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A high LET will slow down the radiation more quickly, generally making shielding more effective and preventing deep penetration. On the other hand, the higher concentration of deposited energy can cause more severe damage to any microscopic structures near the particle track.
Radiation therapy kills cancer cells in two ways depending on the effective energy of the radiative source. The amount of energy deposited as the particles traverse a section of tissue is referred to as the linear energy transfer (LET). X-rays produce low LET radiation, and protons and neutrons produce high LET radiation.
It is unknown whether high-LET radiation could cause the same types of tumors as low-LET radiation, but differences should be expected. [9] The ratio of a dose of high-LET radiation to a dose of x-rays or gamma rays that produce the same biological effect are called relative biological effectiveness (RBE) factors. The types of tumors in humans ...
For such purposes, doses should be evaluated in terms of absorbed dose (in gray, Gy), and where high-LET radiations (e.g., neutrons or alpha particles) are involved, an absorbed dose, weighted with an appropriate RBE, should be used" Radiation weighting factors are largely based on the RBE of radiation for stochastic health risks. However, for ...
Consequently, OER varies from unity in anoxia to a maximum value for 100% oxygen of typically up to three for low ionizing-density-radiation (beta-, gamma-, or x-rays), or so-called low linear energy transfer (LET) radiations. Radiosensitivity varies most rapidly for oxygen partial pressures below ~1% atmospheric (Fig. 1).
High-LET radiation at doses that are below 0.5 Gy show greater relative biological effectiveness compared to low-LET radiation. [63] The acute effects on the CNS, which are associated with increases in cytokines and chemokines, may lead to disruption in the proliferation of stem cells or memory loss that may contribute to other degenerative ...
High-LET alpha radiation produces larger amounts of radiolysis products. In presence of dissolved oxygen, radiolysis always occurs. Dissolved hydrogen completely suppresses radiolysis by low-LET radiation while radiolysis still occurs with The presence of reactive oxygen species has strongly disruptive effect on dissolved organic chemicals.
Radiation with higher LET and higher relative biological effectiveness (RBE) have a lower OER in mammalian cell tissues. [2] The value of the maximum OER varies from about 1–4. The maximum OER ranges from about 2–4 for low-LET radiations such as X-rays, beta particles and gamma rays, whereas the OER is unity for high-LET radiations such as ...