在X线直接数字成像系统上进行双能量分离成像

了一种基于Ｘ线直接数字成像 胸部骨和软组织双能量分离的方法。文中讨论了高能Ｘ线束滤过板的最佳厚度。在进行双能分离运算之前，我们对原始Ｘ线图像地散校正。研究结果结果利用广谱Ｘ线束获取双能量Ｘ线图像并将其用于常规检查是可行的。     

数字化X线成像系统的成像特性及其校正技术

随着一些新的Ｘ线图像处理方法的出现，对数字Ｘ互图像性能的要求将越来越高，本文从分析数字化Ｘ线成像系统的物理机制出发，提出了数字化Ｘ线成像系统的数学模型，并根据这一模型导出了Ｘ线成像的非线性规律及面不均匀性的规律，给出了对这些不利因素的校正方法，为进行数字Ｘ线图像的后续处理打下了坚实的基础。     

数字X线摄影中散射线计算机补偿方法的研究进展

在数字X线摄影中，散射线造成了图像对比度的损失、噪声的增加，是使图像质量恶化的主要原因。为了提高数字X线图像的质量，必须采取有效措施减少散射线，减小对比度的损失。除了硬件减少散射线的方法外，国内外学者对数字X线摄影中散射线计算机补偿方法做了一些研究，本文对散射线计算机补偿方法的研究进展作一综述。     

锥形束CT系统的散射校正方法分析

目的：在锥形束CT成像系统中，对投影数据进行适当的散射校正是一步重要的数据校正。方法：本文对目前关于锥形束CT图像散射的软件校正方法做了综述，其中包括了卷积法、反卷积法、蒙特卡罗模拟法以及基于散射校正板（beam stoparray，BSA）的散射校正法，并对各种方法进行了比较和讨论。结论：基于BSA的散射校正方法对三维锥形束CT系统进行散射校正是一种实用有效的校正方法。     

X线滤线栅几何性能微机测试系统的研制及应用

为快速、准确地检测Ｘ线滤线栅的对散射Ｘ线的吸收能力和使用效果，研制了滤线栅几何性能测试系统。该系统在微机控制下，对各个几何性能参数实现自动测量，测试结果精确，测量效率高，排除了人为因素的干扰，实用表明，效果好。     

模体大小对CBCT图像剂量计算的影响

目的：锥形束CT（CBCT）使用宽束X-射线,探测板获取的信号受散射线的影响很大。该文对扫描模体大小及散射体积对CBCT重建图像HU值及剂量计算的影响进行研究。方法：在Elekta Synergy-XVICBCT系统中对不同深度及散射体积的均匀水模和非均匀密度参考模体扫描,并测量感兴趣区域的HU值;建立考虑和不考虑散射的两组HU-物理密度曲线应用于水模及头颈部仿真模体CBCT图像进行剂量计算,与常规CT图像（FBCT）计算结果比较。结果：均匀水模CBCT图像的HU值随水模深度增加先增大后略有减少,随纵轴散射长度增加而减少,变化幅度最大均接近10%。随散射长度增加,非均匀密度参考模体CBCT图像的高密度组织的HU值减少而低密度组织HU值增加,对1.609 g/cm3致密度骨最大减少约1422 HU。均匀水模和头颈部仿真模体CBCT图像使用考虑散射的HU-物理密度修正曲线计算与FBCT图像比较结果为：点绝对剂量（cGy/MU）最大偏差小于1.5%,等剂量线偏差小于2 mm~3 mm,2%/2 mm DTA指数的通过率平均大于97%,明显优于不做散射修正的结果。结论：Elekta Synergy-XVI系统获取CBCT图像的HU值受扫描模体的几何大小及散射体积影响很大,应选择与扫描患者近似几何大小及人体组织等效的HU-密度校准模体。考虑模体大小及散射修正的头颈部模体CBCT图像用于剂量计算能满足临床要求。     

