Physics
X-Ray Image Processing
X-ray image processing involves the manipulation and enhancement of X-ray images to improve their quality and extract useful information. This can include techniques such as noise reduction, contrast enhancement, and image reconstruction. The goal is to produce clearer and more detailed images for accurate diagnosis and analysis in various fields such as medicine, security, and industrial inspection.
Written by Perlego with AI-assistance
Related key terms
1 of 5
4 Key excerpts on "X-Ray Image Processing"
eBook - PDF- Anil Bharath(Author)
- 2022(Publication Date)
- Springer(Publisher)
3 C H A P T E R 2 Diagnostic X-Ray Imaging The contents of this chapter are, essentially, the following: • Basic principles of X-Ray Imaging: Introduction to terminology and mode of operation. • X-Ray physics: Quantum nature; X- Ray interactions with matter; X-Ray spectra; energy range for diagnostic use. • X-Ray image quality parameters: general requirements on physical parameters; image Sig- nal/Noise (S/N); image contrast. • X-Ray production: functional design requirements;tube construction; target selection. • Image receptors: functional design requirements; film-based receptors; image intensifiers. • Patient dosage: trade-offs with image quality; noise and dosage; effective dose equivalent. 2.1 BASIC PRINCIPLES OF X-RAY IMAGING In the simplest case, an X-ray imaging system requires • X-Ray Source • A patient to image • Film (image receptor) • Radiologist/Diagnostician 2.1.1 IDEAL DESCRIPTION OF IMAGING PROCESS X-Rays are generated within the tube, and they are directed towards the patient. As the x-ray photons pass through the patient, some are absorbed, others scattered, and some pass through the patient with no interaction. The transmitted photons i.e., those which do not interact with the patient) are detected (received) by the photon receptor, usually based around film. The formation of an image on the film is dependent on the number of photons which are captured (detected) by the receptor: areas of the film which are dark have received a large number of photons; brighter areas have received fewer. The distribution of the light and dark areas on film is approximately a projection onto a two- dimensional map of the three-dimensional distribution of attenuating structures within the patient. As we shall see, there are many aspects which complicate the simplistic, ideal situation: 4 CHAPTER 2. DIAGNOSTIC X-RAY IMAGING • Statistical arrival of photons (Poisson process). • Photon scatter. • Lines of projection are not parallel i.e., one has beam divergence).
eBook - PDF- Anthony B. Wolbarst, Andrew Karellas, Elizabeth A. Krupinski, and William R. Hendee, (Authors)
- 2010(Publication Date)
- Medical Physics Publishing(Publisher)
CHAPTER 8 Image Processing for Projection Radiography Richard VanMetter, Ph.D. Consultant Washington, D.C. 125 8.1 Introduction 126 8.2 The Digital Imaging Chain 126 8.2.1 Digital Acquisition and the Raw Image 126 8.2.2 Pre-Processing and the Original Image 128 8.2.3 Image Display 128 8.2.4 Post-Processing and the Display-Ready Image 129 8.3 Post-Processing 129 8.3.1 The Need for Post-Processing 129 8.3.2 Automatic Grayscale Post-Processing 131 8.3.3 Characteristics of the Grayscale Mapping 134 8.3.4 Edge Restoration and Enhancement 134 8.3.5 Equalization 137 8.3.6 Surround Masking 139 8.3.7 Grid Line Removal 139 8.4 Future Opportunities and Directions 140 8.5 References 141 8.1 Introduction Projection radiography dates from the time of Roentgen’s discovery of x-rays. Prior to the introduction of digital tech- niques in the 1980s, “image processing” was incorporated into the design of the intensifying screens and films. The user could affect the appearance of an image by choice of screen, film, or radiographic technique. Once an image was acquired, however, there rarely occurred any further alteration of its appearance. Two areas of technological innovation changed this: The development of image acquisition modalities that are inher- ently digital in nature, and rapid advances in computer-based information processing capabilities. Acquisition devices built around the charge-coupled devices (CCDs) of image intensi- fier tube fluoroscopy, the photostimulable storage phosphor imaging plates (PSP IP) of computed radiography (CR), and the active-matrix flat-panel imagers (AMFPI) of digital radi- ography (DR) and digital fluoroscopy (DF) now enabled the acquisition of digital images. But these would have remained only laboratory curiosities without the advances in high- speed digital communication, massive digital data storage, computational power, and display technology.
eBook - PDF- M Flower(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
91 References ....................................................................................................................................... 91 15 Diagnostic Radiology with X-Rays In view of this place in history as well as the vast application of X-rays, it is appropri-ate to begin the discussion of the physics of medical imaging by considering diagnostic radiology with X-rays. In later chapters, we shall see how many of the concepts formed for describing radiography with X-rays are also useful for other modalities. In a sense, the language of imaging was framed for X-radiology, including concepts such as image contrast and noise and spatial resolution, and it has subsequently been taken across to describe these other techniques for imaging the human body. This chapter covers both the essential physics of the design of X-ray imaging equipment and the quality control of the equipment. Quality control is an important component of modern radiographic practice, facilitating the maintenance of the quality of the image and the radiation protection of patients and staff. The radiographic image is formed by the interaction of X-ray photons with a photon detector and is therefore a distribution of those photons, which are transmitted through the patient and are recorded by the detector. These photons can be either primary pho-tons, which have passed through the patient without interacting, or secondary photons, which result from an interaction in the patient (Figure 2.1). The secondary photons will in general be deflected from their original direction and, for our purposes, can be consid-ered as carrying no useful information.* The primary photons do carry useful informa-tion. They give a measure of the probability that a photon will pass through the patient without interacting and this probability will itself depend upon the sum of the X-ray attenuating properties of all the tissues the photon traverses.
eBook - PDFBio-Imaging
Principles, Techniques, and Applications
- Rajagopal Vadivambal, Digvir S. Jayas(Authors)
- 2015(Publication Date)
- CRC Press(Publisher)
Haff and Slaughter (2004) reported that use of digital imaging saves time by a factor of four as compared to film radiographs. The various cameras used in X-ray imaging are CCD (charge-coupled device), line scan cameras, and flat panel sensors, because these cameras could be used in real-time imaging applications. 7.2.4 Image processing system (A/D converter, frame grabber, and computer) The analog-to-digital converter is basically a device that converts the continuously varying analog signal to digital signal in binary form. The frame grabber captures video signals and converts them to digital form, which are displayed, transmitted, or stored. A computer attached to the imaging system serves as the software and hardware component to store and analyze the images using image processing algorithms. 7.2.5 Principle The basic principle underlying X-ray imaging is that different objects absorb X-rays in differ-ent ways depending on the composition, density, and thickness. For instance, in the human body, bone absorbs X-rays much higher than soft tissues or cartilages, and hence they appear white in an X-ray image, whereas soft tissues such as muscles and cartilage appear gray and airspace looks black. The more the object absorbs the X-ray, the brighter it appears. When any material is exposed to X-rays, the X-rays interact with the material and they lose their energy exponentially. This process by which X-rays lose their energy as it passes through objects is called attenuation. When passed through an object, photons present in a soft X-ray beam are transmitted, absorbed, or scattered, and the intensity of the photon is exponentially reduced, which is given by (Curry et al., 1990) I = I 0 e –μ z ρ where I represents the intensity of attenuated photons exiting through an object, I 0 is the intensity of incident photons, μ is the mass attenuation coefficient in square millimeters
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
