生物组织表面散射光子的分布特点与光学参数测量

本文运用光子迁移模型理论分析了在生物组织表面散射光的分布特点，提出用积分球测量组织光学参数的方法，该方法通过测量表面散射光的漫反射系数和散射光的相对强度从而实现光学参数的直接测量。     

扩散磁共振成像中取向分布函数的球面插补方法

目的寻求一种基于少量采样数据即能实现白质纤维束路径跟踪的新方法,提出取向分布函数(orientation diffusion function,ODF)场球面插补算法,以解决q空间球面成像(Q-ball imaging,QBI)数据采样负担过重、耗时过长等临床应用瓶颈。方法首先基于采样数据重建ODF场,然后根据插补点与所有采样点之间夹角确定插补方向矩阵和宽度插补参数,之后基于自然指数函数来计算转换矩阵,最后对采样信号进行转换得到插补ODF场。结果采用流线跟踪法进行了白质纤维束路径跟踪,获得了较为合理的结果;并分析了角度宽度参数对插补结果的影响,确认了最适合的角度宽度参数选取准则。结论该球面插补方法基于少量采样数据即可实现ODF场的有效插补,可进行有效的白质纤维束路径跟踪。     

基于人工免疫网络的小动物PET分子影像动力学参数估计方法

目的基于人工免疫网络提出无需设定初值的示踪剂动力学模型参数估计算法,以提高PET分子影像动力学模型分析方法的可靠性。方法对18F—FDG小鼠PET显像实验中有关数据,用ROI技术获取肝和左心室示踪剂的时间一放射性曲线（TAC）,同时经小鼠尾静脉多点采血获取尾静脉血TAC。对动物实验数据进行示踪剂药代动力学建模,设计人工免疫网络算法估计模型参数,并计算小鼠肝葡萄糖代谢率参数Ki。结果获得肝、左心室和尾静脉血TAC。对小动物实验数据建模,应用基于人工免疫网络的药代动力学参数优化方法（PKAIN）求解模型参数,实现无需设定初始值的模型参数估计,并计算3只小鼠K值,平均值分别为0．0024,0．0417和0．0047。PKAIN算法求出对输出模型参数估计的最大加权残差平方和的平均值小于0．0745,标准差最大为0．0084,表明能够获得准确稳定的模型参数。结论人工免疫网络智能计算方法可提高PET分子影像动力学建模方法的可靠性、实用性提供了新型的智能信息处理技术。     

用于室颤节律辨识的多参数融合BP神经网络设计

目的：构建一个用于区分室颤节律和非室颤节律的多参数融合BP神经网络。方法从心电信号中提取出18个特征值,分别标记心电信号的形态分布、高斯性、幅度谱、变异性、复杂度等各方面特征;以这些特征值作为输入向量,构建一个多参数融合BP神经网络进行训练,得到一个用于区分室颤节律与非室颤节律的分类器。结果与结论将构建的BP神经网络分别基于VFDB数据库和CUDB数据库进行实验,辨识准确率分别高达98．61％和95．37％;相较于现有方法,辨识性能显著提高。     

p（35）Be快中子辐射场生物剂量参数的测定

报道了ｐ（３５）Ｂｅ快中子、γ混合辐射场生物剂量参数，说明了采用双电离室方法测量ｐ（３５）Ｂｅ快中子时，剂量计算中有关因子和参数的确定原则和估算结果；给出了辐射场的中子／γ比，照射野内组织比释动能率分布，以及由比释动能率计算小鼠全身与局部照射和血液样品照射时的吸收剂量转换系数等剂量常参数；最后还对剂量测量的误差问题做了分析。     

战斗机飞行员面部三维形态数字化测量研究

目的 获取我国飞行员面部的三维形态数据与特征.方法 研制了面部空间定位装置,建立了面部定位数字化测量方法,并对154名战斗机飞行员的面部进行了测量.结果 获得了该组飞行员面部65个形态特征点的三维坐标数据.结论 所建立的测量方法实用、有效,能用于大样本飞行员面部三维形态的数字化测量;所获得的结果可用于分析面部三维形态特征,并为供氧面罩等面部防护装具的造型设计提供依据.     

