Cancer-care costs are increasing despite the expansion of disease management and prevention progr... more Cancer-care costs are increasing despite the expansion of disease management and prevention programs. While tremendous scientific progress has led to new tools for diagnosis, treatment, and follow-up, evidence is less complete on the comparative effectiveness of these interventions in actual community practice.
Journal of Radiation Oncology Biology Physics, 2003
Purpose: To report on the implementation of a web-based system (the Resource Center for Emerging ... more Purpose: To report on the implementation of a web-based system (the Resource Center for Emerging Technologies [RCET] System) that provides immediate access to the patient radiotherapy planning and delivery data for clinical quality assurance (QA) by the experts. Methods and Materials: An infrastructure of comprehensive tools required for preparation, submission, autoarchiving, web-based review, and retrieval of diagnostic images, treatment planning images, and radiation therapy objects has been developed. These tools represent approximately 1.1 million lines of computer code development in seven languages (V, C؉؉, Visual Basic, Java, ASP, HTML, and SQL) and consist of a secure auto-anonymizing upload and auto-archiving patient database, a web-based secure object archiving network system, a web-based rapid review tool, a web-based upload/download tool, and a personal computer client data application for data object preparation, visualization, and submission, named NetSys. The RCET system enables users to share radiotherapy data in a secure environment. This paradigm of electronic data exchange makes remote peer review very efficient and convenient. Results: The RCET system can help the radiation therapy community ensure consistent evaluation of its therapies. It will encourage proactive QA. An example of proactive clinical QA would be to provide atlases of target and critical structure definitions, to serve as class solutions, as well as dose prescription, specification, and reporting examples for guidance to the radiation oncologists in the community. The web-based clinical quality assurance is ideally suited for emerging technologies in radiation therapy that generate complex and voluminous multimodality imaging and planning data. Conclusions: The RCET system enables users to share multimodality imaging data, radiation therapy planning, and delivery data on demand. Our design paradigm will allow rapid peer review of radiotherapy data through a simple personal computer-based web browser.
Resumo O objetivo do artigo é conhecer a abordagem de equipes de emergência à assistência de paci... more Resumo O objetivo do artigo é conhecer a abordagem de equipes de emergência à assistência de pacientes com doença crônica avançada, na perspectiva dos cuidados paliativos. O texto traz resultados de revisão integrativa que buscou artigos em cinco bases de dados, utilizando os descritores “serviços médicos de emergência”, “equipe de assistência ao paciente”, “atitude do pessoal de saúde” e “cuidados paliativos”. Inicialmente, foram identificadas 12.290 publicações, reduzidas, após análise, a uma amostra final de 26 artigos. Entre as principais medidas mencionadas na literatura para levar os cuidados paliativos à emergência, estão: plano de cuidados individualizado e flexível; gestão de redes; acesso à equipe de cuidados paliativos; comunicação empática; identificação dos pacientes elegíveis; e controle de sintomas. Conclui-se que as equipes de emergência precisam reconhecer a importância dos cuidados paliativos nesse serviço, redirecionando o cuidado concentrado em “salvar vidas” par...
