Monte Carlo dosimetric study of the BEBIG Co-60 HDR source.

Although not as widespread as Ir-192, Co-60 is also available on afterloading equipment devoted to high dose rate brachytherapy, mainly addressed to the treatment of gynaecological lesions. The purpose of this study is to obtain the dosimetric parameters of the Co-60 source used by the BEBIG MultiSource remote afterloader (BEBIG GmbH, Germany) for which there are no dosimetric data available in the literature. The Monte Carlo code GEANT4 has been used to obtain the TG43 parameters and the 2D dose rate table in Cartesian coordinates of the BEBIG Co-60 HDR source. The dose rate constant, radial dose function and anisotropy function have been calculated and are presented in a tabular form as well as a detailed 2D dose rate table in Cartesian coordinates. These dosimetric datasets can be used as input data and to validate the treatment planning system calculations.

Monte Carlo and experimental derivation of TG43 dosimetric parameters for CSM-type Cs-137 sources.

In this study, complete dosimetric datasets for the CSM2 and CSM3 Cs-137 sources were obtained using the Monte Carlo GEANT4 code. The application of this calculation method was experimentally validated with thermoluminescent dosimetry (TLD). Functions and parameters following the TG43 formalism are presented: the dose rate constant, the radial dose functional, and the anisotropy function. In addition, to aid the quality control process on treatment planning systems, a two-dimensional (2D) rectangular dose rate table (the traditional along-away table), coherent with the TG43 dose calculation formalism, is given. The data given in this study complement existing information for both sources on the following aspects: (i) the source asymmetries were considered explicitly in the Monte Carlo calculations, (ii) TG43 data were derived directly from Monte Carlo calculations, (iii) the radial range of the different tables was increased as well as the angular resolution in the anisotropy function, including angles close to the longitudinal source axis. The CSM2 source TG-43 data of Liu et al. [Med. Phys. 31, 477-483 (2004)] are not consistent with the Williamson 2D along-away data [Int. J. Radiat. Oncol., Biol., Phys. 15, 227-237 (1988)] at distances closer than approximately 2 cm from the source. The data presented here for this source are consistent with this 2D along-away table, and are suitable for use in clinical practice.

Tratamiento quirúrgico de la obesidad: ¿a quién?, ¿qué técnica?, ¿es necesario el seguimiento postoperatorio? / Surgical treatment: of obesity what patient?, what technique?, is postoperative follow-up mandatory?

La obesidad mórbida (índice de masa corporal igual o superior a 40 kg/m2) implica un riesgo elevado de morbimortalidad y suele ser resistente al tratamiento médico. El abordaje quirúrgico puede conseguir una pérdida de peso efectiva a largo plazo, con mejoría de las comorbilidades y de la calidad de vida, pero presenta el riesgo de que se produzcan complicaciones potencialmente graves, si bien constituye una opción válida en pacientes seleccionados con criterios de inclusión en un programa multidisciplinario protocolizado. Las técnicas quirúrgicas actuales pueden ser simples (restrictivas) o complejas, asociando derivación gástrica y/o malabsorción intestinal. En general, las técnicas complejas producen mejores resultados en cuanto a pérdida de peso, pero tienen mayor riesgo de que se produzcan deficiencias nutricionales, por lo que la elección del tipo de intervención debe individualizarse en función de la experiencia del equipo quirúrgico y de las características del paciente. El seguimiento postoperatorio es imprescindible, no sólo para detectar cuanto antes la aparición de complicaciones, sino para validar los resultados de la intervención. Deben valorarse la evolución de los índices ponderales, la mejoría de comorbilidades, la calidad de vida, los parámetros nutricionales y la aparición de complicaciones. Es necesaria una educación nutricional específica para facilitar la tolerancia digestiva y conseguir una buena adherencia al tratamiento (AU)

Technical note: Monte-Carlo dosimetry of the HDR 12i and Plus 192Ir sources.

In this study a complete set of dosimetric data for the GammaMed high dose rate (HDR) 12i and Plus 192Ir sources are presented. These data have been calculated by means of the Monte Carlo simulation code GEANT3. Absolute dose rate distributions in water are presented as conventional two dimensional (2D) Cartesian look-up tables, and in the TG43 formalism.

A Monte Carlo investigation of the dosimetric characteristics of the CSM11 137Cs source from CIS.

The purpose of this study is to calculate basic dosimetry data for a CSM11 low dose rate 137Cs source in water. This source is widely used in afterloadable dome cylinders designed to homogeneously irradiate the vaginal cuff alone or additional areas of the vagina in hysterectomized patients. In this study, the Monte Carlo simulation code GEANT, incorporating in detail source geometry, is used to investigate the dosimetric characteristics of the source. The calculated data were analyzed using a fitting procedure that is described in detail. Absolute dose rate distributions in water were calculated around this source and are presented as conventional 2D Cartesian lookup tables (classically along-away tables). Also, the dose calculation formalism endorsed by the Interstitial Collaborative Working Group and the AAPM Task Group 43 have been calculated. The calculated dose rate constant for this source is lambda = 1.096 +/- 0.002 cGy h(-1) U(-1). The anisotropy function results in about 50% deviations from isotropy at positions near the long axis of the source. The radial dose function is given as a polynomial that reproduces the calculated data up to 20 cm. Best-fit values of attenuation coefficients suitable for use in Sievert integral calculations have been derived.