Introducing interactive inverse FEM simulation and its application for adaptive radiotherapy

International audienceWe introduce a new methodology for semi-automatic deformable registration of anatomical structures, using interactive inverse simulations. The method relies on non-linear real-time Finite Element Method (FEM) within a constraint-based framework. Given a set of few registered points provided by the user, a real-time optimization adapts the boundary conditions and(/or) some parameters of the FEM in order to obtain the adequate geometrical deformations. To dramatically fasten the process, the method relies on a projection of the model in the space of the optimization variables. In this reduced space, a quadratic programming problem is formulated and solved very quickly. The method is validated with numerical examples for retrieving Young's modulus and some pressures on the boundaries. Then, we apply the approach for the registration of the parotid glands during the radiotherapy of the head and neck cancer. Radiotherapy treatment induces weight loss that modifi es the shape and the positions of these structures and they eventually intersect the target volume. We show how we could adapt the planning to limit the radiation of these glands.Nous introduisons une nouvelle méthode de recalage déformable semi-automatique de structures anatomiques, à l'aide de simulations inverses interactives. La méthode est basée sur la méthode des éléments finis(FEM) et revient à résoudre un système de contraintes. Etant donné un ensemble de quelques points fournies par l'utilisateur, une optimisation en temps réel adapte les conditions aux limites et(/ou) des paramètres de la FEM dans le but d'obtenir les déformations géométriques adéquates. Pour accélérer les calculs de manière conséquente, la méthode repose sur une projection du modèle dans l'espace des variables d'optimisation. Dans cet espace réduit, un problème de programmation quadratique est formulé et résolu très rapidement. La méthode est validée par des exemples numériques (récupérer le module de Young et des pressions à appliquer sur le modèle). Ensuite, nous appliquons l'approche pour le recalage des glandes parotides pendant la radiothérapie de la tête et du cou. Un traitement de radiothérapie induit généralement une perte de poids chez le patient qui modifie la forme et la position de ces structures. Structures qui finissent par entrer dans le volume cible. Nous montrons comment nous pourrions adapter la planification afin de limiter le rayonnement de ces glandes

Efecto de conductividades eléctricas de la solución nutritiva en sistema de subirrigación en calceolaria

Resumen (Spanish, English)82 p.Se evaluó el efecto de tres conductividades eléctricas de solución nutritiva en el cultivo en macetas bajo subirrigación de un híbrido de Calceolaria cv F1 Dainty Red, sobre parámetros de precocidad y calidad, tales como días de transplante a primera flor, número de flores por planta, número total de hojas, ancho de las hojas basales, número de tallos florales y largo de tallos florales. Este estudio se realizó en la Estación Experimental Panguilemo, Talca, Chile (35º 21’ LS; 71º 28′ LW, 90 m.s.n.m.). El ensayo se realizó entre los meses de Junio y Noviembre de 1997. Los tratamientos aplicados fueron conductividades eléctricas de 1,5 3,0 y 4,5 dS/m de la solución nutritiva de Cooper. A través del crecimiento de esta especie, no se observaron diferencias entre los tratamientos en cuanto a la precocidad y la calidad de este híbrido de Calceolaria

Particulate air pollution and health effects for cardiovascular and respiratory causes in Temuco, Chile: A wood-smoke-polluted urban area

Temuco is one of the most highly wood-smoke-polluted cities in the world. Its population in 2004 was 340,000 inhabitants with 1587 annual deaths, of which 24% were due to cardiovascular and 11% to respiratory causes. For hospital admissions, cardiovascular diseases represented 6% and respiratory diseases 13%. Emergency room visits for acute respiratory infections represented 28%. The objective of the study presented here was to determine the relationship between air pollution from particulate matter less than or equal to 10 μm in aerodynamic diameter (PM10; mostly PM2.5, or particulate matter <2.5 μm in aerodynamic diameter) and health effects measured as the daily number of deaths, hospital admissions, and emergency room visits for cardiovascular, respiratory, and acute respiratory infection (ARI) diseases. The Air Pollution Health Effects European Approach (APHEA2) protocol was followed, and a multivariate Poisson regression model was fitted, controlling for trend, seasonality, and confounders for Temuco during 1998-2006. The results show that PM10 had a significant association with daily mortality and morbidity, with the elderly (population >65 yr of age) being the group that presented the greatest risk. The relative risk for respiratory causes, with an increase of 100 μg/m3 of PM10, was 1.163 with a 95% confidence interval (CI) of 1.057-1.279 for mortality, 1.137 (CI 1.096-1.178) for hospital admissions, and 1.162 for ARI (CI 1.144-1.181). There is evidence in Temuco of positive relationships between ambient particulate levels and mortality, hospital admissions, and ARI for cardiovascular and respiratory diseases. These results are consistent with those of comparable studies in other similar cities where wood smoke is the most important air pollution problem. Copyright 2009 Air & Waste Management Association