用能量沉积核函数方法计算~(60)Co照射野的吸收剂量

目的　介绍了用能量沉积核函数方法计算60 Co照射野吸收剂量的方法。方法　能量沉积核函数方法将吸收剂量的贡献分为 3部分 :原射线、单次散射和多次散射。它使用基本的剂量学数据 ,如射野中心轴百分深度剂量、离轴比和准直系统散射输出因子等 ,这些数据在Fyc 5 0H治疗机上用方形照射野测量得到。再用能量沉积核函数计算吸收剂量。并讨论了散射线对吸收剂量的影响。结果　从测量数据得到了原射线和散射线的能量沉积核函数 ,并利用能量沉积核函数计算60 Co照射野的主要剂量学参数 ,计算值和测量值是一致的 ;不规则照射野的吸收剂量及其分布的计算结果也和测量结果符合得很好。结论　能量沉积核函数方法适用于较精确地计算60 Co不规则照射野的吸收剂量。     

光谱CT多参数功能成像预测磨玻璃密度肺腺癌侵袭性的价值

目的探讨光谱CT定量参数预测表现为磨玻璃结节(GGN)肺腺癌侵袭性的价值。方法回顾性分析2022年3至10月在郑州大学第一附属医院经手术切除且病理证实为肺腺癌的129例患者的临床及影像资料, 其中男45例, 女84例, 年龄33～81岁。按照病理结果129例患者分为微浸润腺癌(MIA)组64例和浸润性腺癌(IAC)组65例。所有患者均在术前2周内接受光谱CT增强扫描, 在后处理工作站上重建碘密度图、有效原子序数(Zeff)图、电子云密度(ED)图, 测量并计算相关光谱参数, 包括标准化碘浓度(NIC)、动脉增强分数(AEF)、Zeff及ED;分析病灶的常规CT特征, 包括最大径、CT值、结节类型、结节边缘、分叶征、毛刺征、空泡征、胸膜凹陷征、异常血管征及空气支气管征。采用独立样本t检验、Mann-WhitneyU检验、χ2检验比较2组临床特征、常规CT特征及光谱CT参数。采用多因素logistic回归分析评估肺腺癌侵袭性的独立危险因素, 并构建模型。采用受试者操作特征(ROC)曲线评估各参数及模型预测肺腺癌侵袭性的效能。结果 MIA组与IAC组的最大径、CT值、结节类型、边缘、毛刺征、...     

新疆天然草原鲜草产量空间插值制图应用

基于GIS空间插值模拟器,使用反距离权重插值计算方法对新疆7月天然草原高峰期动态监测路线调查数据包括新疆11个草原大类的2013、2014年鲜草产量进行空间插值制图,并将插值预测结果作比较分制图,结果表明:在广域范围以内插值法能较好反映新疆天然草原鲜草产量空间分布格局特征,辅助制图应用操作性强.     

基于脉搏波速法的无创连续血压检测系统

目的设计基于脉搏波速法的无创连续血压测量系统。方法分析基于脉搏波传导时间计算动脉血压的原理，提出脉搏波传导时间与血压的关系方程，并论述了方程参数标定方法。根据心电与脉搏波信号的特点，采用数字信号处理器和16位A／D等先进的电子器件设计了同步采集心电和脉搏波信号，准确计算脉搏波传导时间并计算动脉血压的仪器。结果实验表明，仪器的测量误差优于AAMI推荐标准。结论本系统能满足无创连续血压测量的基本要求，已应用于航天员日常训练。     

Measurement of energy absorption coefficients at 662 keV in soil samples

The sphere transmission method is employed for the direct measurement of the energy absorption coefficients of different soil samples by placing a point source of Cs-137 inside a spherical shell. The transmitted and scattered gamma-rays are detected using a proportional response NaI detector. The measured values are compared with the theoretical values.     

New test to assess pilot's vision following refractive surgery

BACKGROUND: All forms of corneal refractive surgery can sometimes cause an increase in optical aberrations and scattered light, which can affect visual performance. The purpose of this study was to develop a suitable test that was sensitive to retinal image degradation in subjects who have undergone excimer laser refractive surgery and that was also relevant to visual demands in commercial aviation. METHODS: Assessment of the visual environment and the tasks involved in piloting a commercial aircraft formed the basis for the selection of the test parameters. The new contrast acuity assessment (CAA) test covers a functional visual field of +/-5 degrees and is based on minimum spatial vision requirements for commercial pilots. RESULTS: Data measured in 100 normal subjects were used to define the 'standard normal observer' and the range of variation for the parameters of the test. This approach makes it possible to quickly establish whether a given subject's performance falls within the range of the standard normal observer. The test is also administered under low ambient illumination since flying at night involves mesopic levels of light adaptation when the pupil size is large and the effects of aberrations and scattered light are therefore more pronounced. CONCLUSION: The results of the test are simple to interpret and reveal visual performance that falls outside the normal range as a result of either significant degradation of retinal image quality (caused by increased aberrations and scattered light) or abnormal processing of visual information in the retina and/or the visual pathway.     

