看当前医学影像技术发展要关注的几个问题——记中华医学会影像技术分会第15次学术会议

中华医学会影像技术分会第15次全国学术大会于2007年10月在上海召开,与会代表近600人,发表论文800余篇,内容涵盖医学影像技术的各个领域,如：数字成像,CT成像,MR成像,医学工程、影像质量控制和管理等等。大会主题是：医学影像数字化技术和图像后处理。本文据此提出几个有关当前医学影像发展需要特别关注的问题。     

太赫兹成像技术在肿瘤检测中的应用

太赫兹(THz)波是频率位于0.1 THz^10 THz的电磁波。因其具有非电离性,以及可与多数生物分子产生共振响应等特性,在生物医学领域有着巨大应用潜力,尤其在肿瘤检测方面。太赫兹成像技术作为生物医学领域一种新的成像技术,吸引国内外多个研究小组对其开展深入研究。本文列举分析了多种太赫兹成像技术在肿瘤检测的应用,其中可分为太赫兹扫描成像、太赫兹层析成像、太赫兹全息成像以及太赫兹近场成像,介绍了这些成像方式的基本原理以及国内外研究现状,最后对太赫兹成像技术在生物领域的未来做出展望。     

漫话数字影像技术

本文阐述了有关数字影像技术的一些基本概念、其特征、优越性和发展的成果,以及所采用的装备和材料。在数字影像技术的基础上,已开发出新的一代影像设备系列,为当代各行各业的影像体系开创了新的前景,包括:电影、电视、印刷、通讯等等。     

光电子成像:回顾和展望

本文回顾半个世纪以来光电子成像 (包括微光成像和热成像 )的进展 .在微光成像技术方面 ,叙述了一代、二代和三代像增强技术、真空和固体微光摄像技术、光子成像计数技术的现状和发展 ;在热成像技术方面 ,叙述了致冷型一代、二代和三代热成像技术和非致冷型阵列热成像的现状和发展 .文中对新世纪的微光四代像增强技术、新型微光摄像技术和热成像技术的发展作了展望 .     

视窗模型的分类及其在影像学中的研究进展

视窗模型(Window Chamber,WC)是直接在动物活体上研究疾病的发生、发展、及其对治疗药物的反应,尤其对各种肿瘤的研究,提供了很好的平台。目前常用的视窗模型有脊背视窗模型、乳腺视窗模型、脊柱视窗模型以及颅脑视窗模型,目前对其成像方式多种多样,包括荧光成像、超声成像、磁共振(Magnetic Resonance Imaging,MRI)及核医学(Positron Emission Tomography,PET)成像。这些成像方法的发展对于研究视窗内组织的血管、代谢及药物的治疗效果具有重要意义,有利于深入了解疾病进展及研究疾病治疗新方法。     

太赫兹波计算鬼成像:原理和展望

本文立足于太赫兹波成像领域近年来备受关注的研究热点—太赫兹波计算鬼成像,首先回顾了鬼成像从量子到经典再到计算的历史过程,然后阐述了计算鬼成像的数学原理,随后综述了计算鬼成像在太赫兹波段的发展历程,及其在超衍射分辨成像、石墨烯光电导成像、太赫兹光谱成像等方面的应用,并在最后展望了太赫兹波计算鬼成像的发展前景:计算鬼成像作为一种成像手段,可以绕开在太赫兹频段缺乏经济高效的焦面阵列式探测器的难题,但目前的成像帧率还难以满足快速成像的应用需求,相信在未来随着器件性能的提升和成像算法的优化,其成像帧率可以得到大幅提升。     

基于量子关联的显微成像研究进展

简要回顾了量子关联成像的基本原理和发展历程,从量子光源和经典光源的角度详细介绍了量子关联成像在显微成像中的研究进展。做出了基于经典源的量子关联成像因易于实施、成本较低,在显微成像中更具应用前景的判断。     

Data acquisition and postprocessing strategies for fast quantitative sodium imaging