Filogenia de los generos de Amaryllidaceae de Chile: una aproximacion desde la biologia molecular

67 p.La familia Amaryllidaceae comprende aproximadamente 850 especies en 60 géneros. Algunos de sus representantes son cultivados como ornamentales, tales como Amaryllis L., Crinus L., Galanthus L., Leucojum L., Lycoris Herb. y Narcissus L. En Chile, especies de los géneros Placea Miers, Phycella Lindl. y Rhodophiala C.Presl han llamado la atención de investigadores en floricultura, ya que sus vistosas flores representan un potencial ornamental tanto para ser utilizadas como plantas de jardín o de macetas. Sin embargo, para cualquier programa de investigación de biotecnológica vegetal aplicada, es necesaria la identificación del material vegetal que se está utilizando. Esto, en Amaryllidaceae chilenas es un desafío, puesto que la clasificación de los géneros y especies, que se ha hecho en base caracteres morfológicos tradicionales, es aún controvertida, dado por complejas variación morfológica observadas en géneros tales como Hippeastrum Herb., Phycella Lindl. Y Rhodophiala C.Presl, lo que se traduce en caracteres homoplásicos, o bien, en la supresión de la variación fenotípica o canalización. Mediante el uso de secuencias ITS, obtenidas desde material vegetal de 13 especies chilenas pertenecientes a los géneros Phycella Lindl., Rhodophiala C.Presl, Rhodolirium Phil. Famatina Ravenna y Miltinea (Ravenna) Ravenna. Se realizó un análisis filogenético de máxima parsimonia, con apoyo bootstrap, y posteriormente se combinó este análisis molecular con características morfológicas y estudios citológicos para proponer una clasificación mas robusta, predictiva, y consistente de estos 5 géneros nativos de Amaryllidaceae de Chile. La morfología es poco variable, existiendo escasos caracteres que permitan diferenciar géneros, estos son: forma del estigma y de la corola y la presencia y forma del paraperigonio. Los únicos géneros monofiléticos corresponden a Rhodophiala C.Presl, Phycella Lindl. Y Rhodolirium Phil. De esta forma, Famatina Ravenna y Miltinea (Ravenna) Ravenna caben dentro de los límites de los géneros Rhodophiala C.Presl. y Phycella Lindl., respectivamente, por lo que deben ser tratados como sinónimos de éstos taxa. PALABRAS CLAVES: Filogenia, Amaryllidaceae, ITS, Chile./ ABSTRACT: Amaryllidaceae is a family that comprises approximately 850 species in 60 genera. Some of their representatives are grown as ornamentals, such as Amaryllis L., Crinus L., Galanthus L., Leucojum L., Lycoris Herb., and Narcissus L. In Chile, the species of the genera Placea Miers, Phycella Lindl., and Rhodophiala C.Presl have attracted the attention of researchers in floriculture. Their attractive ornamental flowers represent a potential for either uses as garden plants or potted. However, to drive a research program on applied plant biotechnology the identification of plant material is necessary. This, in Chilean Amaryllidaceae is a challenge, due to the fact that the classification of genera and species, which has been made on the basis of traditional morphological characters, is still controversial. This situation is given by complex morphological variation observed in the genera such as Hippeastrum Herb.,Phycella Lindl., and Rhodophiala C.Presl, which are homoplasic characters, or,in the suppression of phenotypic variation or canalization. Using ITS sequences obtained from plant material of 13 species belonging to the Chilean genera Phycella Lindl., Rhodophiala C.Presl, Rhodolirium Phil. Famatina Ravenna Miltinea (Ravenna) Ravenna, we performed a phylogenetic analysis of maximum parsimony and bootstrap. The combination of molecular analysis, with morphological and cytological studies was used to propose a more robust classification, predictive and consistent of these 5 Amaryllidaceae genera,Chilean native species. The morphology showed a small variability with some characters to differentiate genera, such as the stigma and corolla shape and the presence and shape of paraperigonium. The only monophyletic genera comprise Rhodophiala C.Presl., Phycella Lindl., and Rhodolirium Phil. Thus, Famatina Ravenna and Miltinea (Ravenna) Ravenna fit within the limits of the genera Rhodophiala C.Presl., and Phycella Lindl., respectively, so that could be treated as synonyms of these taxa. KEY WORDS: Phylogeny, Amaryllidaceae, ITS, Chile

