Delayed radiation

Gy in eleven fractions followed by a cycle of cisplatin and etoposide followed by the same schedule of radiation and followed again by chemotherapy. The delayed radiation arm gave the chemotherapy first then started the radiation therapy in wk 18 and again in wk 23. The same chemotherapy and radiation doses were given. The 5-yr survival and local recurrence rate were not statistically different. The 5-yr survival for the early arm was 10.8% vs 12% for the delayed radiation therapy arm. The local recurrence rate for the early radiation arm was 76.6% vs 72.8% for the delayed arm (50). 

Hallam A. (1991) Why was there a delayed radiation after the end-Palaeozoic extinctions Hist. Biol 5, 257-262. 

Martins AN, Johnston JS, Henry JM, et al Delayed radiation necrosis of the brain. J Neurosurg 47 336-345, 1977... 

It is the philosophy of the International Commission on Radiological Protection (53) and of most scientists in this field, that the cautious assumption should be made that any exposure to radiation may carry some risk for the development of somatic effects, including leukemia and other malignancies, and of hereditary effects. The Commission and others recognize that this is a conservative assumption and that some effects may exhibit a minimum or threshold dose but most often, the simple pessimistic assumption is made that the chance of delayed radiation injury of this kind is directly proportional to the total dose accumulated by the organ in question (the whole body is included as a special case within this term). 

The radiation protection problems which emerge during the operation of a fusion prototype reactor, either in normal or in accident conditions, are essentially connected with the presence of tritium, with the generation of neutrons with energies of 2.45 and 14.1 MeV (derived from the D-D and D-T reactions) and with the delayed radiation (and related thermal decay power), for the activation of the structures of the machine. 

Wang J, Boerma M, Fu Q etal. (2007a) Significance of endothelial dysfunction in the pathogenesis of early and delayed radiation enteropathy. World J Gastroenterol 13 3047-3055... 

Real Time Radiography (RTR) is an advanced method of radiography in which the image is formed while the job is exposed to ionising radiation. RTR is often applied to objects on assembly lines for rapid inspection. Accept-or-reject decisions may be made immediately without the delay or expense of film development. The main advantages of RTR are thus, reduction in inspection cost and processing time. 

We first supposed that the field radiated into the piece by the transducer is known, thanks to the Champ-Sons model. Then, the main approximation used consists in making far field assumptions in the beam defect interaction area. In the case of a focused transducer we assume that the incident wavefronts on the defect are plane. This is equivalent to say that the defect is located in or near the transducer focal area and that a defect located outside this zone does not cause a significant echo. In the case of planar contact transducer, the incident wavefronts on the defect are assumed to be spherical The incident field on the defect is therefore approximated by the product of a spatial function gfp,0,z)describing the amplitude distribution in the beam and a time-delayed waveform < ) ft) representing the plane or spherical propagation in the beam. The incident field on the defect can therefore be approximated for ... 

FigureBl.5.16 Rotational relaxation of Coumarin 314 molecules at the air/water interface. The change in the SFI signal is recorded as a fimction of the time delay between the pump and probe pulses. Anisotropy in the orientational distribution is created by linearly polarized pump radiation in two orthogonal directions in the surface. (After [90].)...

As an example, we mention the detection of iodine atoms in their P3/2 ground state with a 3 + 2 multiphoton ionization process at a laser wavelength of 474.3 run. Excited iodine atoms ( Pi/2) can also be detected selectively as the resonance condition is reached at a different laser wavelength of 477.7 run. As an example, figure B2.5.17 hows REMPI iodine atom detection after IR laser photolysis of CF I. This pump-probe experiment involves two, delayed, laser pulses, with a 200 ns IR photolysis pulse and a 10 ns probe pulse, which detects iodine atoms at different times during and after the photolysis pulse. This experiment illustrates a frindamental problem of product detection by multiphoton ionization with its high intensity, the short-wavelength probe laser radiation alone can photolyse the... 

There are four modes of radioactive decay that are common and that are exhibited by the decay of naturally occurring radionucHdes. These four are a-decay, j3 -decay, electron capture and j3 -decay, and isomeric or y-decay. In the first three of these, the atom is changed from one chemical element to another in the fourth, the atom is unchanged. In addition, there are three modes of decay that occur almost exclusively in synthetic radionucHdes. These are spontaneous fission, delayed-proton emission, and delayed-neutron emission. Lasdy, there are two exotic, and very long-Hved, decay modes. These are cluster emission and double P-decay. In all of these processes, the energy, spin and parity, nucleon number, and lepton number are conserved. Methods of measuring the associated radiations are discussed in Reference 2 specific methods for y-rays are discussed in Reference 1. 

The reader should note tliat since many risk assessments have been conducted on the basis of fatal effects, there are also uncertainties on precisely what constitutes a fatal dose of thennal radiation, blast effect, or a toxic chemical. Where it is desired to estimate injuries as well as fatalities, tlie consequence calculation can be repeated using lower intensities of exposure leading to injury rather titan dcatli. In addition, if the adverse healtli effect (e.g. associated with a chemical release) is delayed, the cause may not be obvious. Tliis applies to both chronic and acute emissions and exposures. 

The pyrotechnic literature does not contain a critical evaluation of the ignition response time. of primary initiators in terms of their compn, temp tolerance and shock sensitivity. In general, primary expls such as Pb Azide or styphnate are selected whenever a brief (microsecond) response is desired, while, for instance, Pb thiocyanate-chlorate mixts are selected when high temps and high radiation environments are encountered, and presumably a longer ignition delay is the price which is paid for the extra margin of safety... 

Theoretical Analysis of Resonance Tube , The Singer Company, Final Report KD 72-82 (1972) 58) F.J. Valenta, The State of the Art of Navy Pyrotechnic Delays , Expls Pyrots (The Franklin Institute Research Laboratories) 5, Nos 11 12 (Nov-Dec 1972). See also Ref 144, pp 185—95. See also Some Factors Affecting Burning Rates and Variability of Tungsten and Manganese Delay Compositions , Ref 144, pp 157—83. See also Mil Spec for Tungsten Delay Compositions , MIL-T-23132A (June 1972) 59) C.F. Parrish et al, Radiation... 

A delay error shifts the position of zero delay with respect to the overall intensity envelope, resulting in a substantial reduction of overall contrast. The contrast may vanish entirely if the zero delay position coincides with a minimum. Therefore, there is a relation between the allowable delay error max and the spectral bandwidth Aoj of the detected radiation if the amplitude error of the fringe modulation is to remain small, i. e., (5max = A /AA. 

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