An efficient scheme for quantitatively mapping the three-dimensional distribution of the sodium ion in vivo using magnetic resonance imaging is described. To make the methodology totally quantitative, the data acquisition scheme is performed with very short echo times and negligible T₁ saturation. Removal of signal variation due to imperfect radiofrequency (RF) response is accomplished using RF inhomogeneity maps acquired during each study. The high efficiency of the k-space trajectories allows the entire data collection process to be performed in under 10 min. The theory underlying the data collection and processing scheme is described along with representative examples acquired at 1.5 and 3.0 T. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 544–550, 1997     

迅速发展的医学影像技术

本文总结了近些年来医学影像技术取得的新进展，如：计算机X线摄影CR、计算机断层X线摄影CT、磁共振成像MRI、数字减影血管造影DSA、图像存贮与通讯系统PACS等，并综述了中华医学会于2001年召开的医学影像学第三次全国学术会议上发表的一些学术论文。     

当代照相市场及未来的发展

本文叙述了传统感光材料的现状，包括技术、ＡＰＳ和大公司的投资情况，数字成像的基本特征和应用领域，最后从质量和成本的角度，用发展的眼光分析了未来照相市场的基本走势。     

Self‐Assembled Semiconducting Polymer Nanoparticles for Ultrasensitive Near‐Infrared Afterglow Imaging of Metastatic Tumors

Detection of metastatic tumor tissues is crucial for cancer therapy; however, fluorescence agents that allow to do share the disadvantage of low signal‐to‐background ratio due to tissue autofluorescence. The development of amphiphilic poly(p‐phenylenevinylene) derivatives that can self‐assemble into the nanoagent (SPPVN) in biological solutions and emit near‐infrared afterglow luminescence after cessation of light irradiation for ultrasensitive imaging of metastatic tumors in living mice is herein reported. As compared with the counterpart nanoparticle (PPVP) prepared from the hydrophobic PPV derivate, SPPVN has smaller size, higher energy transfer efficiency, and brighter afterglow luminescence. Moreover, due to the higher PEG density of SPPVN relative to PPVP poly(ethylene glycol), SPPVN has a better accumulation in tumor. Such a high sensitivity and ideal biodistribution allow SPPVN to rapidly detect xenograft tumors with the size as small as 1 mm³ and tiny peritoneal metastatic tumors that are almost invisible to naked eye, which is not possible for PPVP. Moreover, the oxygen‐sensitive afterglow makes SPPVN potentially useful for in vivo imaging of oxygen levels. By virtue of enzymatic biodegradability and ideal in vivo clearance, these organic agents can serve as a platform for the construction of advanced afterglow imaging tools.     

柯达数码产品多产的背后

进入21世纪以来,具有一百多年历史并以强大科研力量和先进的生产技术和装备为后盾的、基于化学成像技术的。世界最大的影像产品工业公司-柯达公司,在新的数码成像技术迅速发展的冲击下,最近几年业绩迅速下滑,并连年出现亏损,股票从1997年最高的94．25美元下跌N2008年的17.22美元。因此,柯达公司迅速转型,转向数码成像技术和产品的开发,目前已取得很好的效果,开始扭亏为盈,并向市场推出了很多性能优越的数码成像产品,本文扼要介绍柯达公司转型开发数字成像技术和产品的历程和背景。     

分子影像学基本内涵概述

分子影像学是一门新发展的医学影像学学科。分子影像学通过发展新的造影技术、系统、试剂及方法,探查疾病发展过程中细胞、亚细胞和分子水平的异常变化,在尚无解剖学改变前检出异常,从而为及早发现疾病、正确诊断和有效治疗提供更为丰富多样的医疗手段。本文扼要介绍分子影像学的基本概念、成像原理和实际应用。     

第五十届国际影像科学和技术年会简介

本文为中国感光学会副理事长、知名感光化学家王艳乔教授参加今年在美国波士顿召开的第五十届国际影像科学技术年会后对该会计的简要介绍，会议上发表的论文详见会议论文专集。     