Estudio y catastro de la flora presente en el cordón montañoso Cerro La Virgen

117 p.Los ecosistemas de tipo mediterráneo albergan una importante proporción de la diversidad de flora vascular a nivel mundial, además de poseer un alto nivel de endemismo y múltiples servicios ecosistémicos, características que en conjunto los hacen una comunidad vegetal interesante de conservar. Dichos ecosistemas en Chile se encuentran dominados en su mayoría por el bosque esclerófilo, donde a su vez, se encuentra dentro de un hotspot de la biodiversidad mundial. El bosque esclerófilo ha sido expuesto a un importante cambio de uso de suelo, tanto hacia plantaciones forestales, así como agrícolas o por la expansión de las áreas urbanas. En este estudio, se caracterizó la flora leñosa y herbácea presente en el Cerro La Virgen, cordón montañoso ubicado al poniente de la ciudad de Talca, Chile central; el área de estudio fue sectorizada en tres Macrozonas (Norte, Centro y Sur) donde junto a índices de diversidad, alfa y beta para los componentes herbáceos y arbóreos, se analizó la importancia biológica y ecológica que presenta el sector. Se observó una rica biodiversidad vascular compuesta por 51 familias y 126 especies, que difirió en composición según la Macrozona en la que se encontraba, observándose a la vez las diferentes amenazas que afectan la integridad presente y futura del bosque. Se concluyó que el Cerro La Virgen posee altos niveles de endemismo, principalmente en especies leñosas, donde dentro de las 126 especies, 18 corresponden a especies arbóreas, de las cuales el 50% son endémicas, con composición y degradación diferida según el sector y su topografía. // ABSTRACT: The Mediterranean ecosystems are home to an important proportion of the global vascular flora diversity, in addition of having a high level of endemism and multiple ecosystem services, characteristics that together make them an interesting plant community to conserve. The ecosystems in Chile can be found dominated mostly by the sclerophyll forest, where at the same time, are included within a global biodiversity hotspot. The sclerophyll forest has been exposed to an important change in land use, due to forestry plantations, as well as agricultural plantations or the expansion of urban areas. In this study the woody and herbaceous flora from the Cerro La Virgen was characterized. The Cerro La Virgen is part of a mountain range located to the west of the city of Talca, central Chile. The study area was divided into three main Macrozones (North, Center and South) where together with alpha and beta diversity indexes for herbaceous and arboreal components, the biological and ecological importance were analyzed. A rich vascular biodiversity was observed, composed by 51 families and 126 species, which differed in composition according to the Macrozone in which it was located. At the same time different threats that affect the present and future integrity of the forest were assessed. It was concluded that the Cerro La Virgen has high levels of endemism, mainly in woody species, where among the 126 species, 18 correspond to tree species, of which 50% are endemic, with composition and degradation differing according to the sector and its topography

Re-irradiation of recurrent vertebral metastasis after two previous spinal cord irradiation: A case report

BackgroundManagement of a recurrent vertebral metastasis in a situation of previously irradiated spinal cord is a challenging clinical dilemma.Case presentationWe report a first case of second retreatment of a spinal metastasis initially irradiated with standard radiotherapy and stereotactic body radiation therapy (SBRT), who subsequently progressed with imaging-confirmed local tumor progression at the same level. After a third course of irradiation with SBRT, a complete response was achieved. After 8 months of follow-up, the patients remain free of local recurrence.ConclusionA third course of vertebral irradiation for a recurrent vertebral metastasis failing to two previous irradiations, in this particular case, have shown the feasibility and efficacy of the technique as a salvage treatment option. This approach could be used in a selected group of patient if an adequate dose is delivered to the target while observing critical tissue tolerance limits

