Construction of nomograms with straight parallel lines.
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Breast Neoplasms↗
Biomedical subjects
D Jette
Publications and source records attributed to D Jette.
Colloidal particle-size determination by gel filtration.
The particle sizes of technetium-99m sulfur colloid and technetium-99m antimony sulfide colloid are determined by gel filtration. These results are compared with those obtained by electron microscopy and by ultrafiltration. It is shown that gel filtration is suitable for particle-size determination below 100 nm, whereas above this size ultrafiltration provides the most convenient method.
Chromatography, Gel↗
Second-order multiple-scattering theory for charged-particle teletherapy beams.
The Fermi-Eyges theory of multiple scattering, applicable to charged-particle teletherapy beams, has been generalized to second order in small quantities representing deviations from the particles' initial lines of travel and direction. The second-order multiple-scattering theory provides increased accuracy, and in particular it takes into account the skewness of the particles' paths, in calculating dose. Only the assumptions and certain results of the second-order theory are presented in this communication, for the immediate use of other investigators. An application to rectangular fields shows that the second-order theory predicts one component of the buildup of electron central axis depth dose, which the (first-order) Fermi-Eyges theory cannot do. (The other major component of buildup, which is not yet incorporated into this theoretical work, is due to high-energy secondary electrons). Various approximate calculations of electron central axis depth dose are compared with the second-order calculation.
Humans↗
Collimated electron beams and their associated penumbra widths.
The Fermi-Eyges multiple-scattering theory for electrons is applied to calculate profiles of collimated electron beams. The dose profile below the collimator is a convolution of the intensity distribution of the electrons at the level of the collimator and the distribution arising from the propagation of a Gaussian point source from the collimator to the level of the calculation. The electrons at the level of the collimator possess an angular distribution characteristic of the configuration of the electron beam at the vacuum window. Hence, the dose profile and its associated penumbra width can be expressed in terms of the angular moments of the distribution of the electrons at the collimator. The dependence of the penumbra width on the configuration-dependent angular spread of the electrons at the collimator accounts for differences in the size of the penumbra between two broad-beam configurations. These differences are also seen experimentally. We have also studied the dependence of the angular moments of the electrons upon scattering foils present above the collimator and the position of the beam-broadening device in the accelerator head.
Electrons↗
Electron dose calculation using multiple-scattering theory. A. Gaussian multiple-scattering theory.
This article is the first in a series on the calculation of electron dose using multiple-scattering theory. In it we develop a unified theory, which we term Gaussian multiple-scattering theory, starting from a number of contributions already in the literature: the Fermi-Eyges multiple-scattering theory, the Yang path length distribution, the second-order multiple-scattering theory of Jette [Med. Phys. 12, 178 (1985)], and the diffusion theory of Bethe et al. [Proc. Am. Philos. Soc. 78, 573 (1938)]. After examining in detail the ramifications and limitations of Gaussian multiple-scattering theory, we derive basic formulas generalizing the Fermi-Eyges theory, for use in subsequent articles. We also find explicit, accurate expressions for incorporating the scattering power into the theory.
Fourier Analysis↗
Electron dose calculation using multiple-scattering theory: second-order multiple-scattering theory.
This article is part of a series on the calculation of electron dose using multiple-scattering theory. It presents systematically the second-order multiple-scattering theory which is a generalization of the (first-order) Fermi-Eyges theory, outlining its derivation and giving explicit formulas for its defining functions. The predictions of the Fermi-Eyges theory and of the second-order theory are compared with modified Monte Carlo calculations, demonstrating the increased accuracy of the latter multiple-scattering theory. We derive and compare broad-beam angular distributions for the two theories, and note the effect of large-angle scattering upon dose profiles. Finally, we present the second-order theory in Fourier-transformed space, which is appropriate to a high-speed dose-calculation algorithm using the fast Fourier transform (FFT) technique.
Algorithms↗
Electron dose calculation using multiple-scattering theory: thin planar inhomogeneities.