This thesis is a report of the research conducted to study the non-linear resonant interaction of... more This thesis is a report of the research conducted to study the non-linear resonant interaction of highly energetic particles of a fusion plasma, confined in an axi-symmetric device, with externally imposed electromagnetic propagating waves. The relevance of this analysis to the Lagrangian particle transport and heating kinetic theories is discussed. Hamiltonian mechanics is used to be able to utilize modern theories on nonlinear dynamics. Since the conventional Hamiltonian perturbation theories are not adequate for electromagnetic waves, a general Hamiltonian perturbation theory is developed to include perturbations in phase space by a vector potential. Concepts in modern differential geometry are used to formulate a general Hamiltonian mechanics similar to Birkhoffian mechanics. The Hamilton's equations of motion are expressed in terms of new operators. A direct result is that explicit expressions for the perturbed equations of motion can be obtained. A general symplectic structure for the Hamiltonian phase flow is identified. The new perturbation method is based on the transformation theory of the general symplectic two-form of the phase space. Dynamics of a charged particle in resonant interaction with an electromagnetic field in a uniform magnetic field is examined. The criteria for the onset of global stochastic regions in phase space are derived. The dynamics of three dimensional motion of a charged particle in an axi-symmetrical magnetic field is examined. The effects of perturbations by an electromagnetic field to the phase space of such a particle is studied. It is demonstrated that a frequency -modulated wave can induce a global stochasticity in phase space which results in strong diffusion processes in action space of the particle. Since the required magnitude for the perturbing field to induce strong diffusion processes is very low, it may be well satisfied by the present experiments. The formulation is cast in a suitable coordinate such that the resulting Fokker-Planck kinematic and diffusion coefficients can be used in a Lagrangian kinetic theory.
A commercial linear accelerator with a factory-fitted multileaf collimator (MLC) was commissioned... more A commercial linear accelerator with a factory-fitted multileaf collimator (MLC) was commissioned for clinical use. Measurements made of dosimetric parameters included central axis depth-dose, field-size factors, wedge factors, penumbra, and leaf leakage for the 6-MV and 15-MV photon beams available on this accelerator. The depth-dose characteristics, output factors, and transmission factors were similar to those reported in the literature for a machine by the same manufacturer with a standard treatment head. Because of scalloping, the effective penumbra for the MLC was 3 to 4 mm wider than that for the conventional collimator jaws. The output for the fields shaped by the MLC was generally lower than that for similar fields shaped with Lipowitz's metal (Cerrobend). The magnitude of the difference was field-size dependent and ranged from 0.5% to 4.5% for open shaped fields, increasing to 1% to 5% in the presence of wedges. Further analysis of this observation has shown it to be primarily due to differences in the scattered radiation from the collimator head.
Cancer-care costs are increasing despite the expansion of disease management and prevention progr... more Cancer-care costs are increasing despite the expansion of disease management and prevention programs. While tremendous scientific progress has led to new tools for diagnosis, treatment, and follow-up, evidence is less complete on the comparative effectiveness of these interventions in actual community practice.
Journal of Radiation Oncology Biology Physics, 2003
Purpose: To report on the implementation of a web-based system (the Resource Center for Emerging ... more Purpose: To report on the implementation of a web-based system (the Resource Center for Emerging Technologies [RCET] System) that provides immediate access to the patient radiotherapy planning and delivery data for clinical quality assurance (QA) by the experts. Methods and Materials: An infrastructure of comprehensive tools required for preparation, submission, autoarchiving, web-based review, and retrieval of diagnostic images, treatment planning images, and radiation therapy objects has been developed. These tools represent approximately 1.1 million lines of computer code development in seven languages (V, C؉؉, Visual Basic, Java, ASP, HTML, and SQL) and consist of a secure auto-anonymizing upload and auto-archiving patient database, a web-based secure object archiving network system, a web-based rapid review tool, a web-based upload/download tool, and a personal computer client data application for data object preparation, visualization, and submission, named NetSys. The RCET system enables users to share radiotherapy data in a secure environment. This paradigm of electronic data exchange makes remote peer review very efficient and convenient. Results: The RCET system can help the radiation therapy community ensure consistent evaluation of its therapies. It will encourage proactive QA. An example of proactive clinical QA would be to provide atlases of target and critical structure definitions, to serve as class solutions, as well as dose prescription, specification, and reporting examples for guidance to the radiation oncologists in the community. The web-based clinical quality assurance is ideally suited for emerging technologies in radiation therapy that generate complex and voluminous multimodality imaging and planning data. Conclusions: The RCET system enables users to share multimodality imaging data, radiation therapy planning, and delivery data on demand. Our design paradigm will allow rapid peer review of radiotherapy data through a simple personal computer-based web browser.
