In Particle Therapy, safety margins are applied around the tumor to account for the beam range uncertainties and ensure an adequate dose coverage of the tumor volume during the therapy. The reduction ...of safety margins is in great demand in order to diminish the Particle Therapy side effects especially in the case of treatment of tumors close to Organs at Risk (OAR) and of pediatric patients. To this aim, beam range monitoring techniques are being developed by the scientific community, most of all based on the detection of secondary particles produced by the nuclear interactions of the beam with the patient’s tissue nuclei. In this contribution, a novel beam range monitoring technique is proposed, based on the detection of prompt photons exploiting the pair production mechanism. The proof of principle of the PAir PRoduction Imaging ChAmber (PAPRICA) is studied through the development of a Monte Carlo simulation and the detector performances toward a more realistic scenario are determined.
•Therapeutic 16O beams interacting with a target produce abundant secondary radiation.•Production emission profiles, yields, and energy spectra were characterized experimentally at large angles.•16O ...induced charged secondary particles can be exploited for radiotherapy range monitoring.•The sensitivity of the technique was explored in homogeneous and heterogeneous PMMA targets.•The collected data is essential to assess the range monitoring accuracy and resolution.
Particle therapy is a therapy technique that exploits protons or light ions to irradiate tumor targets with high accuracy. Protons and 12C ions are already used for irradiation in clinical routine, while new ions like 4He and 16O are currently being considered. Despite the indisputable physical and biological advantages of such ion beams, the planning of charged particle therapy treatments is challenged by range uncertainties, i.e. the uncertainty on the position of the maximal dose release (Bragg Peak – BP), during the treatment. To ensure correct ‘in-treatment’ dose deposition, range monitoring techniques, currently missing in light ion treatment techniques, are eagerly needed.
The results presented in this manuscript indicate that charged secondary particles, mainly protons, produced by an 16O beam during target irradiation can be considered as candidates for 16O beam range monitoring. Hereafter, we report on the first yield measurements of protons, deuterons and tritons produced in the interaction of an 16O beam impinging on a PMMA target, as a function of detected energy and particle production position. Charged particles were detected at 90° and 60° with respect to incoming beam direction, and homogeneous and heterogeneous PMMA targets were used to probe the sensitivity of the technique to target inhomogeneities. The reported secondary particle yields provide essential information needed to assess the accuracy and resolution achievable in clinical conditions by range monitoring techniques based on secondary charged radiation.
Soybean looper (SBL), Chrysodeixis includens (Walker), is an economically important soybean and cotton pest in Brazil. Here, we selected an SBL strain resistant to teflubenzuron using F2 screening, ...estimated the resistance allele frequency, characterized the inheritance of resistance, investigated fitness costs, evaluated patterns of cross-resistance, and determined the magnitude of resistance. The teflubenzuron-resistant strain (Teflu-R) was selected from field-collected populations with an estimated allele frequency of 0.1700. Estimated LC50 values were 0.010 and 363.61 μg a.i. cm−2 for the susceptible (Sus) and Teflu-R strains, respectively, representing a 36,361-fold resistance ratio (RR). The LC50 values of reciprocal crosses were 1.02 and 0.59 μg a.i. cm−2, suggesting that resistance is autosomally inherited. The low survival of reciprocal crosses (16 and 20%) on teflubenzuron-sprayed leaves indicates incomplete recessive resistance. The number of segregations influencing resistance was 2.72, suggesting a polygenic effect. The Teflu-R strain showed longer development periods as well as lower survival and population growth than the Sus strain, revealing fitness costs. The Teflu-R strain also showed high cross-resistancesto other chitin inhibitor insecticides, such as novaluron (RR = 6147-fold) and lufenuron (RR = 953-fold), but low cross-resistance to methoxyfenozide, flubendiamide, and indoxacarb (RR < 3.45-fold). On discriminatory concentrations of teflubenzuron and novaluron, populations of SBL showed survival rates from 15 to 52%, indicating field resistance to these insecticides. Our findings indicated that resistance to teflubenzuron in SBL is autosomal, recessive, polygenic, and associated with fitness cost. We also found a high cross-resistance to other benzoylphenylureas and a high frequency of resistance to this mode-of-action in SBL in Brazil.
