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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 ...
The RBE is generally independent of LET for any LET less than 10 keV/μm, so a low LET is normally chosen as the reference condition where RBE is set to unity. Above 10 keV/μm, some systems show a decline in RBE with increasing LET, while others show an initial increase to a peak before declining.
The detailed RBE vs. LET relationship that was found for total exchanges is similar to that of earlier studies of mutation [11] [12] and in vitro neoplastic transformation. [13] For all of these endpoints, RBE peaks at around 100 to 200 keV/μm before it decreases at very high-LET. However, the quality of chromosome damage is different when ...
Heavy ion therapy (e.g. carbon ions) makes use of the similarly high LET of 12 C 6+ ions. [5] [6] Because of the high LET, the relative radiation damage (relative biological effect or RBE) of fast neutrons is 4 times that of X-rays, [7] [8] meaning 1 rad of fast neutrons is equal to 4 rads of X-rays. The RBE of neutrons is also energy dependent ...
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 ...
Thus the RBE of a carbon ion beam increases as the ions advance deeper into the tumor-lying region. [17] CIRT provides the highest linear energy transfer (LET) of any currently available form of clinical radiation. [18] This high energy delivery to the tumor results in many double-strand DNA breaks which are very difficult for the tumor to repair.
The rem and millirem are CGS units in widest use among the U.S. public, industry, and government. [4] However, the SI unit the sievert (Sv) is the normal unit outside the United States, and is increasingly encountered within the US in academic, scientific, and engineering environments, and have now virtually replaced the rem. [5]
There are two basic types of cell survival curves: Linear (exponential) or curved. Linear survival curves reflect cells irradiated with high LET radiation. The relationship between the surviving fraction (S) and the dose (D) is S = e^(-a)D where -a represents the slope. The relationship can also be expressed as S = e^(-D/D0) where D0 represents ...