Localization error analysis for stereo X-ray image guidance with probability method.

The mean value and standard deviation of localization error for the stereo imaging systems are derived based on probability theory. Compared with the maximum error analysis method used in our previous study, the new approach yields more informative and precise results as the guidance for X-ray imaging system design and protocol optimization. The prototype for our current study is a CCD based monoplane digital stereo X-ray imaging system. The imaging model consists of two X-ray sources and one detector plane. With perspective geometry, the least-square solution is derived to reconstruct 3-dimensional object points, such as a biopsy needle tip, from a pair of 2-dimensional digital radiographs. Under the conditions of our specific prototype, the measurement errors of interested points in the radiographs are modeled as random variables with Gaussian distribution. Such variables account for finite image system noise and positioning errors. Then, the 3D localization error, in terms of mean value and standard deviation, is formulated using measurement error, feature point location, and separation between the two X-ray sources and distance from source to detector. Both theoretical analysis and numerical simulation are performed. The mean value and standard deviation of the localization error are first evaluated using numerical simulation under practical imaging conditions. Then, the error estimates are given in simply analytic forms. Simulation and theoretical results are in excellent agreement. The results show that our prototype X-ray stereological imaging system is accurate and reliable to locate feature points in 3D for medical intervention. Imaging protocols can be effectively optimized through the 3D localization error analysis using the approximate formulas proposed in this study.     

Analysis of facial sebum distribution using a digital fluorescent imaging system

Current methods for analysis of sebum excretion have limitations, such as irreproducible results in repeatable measurements due to the point measurement method, user-dependent artifacts due to contact measurement or qualitative evaluation of the image, and long measurement time. A UV-induced fluorescent digital imaging system is developed to acquire facial images so that the distribution of sebum excretion on the face could be analyzed. The imaging system consists of a constant UV-A light source, digital color camera, and head-positioning device. The system for acquisition of a fluorescent facial image and the image analysis method is described. The imaging modality provides uniform light distribution and presents a discernible color fluorescent image. Valuable parameters of sebum excretion are obtained after image analysis. The imaging system, which provides a noncontact method, is proved to be a useful tool to evaluate the amount and pattern of sebum excretion. When compared to conventional "Wood's lamp" and "Sebutape" methods that provide similar parameters for sebum excretion, the described method is simpler and more reliable to evaluate the dynamics of sebum excretion in nearly real-time.     

A system for the acquisition of reproducible digital skin lesions images.

A major issue concerning the design and implementation of an image acquisition system for skin lesions is its ability to capture reproducible images. The reproducibility is considered essential for image analysis and for the comparison of sequential images during follow-up studies. This paper describes a prototype image acquisition system that includes a standardized illumination and capturing geometry with polarizing filters and a series of software corrections: Calibration to Black, White and Color for color constancy, Internal camera Parameters adjustment and Pose extraction for stereo vision, Shading correction and Noise Filtering for color quality. The validity of the calibration procedure and the images' reproducibility were tested by capturing sample images in three different lighting conditions: dark, medium and intense lighting. For each case the average values of the three color planes RGB and their standard deviations were calculated; the measured error differences ranged between 0.7 and 12.9 (in the 0-255 scale). Preliminary experiments for stereo measurements provided repeatability of about 0.3 mm. The above results demonstrate the reproducibility of the captured images at a satisfactory level. The developed prototype was also evaluated clinically, for its ability to support the construction of knowledge-based decision systems and for telemedicine, thus to support telemedical sessions in dermatology.     

数字化摄影流程中常见的问题与质量控制

目的分析全数字化摄影流程中常见的问题及原因,总结和改进数字化摄影条件下技术组质量控制方法。方法将数字化摄影流程的质量控制细分为影像输入、处理、输出、阅读4个质量控制过程,仅就技术方面逐项分析解决质量控制问题。依据不同时间段抽取对照组和试验组各2000份影像资料进行比较。结果依据质量管理机制,在摄影技术工作范畴内,分析总结了数字化摄影流程中最容易出现问题的几个关键点。对照组2 000份网络存储胸部摄影资料,存在各类影像缺陷689份,占34.45%。施行质量控制评价机制,尤其是全程陪伴检查并现场纠正操作错误后,抽取试验组2 000份胸部资料,缺陷项由6项降低为3项,为106份,占总数的5.3%,图像质量较前有明显改善。结论通过规范登记流程、摄影摆位,改善摄影条件,规范化后处理软件的应用,减少人为因素造成的失误,使数字摄影工作质量得到显著提高。     