用非线性统计估计技术进行骨肿瘤X线图像的散射校正

本文基于泊松数据模型，利用MLEM（Maximum Likelihood Expectation Maximization)算法进行骨肿瘤X线图像的散射校正。最后将本文方法和去卷积方法分别应用于临床骨肿瘤X线图像。实验结果表明本文方法明显优于去卷积方法。     

数字X线成像术探测器

数字化Ｘ射线成像技术提高了图象质量，使其能够进行医学图像处理、计算机辅助诊断及远程放射成像。图象质量与从病人身上透射过来的Ｘ线信息的准确探测紧密相关，即与Ｘ线探测器的性能关系密切。数字放射成像术的探测器必须适合它们被应用的特殊的放射学过程。主要的参数有：空间分辨率、响应均匀性、对比灵敏度、动态范围、探测速度。下面将对一些适合数字Ｘ射线成像的探测器技术进行回顾，探讨用于全方位探测器的设备及适于Ｘ线扫描系统的设备。     

数字X线成像术探测器

数字化Ｘ射线成像技术提高了图像质量，使其能够进行医学图像处理、计算机辅助诊断及远程放射成像。图象质量与从病人身上透射过来的Ｘ线信息的准确探测紧密相关，即与Ｘ线探测器的性能关系密切。数字放射成像术的探测器必须适合它们被应用的特殊的放射学过程。主要的参数有：空间分辨率、响应均匀性、对比灵敏度、动态范围、探测速度。下面将对一些适合数字Ｘ射线成像的探测器技术进行回顾，探讨用于全方位探测器的设备及适于Ｘ线扫     

X射线机数字化成像

随着ＣＴ、ＭＲＩ、ＤＳＡ等数字化影像技术在临床的广泛应用，作为正在逐步取代普遍放射照像技术（增感屏／胶片系统）的数字化Ｘ线影像系统也日趋成熟。数字化Ｘ线影像系统在图像的采集、显示、后处理、管理和传送等功能方面有着传统Ｘ线成像无可比拟的优势和发展前景，它与快速发展的计算机网络技术逐步融合，使整个放射科发生着重大变化。     

Computation of realistic virtual phantom images for an objective lesion detectability assessment in digital mammography

Image quality assessment is required for an optimal use of mammographic units. On the one hand, there are objective image quality assessment methods based on the measurement of technical parameters such as modulation transfer function (MTF), noise power spectrum (NPS) or detection quantum efficiency (DQE) describing performances of digital detectors. These parameters are, however, without direct relationship with lesion detectability in clinical practice. On the other hand, there are image quality assessment methods involving time consuming procedures, but presenting a direct relationship with lesion detectability. This contribution describes an X-ray source/digital detector model leading to the simulation of virtual contrast-detail phantom (CDMAM) images. The virtual image computation method requires the acquisition of only few real images and allows for an objective image quality assessment presenting a direct relationship with lesion detectability. The transfer function of the proposed model takes as input physical parameters (MTF* and noise) measured under clinical conditions on mammographic units. As presented in this contribution, MTF* is a modified MTF taking into account the effects due to X-ray scatter in the breast and magnification. Results obtained with the structural similarity index prove that the simulated images are quite realistic in terms of contrast and noise. Tests using contrast detail curves highlight the fact that the simulated and real images lead to very similar data quality in terms of lesion detectability. Finally, various statistical tests show that quality factors computed for both the simulated images and the real images are very close for the two data sets.     

A Study on Image Quality Management in PACS Used by Korean Hospitals

This study evaluated a method to maintain the optimal image quality in clinical practice for image quality management in a picture archiving and communication system (PACS) that uses typical technology for digital medical images. This study conducted a survey of 25 hospitals in Seoul and metropolitan areas that had installed PACS to examine the reality of image quality management. Sixteen diagnostic monitors were used as calibration tools to compare and analyze the external illuminance uniformity and grayscale standard display function (GSDF) values at each frequency. According to the survey results, most of the hospitals did not have any particular rules or standardized methods for image quality control. In a PACS, the calibration frequency was examined within the allowable limits of error for each week and month. The calibration was not affected by the difference in brightness of the environment for reading an image. The GSDF measurement values were quite different from the standard values. In conclusion, to improve the image quality of the digital system, it is important to make good use of the system and maintain the image quality. Therefore, it is critical to capitalize on the method suggested in this study and maintain the optimal image quality to guarantee a high level of observer satisfaction.     

