医学成像原理

Reference-book：
Medical Imaging Physics, Fourth Edition, By William R. Hendee, & E. Russell Ritenour
Chapter 1. Preface (前言)
1.1 对医学成像过程理解的意义
任何医学成像模式的有效利用和图像的
图1-1 (p2) 是一幅医学成像过程的总体视
图。五个主要部分组成是病人，成像系 统，系统的操作者，图像本身以及观察 者。它的目的是使人体内部的一个目标 （Object）或者状态（Condition）能够被 观察者看见。特殊解剖特征的可视性取 决于成像系统的特性和操作者的风格。
Most medical imaging systems have a considerable number of variables that must be selected by the operator. They can be changeable system components, such as intensifying screens（增感 屏） in radiography, transducers in sonography, or coils in magnetic resonance imaging (MRI).
对于人类观察者而言，人体内部结构和
功能一般来说是看不见的。然而，借助 于各种技术，我们可以创建图像。通过 图像，医务人员就可以窥视人体以诊断 非正常状态并指导治疗过程。医学图像 是人体的一个窗口，没有图像窗口可以 揭示一切。
Different medical imaging methods reveal different characteristics of the human body. With each method, the range of image quality and structure visibility can be considerable, depending on characteristics of the imaging equipment, skill of the operator, and compromises with factors such as patient radiation exposure and imaging time.
Principles of Medical Imaging (医学成像原理)
生物医学工程研究所 邓振生 Zhensheng Deng from Institute of Biomedical Engineering
Principles of Medical Imaging (医学成像原理)
Personal Data：
大多数医学成像系统都具有必须
由操作人员选择的一定数量的变 量。它们可能是可变的系统的组 件，例如放射摄影中使用的增感 屏，超声波检查术中的换能器， 磁共振成像（MRI）中的线圈等。
However, most variables are adjustable physical quantities associated with the imaging process such as kilovoltage in radiography, gain in sonography, and echo time (TE) in MRI. The values selected will determine the quality of the image and the visibility of specific body features.
2.1 Introduction
To the human observer, the internal structures and functions of the human body are not generally visible. However, by various technologies, images can be created through which the medical professional can look into the body to diagnose abnormal conditions and guide therapeutic procedures. The medical image is a window to the body. No image window reveals everything.
观察者检测病理进程标志
的能力取决于三个因素的 综合： 1）图像质量； 2）观看条件； 3）观察者的执行特征。
2.2 Image Quality
The quality of a medical image is determined by the imaging method, the characteristics of the equipment, and the imaging variables selected by the operator. Image quality is not a single factor but is a composite of at least five factors: contrast, blur, noise, artifacts, and distortion, as shown in Figure 1-1. The relationships between image quality factors and imaging system variables are discussed in detail in later chapters.
图像质量 一幅医学图像的质量由成像方法、 设备特性以及操作者所选定的变量 所确定。图像质量不是单一因素， 而是至少五个因素的复合：对比度， 模糊，噪声，伪迹和失真等，如图11所示。图像质量因素和成像系统变 量之间的关系将在后续章节中详细 讨论。
Here show fig.1-1 again.
然而，大多数变量是与成像过程
相关联的可调节的物理量，例如， 放射摄影中的千伏值，超声检查 术中的的增益和MRI中的回波时 间等。这些选定的值将决定图像 的质量和特定人体特征的能见度。
The ability of an observer to detect signs of a pathologic process depends on a combination of three major factors: (1) image quality (2) viewing conditions (3) observer performance characteristics
Chapter 2 Image Characteristics and Quality
By Zhensheng Deng From Institute of BME
Summary：
2.1 Introduction
2.2 Image Quality
2.3
Tissue Characteristics and Image Views 2.4 Image Viewing Conditions 2.5 Observer Performance
不同的医学成像方法揭示人体的不
同特征。利用每一方法，图像质量 和结构的能见度的范围可能是相当 大的，这取决于成像设备的特征、 操作者的技巧以及与病人曝光量和 成像时间等这样的因素的折衷。
Figure 1-1 is an overview of the medical imaging process. The five major components are the patient, the imaging system, the system operator, the image itself, and the observer. The objective is to make an object or condition within the patient's body visible to the observer. The visibility of specific anatomical features depends on the characteristics of the imaging system and the manner in which it is operated.
解释都要求对图像形成过程的物理原理 的理解。这是因为显化特定解剖结构或 病理状态的能力取决于由使用者选定的 特定模式的固有特征和成像因素组。能 见度和成像因素之间的关系相当复杂， 并通常涉及到图像质量的各方面的折衷 和平衡。

Some Words Important In This Paragraph 1. anatomical structures, 2. pathologic conditions, 3. medical imaging modality, 4. compromise, 5. trade off, 6. visibility, 7. visualize.
Email Address: dzs@fmmu.edu.cn，or

bmedzs@csu.edu.cn Tel. No. : 8836362 (Work) Office Location: #226, Di Xue Lou
Text Book:
Physical Principles of Medical Imaging, Second Edition, By Perry Sprawls & Ye-cho Huang
1.5 本Leabharlann Baidu材的目的
主题和概念表达的选择基于Emory
University的放射住院医生培训项目的物 理部分，它假设没有先前的物理知识， 而读者又有理解医学成像职业的物理原 理的相当真诚的愿望。
1.6 本教材的目标
特定的目标是增强读者的能力以：
理解图像形成的基本原理； 选择适合特定临床要求的成像因素； 优化关于图像质量和病人曝光量的成像过程； 与技术组成员有效地沟通； 在选择设备与成像源时，做出明智的决策。
本教材包括许多来自作者先前的著作的
资料：The Physical Principles of Diagnostic Radiology, The Physics and Instrumentation of Nuclear Medicine 和医 学成像的物理原理的第一版，它已经在 超声、ECT(Emission Tomography)和 MRI(Magnetic Resonance Imaging)等领域 中进行了更新和增补。
1.3 本教材的用途
本课本提供了使医生在成像过程中的所
有阶段中都能够做出适当的技术决策物 理学和科学知识。 本书主要为在放射科住院医生培训计划 中学习的医生们而作。它同时还是常常 面临着日复一日地关于成像设备、过程 和病人安全决策的实践放射学家的有用 的参考资料。
1.4 本教材的资料来源
1.2 医学成像对人体可能的风险
所有的成像方法都在病人体内淀积某种
形式的能量。这样并非没有风险。辐射 曝光量通常是一个可变因子，它常常影 响图像质量。一种优化图像的程式这样 一个过程，在这个过程中，这两个因 素——图像质量和辐射曝光量被适当地 平衡。 1. Image Quality, 2. Radiation Exposure。
The human body contains many structures and objects that are simultaneously imaged by most imaging methods. We often consider a single object in relation to its immediate background. In fact, with most imaging procedures the visibility of an object is determined by this relationship rather than by the overall characteristics of the total image.