基于数字图像视觉特征自动检测超声图像中胎儿颈项透明层

目的利用计算机技术设计一种基于数字图像视觉特征的超声图像中胎儿颈项透明层（NT）的自动检测方法。方法建立基于数字图像视觉特征自动检测超声图像中胎儿NT的方法,包括胎儿超声图像提取、连通分量提取、目标检测和NT测量的实现共4个主要步骤。评价标准实验图像（n=35）、临床挑选图像（n=1208）和人工已标注图像（n=120）3组图像采用自动检测方法进行NT测量的实验结果,包括其定位准确性和测量误差,并记录最大误差值。结果应用自动检测方法检测标准实验图像、临床挑选图像和人工已标注图像中胎儿NT的定位准确率分别为100％（35／35）、90．7％（1096／1208）、90．8％（109／120）,NT的测量误差均小于0．03mm。结论成功建立了基于数字图像视觉特征自动检测超声图像中胎儿NT的方法,可减少人工测量的主观性和随机性,提高超声筛查的准确性。     

Image compression in morphometry studies requiring 21 CFR Part 11 compliance: procedure is key with TIFFs and various JPEG compression strengths

This study aims to compare the integrity and reproducibility of measurements created from uncompressed and compressed digital images in order to implement compliance with 21 CFR Part 11 for image analysis studies executed using 21 CFR Part 58 compliant capture systems. Images of a 400-mesh electron microscope grid and H&E stained rat liver tissue were captured on an upright microscope with digital camera using commercially available analysis software. Digital images were stored as either uncompressed TIFFs or in one of five different levels of JPEG compression. The grid images were analyzed with automatic detection of bright objects while the liver images were segmented using color cube-based morphometry techniques, respectively, using commercially-available image analysis software. When comparing the feature-extracted measurements from the TIFF uncompressed to the JPEG compressed images, the data suggest that JPEG compression does not alter the accuracy or reliability to reproduce individual data point measurements in all but the highest compression levels. There is, however, discordance if the initial measure was obtained with a TIFF format and subsequently saved as one of the JPEG levels, suggesting that the use of compression must precede feature extraction. It is a common practice in software packages to work with TIFF uncompressed images. However, this study suggests that the use of JPEG compression as part of the analysis work flow was an acceptable practice for these images and features. Investigators applying image file compression to other organ images will need to validate the utility of image compression in their work flow. A procedure to digitally acquire and JPEG compress images prior to image analysis has the potential to reduce file archiving demands without compromising reproducibility of data.     

Smartphone-based photoplethysmographic imaging for heart rate monitoring

The purpose of this study is to make use of visible light reflected mode photoplethysmographic (PPG) imaging for heart rate (HR) monitoring via smartphones. The system uses the built-in camera feature in mobile phones to capture video from the subject’s index fingertip. The video is processed, and then the PPG signal resulting from the video stream processing is used to calculate the subject’s heart rate. Records from 19 subjects were used to evaluate the system’s performance. The HR values obtained by the proposed method were compared with the actual HR. The obtained results show an accuracy of 99.7% and a maximum absolute error of 0.4 beats/min where most of the absolute errors lay in the range of 0.04–0.3 beats/min. Given the encouraging results, this type of HR measurement can be adopted with great benefit, especially in the conditions of personal use or home-based care. The proposed method represents an efficient portable solution for HR accurate detection and recording.     

Thick-section histometry of porous hydroxyapatite implants using backscattered electron imaging

A histometry system has been developed to measure bone ingrowth into porous hydroxyapatite implants utilizing the backscattered electron image of thick sections. The system consists of a scanning electron microscope (SEM) with backscattered electron detector, digital beam controller, minicomputer based image digitization, and microcomputer based image processing, point counting, and lineal analysis. The SEM backscattered electron imaging mode yields high tissue contrast and sharp tissue boundaries, substantially reducing the lost cap and projection effect errors of thick sections. High-resolution digitization of the image substantially reduces the standard error of the estimates. By using the digitized image the tedious process of filtering artifacts and recording actual point counts, intersections, and intercept lengths is delegated to computer software. Performance of this system in a recent study demonstrated substantial ease of operator use and speed of measurement. In the absence of a digital beam controller an inexpensive video digitizer circuit board may be used to digitize photographic prints of the SEM images. The combination of increased accuracy, precision, operator ease, and speed suggests that this system can be useful for soft tissue-bone-implant histometry.     

Evaluation of Low-Cost Telemammography Screening Configurations: A Comparison with Film-Screen Readings in Vulnerable Areas