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•A selected soybean looper (SBL) strain showed > 36,300-fold resistance to teflubenzuron.•Resistance is autosomal, recessive, polygenic, and associated with high fitness cost.•SBL showed high cross-resistance to other chitin inhibitor insecticides.•Populations of SBL had high resistance frequencies to chitin synthesis inhibitor insecticides.
FLUKA is a Monte-Carlo code able to simulate interaction and transport of hadrons, heavy ions and electromagnetic particles from few keV (or thermal neutron) to cosmic ray energies in whichever ...material. The highest priority in the design and development of the code has always been the implementation and improvement of sound and modern physical models. A summary of the FLUKA physical models is given, while recent developments are described in detail: among the others, extensions of the intermediate energy hadronic interaction generator, refinements in photon cross sections and interaction models, analytical on-line evolution of radio-activation and remnant dose. In particular, new developments in the nucleus–nucleus interaction models are discussed. Comparisons with experimental data and examples of applications of relevance for space radiation are also provided.
Abstract Background It is not quite well established how immune responses differ in term and preterm infants beyond the first year of life. This study aimed to evaluate aspects of the innate and ...adaptive immune responses in a group of preterm infants in comparison with their term peers. Methods In this cross-sectional study peripheral blood mononuclear cells (PBMC) were isolated from preterm and term children at age three years. Innate immune response was evaluated by the analysis of TLR receptors expression on CD11c+ HLADRhigh cells and inflammatory cytokine production after PBMC stimulation with Toll like receptors (TLR) ligands. Adaptive immune response was evaluated by T cells’ phenotyping and function after stimulation with polyclonal conventional T cell stimulus. Conclusion We have found that the patterns of innate and adaptive immune responses at 3 years of age were not affected by the fact of the children having being born preterm or at term.
Fall armyworm (FAW), Spodoptera frugiperda (Smith), is one of the major pests targeted by transgenic crops expressing insecticidal proteins from Bacillus thuringiensis (Bt) Berliner. However, FAW ...presents a high capacity to develop resistance to Bt protein-expressing crop lines, as reported in Brazil, Argentina, Puerto Rico and the southeastern U.S. Here, FAW genotypes resistant to pyramided maize events expressing Cry1F/Cry1A.105/Cry2Ab2 (P-R genotype) and Cry1A.105/Cry2Ab2 (Y-R genotype) from Brazil were used to investigate the interactions between non-Bt hosts (non-Bt maize, non-Bt cotton, millet and sorghum) and fitness costs. We also tested a FAW genotype susceptible to Bt maize and F1 hybrids of the resistant and susceptible genotypes (heterozygotes). Recessive fitness costs (i.e., costs affecting the resistant insects) were observed for pupal and neonate to adult survival of the P-R genotype on non-Bt cotton; larval developmental time of the P-R genotype on millet and sorghum; larval and neonate-to-adult developmental time of the Y-R genotype on non-Bt cotton and sorghum; the fecundity of the Y-R genotype on non-Bt cotton; and mean generation time of both resistant genotypes. However, on non-Bt cotton and non-Bt maize, the P-R genotype had a higher fitness (i.e., fitness benefits), displaying greater fecundity and rates of population increases than the Sus genotype. Non-recessive fitness costs (i.e., costs affecting heterozygotes) were found for fecundity and population increases on millet and sorghum. These findings suggest that, regardless of the disadvantages of the resistant genotypes in some hosts, the resistance of FAW to Cry1 and Cry2 Bt proteins is not linked with substantial fitness costs, and may persist in field conditions once present.
