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Still Image Compression Standards in DICOM<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
黄志聪 张长虹
北京军区总医院医学工程科，北京 100700
Zhi cong Huang, Chang hong Zhang
General Hospital of Beijing Military Region, Beijing 100700, China
Abstract
DICOM is the de-facto standard for medical image encoding and transmission. It has promoted the successful implementation of PACS in hospital and played an important part in the integration among hospital information systems. This paper first gives concise interpretations of some basic terminologies in DICOM, then describes data coding format and its structure briefly, followed by encapsulated image pixel coding and the three compression standards JPEG、JPEG-LS and JPEG2000 adopted by DICOM one by one. Deep understanding of image compression standards and their transfer syntaxes in DICOM standard is useful for the software programming of DICOM application and is also helpful to select appropriate compression scheme for PACS deployment.
Key Words: DICOM; JPEG; JPEG-LS; JPEG2000; Image Compression; Standard
医学数字成像与通信（Digital Imaging and Communications in Medicine，DICOM）标准是美国放射学会（American College of Radiology，ACR）和美国国家电器制造商协会（National Electrical Manufacturers Association，NEMA）联合制定的专门用于医学图像的存储和传输的标准。经过十多年的发展，该标准已经被医疗设备生产商和医疗界广泛接受，在医疗成像设备中得到普及和应用。带有DICOM接口的计算机断层成像（Computed Tomography ，CT）、核磁共振（Magnetic Resonance，MR）、心血管造影（X-Ray Angiography，XA）、超声扫描（Ultrasonography，US）、正电子发射断层成像（Positron Emission Tomography，PET）、单光子发射计算机断层成像（Single-Photon Emission Computed Tomography，SPECT）、计算机X射线成像（Computed Radiography，CR）、数字化X射线成像（Digital Radiography，DR）设备大量出现，对图像存档与通信系统（Picture Archiving and Communication Systems，PACS）的发展起了重要的推动作用。
一、DICOM标准的一些基本概念[1]
DICOM标准中有很多专业术语。下面简要地将本文涉及的一些术语予以简要地解释。
1.实体（Entity）: 表示一个或一类有相同特性个体的应用对象。在计算机系统分析中，凡是可以区别并被人们识别的事、物、概念等，都可以被抽象为实体。实体一般具有若干特征，称为属性（Attribute）。如: 患者是一个实体，具有姓名、性别、年龄等属性。图像也是一个实体，具有图像尺寸、图像数据等属性。 | 
