Johns, H. E., Cunningham, R. J.: "The Physics of radiology", (Thomas, Springfield, IL), 1983  Home/Search   Document Not in Database   Summary   Related Articles   Check

....selected from the 2D spectrum, for the achievement of the 1D NPS, useful for DQE calculation. The 1D NPS is then normalized for the squared mean signal value of the ROI. For the determination of the X ray photon fluence, HVL measurements are made with 4 cm plexiglas filter. From tabulated data [4] we calculate the photon fluence at the considered X ray average energy, and then the number of photons per unit area at the measured exposure is computed. The DQE is then calculated as: q q f NPS f MTF f DQE = 1) where q is the number of photons per unit area. y = 15.7x 23.9 ....

Johns, H. E., Cunningham, R. J.: "The Physics of radiology", (Thomas, Springfield, IL), 1983

....from control problems, for which approaches towards exact solutions exist even if chiefly for textbook examples, there are also many problems requiring software implementation that require applied mathematics of a different kind. A typical case in point is dose calculation in cancer radiotherapy [Johns and Cunningham (1976), Khan (1994) Cunningham (1989) Hounsell and Wilkinson (1994) Here the problem to be solved centres on the Boltzmann transport equation [Huang (1963) a three dimensional nonlinear integro differential equation that describes the electron (or X ray) density. Not only is this not a typical one ....

Johns, H. E., Cunningham J. R. (1976); The Physics of Radiology. Charles C. Thomas.

....in limited precision and finite software. The paper proceeds as follows: section 2 gives a brief resum e of the B notation of Jean Reymond Abrial [Abr96] which is the formal framework for the presentation of the work. Section 3 presents a motivating example of dose calculation in radiotherapy [JC76, Kha94, HW94], leading to a formal definition of retrenchment. The dosimetry example is (partially) recast as a retrenchment. Section 4 states the transitivity and monotonicity results required for a full calculus of retrenchment. In section 5 the generalising notion of evolving retrenchment is proposed, with ....

.... This path will be very irregular and characterised by many thousands of atomic interaction events that disperse the particle energy: an X ray will attenuate and be deflected while dislodging electrons and releasing secondary Compton radiation from any atom in its path (very simply speaking see [JC76] for the detailed physics involved) Thus, any small tissue volume in the beam volume can be regarded as subject to incident radiation of two kinds: primary radiation arriving directly from the beam source, and scattered radiation resulting from the myriad atomic scattering events. Avoiding the ....

H.E. Johns and J.R. Cunningham. The Physics of Radiology. Charles C. Thomas, 1976.

....Dose depends on position; to emphasize this dependence, it is often called the dose distribution. Strictly speaking, the dose distribution is not all that matters. Biological effects also depend on the type and energy of radiation used, the fractionation schedule, etc. see Chapter 17 of Ref. [23] for a discussion of these factors. However, in practice it is usually assumed that for a given type of treatment (for instance, treatment with X rays of a given energy range, and using a standard fractionation schedule) the effectiveness of a given treatment plan can be predicted from the dose ....

H. E. Johns and J. R. Cunningham, The Physics of Radiology, fourth edition, Charles C. Thomas, 1983.

....of the system s behaviour. Over the years, a large amount of work has been directed at taming the difficulties that arise. However there are also increasingly problems that involve applied mathematics of a different kind. Dose calculation in cancer radiotherapy is a typical case in point [Johns and Cunningham (1976), Khan (1994) Cunningham (1989) Hounsell and Wilkinson (1994) Here the problem to be solved centres on the Boltzmann transport equation [Huang (1963) a three dimensional nonlinear integro differential equation that describes the electron (or X ray) density. Not only is this not a typical one ....

Johns, H. E., Cunningham J. R. (1976); The Physics of Radiology. Charles C. Thomas.

.... to as the modulation transfer function (MTF) The following expression can be used as a model for an MTF with circular symmetry MTF( e Gamma ( c ) n ; 8) with [lp mm] line pairs per millimeter) the radial spatial frequency, c a frequency scaling parameter, and n the device index [7, 8]. In practice, the choice of n = 2 is a fair approximation of the true MTF. The acquisition system has two main sources of noise. The counted number of quanta per unit area p is Poisson distributed, Probfp = kg = k k e Gamma : 9) The parameter can be interpreted as the mean photon ....

H. E. Johns and J. R. Cunningham, The Physics of Radiology. Springfield, IL: Charles C. Thomas, 4 ed., 1983.

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HE Johns and JR Cunningham, The Physics of Radiology, Charles C Thomas, Springfield, p. 722, 1983.

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H. E. Johns and J. R. Cunningham, The Physics of Radiology, Charles C. Thomas, Springfield, IL, 4 ed., 1983.

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