我国医学影像技术的最新发展

随着医学数码影像技术的迅速发展，我国已经大量引进各种现代化的先进医学数码影像装备和相关的技术，并且已广泛地应用于临床诊断和治疗，取得了良好的效果。最近召开的全国医学影像技术专业会议就着重研究这一方面的课题，尤其是计算机X线摄影CR和影像存档和通讯系统PACS等，本文对大会上发表的论文进行综述。     

High-resolution underwater acoustic imaging with lens-based systems

In recent years, several sonars designed for high-resolution, short-range underwater imaging have been developed. These imaging systems use an acoustic lens to focus the incoming waves on an array of transducers. In this article we describe three prototype systems that use a line-focus or a point-focus lens and operate at a frequency of 300 kHz or 3 MHz. The line-focus lens produces two-dimensional (2D) intensity images, while the point-focus lens produces 3D intensity images. We present sample images taken from moving and stationary platforms, and discuss the techniques used for processing the acoustic backscatter data to reconstruct and visualize the scene. The images, particularly those taken with a point-focus lens, show a remarkable degree of detail. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 377–385, 1997     

Feasibility of a New Moving Collimator for Industrial Backscatter Imaging

Conventional direct radiography may fail to successfully produce images of corrosion in large pipes containing liquid and in tanks because the attenuation can be very high. It also fails when either side of the object is not accessible. These limitations do not exist in backscatter imaging because it is a one-sided imaging technique. However, backscatter imaging can be slow. In this study, the feasibility of a new backscatter imaging system based on a moving collimator that can produce images quickly is studied. Backscattered radiation from a broad-beam industrial X-ray machine is collimated by a special collimator to allow only parallel scattered radiation to pass and reach the image plate. Because part of the backscattered radiation can be stopped by the collimator septa, the collimator is put into motion; this allows a complete image to be revealed. An electro-mechanical system is designed to move the collimator either in steps or continuously. The distance, speed and direction of the movement are controlled by a smart motor using LabVIEW. Images of Polyvinylchloride (PVC) and aluminum objects are shown. Moving collimators can be added to existing radiographic systems to make them useful for both direct and backscatter imaging.     

Preliminary study of coded-source-based neutron imaging at the CPHS

A cold neutron radiography/tomography instrument is under construction at the Compact Pulsed Hadron Source (CPHS) at Tsinghua University, China. The neutron flux is so low that an acceptable neutron radiographic image requires a long exposure time in the single-hole imaging mode. The coded-source-based imaging technique is helpful to increase the utilization of neutron flux to reduce the exposure time without loss in spatial resolution and provides high signal-to-noise ratio (SNR) images. Here we report a preliminary study on the feasibility of coded-source-based technique applied to the cold neutron imaging with a low-brilliance neutron source at the CPHS. A proper coded aperture is designed to be used in the beamline instead of the single-hole aperture. Two image retrieval algorithms, the Wiener filter algorithm and the Richardson-Lucy algorithm, are evaluated by using analytical and Monte Carlo simulations. The simulation results reveal that the coded source imaging technique is suitable for the CPHS to partially solve the problem of low neutron flux.     

An improved adaptive detail enhancement algorithm for infrared images based on guided image filter

Detail enhancement algorithms are important for raw infrared images to improve their overall contrast and highlight important information in them. To solve the problems that current algorithms like GF&DDE have, an improved adaptive detail enhancement algorithm for infrared images based on a guided image filter is proposed in this paper. It chooses the threshold for the base layer image adaptively according to the histogram statistical information and adjusts the mapping range of the histograms according to the dynamic range of the image. Besides, the detail layer is handled by a simpler adaptive gain control method to achieve the good detail enhancement effect. Finally, the base layer and the detail are merged according to the approximate proportion of the background and the details. Experimental results show that the proposed algorithm can adaptively and efficiently enhance different dynamic range images in different scenarios. Moreover, this algorithm has high real-time performance.