3D Isotropic Super-resolution Prostate MRI Using Generative Adversarial Networks and Unpaired Multiplane Slices

We developed a deep learning–based super-resolution model for prostate MRI. 2D T2-weighted turbo spin echo (T2w-TSE) images are the core anatomical sequences in a multiparametric MRI (mpMRI) protocol. These images have coarse through-plane resolution, are non-isotropic, and have long acquisition times (approximately 10–15 min). The model we developed aims to preserve high-frequency details that are normally lost after 3D reconstruction. We propose a novel framework for generating isotropic volumes using generative adversarial networks (GAN) from anisotropic 2D T2w-TSE and single-shot fast spin echo (ssFSE) images. The CycleGAN model used in this study allows the unpaired dataset mapping to reconstruct super-resolution (SR) volumes. Fivefold cross-validation was performed. The improvements from patch-to-volume reconstruction (PVR) to SR are 80.17%, 63.77%, and 186% for perceptual index (PI), RMSE, and SSIM, respectively; the improvements from slice-to-volume reconstruction (SVR) to SR are 72.41%, 17.44%, and 7.5% for PI, RMSE, and SSIM, respectively. Five ssFSE cases were used to test for generalizability; the perceptual quality of SR images surpasses the in-plane ssFSE images by 37.5%, with 3.26% improvement in SSIM and a higher RMSE by 7.92%. SR images were quantitatively assessed with radiologist Likert scores. Our isotropic SR volumes are able to reproduce high-frequency detail, maintaining comparable image quality to in-plane TSE images in all planes without sacrificing perceptual accuracy. The SR reconstruction networks were also successfully applied to the ssFSE images, demonstrating that high-quality isotropic volume achieved from ultra-fast acquisition is feasible.

     

基于模糊最大熵的医学X增强方射线图像边缘法研究

目的：由于医学X射线图像在数字化成像过程中容易受到成像设备中射线散射、电器噪声以及人体组织结构的复杂性等因素的影响,导致数字医学x射线图像的质量不高。因此,针对数字医学X射线图像对比度较差,目标细节信息不明显的特点,研究了一种基于模糊最大熵的图像边缘增强算法。方法：首先将医学X射线图像从灰阶域变换到模糊域。然后通过最大熵准则确定模糊阈值将医学X射线图像分为目标和背景两部分．并分别对其进行图像增强处理．最后再映射回到灰阶域。结果：本文以主动脉造影X射线图像为例,对其分别进行经典模糊边缘增强、反锐化边缘增强和模糊最大熵边缘增强处理,并对处理后图像的相关参数进行定量分析。结论：结果表明基于模糊最大熵算法处理后的图像质量高．边缘细节信息明显增强,且该算法相比其它两种算法具有更好的抗噪性。     

Translating the IHE Teaching File and Clinical Trial Export (TCE) Profile Document Templates into Functional DICOM Structured Report Objects

The Integrating the Healthcare Enterprise (IHE) Teaching File and Clinical Trial Export (TCE) integration profile describes a standard workflow for exporting key images from an image manager/archive to a teaching file, clinical trial, or electronic publication application. Two specific digital imaging and communication in medicine (DICOM) structured reports (SR) reference the key images and contain associated case information. This paper presents step-by-step instructions for translating the TCE document templates into functional and complete DICOM SR objects. Others will benefit from these instructions in developing TCE compliant applications.     