The aim of this study was to evaluate the diagnostic accuracy for detecting breast cancer using different telemammography configurations, including combinations of both low-cost capture devices and consumer-grade color displays. At the same time, we compared each of these configurations to film-screen readings. This study used a treatment-by-reader-by-case factorial design. The sample included 70 mammograms with 34 malignant cases. The readers consisted of four radiologists who classified all of the cases according to the categories defined by the Breast Imaging Reporting and Data System (BI-RADS). The evaluated capture devices included a specialized film digitizer and a digital camera, and the evaluated displays included liquid crystal display (LCD) and light-emitting diode (LED) consumer-grade color displays. Receiver operating characteristic curves, diagnostic accuracy (measured as the area under these curves), accuracy of the composition classification, sensitivity, specificity, and the degree of agreement between readers in the detection of malignant cases were also evaluated. Comparisons of diagnostic accuracy between film-screen and the different combinations of digital configurations showed no significant differences for nodules, calcifications, and asymmetries. In addition, no differences were observed in terms of sensibility or specificity when the degree of malignancy using the film-screen method was compared to that provided with digital configurations. Similar results were observed for the classification of breast composition. Furthermore, all observed reader agreements of malignant detection between film-screen and digital configurations were substantial. These findings indicate that the evaluated digital devices showed comparable diagnostic accuracy to the reference treatment (film-screen).     

彩色医学内窥镜图像的增强处理方法研究

本文利用一个适应于表达和处理彩色医学内窥镜图像的颜色空间，分别从空间域和频率域两个方面讨论了该类图像的增强处理方法。并结合实例，找出适应直方图均衡化和照明反射模型两种最佳处理方案。     

Accurate measurement of characteristic curves of II-TV digital systems by use of aluminum stepwedge technique

In order to determine accurately the relative x-ray intensities transmitted through the different steps of an aluminum stepwedge and incident on an image intensifier (II)-TV digital system, we used a 100-mm camera which was attached to the II output. The characteristic curves of an II-TV digital system, which relate the output pixel value to the input relative x-ray intensity, were determined at 65 and 90 kV by the use of the aluminum attenuation curves measured at the two energies. We found that the two curves agreed within the experimental errors; this result indicates that the characteristic curve does not depend on the x-ray beam quality used. Furthermore, for accurate measurement of the characteristic curve, it is necessary to collimate the x-ray beams to a narrow width, approximately 0.6 X 10 cm, so that the effect of veiling glare from the thinner to the thicker parts of the stepwedge is eliminated.     

三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

“Evaluation of a Very Low-Cost and Simple Teleradiology Technique”

This paper describes and analyzes a proposed solution of fundamental limitative factor of teleradiology to overcome the teleradiology usages problems in underdeveloped and developing countries. The goal is to achieve a very simple and cost-efficient way to take advantage of teleradiology in anywhere even in remote and rural areas. To meet the goal of this study, the following methodology which is consists of two main procedures was done: (1) Using a digital camera in order to provide a digital image from radiographs. (2) Using an image compression tool in order to compress digital images. The results showed that there is no significant difference between digital images (non-compress and compress images) and radiographic films. Also, there was a logic relationship between the diagnostic quality and diagnostic accuracy. Since the maximum percent of diagnostic accuracy can be seen among “Good” quality images and the minimum to was related “Poor”. The results of our study indicate that a digital camera could be utilized to capture digital images from radiographic films of chest x-ray. To reduce the size of digital images, a lossy compression technique could be applied at compression percent of 50 or less without any significant differences. The compressed images can be sent easily by email to other places for consultation and also they can be stored with a smaller size.     

Assay of prick test inoculum volume. I. Use and reliability of a gamma camera-based method.

INTRODUCTION: In dermatology and allergy there are clinical research circumstances where very small amounts of substances introduced into the skin have to be measured "in vivo." An example is the assay of reagents injected by prick test. As injected volumes are very small, it is necessary to use indicators that can be measured at very low concentrations. In in vitro studies, gamma-emitting radioisotopes have been shown suitable for use as the indicators. In in vivo studies, except for instruments devised for specific research requirements, the measurement of small sources is taken with a common gamma camera. OBJECTIVE: The purpose of the present study is to evaluate the experimental reliability of a gamma camera-based method to measure microvolumes labeled with radioisotopes and its suitable application in vivo studies. METHODS: Using a solution of 99m Tc-pertechnetate, we prepared, with precision pipettes, some sets of scalar volumes ranging from 1 micro to 200 picoliters, which correspond to activities between some micros and some hundreds of picocuries. The volumes were measured with a gamma camera both with and without a collimator. The overall reliability of the method under different experimental conditions was evaluated for sensitivity, precision, and accuracy. Last, a blind measurement was taken as a final check on the overall reliability of the method. RESULTS: The volume-activity correlation appeared to be linear, with a Spearman coefficient higher than 0.99. The correlation straight lines of the measurements taken with and without a collimator proved that, in both cases, the linearity of the system did not change. The method showed a high degree of precision and accuracy. The maximum variation coefficient never exceeded 1.5% and the standard error 2%. The sampling error of the measured volumes was less than 8% in all the sets: up to 7% was due to the manual operations and to the technical characteristics of the micropipettes. The gamma camera measurement error ranged from 1% to 3%. The blind tests experimentally confirmed the overall reliability of the method. CONCLUSIONS: The method we studied proved highly reliable and inexpensive. Measurement errors are almost exclusively due to sampling errors. The gamma camera is a device any nuclear medicine department is equipped with, and a solution of 99m Tc-pertechnetate is readily available.     