Soybean looper (SBL), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), is an important pest of soybean and cotton in Brazil. The use of insecticides is one of the main control tactics ...against this pest. To support Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs, we characterized the susceptibility of Brazilian populations of SBL to insecticides. Field populations were collected from soybean fields during the 2016–2017 and 2017–2018 crop seasons. In the laboratory, late L2/early L3 larvae were exposed to insecticides in diet-overlay or topical bioassays. Field populations of SBL showed high susceptibility to spinetoram (LC50 = 0.074–0.25 μg a.i. per cm2), indoxacarb (LC50 = 0.46–0.94 μg a.i. per cm2), thiodicarb (LC50 = 9.14–36.61 μg a.i. per cm2), chlorantraniliprole (LC50 = 0.15–0.57 μg a.i. per cm2), flubendiamide (LC50 = 0.45–2.01 μg a.i. per cm2), and chlorfenapyr (LC50 = 0.15–0.25 μg a.i. per cm2); the resistance ratios were less than 16-fold. In contrast, SBL populations have reduced susceptibility to lambda-cyhalothrin (LC50 = 3.71–9.54 μg a.i./cm2), methoxyfenozide (LC50 = 0.67–4.23 μg a.i. per cm2), novaluron (LC50 = 27.52–77.63 μg a.i. per cm2), and teflubenzuron (LC50 = 13.41–73.02 μg a.i. per cm2). The resistance ratios relative to a Lab population (susceptible of reference) was up to 38-, 63-, 1,553-, and 5,215-fold, respectively. These high resistance ratios can be associated with resistance evolution. Implications of these findings to IPM and IRM programs are discussed.
Helicoverpa armigera caterpillars are polyphagous and exhibit high migratory potential. Given the traits of this pest, alternative hosts located in or near the crop stand may support the survival and ...permanence of H. armigera in the field. The aim of this study was to investigate Conyza sp. as a food source for H. armigera caterpillars in scenarios with conventional and Bt soybean. Two experiments were conducted in biochemical oxygen demand incubators. The first assessed consumption of conventional soybean, Bt soybean and Conyza sp. leaves by 3rd and 5th instar caterpillars, with no choice given (no-choice test). The second test evaluated the food preference of 3rd instar H. armigera larvae, with two choices given (dual-choice test). Fifth instar larvae favored Conyza sp. leaves to Bt soybean, but preferred conventional soybean to both of these options. The survival of 3rd instar caterpillars did not differ statistically regardless of the plant species used as a food source. Fifth instar larvae fed Bt soybean exhibited lower survival rates when compared to Conyza sp. and conventional soybean. In dual-choice test arenas, soybean leaf consumption was superior to Conyza sp. Conventional soybean consumption was also greater when offered in conjunction with Bt soybean. Caterpillars offered Conyza sp. and Bt soybean leaves only consumed the weed species. Conyza sp. plants can serve as a food source for H. armigera larvae, which showed a preference for Conyza sp. leaves to Bt soybean.
RESUMO: Lagartas de Helicoverpa armigera apresentam alta capacidade de migração e hábito alimentar polífago. Devido às características dessa praga, hospedeiros alternativos localizados nas proximidades ou interior da lavoura podem dar suporte para sua sobrevivência. O objetivo deste trabalho foi investigar a possibilidade de plantas de buva serem alimento para lagartas de H. armigera em cenários com soja convencional e Bt. Foram conduzidos dois experimentos em câmaras do tipo biochemical oxygen demand. O primeiro avaliou o consumo foliar de soja convencional, soja Bt e buva, sem chance de escolha, de lagartas de 3o e 5o ínstares. No segundo, avaliou-se a preferência de alimentação de lagartas H. armigera de 3o ínstar, com dupla chance de escolha. Quando avaliado o consumo foliar de lagartas de 5o ínstar, observou-se preferência por buva em relação à soja Bt, porém ambas inferiores à soja convencional. A sobrevivência de lagartas de 3o ínstar não diferiu estatisticamente, independentemente da espécie fornecida como alimento. Lagartas de 5o ínstar alimentadas com soja Bt apresentaram menor sobrevivência em comparação com buva e soja convencional. Em arenas com dupla chance de escolha, o consumo foliar de soja foi superior ao da buva. O consumo de soja convencional foi superior também quando ofertada em conjunto com a soja Bt. A oferta de buva e soja Bt apresentou consumo foliar apenas na espécie daninha. Plantas de buva podem servir de alimento para lagartas de H. armigera. As lagartas têm preferência por consumir folhas de buva, em comparação à soja Bt.
Cette étude propose un modèle prédictif basé sur les indices de complexité, pour évaluer la faisabilité des plans de traitement d’arcthérapie volumétrique modulée.
