Radiographic Capabilities of the MERCURY Monte Carlo Code

MERCURY is a modern, parallel, general-purpose Monte Carlo code being developed at the Lawrence Livermore National Laboratory. Recently, a radiographic capability has been added. MERCURY can create a source of diagnostic, virtual particles that are aimed at pixels in an image tally. This new feature is compared to the radiography code, HADES, for verification and timing. Comparisons for accuracy were made using the French Test Object and for timing were made by tracking through an unstructured mesh. In addition, self consistency tests were run in MERCURY for the British Test Object and scattering test problem. MERCURY and HADES were found to agree to the precision of the input data. HADES appears to run around eight times faster than the MERCURY in the timing study. Profiling the MERCURY code has turned up several differences in the algorithms which account for this. These differences will be addressed in a future release of MERCURY

Doxycycline pharmacokinetics in the absence of renal function

Doxycycline pharmacokinetics in the absence of renal function. Doxycycline is a new tetracycline that is now in widespread clinical use. It differs from the other tetracycline drugs in many important respects including small daily dosage schedules, essentially complete upper gastrointestinal absorption and excretory characteristics that are independent of renal function. Our studies demonstrate that in anephric patients and patients with varying degrees of renal function the plasma t½ of biologically active doxycycline is not significantly extended and that in such a clinical situation the usual therapeutic regimen of the drug is necessary. Clearance rate of the compound from the systemic circulation by hemodialysis is only 10ml/min or less. In addition, our investigations identify the importance of the nonhepatic gastrointestinal pathway of elimination of doxycycline from the systemic circulation. Doxycycline therefore appears to be unique among the tetracyclines in that it may be utilized as a drug of choice for the therapy of systemic infections when a tetracycline compound is indicated in the clinical setting of impaired renal function.Pharmacocinétique de la doxycycline en l'absence de fonction rénale. La doxycycline est une nouvelle tétracycline dont l'usage clinique est maintenant largement répandu. Elle diffère des autres tétracyclines à plusieurs égards importants parmi lesquels la faible posologie quotidienne, l'absorption totale dans la partie haute du tractus digestif et des modalités d'excrétion indépendantes de la fonction rénale. Notre travail démontre que chez les sujets anéphriques et les malades atteints d'insuffisance rénale de sévérité variable la demie vie de la doxycycline biologiquement active n'est pas significativement allongée et que dans ces situations cliniques les modalités thérapeutiques habituelles sont nécessaires. La clearance du composé observée au cours de l'hémodialyse est égale ou inférieure à 10 ml/min. De surcroît nos travaux identifient l'importance de la voie d'élimination hépatique non intestinale de la doxycycline. La doxycycline apparaît donc être unique parmi les tétracyclines en ce sens qu'elle peut être utilisée comme une drogue de choix pour le traitment des infections systémiques quand une tétracycline est indiquée et qu'il existe une altération de la fonction rénale

HADES, A Radiographic Simulation Code

We describe features of the HADES radiographic simulation code. We begin with a discussion of why it is useful to simulate transmission radiography. The capabilities of HADES are described, followed by an application of HADES to a dynamic experiment recently performed at the Los Alamos Neutron Science Center. We describe quantitative comparisons between experimental data and HADES simulations using a copper step wedge. We conclude with a short discussion of future work planned for HADES

Source description and sampling techniques in PEREGRINE Monte Carlo calculations of dose distributions for radiation oncology

We outline the techniques used within PEREGRINE, a 3D Monte Carlo code calculation system, to model the photon output from medical accelerators. We discuss the methods used to reduce the phase-space data to a form that is accurately and efficiently sampled

Treatment of patient-dependent beam modifiers in photon treatments by the Monte Carlo dose calculation code PEREGRINE

The goal of the PEREGRINE Monte Carlo Dose Calculation Project is to deliver a Monte Carlo package that is both accurate and sufficiently fast for routine clinical use. One of the operational requirements for photon-treatment plans is a fast, accurate method of describing the photon phase-space distribution at the surface of the patient. The open-field case is computationally the most tractable; we know, a priori, for a given machine and energy, the locations and compositions of the relevant accelerator components (i.e., target, primary collimator, flattening filter, and monitor chamber). Therefore, we can precalculate and store the expected photon distributions. For any open-field treatment plan, we then evaluate these existing photon phase-space distributions at the patient`s surface, and pass the obtained photons to the dose calculation routines within PEREGRINE. We neglect any effect of the intervening air column, including attenuation of the photons and production of contaminant electrons. In principle, for treatment plans requiring jaws, blocks, and wedges, we could precalculate and store photon phase-space distributions for various combinations of field sizes and wedges. This has the disadvantage that we would have to anticipate those combinations and that subsequently PEREGRINE would not be able to treat other plans. Therefore, PEREGRINE tracks photons through the patient-dependent beam modifiers. The geometric and physics methods used to do this are described here. 4 refs., 8 figs

Benchmarking of the Dose Planning Method (DPM) Monte Carlo code using electron beams from a racetrack microtron

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135135/1/mp1512.pd

Photon beam relative dose validation of the DPM Monte Carlo code in lung‐equivalent media

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134925/1/mp5671.pd