Physics Behind The Phantom Volume 2 The Neonatal Chest Phantom A White Paper Report September 23, 2008 Gammex Inc. White Paper Report – March 28, 2008

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom Physics Behind The Phantom Volume 2 The Neonatal Chest Phantom Gammex Inc. has developed the new Neonatal Chest Phantom, a unique, anthropomorphic phantom designed for use in quality assurance of computed and digital radiography systems. To evaluate the significance of this product, it is instructive to look at the industry’s trend toward wider use of computed radiography, along with its benefits, limitations and special requirements, especially as computed radiography relates to neonatal chest imaging, image quality and patient...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom The Trend to Computed Radiography Traditional x-ray studies use screen-film radiography (SFR) to irradiate an intensifying screen and film in a cassette. When irradiated, the screen emits visible light, which then exposes the film. The exposed film is chemically processed to display the image. Over the past 20 years, digital x-ray imaging, in the form of computed radiography (CR), has been increasingly used in place of traditional screen-film radiography. CR replaces the screen/film combination with a photostimulable phosphor plate...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom Requirements and limitations of screen/film radiography In SFR the film acts as both receptor and display device. The resolution and contrast of the final image is limited by the screen/film characteristics. The exposure required to create an image is determined by the speed and noise characteristics of the screen and film. The image quality is further affected by such film characteristics as the H&D curve, the screen speed and the film grain — all of which are fixed once the screen/film combination has been selected. Finally,...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom CR provides more information, more simply and safely CR, on the other hand, is able to handle all imaging with a single linear detector with a dynamic range of over four orders of magnitude. This wide dynamic range permits all the information in the patient to be captured. Because the detector is decoupled from the display, over- and under-exposure of a radiograph are virtually eliminated by digitally moving the data into a useful display range. Lowdose radiographs offer image quality limited only by the noise levels acceptable...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom With CR, anatomic detail is relevant for image optimization Most CR systems use a type of histogram analysis to process the image data. In order to create the best scaling and processing of the image data, computed radiography systems must have a priori knowledge of the anatomy being radiographed. The histogram is analyzed according to characteristics which are expected for that anatomy. This analysis directly impacts everything from auto-ranging of the data to appropriate spatial frequency processing. For example, using the same...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom can only be used with test protocols which vary dramatically from clinical imaging protocols. Thus, manufacturers face major challenges in optimizing system parameters for particular user tasks, and service and support engineers find trouble-shooting in the field problematic because there are no tools which allow system characterization and performance optimization. Similarly customers are faced with related challenges when acquiring and establishing quality assurance for CR systems. They must evaluate products and vendors, decide...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom Quality control of CR is especially important in pediatric imaging Because of their high sensitivity and extended dynamic range, digital receptors open the way for reduced-dose radiography. This is of major importance for pediatrics. Because children are still developing, their tissues are in a state of rapid differentiation and growth. This is known to put children at high risk of cancers from all carcinogens, including radiation. In two recent studies it was shown that radiation to children, even at diagnostic imaging levels,...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom The Gammex 610 Neonatal Chest Phantom addresses image quality and patient exposure concerns The new Gammex 610 Neonatal Chest Phantom is designed for routine quality assurance of computed and digital radiography systems. The Gammex 610 is a unique anthropomorphic neonatal phantom that mimics a 1-2 Kg neonate in its transmission characteristics, histogram, physical size and structure. Because the phantom replicates both the anatomic structure and the tissue attenuation characteristics of a real neonate, the phantom can be imaged...

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom Gammex 610 Specifications: Size Weight Composition Membrane Lung, Approx. 100mm x 100mm x 54mm Approx. 500 grams Air, (Tissue Equivalent Materials) Muscle, Normal Lung, Hyaline Bone Lungs Included #1 Left – Hyaline Membrane Disease: Pneumothorax #2 Right – Hyaline Membrane Disease Texture: No Pneumothorax #3 Left – Normal Texture: Pneumothorax #4 Right – Normal Texture: No Pneumothorax Gammex 610 Neonatal Chest Phantom comes with a custom carrying case. Gammex Inc. White Paper Report

Physics Behind the Phantom – Volume 2, The Neonatal Chest Phantom