Le modèle clinique a été créé en ...trois étapes. Tout d’abord, le développement d’un algorithme en langage python, intégrant le calcul de sept scores de complexité (MCS/LTMCS/MAD/MFA/CLS/CAS). Ces scores décrivent des paramètres tels que le déplacement des lames pour chaque point de contrôle. Un score ad hoc a été développé pour intégrer la variabilité des unités moniteur (MUV). Ensuite, une étude rétrospective a permis d’évaluer la corrélation entre les scores et l’indice gamma à partir d’une base de données contenant un échantillon de 700 plans de d’arcthérapie volumétrique modulée. Pour valider le modèle, une évaluation prospective a été réalisée sur 200 plans de d’arcthérapie volumétrique modulée.
Une forte corrélation (r=0,79) a été trouvée avec la combinaison LTMCS/MUV et l’indice gamma (3 % 3mm) pour les plans normofractionnés et (2 % 2mm) pour les plans stéréotaxiques. Les résultats ont montré qu’un LTMCS supérieur à 0,15 et un MUV inférieur à 5 d’un plan, signifie que ces faisceaux sont prédits comme des vrais positifs (indice gamma supérieur à 95 %). Un tri par le LTMCS et MUV a permis d’avoir 75 % de vrais positifs (1035 faisceaux sur 1379; p<0,001). Les scores calculés pour les 25 % des plans restant traduisaient une forte complexité entre chaque point de contrôle, et pourra conduire à des indices gamma inférieurs à 95 % (90 sur 344 faisceaux). La méthode combinant le LTMCS/MUV a permis de discriminer le risque des faux positifs (p<0,001). L’utilisation prospective du modèle a prouvé son efficacité de détection des 75 % de vrais positifs (soit 339 sur 451 faisceaux; p<0,001), sur les faisceaux qui restaient, seuls 25 étaient des vrais négatifs (indice gamma inférieur à 95 %).
L’étude des scores et les seuils déterminés sont dépendants de chaque couple système de planification des traitements–accélérateur linéaire. Les deux scores LTMCS/MUV permettent d’écarter les faux positifs, l’étude se poursuit pour réduire les 15 % de faux négatifs.
Le traitement des cancers de la sphère ORL est fractionné en 35 séances de 2Gy, étalées sur 7 semaines. Des modifications anatomiques peuvent apparaître et perturber le repositionnement du patient ...ainsi que la distribution de dose. Pour les besoins de la radiothérapie adaptative, un calcul dosimétrique précis à partir de la tomographie conique et une méthode d’évaluation des modifications entre les fractions du plan de traitement doivent être établis. L’étude présente la mise en place de critères de replanification dosimétrique dans le cadre de la mise en œuvre de la radiothérapie adaptative.
Une cohorte rétrospective de 38 patients atteints d’un carcinome épidermoïde (de stades T1 à T4) non métastatique de la sphère ORL avec des adénopathies régionales (de stades N0 à N3) et ayant bénéficié d’une arcthérapie volumétrique modulée avec une tomographie conique (Varian Clinac®) par semaine, ont été inclus dans cette étude. Pour chaque patient, un algorithme de recalage déformable (RD) via Syngo.via (Siemens Healthineers) a été appliqué aux images scanographiques dosimétriques (Siemens Somatom), modifiant ainsi les structures anatomiques pour se conformer aux tomographies coniques hebdomadaires. Un calcul de dose précis sur tomographie conique a alors été réalisé afin d’évaluer la nécessité de replanification avant chaque fraction.
Une perte de poids moyenne de 4,7±1,8kg a été observée entre le début et la fin du traitement. L’étude des histogrammes dose–volume a montré une différence significative (p<0,05) de la dose maximale dans la moelle de l’ordre 1,7Gy (+4,2 %) au bout de la 11e fraction par rapport à la scanographie. Les tolérances médicales pour la dose maximale dans la trachée (70Gy) ont été atteintes dès la 16e fraction (p=0,27). Aucun changement du volume couvert par 95 % de la dose dans le volume cible prévisionnel (V95 %=99 %) n’a été constaté (p=0,47).
Une replanification est jugée nécessaire à partir de la 11e fraction. Suite à cette étude, un protocole d’alerte dosimétrique a été mis en place afin d’évaluer la nécessité d’une replanification au cours du traitement.
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