RESUMO
BACKGROUND AND PURPOSE: Several commercially available p-type diodes do not provide sufficient build-up for in-vivo dosimetry in 'higher' energy photon beams, and only limited information could be found in the literature describing the correction factor variation and/or the achievable accuracy for in-vivo dosimetry methods in this energy range. The first aim of this study is to assess and analyze the variation of diode correction factors for entrance dose measurements at higher photon energies. In a second step the total build up thickness of the diode has been modified in order to minimize the correction factor variation. MATERIALS AND METHODS: Diode correction factors accounting for non-reference conditions (field size, source surface distance, tray, wedge, and block) are determined in 18-25 MV photon beams provided by different treatment units for Scanditronix p-type diodes recommended for higher energy photon beams: old type and new type EDP-20, and EDP-30 diodes. Hemispherical build-up caps of different materials (copper, iron, lead) are used to increase the total build-up thickness. Perturbation effects with and without additional build-up caps are assessed for the three diode types. RESULTS: For unmodified diodes field size correction factors (C(FS)) vary between 1.7% and 6%, dependent on diode type and treatment unit. For example, for an old type EDP-20 the C(FS) variation at 18 MV is much higher on a GE linac (5%) as compared to the Philips machine (1.7%). Depending on diode type, this variation can be reduced to 1-2% when adding additional build-up. The variation of source to surface distance correction factors is almost independent of build-up thickness. By adding additional build-up the influence of trays and blocks can be almost eliminated. CONCLUSIONS: The correction factor variation of unmodified diodes reflects the variation of the electron contamination with treatment geometry. A total build-up thickness of 30 mm is found to be the 'best compromise' for the three types of diodes investigated when measuring entrance doses in the energy range between 18 and 25 MV.
Assuntos
Radioterapia de Alta Energia/instrumentação , Relação Dose-Resposta à Radiação , Humanos , Aceleradores de Partículas , Radiometria , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Alta Energia/métodos , Valores de ReferênciaRESUMO
A therapeutic nurse-patient relationship is based upon the effective management of professional practice boundaries. Boundary violations may be difficult to detect and manage because they often are subtle and driven by one's own needs. Early detection and response is critical to preventing boundary relaxation and violation. Self-assessment is an important aspect of boundary management. Identification of vulnerability to boundary violation may assist the nurse in determining the need for supervision or consultation.
Assuntos
Comportamento de Ajuda , Transtornos Mentais/enfermagem , Relações Enfermeiro-Paciente , Adaptação Psicológica , Adulto , Idoso , Transtorno Bipolar/enfermagem , Transtorno Bipolar/psicologia , Neoplasias da Mama/enfermagem , Neoplasias da Mama/psicologia , Mecanismos de Defesa , Dependência Psicológica , Feminino , Humanos , Masculino , Mastectomia/enfermagem , Mastectomia/psicologia , Transtornos Mentais/psicologia , Equipe de Assistência ao Paciente , Papel do DoenteRESUMO
Spurred by the shortage of nurses, hospitals are turning to overseas recruitment. The success of such recruitment rests in large measure on an organization's address of an immensely and immediately practical consideration: What is the nature of the adjustment process for the international nurse, and what can a hospital do to facilitate this adjustment? This article describes the four phases of the adjustment process that are generic to the first-year experience of the international nurse and offers suggestions for an assimilation program.