数码技术测定虹膜色彩的可行性

背景：天然虹膜颜色个体差异大、种类多,常规肉眼比色由于比色方法、比色环境及操作者的个体差异的局限性,选色结果往往不能令患者满意。 目的：评价数码技术应用于虹膜配色的可行性与合理性。 方法：使用数码相机,在稳定光源环境(D65标准光源)、固定拍摄参数(光圈f/2.8,快门1/45 s,感光度ISO 100,图像格式RAW)条件下,拍摄148例单眼球缺失病例的虹膜,患者年龄24~49岁;图像经Camera RAW for Adobe Photoshop 7.0专业软件处理后,观察虹膜的色彩特征,采集虹膜色彩数据,运用“HSB模型”滑杆显示不同患者天然虹膜的色相(H)、饱和度(S)、亮度(B)数值。使用SPSS 13.0统计软件作进一步描述性分析及χ²检验。 结果与结论：148例单眼球缺失患者运用“HSB模型”比色,141例义眼虹膜色质良好,与健眼协调;4例色质稍偏差,细看能区别出修复体;3例与健眼虹膜有较大差别。提示依据孟赛尔HVC颜色系统,运用“HSB模型”,借助数码相机、计算机并结合相关软件,对不同颜色进行测定、分析,方法科学、具有量化性,比色快速、方便、准确。所取设备易取,具有一定的临床应用价值。     

构建高分辨率中国数字人男性数据集

目的构建高分辨率中国男性数字人0.2mm断层间距图像数据集。方法取捐献健康男性遗体,经颈动脉红色灌注、低温冷冻定型、专用包埋模具垂直包埋、一次装夹连续等间距铣削、PhaseOneH25数码相机采集连续断层数据以构建数据集。结果共获得9320个RAW格式断层图像数据,分辨率为4080×5440象素,RAW格式单层数据量为27.5M,RAW格式总数据量为260G。结论高分辨率中国数字人男性数据集由于采用了2200万象素的高分辩率数码相机,断层上如血管、脂肪、软骨和骨骼等组织的边界清晰。并可用随机软件对图像的色彩、曝光量以及断层感兴趣区域进行重新处理。     

Segmentation of the optic disk in color eye fundus images using an adaptive morphological approach

The identification of some important retinal anatomical regions is a prerequisite for the computer aided diagnosis of several retinal diseases. In this paper, we propose a new adaptive method for the automatic segmentation of the optic disk in digital color fundus images, using mathematical morphology. The proposed method has been designed to be robust under varying illumination and image acquisition conditions, common in eye fundus imaging. Our experimental results based on two publicly available eye fundus image databases are encouraging, and indicate that our approach potentially can achieve a better performance than other known methods proposed in the literature. Using the DRIVE database (which consists of 40 retinal images), our method achieves a success rate of 100% in the correct location of the optic disk, with 41.47% of mean overlap. In the DIARETDB1 database (which consists of 89 retinal images), the optic disk is correctly located in 97.75% of the images, with a mean overlap of 43.65%.     

Comparison between Different Cost Devices for Digital Capture of X-ray Films: An Image Characteristics Detection Approach

A common teleradiology practice is digitizing films. The costs of specialized digitizers are very high, that is why there is a trend to use conventional scanners and digital cameras. Statistical clinical studies are required to determine the accuracy of these devices, which are very difficult to carry out. The purpose of this study was to compare three capture devices in terms of their capacity to detect several image characteristics. Spatial resolution, contrast, gray levels, and geometric deformation were compared for a specialized digitizer ICR (US$ 15,000), a conventional scanner UMAX (US$ 15,000), a conventional scanner UMAX (US 1,800), and a digital camera LUMIX (US$ 450, but require an additional support system and a light box for about US$ 450, but require an additional support system and a light box for about US 400). Test patterns printed in films were used. The results detected gray levels lower than real values for all three devices; acceptable contrast and low geometric deformation with three devices. All three devices are appropriate solutions, but a digital camera requires more operator training and more settings.     

Digital image capture and analysis for split-drop micropuncture

A method for automated image capture and analysis of shrinking drop sequences is described. The procedure can be managed by a single operator and allows estimates of proximal tubule volume flux to be calculated during the experiment. Speed of analysis is increased considerably (mean time 1.5 min per sequence) compared with previous methods. The potential exists for measurement of droplets in tubules that follow a tortuous path in the horizontal plane and further increases in capture and analysis rate would allow estimation of volume flux under non-steady state conditions. Film processing is eliminated and the removal of operator errors, bias and fatigue associated with manual measurement, coupled with the greatly reduced time required for analysis of sequences makes the shrinking drop method much more reliable and attractive.