Quantitative digital subtraction angiography: two scanning techniques for correction of scattered radiation and veiling glare. Work in progress

Scattered radiation and veiling glare in digital subtraction angiography degrade contrast signals in a nonlinear and nonuniform way. This effect prohibits direct use of image data for accurate iodine measurement or energy subtraction imaging. Two techniques based on the use of scanning lead bars were proposed to measure the spatial distribution of scattered radiation and veiling glare in the unprocessed image data. With either technique, signals behind the lead bars were used to estimate the scatter-glare component and remove it from the image data. The scanning-lead-bar techniques can be used to reduce the scatter-glare component by a factor of up to 10. The scatter-glare correction leads to the recovery of degraded contrast signals and achieves reasonable linearity, uniformity, and consistency in the contrast measurement.     

Investigation on Changes of Optical Tissue Properties related to iPDT on Malignant Gliomas

Brain tumor treatment via interstitial photodynamic therapy (iPDT) needs precise treatment light delivery, which is essential for the conduction of the therapy [1]. The light delivery and the resulting light dosimetry are highly dependent on the optical tissue properties of the tumor tissue and the surrounding brain tissue. Employing intraoperative spectral online monitoring (SOM), it looks possible to assess the treatment light transmittance between the used light applicators and monitor potential changes during therapy [2]. Changes have been observed during clinical iPDT-illumination and can be interpreted as changes in the optical tissue properties [2, 3]. In vitro experiments mimicking the clinical iPDT-illumination situation using liquid optical tissue phantoms, including blood, showed SOM intensity changes in transmittance. Due to simultaneous remission spectroscopy, this can be related to the deoxygenation of hemoglobin and its oxidation to methemoglobin (MetHb) [4]. The analysis of data from clinical iPDT-procedures confirmed this interpretation. Based on intraoperative SOM data, changes in the optical absorption coefficient have been calculated and correlated with newly diagnosed early visible intrinsic T1-hyperintensity in the treatment volume [3]. The intrinsic T1 hyperintensity is clinically an indicator of the formation of MetHb after silent hemorrhages, which may occur during iPDT. As the T1 hyperintensity was early visible in the MRI, the corresponding early appearance of MetHb was in context with the iPDT and consistent with the in vitro experiments. Further in vitro experiments showed that changes in optical tissue properties and hemoglobin oxidation is not only possible due to ROS production during iPDT but also due to a slight temperature increase during iPDT by 4°C [5]. These results give more insight into mechanisms occurring during iPDT irradiation, but the impact on treatment outcome has still to be assessed.     

Near-infrared frequency domain system and fast inverse Monte Carlo algorithm for endoscopic measurement of tubular tissue

A near infrared diffuse reflectance system for endoscopic measurement and an inverse algorithm for extracting optical properties of tubular tissues were developed in this paper. The measurement system worked in the frequency domain mode and a custom probe was employed for endoscopic detection of cervical cancer. Experiments for evaluating the measurement accuracy indicate that the model-to-data mismatch for the AC amplitude and phase lag is less than 3.7% and 6.7%, respectively. To facilitate the extraction of the optical properties in tubular tissues and to minimize the influence of the initial guess on the reconstruction accuracy, a fast inverse Monte Carlo simulation algorithm with cluster analysis method was proposed. Simulation results showed that the relative errors of the absorption coefficient recovered using the proposed inverse algorithm are less than 5.8% and those of the sacttering coefficient are less than 10.2%. Endoscopic measurement on two tubular solid phantoms were also carried out to evaluate the system and the inversion scheme. The results demonstrated that less than 20% relative error can be achieved.     

人工、半自动及自动方法测量肺实性结节直径和体积的一致性研究

目的:评估人工测量方法、基于计算机辅助诊断（CAD）的半自动测量方法和基于人工智能的全自动测量方法在肺实性结节直径和体积测量中的一致性。方法:回顾性分析2018年7月至2020年4月四川省肿瘤医院接受肺癌筛查的165例受检者的临床和低剂量CT（LDCT）资料。选取每例受检者直径最大的结节作为研究对象,由1名初级和1名高...     

Characterization of scatter and penetration using Monte Carlo simulation in 131I imaging.

