髓、正常组织的剂量。与胸上段食管癌相比,胸中段食管癌使用BAO技术能够更好的改进调强放疗计划的质量。     

下咽癌静态调强放疗与两种射野宽度设计螺旋断层治疗的剂量学研究

目的:通过比较下咽癌常规静态调强(SaSIMRT)与钨门宽度分别设置1.05 cm、2.50 cm两种螺旋断层治疗(Helical tomotherapy,HT/HT1.05、HT2.50)的剂量学差异,探讨两种照射技术的特点及剂量学优势的可能性.方法:选择10例下咽癌术后患者分别设计SaS IMRT、HT1.05、H...     

非基于先验知识的胃癌容积弧形调强治疗自动计划

目的:评估非基于先验知识的容积弧形调强治疗（VMAT）自动计划在胃癌放疗中的可行性。方法:回顾性地收集胃癌术后放疗患者30例。使用基于Python语言开发的自动VMAT计划程序设计胃癌放疗计划。所有目标参数设置和优化基于处方和目标函数值而非历史计划;然后对比自动计划和人工计划的剂量学参数、计划时间。结果:人工计划与自动计划均能满足靶区剂量覆盖。对比人工计划,自动计划的脊髓、小肠和肾脏的吸收剂量均显著降低（P<0.05）。然而,两种计划中十二指肠、肝脏等邻近靶区的危及器官的吸收剂量差异无统计学意义（P>0.05）。此外,自动计划的中位计划时间较人工计划减少23.9 min（P<0.05）。结论:对于胃癌,非基于先验知识的自动计划能在满足靶区剂量覆盖的同时显著降低远离靶区的危及器官放疗剂量,提高计划效率。     

宫颈癌后装治疗剂量的调强优化方法

目的：通过计算机编程,实现两种宫颈癌后装治疗剂量的调强优化方法,并与传统的A点优化方法进行比较。方法：选择一套已放置3根施源器（1根在宫腔,2根在隆穹）的宫颈癌患者的CT图像,采用VC＋＋编程,读入图像并重建施源器,然后根据靶区器官的限量约束条件（处方剂量为5 Gy）,自动激活部分驻点,分别采用模拟退火算法和随机最小二乘法进行调强逆向计算驻点的时间。接着,设A点（宫口上2 cm,旁开2cm）为剂量参考点,取上述相同的驻点,以均等权重方式计算驻点时间。最后比较3种优化方法的剂量分布。结果：在模拟退火法、随机二乘法和A点方法中,5 Gy覆盖靶区的体积分别为84.2%、80.2%和79.5%,靶区的D90分别为4.1 Gy、4.3 Gy和3.7 Gy,直肠D2cc为4.6 Gy、3.2 Gy和3.9 Gy,膀胱的D2cc为5.0 Gy、2.7Gy和4.1 Gy,靶区剂量的均匀度为65%、49%和45%。结论：模拟退火算法可以同时兼顾靶区受量和重要器官限量,剂量均匀性好,能满足个体化后装治疗的需求。随机最小二乘法虽能提高靶区的D90,减少直肠膀胱的受量,但相邻驻点之间的时间梯度变化较大。     

遗传算法在放射治疗计划射野参数优化中的应用

随着调强放疗和逆向治疗计划的发展,在放射治疗中如何自动选择射野参数受到广泛的关注,由于遗传算法具有搜索速度快,搜索空间广的特点,在放射治疗计划参数优化中得到了越来越多的应用,本文在积极跟踪国内外最新文献的基础上对常规优化算法的优缺点进行了比较,并重点介绍和讨论了遗传算法在优化射野参数方面的应用和发展.     

食管癌调强放疗计划中AAA算法与PBC算法的对比研究

目的：比较Varian治疗计划系统Eclipse中AAA算法和PBC算法在食管癌调强放疗中的剂量学差异。方法：选择22例中段食管癌患者,分别采用AAA算法与PBC算法设计两种调强计划,比较靶区的剂量分布,肺、脊髓和心脏等危及器官受照剂量的差异。结果：PGTV最大剂量、PTV平均剂量和左肺的平均剂量两种算法无显著性差异（P〉0．05）,PGTV和PTV最小剂量、PTV最大剂量、参考剂量所包靶区的体积（V95）和其他危及器官的受量,两种算法均有显著性差异（P〈0．05）。结论：与PBC算法相比,AAA算法对不均匀组织的修正更加精确,对于食管癌这种与肺相关的剂量计算采用AAA算法更准确一些。     

