迭代重建联合低电压技术应用于儿童低剂量CT的进展

CT检查以其快速、简便、无创的特点在临床应用日益广泛,如何降低CT检查的辐射剂量,尤其是降低儿童CT检查的辐射剂量是热点问题。迭代重建技术（IR）可降低儿童CT扫描剂量,联合低电压技术可进一步实现降低辐射剂量。本文对IR联合低电压技术应用于儿童低剂量CT的研究进展进行综述。     

多频域后处理图像对计算机辅助检测数字胸片上肺结节能力的影响

目的评价多频域后处理数字胸片图像对计算机辅助检测系统输出结果的影响。方法选择经CT证实正常248名受检者的DR后前位胸片和30例有肺结节的DR后前位胸片,并应用Philips UNIQUE软件对其进行高频、低频处理。由2名10年以上经验的放射科医生结合CT图像阅读胸片,二人意见达成一致后,在数字化胸片上标记结节位置,保存标记结果并将其作为金标准。然后由CAD系统阅读后处理图像,由2名医师评价CAD系统在后处理图像上肺结节检测的假阳性区域和敏感度。结果 CAD系统在248例低频、常规和高频图像上分别显示了715、585和286个可疑区域,平均每例检出的假阳性区域分别为2.88个、2.36个和1.15个,3组图像检测的假阳性区域及组间差异均具有统计学意义。30例DR图像上共有38个金标准结节,CAD系统在低频、常规和高频图像上分别检测到33、30、28个结节,其检测敏感度分别为86.84%、78.95%和73.68%,ROC曲线下面积分别为0.722、0.670和0.618,3组图像之间检测的差异无统计学意义。结论高频、低频和常规图像模式对CAD系统检测能力无明显影响,但其在低频、常规和高频图像中检测的假阳性有逐渐增高的趋势,肺结节检测敏感度有逐步下降的趋势。     

正弦图确定迭代重建技术在降低胸部扫描剂量中的应用

目的 探讨正弦图确定迭代重建(SAFIRE)技术在降低胸部扫描剂量中的价值.方法 收集64例胸部疾病患者,采用第二代双源CT(Somatom Definition Flash CT)Flash Spiral模式进行平扫.将患者随机均分为2组.低剂量组:采用100 kV,并采用SAFIRE(值为3)技术进行重建.对照组:采用常规120 kV、滤波反投影(FBP)重建技术.测量比较2组患者气管分杈层面降主动脉的CT值与标准差(SD)、同层背部肌肉的CT值与SD值;比较两组胸部CT剂量指数(CTDI)及剂量长度乘积(DLP).由2名医师采用5分制对图像质量进行评价,并用Kappa检验评价观察者间的一致性.结果 两组图像质量均能完全满足临床诊断需求,观察者间具有较好一致性(Kappa=0.795).低剂量组CTDI为(3.23±0.53)mGy,DLP为(114.96±18.90)mGy·cm,有效剂量为(1.60士0.26)mSv,对照组CTDI为(5.27±1.07) mGy,DLP为(184.40±36.85)mGy· cm,有效剂量为(2.58±0.51)mSv;两组差异均有统计学意义(P均＜0.001).低剂量组和对照组气管分杈层面降主动脉CT值分别为(39.90±8.31)HU和(43.12±7.43) HU,图像噪声值分别为13.61±2.00和13.00±3.39;同层背部肌肉的CT值分别为(45.50±11.85)HU和(48.23±10.99) HU,图像噪声值分别为10.34±1.55和8.53士1.99,差异均无统计学意义(P均＞0.05).结论 在成人胸部扫描中,利用SAFIRE技术可在不影响图像质量的同时降低辐射剂量.     

一种基于形态学方法优化的种子填充算法及其在脑组织CT影像自动分割中的应用

医学图像的自动组织分割技术已经成为一种迫切的需求和发展趋势。本文将图像腐蚀和膨胀应用到基本种子填充算法中，提出了一种优化的种子填充分割算法，并应用于脑组织CT影像自动分割中。在进行种子选取时，利用腐蚀方法去除种子噪声，使种子的选取达到最优化。对分割后的图像借助膨胀方法消除空白点，使图像更平滑、清晰。实验证明了该方法的有效性。     