Validation of a digital mammographic unit model for an objective and highly automated clinical image quality assessment

In mammography, image quality assessment has to be directly related to breast cancer indicator (e.g. microcalcifications) detectability. Recently, we proposed an X-ray source/digital detector (XRS/DD) model leading to such an assessment. This model simulates very realistic contrast-detail phantom (CDMAM) images leading to gold disc (representing microcalcifications) detectability thresholds that are very close to those of real images taken under the simulated acquisition conditions. The detection step was performed with a mathematical observer. The aim of this contribution is to include human observers into the disc detection process in real and virtual images to validate the simulation framework based on the XRS/DD model. Mathematical criteria (contrast-detail curves, image quality factor, etc.) are used to assess and to compare, from the statistical point of view, the cancer indicator detectability in real and virtual images. The quantitative results given in this paper show that the images simulated by the XRS/DD model are useful for image quality assessment in the case of all studied exposure conditions using either human or automated scoring. Also, this paper confirms that with the XRS/DD model the image quality assessment can be automated and the whole time of the procedure can be drastically reduced. Compared to standard quality assessment methods, the number of images to be acquired is divided by a factor of eight.     

通过屏幕检测获取数字化X射线照片密度的方法

目的找到一种在数字化X射线照片打印前预测照片密度的方法,以实现更好的照片质量控制,避免在照片密度调整过程中不必要的浪费。方法通过编写计算机程序检测屏幕上指定位置的输出值。采用适当条件对铝梯进行投照,投照后在工作站上调整图像。使得铝梯各阶对比良好,保存并打印图像。在屏幕上由低到高对铝梯各阶进行采样,获取屏幕上各点输出值。使用密度计对打印后的照片进行测量,获得照片上铝梯各阶对应的照片密度。绘制密度曲线,再与相应的照片密度相关联。结果通过上述方法对100张照片进行检测．将对应点预测值和密度计实际测量值进行比较,误差小于5％。结论该方法是对数字化X射线照片密度预测的一种新的尝试．通过一个小程序跨越了从影像的屏幕显示到照片打印之间的多个设备和程序调试环节．直接将屏幕上的输出值和打印后的照片密度进行关联。通过检测屏幕输出值获得照片密度的预测值。     

Étude de la faisabilité du scorage automatique de fantômes mammographiques par traitement d’image

Nowadays, X-ray mammography is one of the most effective methods for early and reliable breast cancer detection and diagnosis. Periodic quality control in mammographic facilities is necessary to provide high quality mammograms. This evaluation is done by visual observation of mammographic phantom films. To prepare Full Field Digital Mammography advent and to get rid of this subjective quality control, digital image and signal processing techniques may be used in order to make this control easier and more objective. This paper presents an automatic method for scoring mammographic phantoms using digital image processing. Phantom films were first digitized and images containing microcalcifications, masses and fibers were extracted. Theses noisy and low contrasted images were preprocessed using an adaptive contrast enhancement method and then segmented in order to extract objects embedded in phantom images. Nine digitized phantom films were studied and results show that a more objective quality control evaluation of mammographic facilities can be done using digital image processing techniques on phantom images.     

Image quality in digital chromosome analysis systems

This paper reports on an investigation into the differences in image quality of different components used in a digital image processing system for chromosome analysis. As chromosome aberrations are important tools in the cloning of genes, it is important to know if the introduction of computerized analysis systems increases the risk of missing small aberrations. In this investigation the number of visible bands on a number of chromosomes has been used as a measure of quality. The images compared are microscope ocular images, photographs from a microscope builtin camera, digital images from a high and from a standard resolution camera, presented both on screen and print-out on paper. The main conclusions are that: (1) the view in the microscope ocular gives the best resolution, (2) there are risks of losing vital information using the digital image processing system for chromosome analysis, and (3) this risk is significantly reduced when using a high resolution camera.     

Gastrointestinal examinations with a 2,048-×2,048-pixel image intensifier television digital radiography system

The clinical usefulness of a 2,048-×2,048-pixel matrix image intensifier television digital radiography system was evaluated. Screen-film and digital images (with and without postprocessing) of the upper and lower gastrointestinal (GI) tract were used for clinical evaluation. For the upper GI tract, digital images processed with unsharp mask techniques were comparable in quality to screen-film images before and after upgrading the system. For the lower GI tract, screen-film images were better than digital images, except for those processed with a 2,048-×2,048-line monitor was comparable to a screen-film system.