PubMed · 5078248
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R L Fleischer, H W Alter, S C Furman, P B Price, R M Walker. 1972-10-20. Particle track etching.. https://doi.org/10.1126/science.178.4058.255
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BACKGROUND: Radioimmunotherapy has primarily utilized high-energy beta-particles, which are intended to kill macroscopic tumor masses. Such conjugates do not kill single cells or micrometastases efficiently. For killing single cells, it may be preferable to use radiation with a much shorter path length, such as alpha-particles or Auger or conversion electrons. METHODS: This selective review focuses on the use of radiolabeled antibody (Ab) conjugates to achieve single-cell kill. The advantages and disadvantages of particular types of radionuclides, the significance of intracellular localization of the Ab, and the potential clinical application of this approach are discussed. Potentially useful radionuclides are listed. RESULTS: Auger and conversion electrons can kill cells effectively, with at least 6 logs of cell kill. Abs on the cell surface are only slightly less potent than Abs internalized into the cytoplasm, and this is consistent with theoretical considerations. alpha-Particles kill single cells very effectively, but the short half-lives of the available alpha-particle emitters are probably a disadvantage. High-energy beta-particles can also kill single cells if they bind in sufficient amounts, but their disadvantage appears to be greater nonspecific toxicity. CONCLUSIONS: Single-cell kill can be obtained with radionuclide-Ab conjugates. The selection of the optimal radionuclide may depend on the details of the clinical situation, such as the size and accessibility of the tumor burden, and the particular Ab to be used. Direct comparisons of various radionuclides are required in order to identify the optimal approach. However, for single-cell kill, as required for therapy of micrometastases, the use of Auger and conversion electron emitters appears to have substantial advantages. While current methods limit the applicability of this approach to Abs having a high level of binding, it may be applicable to lower-density antigens if higher specific activities or more potent radionuclides can be used. Tumor cure may require a mixture of radionuclides intended to kill both single cells and large tumor masses.
A concept of a mean or dose averaged quality factor was defined in ICRP Publication 26 using relationships for quality factor as a function of LET. The concept of radiation weighting factors, wR, was introduced in ICRP Publication 60 in 1990. These are meant to be generalized factors that modify absorbed dose to reflect the risk of stochastic effects as a function of the quality of the radiation incident on the body or emitted by radioactivity within the body. The values of wr are equal to 20 for all alpha particles externally or internally emitted. This note compares the dose averaged quality factor for alpha particles originating in tissue using the old and revised recommendations for quality factor as a function of LET. The dose averaged quality factor never exceeds 20 using the old recommendations and is never less than 20 with the revised recommendations.
This study was carried out to lay down the radiological limits of color-glazed tiles used in home decoration. The activity concentrations of various end products and raw materials as well as processed materials were measured using gamma spectroscopy. 222Rn exhalation rates from the surface of color-glazed tiles were measured using charcoal canister method. Levels of exposure to alpha ray and beta ray from the surface of glazed tiles were measured by surface alpha and beta contaminant instrument. The results show a great difference between the radioactive levels of the surface glaze and the matrix of color-glazed tiles. The 222Rn exhalation rates from the surface of color-glazed tiles are in the range of 10(-3) - 10(-4) Bq m(-2) s(-1). The concentrations of some natural radionuclides in glaze exceed the exempt limits of International Basic Safety Standards for Protection against Ionizing Radiation Sources (IAEA 1997). The limits for color-glazed tiles were deduced according to these data and the theory of UNSCEAR (1993). The activity concentration of 226Ra (Bq kg(-1)) in the glaze of color-glazed tiles should be in the range of A(226Ra) < or = 1,000 (Bq kg(-1)), and, at the same time, the specific activity of the natural radionuclides (Bq kg(-1)) should be in the range of A(232Th)/230 + A(226Ra)/310 + A(40K)/3,500 < or = 1.