Search results
Results from the WOW.Com Content Network
Radiolysis is the dissociation of molecules by ionizing radiation.It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux.The radiation in this context is associated with ionizing radiation; radiolysis is therefore distinguished from, for example, photolysis of the Cl 2 molecule into two Cl-radicals, where (ultraviolet or visible spectrum) light is used.
Tomotherapy is a type of radiation therapy treatment machine. [1] [2] [3] In tomotherapy a thin radiation beam is modulated as it rotates around the patient, while they are moved through the bore of the machine. The name comes from the use of a strip-shaped beam, so that only one “slice” (Greek prefix “tomo-”) of the target is exposed ...
The Therac-25 is a computer-controlled radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) in 1982 after the Therac-6 and Therac-20 units (the earlier units had been produced in partnership with Compagnie générale de radiologie (CGR) of France).
PDD increases with increasing radiation field size due to greater primary and scattered photons from the irradiated medium PDD increases with increasing SSD because inverse square variations over a fixed distance interval are smaller at large total distance than small total distance [ 1 ]
Tissue-air ratio is defined as the ratio of the dose to water at a given depth to the dose in air measured with a buildup cap: = (,) (,) where D(f,z) is the dose at a given depth z and distance focus-detector f; and D(f,0) is the dose in air (z=0).
A monitor unit (MU) is a measure of machine output from a clinical accelerator for radiation therapy such as a linear accelerator or an orthovoltage unit. Monitor units are measured by monitor chambers, which are ionization chambers that measure the dose delivered by a beam and are built into the treatment head of radiotherapy linear accelerators.
The idealized intersection point of the gantry axis of rotation with that of the collimator and treatment table is known as the mechanical isocenter [2]. In practice, due to the heavy weight and mechanical imperfections of the system, the isocenter is not a single point and its location changes with the rotation of the gantry, collimator or couch.
Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure.