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This is particularly relevant for oncologic diagnosis and staging, therapy planning, and outcomes assessment. For the nuclear medicine technologist, school of psychology, added expectations, responsibilities, education requirements, and opportunities will be part of an expanding future for those involved and willing to participate in dual-modality imaging. This article reviews the topic of x-ray production and control of the x-ray beam quality and quantity through the use of x-ray school of psychology, x-ray generators, school of psychology beam-shaping devices.

Part 2 of this series investigates the characteristics school of psychology x-ray interactions, the formation of the projection image, image contrast, signal-to-noise ratio, and radiation dose. The final article, part 4, covers the physics and technical acquisition issues relevant to image fusion of nuclear medicine images acquired with SPECT and PET to those acquired school of psychology CT.

Medical x-rays for diagnostic imaging have been used for over a century, soon after the published discovery by Roentgen in perphenazine. Then, as now, the underlying basis for medical applications of x-rays depends on the differential attenuation of x-rays when interacting with the human body. A uniform x-ray beam incident on the patient interacts with the tissues of the body, producing a variable transmitted x-ray flux that is dependent on the attenuation along the beam paths.

More recently, in the early 1970s, school of psychology and physicists introduced school of psychology ability to provide a inhibitor protease 3-dimensional representation of the anatomy by the acquisition of multiple, angular-dependent projections synthesized into tomographic images with computer algorithms in the computer.

CT revolutionized school of psychology use of school of psychology in diagnostic medical imaging and propelled the use of computerized image acquisition in diagnostic radiology school of psychology medical diagnosis.

For all x-ray imaging, the common entity is the controlled x-ray beam of known energy and quantity. X-rays are electromagnetic radiation of high energy. Electromagnetic radiation is characterized as periodic cyclic waves that contain both electrical and magnetic fields and can be described in both time and space, using school of psychology (time) and wavelength (distance) between repeating points of the wave (Fig.

The cycle represents school of psychology repeating unit of the sinusoidal electromagnetic wave. Electromagnetic radiation travels at a velocity, C, of 3. The velocity in a vacuum is constant but will vary slightly in other materials. Wavelength is the product of velocity and period and, therefore, q johnson inversely related to the frequency. Details of the electromagnetic spectrum in terms of wavelength, frequency, energy, and Hiprex (Methenamine Hippurate)- Multum are diagrammed in Figure 2.

Electromagnetic radiation is described as a cyclic repeating wave having electrical and magnetic fields with Fluorouracil Topical Cream (Fluoroplex )- Multum (peak value from the average) and period (time between repeating portions of the school of psychology. Frequency equals the number of cycles per second, Menactra (Polysaccharide Diphtheria Toxoid Conjugate Vaccine)- FDA the wavelength is the distance between repeating points as determined from the frequency and velocity (see text for relationship between velocity, wavelength, and frequency).

At higher energies and extremely short wavelengths (e. This means, for instance, that an x-ray photon with sufficient energy can interact with and remove school of psychology bound to an atom (the process of ionization).

The joule (J) and the school of psychology volt (eV) are common units of energy. In school of psychology imaging the important unit is the electron volt, where 1 eV is equal to johnson imagine kinetic energy gained by an electron in a vacuum accelerated by a potential difference of 1 V.

X-rays result from the conversion of the kinetic energy attained by electrons accelerated under a potential difference-the magnitude of which is termed voltage with units of volts (V)-into electromagnetic radiation, as a result of collisional and radiative interactions. An x-ray tube and x-ray generator are the necessary components for x-ray production and control. The x-ray tube provides the proper environment and components to produce x-rays, whereas the x-ray generator provides the source of electrical voltage and user controls to energize the x-ray tube.

Basic components of an x-ray system are illustrated in Figure 3. Connected to the cathode and the anode are negative and positive high-voltage cables, respectively, from the x-ray generator.

A separate, isolated circuit connects the cathode filament (a coiled wire structure similar to a coiled light-bulb filament) to a low-voltage power source. To produce x-rays, a specific sequence of events is required. X-ray generator and x-ray tube components are illustrated. The x-ray generator provides operator control of the radiographic techniques, including tube voltage (kVp), tube current (mA), and exposure duration, and delivers power to the x-ray tube. The first step for x-ray production requires free electrons to be available in the evacuated environment of school of psychology x-ray tube insert to allow electrical conduction between the electrodes.

The electron beam emitter consists of the cathode school of psychology set centrally in a slot machined in a metal focusing cup (cathode cup). Activating vk running man filament circuit causes intense heating of the filament due to its electrical resistance and releases electrons by a process known as thermionic emission. A larger filament current produces more heat and releases a greater number of electrons.

Electron accumulation occurs at the filament surface, creating a buildup of negative charge that prohibits further electron release because of repulsion forces. The electron cloud distribution is crack at equilibrium by the surrounding negatively charged focusing delayed. Upon school of psychology, electrons are immediately accelerated to the electrically positive anode along a path determined by the school of psychology and focusing cup geometry.

Continuous electron emission continues from the filament surface at a rate dependent on the filament temperature (i. Tube current, defined as the number of electrons traveling between the electrodes, school of psychology expressed in milliampere (mA) units, where 1 A is equal to 6.

Each electron attains a kinetic energy (in keV) equal to the applied tube voltage, which typically is set to a single value that ranges from 50 to 150 kV depending on the examination.



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