Focal radiotherapy for multiple brain metastases

Brain metastases (BM) develop in up to 30% of patients with cancer. There is marked heterogeneity in outcomes for patients with BM, and these outcomes vary not only by diagnosis, but also by diagnosis-specific prognostic factors; we should not treat all patients with brain metastases the same way, treatment should be individualized. Phase III randomized trials have shown that upfront whole brain radiotherapy (WBRT) may decrease brain recurrence both in terms of better local and improved distant brain tumour control rate, and that neurological death rate may be reduced in patients treated with WBRT + stereotactic radiosurgery (SRS), but no survival benefit is reached. The EORTC 22952-26001 study (Kocher M et al) shows that adjuvant WBRT fails to improve the duration of functional independence. The use of SRS in the treatment of multiple BM has increased dramatically during the past decade to avoid the neurocognitive dysfunction induced by WBRT. One of the biggest (1194 patients) multi-institutional prospective observational studies (JLGK0901, Yamamoto M et al and Watanabe S et al) including patients with multiple BM (even more han 10) have shown that SRS without WBRT in patients with five to ten BM is non-inferior to that in patients with two to four BM in terms of median OS (10,8 months for both groups), 1-year local recurrence (6,5% and 7%), with a very low incidence of side effects (less than 3%). They also concluded that carefully selected patients with 10 or more BM are not unfavourable candidates for SRS alone, having these patients a median survival time and neurological deathfree survival times comparables to the group with 9-10 BM; their results suggest also that even among patients 80 years and older, those with modified-RPA Class I+IIa or IIb disease are considered to be favourable candidates for more aggressive treatment of BM. SRS has been an option for limited (1-3) metastatic brain lesions, and nowadays the updated guidelines (for example, the NCCN panel) have recently added SRS as a primary treatment option for multiple (>3) metastatic lesions. The exclusive SRS approach for patients with multiple BM is mostly curative for each treated lesion, it can be repeated several times (the limits in terms of median cumulative dose to the normal brain must be explored), and WBRT remains an option as salvage treatment. Exclusive SRS with frequent magnetic resonance imagingbased follow-ups (every 2-3 months) in order to salvage recurrent BM before symptomatic manifestations, should be routinely offered to selected patients as a treatment option to consider (Lester SC et al). Initial treatment with a combination of SRS and close clinical monitoring should be recommended as the preferred treatment strategy to better preserve learning and memory in good prognosis patients with newly diagnosed BM (Chang EL et al). The Lausanne University Hospital (CHUV) has created a brain metastases clinic to provide medical and radiation oncology, neurosurgical, and supportive services to this complex patient population. During the first 18 months, 250 cases were discussed, 55% of patients had more than one brain metastases, and focal treatments were proposed in 69% of treated cases (for 50% of them radiosurgery or fractionated stereotactic radiotherapy, FSRT). WBRT was proposed to only 16% of patients (some of them as salvage therapy after sequential treatments with SRS). Higher BM burden (in terms of size and volume) and higher integral SRS dose to the brain are the main predictive factors for late toxicity after SRS. The cumulative neurocognitive effect of numerous SRS sessions remains unknown. In order to reduce the cumulative median dose to the brain, the SRS technique must be carefully chosen. At CHUV, we have performed a dosimetric comparison study in cases with multiple brain metastases (up to 10), comparing a radiosurgical planning (same dose and isodose prescription) with Gamma Knife (GK), CyberKnife (CK), VMAT and Helical Tomotherapy (HT). Gradient index was better with GK and CK (3.4 and 4.1, compared to 17.8 and 19), as well as PTV coverage (100% with GK and CK, compared to 97% with VMAT and 90% with HT); brain Dmean was lower with GK (3 Gy) and CK (2.66 Gy), compared to VMAT (6.4 Gy) and HT (6.72 Gy). SRS alone should be considered a routine treatment option in patients with multiple BM due to favourable neurocognitive outcomes, less risk of late side effects, without adversely affecting the patients performance status

Probing the nature of GCs multiple populations through chemistry: Li and heavy elements