Resumo O objetivo do artigo é conhecer a abordagem de equipes de emergência à assistência de paci... more Resumo O objetivo do artigo é conhecer a abordagem de equipes de emergência à assistência de pacientes com doença crônica avançada, na perspectiva dos cuidados paliativos. O texto traz resultados de revisão integrativa que buscou artigos em cinco bases de dados, utilizando os descritores “serviços médicos de emergência”, “equipe de assistência ao paciente”, “atitude do pessoal de saúde” e “cuidados paliativos”. Inicialmente, foram identificadas 12.290 publicações, reduzidas, após análise, a uma amostra final de 26 artigos. Entre as principais medidas mencionadas na literatura para levar os cuidados paliativos à emergência, estão: plano de cuidados individualizado e flexível; gestão de redes; acesso à equipe de cuidados paliativos; comunicação empática; identificação dos pacientes elegíveis; e controle de sintomas. Conclui-se que as equipes de emergência precisam reconhecer a importância dos cuidados paliativos nesse serviço, redirecionando o cuidado concentrado em “salvar vidas” par...
This thesis is a report of the research conducted to study the non-linear resonant interaction of... more This thesis is a report of the research conducted to study the non-linear resonant interaction of highly energetic particles of a fusion plasma, confined in an axi-symmetric device, with externally imposed electromagnetic propagating waves. The relevance of this analysis to the Lagrangian particle transport and heating kinetic theories is discussed. Hamiltonian mechanics is used to be able to utilize modern theories on nonlinear dynamics. Since the conventional Hamiltonian perturbation theories are not adequate for electromagnetic waves, a general Hamiltonian perturbation theory is developed to include perturbations in phase space by a vector potential. Concepts in modern differential geometry are used to formulate a general Hamiltonian mechanics similar to Birkhoffian mechanics. The Hamilton's equations of motion are expressed in terms of new operators. A direct result is that explicit expressions for the perturbed equations of motion can be obtained. A general symplectic structure for the Hamiltonian phase flow is identified. The new perturbation method is based on the transformation theory of the general symplectic two-form of the phase space. Dynamics of a charged particle in resonant interaction with an electromagnetic field in a uniform magnetic field is examined. The criteria for the onset of global stochastic regions in phase space are derived. The dynamics of three dimensional motion of a charged particle in an axi-symmetrical magnetic field is examined. The effects of perturbations by an electromagnetic field to the phase space of such a particle is studied. It is demonstrated that a frequency -modulated wave can induce a global stochasticity in phase space which results in strong diffusion processes in action space of the particle. Since the required magnitude for the perturbing field to induce strong diffusion processes is very low, it may be well satisfied by the present experiments. The formulation is cast in a suitable coordinate such that the resulting Fokker-Planck kinematic and diffusion coefficients can be used in a Lagrangian kinetic theory.
A commercial linear accelerator with a factory-fitted multileaf collimator (MLC) was commissioned... more A commercial linear accelerator with a factory-fitted multileaf collimator (MLC) was commissioned for clinical use. Measurements made of dosimetric parameters included central axis depth-dose, field-size factors, wedge factors, penumbra, and leaf leakage for the 6-MV and 15-MV photon beams available on this accelerator. The depth-dose characteristics, output factors, and transmission factors were similar to those reported in the literature for a machine by the same manufacturer with a standard treatment head. Because of scalloping, the effective penumbra for the MLC was 3 to 4 mm wider than that for the conventional collimator jaws. The output for the fields shaped by the MLC was generally lower than that for similar fields shaped with Lipowitz's metal (Cerrobend). The magnitude of the difference was field-size dependent and ranged from 0.5% to 4.5% for open shaped fields, increasing to 1% to 5% in the presence of wedges. Further analysis of this observation has shown it to be primarily due to differences in the scattered radiation from the collimator head.
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Papers by Vincent Frouhar