In 131I SPECT, image quality and quantification accuracy are degraded by object scatter as well as scatter and penetration in the collimator. The characterization of energy and spatial distributions of scatter and penetration performed in this study by Monte Carlo simulation will be useful for the development and evaluation of techniques that compensate for such events in 131I imaging. METHODS: First, to test the accuracy of the Monte Carlo model, simulated and measured data were compared for both a point source and a phantom. Next, simulations to investigate scatter and penetration were performed for four geometries: point source in air, point source in a water-filled cylinder, hot sphere in a cylinder filled with nonradioactive water, and hot sphere in a cylinder filled with radioactive water. Energy spectra were separated according to order of scatter, type of interaction, and gamma-ray emission energy. A preliminary evaluation of the triple-energy window (TEW) scatter correction method was performed. RESULTS: The accuracy of the Monte Carlo model was verified by the good agreement between measured and simulated energy spectra and radial point spread functions. For a point source in air, simulations show that 73% of events in the photopeak window had either scattered in or penetrated the collimator, indicating the significance of collimator interactions. For a point source in a water-filled phantom, the separated energy spectra showed that a 20% photopeak window can be used to eliminate events that scatter more than two times in the phantom. For the hot sphere phantoms, it was shown that in the photopeak region the spectrum shape of penetration events is very similar to that of primary (no scatter and no penetration) events. For the hot sphere regions of interest, the percentage difference between true scatter counts and the TEW estimate of scatter counts was <12%. CONCLUSION: In 131I SPECT, object scatter as well as collimator scatter and penetration are significant. The TEW method provides a reasonable correction for scatter, but the similarity between the 364-keV primary and penetration energy spectra makes it difficult to compensate for these penetration events using techniques that are based on spectral analysis.     

Rapid measurement of blood leakage during regional chemotherapy

In order to avoid complications after regional chemotherapy (isolated hyperthermic perfusion) of the extremities, rapid measurement of blood leakage from the extracorporeal to the systemic circulation is important. A method using technetium-99m in vivo red blood cell (RBC) labelling is reported that provides results within 3 min. Blood samples drawn from the systemic and the extracorporeal circulation were measured for ^99mTc activity using a mobile well counter, and the leakage values calculated. The mean result was 7.6%±6.5%/15 min (n=209). The corresponding flow rate was 100.2±85.7 ml/15 min (mean ± SD). The values for isolation perfusion of the upper and the lower extremities are compared. The leakage results using ^99mTc RBC labelling were correlated with other blood pool markers. Iodine-125 human serum albumin and indium-113 m transferrin were administered in subgroups of 4 and 19 patients simultaneously. Using linear regression, the coefficient of correlation was 0.72 for ^99mTc/^113mIn and 0.58 for ^99mTc/¹²⁵I. Comparison with the alternatives suggests that the rapid method of leakage measurement after ^99mTc RBC labelling can be considered one of the most practicable and reliable methods available.This paper is dedicated to Prof. E. Oberhausen, Homburg/Saar, on the occasion of his 65th birthday Correspondence to: C. Alexander     

Retest reliability of spatiotemporal gait parameters in children and adults

The objective of the study was to assess the retest-reliability of ten different gait parameters in healthy children (n=12; age 6-7 years) and adults (n=12; age 21-35 years) during free-speed locomotion on a simple walkway. Further the intra-subject variability of the stride dimensions was checked. On two occasions, spatial gait parameters were measured by footprint analysis, temporal dimensions were recorded using video-analysis. For spatial gait parameters, correlation coefficients (ICC, Pearson's r) between the test and the retest results were found to be high in adults and satisfying in children. The temporal parameters were less consistent. Generally the within-trial variability was higher in children than in adults. Conclusions: (i) The retest reliability for the measurement of the spatial gait parameters can be judged as high. (ii) For gait analysis in children it should be taken into account that gait parameters are more variable from trial to trial than in adults. Copyright 1997 Elsevier Science B.V.     

三维DSA距离测量准确性的模体定量评价研究

目的：运用模体定量评估三维DSA距离测量的准确性,以指导临床工作。方法：应用模拟动脉瘤模体和动脉狭窄模体,改变不同的扫描野、重建矩阵、模体方向来研究三维空间距离测量的准确性。通过对模体中球体和圆柱体三维容积重建图像尺寸测量与模体实际尺寸进行对比评估。结果：在三维图像重建中不同的扫描野、重建矩阵、模体方向均能清晰显示圆柱体、球体影像及模拟狭窄的程度。随着扫描野的缩小,对球体直径和狭窄直径的测量精度提高,对于圆柱体长度测量元变化。重建矩阵加大,球体直径测量误差减少（1283最大为0．36mm,2563最大为0．12mm）。圆柱体狭窄百分率测量误差大约为3％。结论：当选用合适的图像成像参数和后处理方法时,利用重建后的三维图像测量动脉瘤的大小和动脉狭窄的程度是相当可靠的。