In this article in our series on electron dose calculation using multiple-scattering theory, we apply the Fermi-Eyges theory to the problem of a thin planar inhomogeneity present in an otherwise-layered medium. We derive expressions for the distribution function P and the location distribution L (which multiplied by the restricted mass collision stopping power is the dose directly deposited by the primary electrons) for various types of incident beams: a completely arbitrary distribution, a Gaussian point source, a pencil beam, an isotropic point source, and a broad parallel beam. We show how divergent-beam dose distributions can be determined from parallel-beam calculations, through use of equivalent configurations dependent upon the depth of dose calculation. Also, we indicate how this work can be applied to the design of wedges (or "compensators") for beam shaping to provide desired dose distributions or to match juxtaposed radiation fields. Explicit formulas for thin plates are then worked out, and we examine the appearance of hot and cold spots distal to the edge of a localized inhomogeneity, for thin half-slabs and for narrow strips. Finally, considering the case of a thin straight wedge-shaped inhomogeneity, we theoretically discover the phenomenon of a "focused hot spot" without an accompanying cold spot, and suggest the design of a "multiple-scattering lens".
Electrons↗
Electron dose calculation using multiple-scattering theory: localized inhomogeneities--a new theory.
In this fourth article in a series on the calculation of electron dose using multiple-scattering theory, we deal with localized inhomogeneities by solving the Fermi equation for scattering power which is an arbitrary function of position. In fact, we go further, by solving the second-order multiple-scattering equation which supersedes the (first-order) Fermi equation, again for scattering power which is an arbitrary function of position. Thus, we are no longer restricted to a horizontally layered medium, as is the case with the Fermi-Eyges theory. Our general solution is in the form of a perturbation series which evidently converges rapidly enough that only its first two or three terms need be taken for accurate dose calculation. Regarding the energy directly deposited by the primary electrons, the formulas developed in this article give very good agreement with Monte Carlo calculations for the thick half-slab configuration, as will be seen in the next article in this series. Moreover, our first-rank, second-order formulas, when expressed in Fourier-transformed space, are simple enough to be implemented in a treatment planning system providing full three-dimensional electron dose calculation for arbitrary configurations of inhomogeneities.
Electrons↗
Electron dose calculation using multiple-scattering theory: evaluation of a new model for inhomogeneities.
In this article, the fifth in a series on the calculation of electron dose using multiple-scattering theory, the predictions of a new model for dealing with localized inhomogeneities will be examined (Med. Phys. 18, 123-132, 1991). That model is in the form of a perturbation series, and for a thick half-slab configuration explicit formulas are worked out for the dose directly deposited by the primary electrons, for three reasonable cutoffs of the series. The predictions of this model with EGS4 Monte Carlo calculations for the half-slab configuration are compared, and they are found to be quite accurate in the region under the edge of the half-slab. On the other hand, the "Hogstrom algorithm," which is currently the most advanced method in routine clinical use, is found to give poor accuracy for this configuration.
Algorithms↗
Installation of EGS4 Monte Carlo code on an 80386-based microcomputer.
This article presents the considerations and efforts involved to install and fully support the EGS4 radiation-transport Monte Carlo simulation code on an 80386-based microcomputer. It also presents some EGS4 benchmark timing comparisons between this and other computer architectures.
Electrons↗
Possible utility of serum determinations of CA 125 and CA 27.29 in breast cancer management.
The utility of measurement of serum levels of the tumor associated antigens CA 125 and CA 27.29 in detecting the presence of disease and in monitoring changes in disease status was examined in 63 patients with breast cancer. In patients with clinically detectable disease the CA 125 level was elevated in 59%, the CA 27.29 level in 59.5% and one or both markers in 84.6%. Specificity for presence of disease was 83.6% for CA 125, 88% for CA 27.29, and 69.1% for the two markers combined. Changes in marker levels of more than 50% correlated with clinical changes in disease status in 58% of cases for either CA 125 or CA 27.29 alone. In 87.5% of cases with clinically progressive disease one or both marker levels increased by more than 50% from the previous levels. In no case with greater than 50% increase in a marker level was there regression of disease. Thus, the use of these markers in combination might have utility in cases where diagnosis of recurrent disease is difficult or where monitoring of response to treatment is hampered by lack of measurable disease.
Adenocarcinoma↗