James B Smathers

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Since September 11, 2001, there has been the recognition of a plausible threat from acts of terrorism, including radiological or nuclear attacks. A network of Centers for Medical Countermeasures against Radiation (CMCRs) has been established across the U.S.; one of the missions of this network is to identify and develop mitigating agents that can be used to(More)
PURPOSE This study was undertaken to investigate the perturbation of small radiation beams by low density heterogeneities and to evaluate the ability of a Monte Carlo code to account for such perturbation. Performance of an inexpensive film scanning system was also evaluated. METHODS AND MATERIALS Film and diode measurements were made in an acrylic(More)
PURPOSE A new method for stereotactic irradiation of spinal malignancies is presented, with evaluations of the theoretic and practical limitations of localization accuracy and the implementation of the method in swine. MATERIALS AND METHODS In a percutaneous procedure, a minimum of three small (1.7-mm-diameter) titanium markers are permanently affixed to(More)
BACKGROUND AND PURPOSE Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first ever measurements of the biological effectiveness of(More)
The Los Alamos code MCNP4A (Monte Carlo N-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. A graphical user interface has been developed that automatically sets up the MCNP4A geometry and radiation source requirements for a three-dimensional Monte Carlo(More)
OBJECTIVES In radiosurgery treatment planning there is general acceptance that the target volume can be assumed to be homogeneous and that corrections for variations in contour are unnecessary. Thus, dose algorithms employed in radiosurgery treatment planning are quite unsophisticated; in almost every case the algorithms are the simple product of(More)
PURPOSE Radiotherapy plans based on physical dose distributions do not necessarily entirely reflect the biological effects under various fractionation schemes. Over the past decade, the linear-quadratic (LQ) model has emerged as a convenient tool to quantify biological effects for radiotherapy. In this work, we set out to construct a mechanism to display(More)
Due to the significant interest in Monte Carlo dose calculations for external beam megavoltage radiation therapy from both the research and commercial communities, a workshop was held in October 2001 to assess the status of this computational method with regard to use for clinical treatment planning. The Radiation Research Program of the National Cancer(More)
The bremsstrahlung spectra from thick targets of Be, Al, and Pb are calculated using the Monte Carlo code MCNP (Monte Carlo N-particle). The current version of MCNP (v.4A) incorporates a coupled electron-photon transport scheme that allows the user to estimate the photon fluence produced from primary electron interactions. The simulation parameters are(More)
PURPOSE To evaluate the Monte Carlo code MCNP4B for low-energy brachytherapy calculations, including the effects of interseed attenuation and patient specific heterogeneities, on the calculated dose distribution from transperineal implantation of 125I. METHODS AND MATERIALS The Monte Carlo code MCNP4B was used to model and benchmark the absolute dose(More)