基于向量选择的神经纤维跟踪改进算法

为了使跟踪出的神经纤维更加平滑,本研究在基于向量选择跟踪算法的基础上,提出了一种改进方法。首先将向量选择的标准细化,区分出与前步纤维路经方向大致相反的体素;然后将此类体素的距离权重系数进行调整,将反方向贡献转化为正向贡献实现平滑跟踪。对比实验结果表明:本研究的改进算法能够有效去除纤维跟踪过程中出现的抖动,使纤维路径延长,更好的表现神经纤维的解剖特点和脑白质区域的连通性。     

一种基于特征选择的医学图像检索方法

提出了一种基于特征选择的医学图像检索方法。考虑到医学图像的多类别特性，将分类与检索结合，采用AdaBoost方法对样本进行多次抽样，并将分类精度作为判据对特征进行选择，选取少量有利于分类的特征，同时将单特征弱分类器增强为强分类器。在检索阶段，本方法在选择后的特征子集以及类别子空间中进行检索。实验结果表明，与传统方法相比，本方法能达到较高的查准率，计算量也明显降低。     

Prevalence of Cervical Enamel Projection and Its Impact on Furcation Involvement in Mandibular Molars: A Cone‐Beam Computed Tomography Study in Koreans

This study evaluated the prevalence of cervical enamel projections (CEPs) in mandibular molars, and analyzed the correlation between CEPs and furcation involvement (FI) based on cone‐beam computed tomography (CBCT) data in a Korean population. CBCT images obtained from March 2012 to August 2012 were analyzed. CEPs and FI on the buccal and lingual surface were classified in three‐dimensionally reconstructed images and cross‐sectional views, and the correlation between these two parameters was analyzed. In total, 982 teeth in 425 patients were analyzed. The overall prevalence rate of CEPs was 76% (71% and 27% on the buccal and lingual surfaces, respectively). Grade I CEPs were the most common, followed by CEPs of grades II and III. There was a statistically significant, but negligible correlation between the CEP grade and the degree of FI on the buccal and lingual surfaces. Within the limitations of this cross‐sectional study, a high prevalence of CEPs were found in a Korean population, but the role of CEPs in provoking FI appeared not to be decisive. Anat Rec, 299:379–384, 2016. © 2015 Wiley Periodicals, Inc.     

中学教师择业动机、职业认同和职业倦怠的关系

目的:探讨中学教师择业动机、职业认同和职业倦怠三者间的关系。方法:采用自己设计的择业动机类型调查题项、教师职业认同量表和中小学教师职业枯竭量表对241名中学教师进行调查。结果:①角色价值观和职业归属感对情绪衰竭、去个性化和知识枯竭分别具有负向预测作用和正向预测作用,职业价值观对去个性化和知识枯竭具有负向预测作用,职业行为倾向对个人成就感具有正向预测作用;②相比内部动机型教师和复合动机型教师,无动机型教师和外部动机型教师表现出了更低的职业认同度、更强的情绪衰竭感和更高的去个性化水平。结论:激发教师内部动机型,提高教师的职业认同,有助于降低其职业倦怠。     

Evaluation of rationality in prescribing,adherence to treatment guidelines,and direct cost of treatment in intensive cardiac care unit: A prospective observational study

Background:

Cardiovascular diseases (CVDs) remain the most common cause of sudden death. Hence, appropriate drug therapy in intensive cardiac care unit (ICCU) is crucial in managing cardiovascular emergencies and to decrease morbidity and mortality.

Objective:

To evaluate prescribing pattern of drugs and direct cost of therapy in patients admitted in ICCU.

Materials and Methods:

Patients admitted in ICCU of a tertiary care teaching hospital were enrolled. Demographic data, clinical history, and complete drug therapy received during their stay in ICCU were noted. Data were analyzed for drug utilization pattern and direct cost of treatment calculated using patient''s hospital and pharmacy bills. Rationality of therapy was evaluated based on American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

Result:

Data of 170 patients were collected over 2 months. Mean age of patients was 54.67 ± 13.42 years. Male to female ratio was 2.33:1. Most common comorbid condition was hypertension 76 (44.7%). Most common diagnosis was acute coronary syndrome (ACS) 49.4%. Mean stay in ICCU was 4.42 ± 1.9 days. Mean number of drugs prescribed per patient was 11.43 ± 2.85. Antiplatelet drugs were the most frequently prescribed drug group (86.5%). Mean cost of pharmacotherapy per patient was ‘2701.24 ± 3111.94. Mean direct cost of treatment per patient was ‘10564.74 ± 14968.70. Parenteral drugs constituted 42% of total drugs and 90% of total cost of pharmacotherapy. Cost of pharmacotherapy was positively correlated with number of drugs (P = 0.000) and duration of stay (P = 0.027).

Conclusion:

Antiplatelet drugs were the most frequently prescribed drug group. Mean number of drugs per encounter were high, which contributed to the higher cost of pharmacotherapy. ACC/AHA guidelines were followed in majority of the cases.