Globular clusters have been widely studied in terms of light element variations present in their different stellar populations. However, the nature of the polluter(s) responsible for this phenomenon is still debated. The study of heavy elements and their relation to light ones can provide further constraints. To do so, this thesis studied two samples looking to approach the problem from different aspects. In the first one 217 stars of the metal-poor globular cluster, NGC 6752 were analysed through spectrum synthesis on GIRAFFE and UVES spectra to get the Li, Na, Mg, Al, Ca, Sc, Cu, Y, and Ba abundances. By doing so, this thesis aims both to gain insight into the nature of the polluter(s) responsible for the abundance variations and the C-N, Na-O, Al-Mg anti-correlations associated with the multiple-population phenomenon and to explore the possible contribution of asymptotic giant branch stars of different stellar masses to the internal pollution in the cluster. In addition to a continuous Li depletion of the average content from unevolved to evolved stars, there was detected a large Li spread at every log g. There were identified second-generation stars with Li content suggesting the need for Li production, known to happen in intermediate-mass (4-8 Msun) asymptotic giant branch stars through the Cameron-Fowler mechanism. Moreover, there were not found clear relations between the light s-process elements (represented by Y II) or heavy ones (represented by Ba II) with light elements (Li, Na, or Al). This indicates that the polluter(s) responsible for the Na (Al) or Li production does not produce large amounts of Y II and Ba II. Furthermore, the comparison with models discards a possibly significant contribution to the cluster pollution from AGB stars with masses lower than 5 Msun. In the second one, a large sample of 210 stars of 18 globular clusters with a large range of metallicities was analysed. The abundances of Cu, Y, Ba, La, and Eu were derived through spectral synthesis applied to UVES spectra. Using the mentioned data, the present thesis aims to analyse both the individual chemical enrichment and the overall behaviour of these clusters with respect to the galactic field. With some exceptions these clusters follow closely the patterns found in the field for stars with similar metallicity, however, a significant spread was found in some clusters suggesting enrichment in s- and/or r-process elements. In addition, it was found evidence of a weak -but significant- correlation between Y/Ba and Na in the mid-metallicity regime, which will be further investigated. Finally, intriguing suggestions of different chemical enrichment in n-capture elements between in-situ and accreted clusters, in which the first display a steeper distribution along with the orbital energy compared to the second ones. This result should be compared with chemical evolution models.Globular clusters have been widely studied in terms of light element variations present in their different stellar populations. However, the nature of the polluter(s) responsible for this phenomenon is still debated. The study of heavy elements and their relation to light ones can provide further constraints. To do so, this thesis studied two samples looking to approach the problem from different aspects. In the first one 217 stars of the metal-poor globular cluster, NGC 6752 were analysed through spectrum synthesis on GIRAFFE and UVES spectra to get the Li, Na, Mg, Al, Ca, Sc, Cu, Y, and Ba abundances. By doing so, this thesis aims both to gain insight into the nature of the polluter(s) responsible for the abundance variations and the C-N, Na-O, Al-Mg anti-correlations associated with the multiple-population phenomenon and to explore the possible contribution of asymptotic giant branch stars of different stellar masses to the internal pollution in the cluster. In addition to a continuous Li depletion of the average content from unevolved to evolved stars, there was detected a large Li spread at every log g. There were identified second-generation stars with Li content suggesting the need for Li production, known to happen in intermediate-mass (4-8 Msun) asymptotic giant branch stars through the Cameron-Fowler mechanism. Moreover, there were not found clear relations between the light s-process elements (represented by Y II) or heavy ones (represented by Ba II) with light elements (Li, Na, or Al). This indicates that the polluter(s) responsible for the Na (Al) or Li production does not produce large amounts of Y II and Ba II. Furthermore, the comparison with models discards a possibly significant contribution to the cluster pollution from AGB stars with masses lower than 5 Msun. In the second one, a large sample of 210 stars of 18 globular clusters with a large range of metallicities was analysed. The abundances of Cu, Y, Ba, La, and Eu were derived through spectral synthesis applied to UVES spectra. Using the mentioned data, the present thesis aims to analyse both the individual chemical enrichment and the overall behaviour of these clusters with respect to the galactic field. With some exceptions these clusters follow closely the patterns found in the field for stars with similar metallicity, however, a significant spread was found in some clusters suggesting enrichment in s- and/or r-process elements. In addition, it was found evidence of a weak -but significant- correlation between Y/Ba and Na in the mid-metallicity regime, which will be further investigated. Finally, intriguing suggestions of different chemical enrichment in n-capture elements between in-situ and accreted clusters, in which the first display a steeper distribution along with the orbital energy compared to the second ones. This result should be compared with chemical evolution models