Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 15308153

BNCT dose calculation in irregular fields using the sector integration method.

H R Blaumann·D E Sanz·J M Longhino·O A Calzetta Larrieu
View original source ↗Export metadata ↓

Abstract

Irregular fields for boron neutron capture therapy (BNCT) have been already proposed to spare normal tissue in the treatment of superficial tumors. This added dependence would require custom measurements and/or to have a secondary calculation system. As a first step, we implemented the sector-integration method for irregular field calculation in a homogeneous medium and on the central beam axis. The dosimetric responses (fast neutron and photon dose and thermal neutron flux), are calculated by sector integrating the measured responses of circular fields over the field boundary. The measurements were carried out at our BNCT facility, the RA-6 reactor (Argentina). The input data were dosimetric responses for circular fields measured at different depths in a water phantom using ionisation and activation techniques. Circular fields were formed by shielding the beam with two plates: borated polyethilene plus lead. As a test, the dosimetric responses of a 7x4 cm(2) rectangular field, were measured and compared to calculations, yielding differences less than 3% in equivalent dose at any depth indicating that the tool is suitable for redundant calculations.

Explore related subjects

ArgentinaBoron Neutron Capture TherapyHumansNeoplasmsPhantoms, ImagingRadiotherapy Planning, Computer-AssistedRelative Biological EffectivenessJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

H R Blaumann, D E Sanz, J M Longhino, O A Calzetta Larrieu. 2004. BNCT dose calculation in irregular fields using the sector integration method.. https://doi.org/10.1016/j.apradiso.2004.05.037

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Molecular diagnosis of spinal muscular atrophy: Experience in a pediatric hospital in Argentina.

Introduction. Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease caused by the loss of the SMN1 gene, with a variable clinical spectrum determined primarily by the number of copies of the SMN2 gene. The development of new therapies underscores the importance of early molecular diagnosis and genotype-phenotype characterization. Objective. To describe 27 years of experience in the molecular diagnosis of SMA at a pediatric referral hospital in Argentina and to evaluate the correlation between SMN2 copy number and the SMA types.Population and methods. A retrospective descriptive study was conducted on 1060 pediatric patients with clinically suspected SMA who were evaluated between 1997 and 2024. Molecular diagnosis was performed using PCR-RFLP and, since 2012, MLPA to determine SMN1 and SMN2 copy number. Genotype-phenotype correlation was evaluated in 260 patients with complete clinical characterization. Results. The diagnosis was confirmed in 513 patients. A homozygous deletion of the SMN1 gene was detected in 99.6% of unrelated cases. The positivity rate increased over time. A significant correlation was observed between the number of SMN2 copies and the type of SMA, with milder phenotypes associated with a higher number of copies. Conclusion. Molecular diagnosis of SMA enabled accurate and timely characterization of patients, avoiding invasive procedures and optimizing therapeutic decision-making. Genotype-phenotype correlation is a fundamental tool for prognosis and clinical management, highlighting the importance of an interdisciplinary approach.

Argentina↗
PubMed2005

Eocene plant diversity at Laguna del Hunco and Río Pichileufú, Patagonia, Argentina.

The origins of South America's exceptional plant diversity are poorly known from the fossil record. We report on unbiased quantitative collections of fossil floras from Laguna del Hunco (LH) and Río Pichileufú (RP) in Patagonia, Argentina. These sites represent a frost-free humid biome in South American middle latitudes of the globally warm Eocene. At LH, from 4,303 identified specimens, we recognize 186 species of plant organs and 152 species of leaves. Adjusted for sample size, the LH flora is more diverse than comparable Eocene floras known from other continents. The RP flora shares several taxa with LH and appears to be as rich, although sampling is preliminary. The two floras were previously considered coeval. However, (40)Ar/(39)Ar dating of three ash-fall tuff beds in close stratigraphic association with the RP flora indicates an age of 47.46+/-0.05 Ma, 4.5 million years younger than LH, for which one tuff is reanalyzed here as 51.91+/-0.22 Ma. Thus, diverse floral associations in Patagonia evolved by the Eocene, possibly in response to global warming, and were persistent and areally extensive. This suggests extraordinary richness at low latitudes via the latitudinal diversity gradient, corroborated by published palynological data from the Eocene of Colombia.

Argentina↗
PubMed2005

[Utilization of task projects in a public sector health organization in Argentina: paradoxes, dilemmas, and opportunities].

The purpose of this article is to present the experience with application of a management tool in a health organization from the public sector in Argentina and to reflect on the interactions between its components, potentialities, and difficulties and the complications involved in reporting, analyzing, and interpreting it. The study followed a descriptive design, analyzing records, files, and institutional documents, consulting key informants, and conducting a literature review. The introduction of personnel planning was analyzed from the perspective of workers' development and performance improvement in organizations. The main finding was that task projects helped orient individual effort towards meeting institutional objectives and provided elements for organizational design. The projects were characterized by different degrees of adherence and compliance, besides generating conflicts, distrust, and resistance. Finally, in public sector health organizations it is possible to achieve results-based management and a balance between trust and oversight. The scope reflects the tensions from external pressures, internal power struggles, non-compliance with supervision and monitoring, rigidity of centralized norms, and the tendency to turn management tools into mere elements for routine control.

Argentina↗