Basics of X-Ray Technology Job Aid

SIEMENS Healthineers -- --- X-ray Essentials Basics of X-ray technology Job Aid Template Effective Date: 01/08/2018| HOOD05162002751995 Job Aid Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019 Basics of X-ray technology Generating X-rays Tungsten/rhenium Andode stem anode disk X-rays as well as light and radio waves are part of the electromagnetic Stator spectrum and they are differentiated by their energy level. It is only their higher energy level which differentiates them from other Anode + Cathode – electromagnetic waves such as light, heat or radio waves. X-rays are generated when electrons hit matter at a great velocity. In the vacuum e – Rotor of the X-ray tube, the electrons are accelerated until they reach Glass envelope Port this velocity (Fig. 1). The crucial factor hereby is the X-ray tube voltage Tube housing X-radiation Filament in U (the kV value). After passing through the electrical field generated focusing cup by U, the electrons hit the anode (= focal spot). Thus, their kinetic Fig. 1: Generation of X-rays in the focal spot of the anode energy is converted into X-radiation (about 1%) and heat (about 99%). Interaction between X-rays and matter A variety of effects occur when radiation passes through matter. One is that radiation becomes weaker as it passes through matter. This means with regard to X-radiation used for diagnostic purposes that two processes cause weakening: absorption and scattering. 2 Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019 Basics of X-ray technology Focus Scattered radiation When passing through matter, X-rays may divert and change direction – which results in scattered radiation. This affects the image quality negatively and image appears foggier. The amount of scattered radiation Primary depend on the size and thickness of the object, the ratio of scattered X-ray beam f0 radiation to useful radiation can be up to 80:20. Patient In most cases, a scattered-radiation grid is used to reduce the scattered Scatter beam radiation (Fig. 2). The grid is positioned in the X-ray path – in front of the X- Www Lead strips ray detector and filters scattered radiation. Grids also filter a slight amount of useful radiation. Therefore, young Grid children or very slender adults that cause little scattered radiation should Detector be examined without using a grid in order to save dose. Fig. 2: A scattered-radiation grid reduces scattered radiation 3 Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019 Basics of X-ray technology X-radiation Flat detector (FD) imaging fundamentals A dynamic flat detector (FD), acquires digital images. The incoming X-radiation is absorbed in a scintillator layer. The energy of the X-radiation is converted to visible light. The light is emitted from the highly transparent scintillator and converted to an electrical signal Scintillator in a photosensor. The dynamic flat detector enables high-quality digital imaging for dynamic sequences and static imaging, and supports the imaging mode fluoroscopy, Photosensor DFR, and RAD. + Electric signal – Scintillator The scintillator material is the cesium iodine (CsI), which has been successfully used in X-ray image intensifiers and is highly efficient. It is arranged to a continuous element which is active over its entire surface. Glass substrate Functional principle of a solid-state detector 4 Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019 Basics of X-ray technology X-radiation Structure Under the scintillator there is a matrix of 2880 x 2880 pixels. Amorphous silicon (“a-Si”) technology was used to make this matrix. Each pixel consists Scintillator of a photosensor and a semiconductor switch. With the aid of the switches and control and read-out electronics, it is possible to register and digitize the signals of each pixel. To the Calibration electronics Like a computer tomograph, a solid-state detector must be calibrated. That is done by making acquisitions without an object in order to define and Control Switch store the individual pixel sensitivity. During calculation of any subsequent image, the slight differences in pixel sensitivity can be compensated to make Pixel the sensitivity over the whole surface identical. Light sensor Structure of the “a-Si” solid-state detector (schematic) Dose After calibration, the system knows how much of a signal a certain dose generates. The conversion factor from gray scales to dose is therefore known. With this information, the solid - state detector can be used as a dose measurement chamber for the applied dose within certain limits. 5 Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019 SIEMENS Healthineers Please note that the learning material is for training purposes only! For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (hereinafter collectively “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training. The Operator's Manual shall be used as your main reference, in particular for relevant safety information like warnings and cautions. Note: Some functions shown in this material are optional and might not be part of your system. Certain products, product related claims or functionalities (hereinafter collectively “Functionality”) may not (yet) be commercially available in your country. Due to regulatory requirements, the future availability of said Functionalities in any specific country is not guaranteed. Please contact your local Siemens Healthineers sales representative for the most current information. The reproduction, transmission or distribution of this training or its contents is not permitted without express written authority. Offenders will be liable for damages. All names and data of patients, parameters and configuration dependent designations are fictional and examples only. All rights, including rights created by patent grant or registration of a utility model or design, are reserved. Copyright © Siemens Healthcare GmbH Global Siemens Healthineers Headquarters Henkestr. 127 91052 Erlangen, Germany Phone: +49 9131 84 0 siemens.com/healthineers 6 Effective Date: 11/16/2018 | HOOD05162002961332 © Siemens Healthcare GmbH, 2019