定量CT评价骨折愈合的有效性

目的 探讨定量CT(quantitative computed tomography,QCT)评价骨折愈合的有效性和准确性.方法 将24只健康新西兰兔随机数字表法分为A组(骨折愈合组,右胫骨中段横形骨折,用克氏针内固定)和B组(不愈合组,右胫骨中段横断骨折,制作5 mm骨缺损后以骨蜡封填断端和髓腔),分别于第2,4,8,12周各处理3只兔:先摄两侧胫骨X线片,拔出克氏针及定量CT检测,之后处死动物,将骨折段切取行组织学分析.以X线片和组织学表现为骨折愈合及不愈合的金标准,以受试者工作特征曲线(ROC)分析定量CT检测参数的评价效能,并以健侧胫骨相应节段为对照,观察定量CT参数结果的变化趋势.结果 A组X线片和组织学证实骨折在第2,4周骨折线清晰,为纤维骨痂填充,8～12周骨折线模糊至消失,骨皮质恢复完整连续性.B组X线片和组织学在第2、4周骨折线清晰,骨化不活跃,8～12周骨折线仍存在,骨细胞和骨小梁稀少.将定量CT检测结果进行ROC分析显示,材料学参数骨痂骨密度(BMD)、骨痂骨矿含量(BMC)的曲线下面积(准确度)为0.781和0.750,结构学参数横截面积(CSA)和截面惯性矩(CSMI)的曲线下面积(准确度)为0.781和0.469(P<0.05),材料学参数和结构学参数乘积引伸所得的横截面积力学强度指数(BSICSA)、截面惯性矩力学强度指数(BSICSMI)的曲线下面积(准确度)分别为0.913和0.813(P<0.05),BMD、CSA、BSICSA三者曲线下面积(准确度)分别为0.905,0.921,0.905(P<0.05).结论 定量技术测量骨折局部形态具有区分和反映骨折愈合与骨折不愈合模型及过程的潜能,所筛选出具有准确度的参数有BMD、CSA和BSICSA,这些参数具有准确、特异的优越性.     

《临床检验基础》CAI教学课件的制作与应用

结合普通高等教育“十一五”国家级规划教材《临床检验基础》内容，应用Authorware，Flash，Premiere等软件进行了《临床检验基础》CAI教学课件的制作，并广泛应用于教学实践。《临床检验基础》CAI教学课件符合教学规律，内容新颖、操作方便、人机对话良好，能提高学生学习的积极性和教师教学的积极性，并具有较高的实用性。     

A comparison of performance by medical and midwifery students in multiprofessional teaching

AIM: At Dundee University, midwifery and medical students are taught obstetrics together in a 2-week intensive course. We set out to test the hypothesis that staff time and effort could be saved by using shared resources in teaching a multidisciplinary group of students to an acceptable level. METHOD: In order to measure the knowledge gain by two different groups of students, we tested the students before and after a timetabled computer-assisted learning (CAL) session focusing on how to interpret a cardiotocograph (CTG). Also, half of each student group was given extra CTG teaching before the CAL session. RESULTS: The medical students (n=38) increased their median score from 9 to 17 after the CAL (P<0.001) but the midwifery students (n=13) only increased their median score from 12 to 14 after the CAL (n.s.). However, when given a tutorial and CAL, the post-test scores for both medical and midwifery students were similar and significantly higher than pre-test scores (median score increase from 8.5 to 18 for medical students, P<0.001, n=34, and from 9 to 16 for midwifery students, P<0.01 n=11). There was no significant knowledge gain by the medical students who undertook the additional tutorial. CONCLUSION: We conclude that shared resources could be used by medical and midwifery students to reach equivalent levels of skill in CTG interpretation. However, in order to achieve equivalence, staff time and effort was wasted as medical students were given unnecessary tuition.     

Maintaining the Characteristics of Effective Clinical Teachers in Computer Assisted Learning Environments

There has been a growing trend in medical education to integrate the use of computers into the undergraduate medical curriculum. While it seems intuitively obvious that personal computers and the Internet can be useful learning tools, it is not clear that the perceived advantages of Computer Assisted Instruction (CAI)are warranted. One problem is that computers are too often used in CAI simply as presentation devices for predefined material without ample consideration paid to the pedagogical principles that have informed more conventional teaching practices. The creation of an environment that is conducive to effective learning has often been overlooked in favour of the development and use of increasingly more sophisticated technologies. The current paper represents an attempt to delineate ways in which we might better develop instructional multimedia programs by employing some of the strategies believed to characterize effective clinical teaching. To do so, this paper will briefly review the work of Irby and others in an attempt to draw attention to ways in which the characteristics identified by these researchers might be implemented for the use of CAI. This revised version was published online in June 2006 with corrections to the Cover Date.     

谈医学多媒体课件的制作

随着计算机网络技术与多媒体技术的高速发展,信息技术与医学教育的结合日益紧密,计算机辅助教学已成为医学高等院校教育技术研究发展的方向和教学中重要的辅助手段.文章详细介绍了医学多媒体课件制作过程中的教学设计、系统设计、注意事项以及课件完善等具体操作,为医学多媒体课件的开发和制作提供实际指导.     

鼻咽癌CT/MRI配准方法的临床研究

目的 探讨鼻咽癌CT／MRI的临床配准方法并评价配准效果。方法 8例未经治疗的鼻咽癌患者采用相同放疗体位和面罩固定方法，Cr、MRI扫描后全部图像经网络传输至AcQSIM4．9．2及Pinnacle3 V7．0工作站，分别由两名医师和一名物理师在AcQSIM4．9．2采用点标记法、交互法及在Pinnacle3 V7．0上采用归一化互信息法来配准。采用盲法由两名医师分别在不同工作站上目测评价，评价配准结果采用四点法：极差、差、良、很好；评价配准时间采用三点法：短时（（1min）、长时（1～3min）、很长（〉3min）。结果 归一化互信息法较交互法、点标记法更为准确，配准速度最快。医生组较物理师配准更为准确，速度快，其中点标记法医生组较物理师配准更为准确，速度快，而归一化互信息法和交互法医生组与物理师配准准确性及速度相当。结论 归一化互信息法在速度和Robust上占优势，因由软件自动配准、人为因素影响较小故适合放疗计划配准应用。