Mirjan M. Nadrljanski

Jul 8, 2024 | radiopaedia.org | Mirjan M. Nadrljanski |Tariq Walizai

X-rays (or much more rarely, and usually historically, x-radiation or Roentgen rays) represent a form of ionizing electromagnetic radiation. They are produced by an x-ray tube, using a high voltage to accelerate the electrons produced by its cathode. The produced electrons interact with the anode, thus producing x-rays. The x-rays produced include Bremsstrahlung and the characteristic radiation for the anode element.

Jun 26, 2024 | radiopaedia.org | Mirjan M. Nadrljanski |Arlene Campos

The cathode is part of an x-ray tube and serves to expel the electrons from the circuit and focus them in a beam on the focal spot of the anode. It is a controlled source of electrons for the generation of x-ray beams. The electrons are produced by heating the filament (Joule heating effect) i.e. a coil of wire made from tungsten, placed within a cup-shaped structure, a highly polished nickel focusing cup, providing electrostatic focusing of the beam on the anode.

Jun 13, 2024 | radiopaedia.org | Mirjan M. Nadrljanski |Rohit Sharma

Ultrasound frequencies in diagnostic radiology range from 2 MHz to approximately 15 MHz. Higher ultrasound frequencies have shorter wavelengths and provide better detail and spatial resolution (recall that axial resolution (ultrasound) = ½ ⨉ spatial pulse length). However, shorter wavelengths are absorbed/attenuated more easily. Therefore, higher frequencies are not as penetrating.

Apr 9, 2024 | radiopaedia.org | Mirjan M. Nadrljanski |Raymond Chieng

Alpha decay (a.k.a. α decay) is the radioactive process in which an alpha (α) particle (containing two neutrons and two protons) is ejected from the nucleus. An alpha particle is identical to the nucleus of a helium atom. All nuclei with an atomic number (Z) greater than 82, are considered unstable. These are considered “neutron-rich” and undergo alpha decay commonly. Alpha decay occurs in the nuclei of heavy elements, like radium, uranium, thorium, etc.

Apr 4, 2024 | radiopaedia.org | Mirjan M. Nadrljanski |Lachlan McKay

Beta decay represents radioactive decay in which a beta particle is emitted. Beta particles may be either electrons or positrons (β- or β+), having negative or positive charge respectively. The kinetic energy of beta particles has a continuous spectrum. If the number of neutrons in a nucleus is in excess, a neutron will undergo the following transformation: n --> p + β- + νe*, i.e., a neutron will be converted into a proton with the emission of a beta-minus particle (electron) and an antineutrino.