Interobserver agreement on definition of the target volume in stereotactic radiotherapy for pancreatic adenocarcinoma using different imaging modalities.

PURPOSE: The aim of this study was to evaluate interobserver agreement (IOA) on target volume definition for pancreatic cancer (PACA) within the Radiosurgery and Stereotactic Radiotherapy Working Group of the German Society of Radiation Oncology (DEGRO) and to identify the influence of imaging modalities on the definition of the target volumes. METHODS: Two cases of locally advanced PACA and one local recurrence were selected from a large SBRT database. Delineation was based on either a planning 4D CT with or without (w/wo) IV contrast, w/wo PET/CT, and w/wo diagnostic MRI. Novel compared to other studies, a combination of four metrics was used to integrate several aspects of target volume segmentation: the Dice coefficient (DSC), the Hausdorff distance (HD), the probabilistic distance (PBD), and the volumetric similarity (VS). RESULTS: For all three GTVs, the median DSC was 0.75 (range 0.17-0.95), the median HD 15 (range 3.22-67.11) mm, the median PBD 0.33 (range 0.06-4.86), and the median VS was 0.88 (range 0.31-1). For ITVs and PTVs the results were similar. When comparing the imaging modalities for delineation, the best agreement for the GTV was achieved using PET/CT, and for the ITV and PTV using 4D PET/CT, in treatment position with abdominal compression. CONCLUSION: Overall, there was good GTV agreement (DSC). Combined metrics appeared to allow a more valid detection of interobserver variation. For SBRT, either 4D PET/CT or 3D PET/CT in treatment position with abdominal compression leads to better agreement and should be considered as a very useful imaging modality for the definition of treatment volumes in pancreatic SBRT. Contouring does not appear to be the weakest link in the treatment planning chain of SBRT for PACA.

Low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope: Monte Carlo treatment planning and dose measurements in a postmortem subject.

Objective.The goal of this study was to use Monte Carlo (MC) simulations and measurements to investigate the dosimetric suitability of an interventional radiology (IR) c-arm fluoroscope to deliver low-dose radiotherapy to the lungs.Approach.A previously-validated MC model of an IR fluoroscope was used to calculate the dose distributions in a COVID-19-infected patient, 20 non-infected patients of varying sizes, and a postmortem subject. Dose distributions for PA, AP/PA, 3-field and 4-field treatments irradiating 95% of the lungs to a 0.5 Gy dose were calculated. An algorithm was created to calculate skin entrance dose as a function of patient thickness for treatment planning purposes. Treatments were experimentally validated in a postmortem subject by using implanted dosimeters to capture organ doses.Main results.Mean doses to the left/right lungs for the COVID-19 CT data were 1.2/1.3 Gy, 0.8/0.9 Gy, 0.8/0.8 Gy and 0.6/0.6 Gy for the PA, AP/PA, 3-field, and 4-field configurations, respectively. Skin dose toxicity was the highest probability for the PA and lowest for the 4-field configuration. Dose to the heart slightly exceeded the ICRP tolerance; all other organ doses were below published tolerances. The AP/PA configuration provided the best fit for entrance skin dose as a function of patient thickness (R2 = 0.8). The average dose difference between simulation and measurement in the postmortem subject was 5%.Significance.An IR fluoroscope should be capable of delivering low-dose radiotherapy to the lungs with tolerable collateral dose to nearby organs.

Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope.

PURPOSE: To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs. MATERIALS AND METHODS: PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations. RESULTS: Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover âˆ¼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment. CONCLUSION: A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.

Dosimetric Comparison Between Helical Tomotherapy and Volumetric Modulated Arc Therapy in Patients With Malignant Pleural Mesothelioma.

AIMS: To carry out a dosimetric comparison and constraints feasibility proof of adjuvant radiotherapy through helical tomotherapy or volumetric modulated arc therapy (VMAT) for malignant pleural mesothelioma patients after pleurectomy/decortication. MATERIALS AND METHODS: Retrospective calculations were carried out on previously acquired simulations. A whole-pleura volume with 50.4 Gy in 28 fractions was prescribed, simulating a no residual tumour situation. Calculations were carried out using an anisotropic analytical algorithm with a 2.0 mm grid. Beam-on time, planning target volume (PTV) coverage, homogeneity index and organ at risk exposure were compared. RESULTS: Sixteen patient plans were calculated per device. Constraints were met overall by both modalities. For helical tomotherapy and VMAT plans, median beam-on times were 13.8 (11.6-16.1) min and 6.4 (6.1-7.0) min; P = 0.006. The median left-sided radiotherapy PTV D98 were 48.1 (48.0-48.8) Gy and 47.6 (46.5-48.3) Gy; P = 0.023. No significant difference for right-sided radiotherapy was found. PTV D2 for left-sided radiotherapy was higher with VMAT (P = 0.014). For right-sided radiotherapy, helical tomotherapy showed higher doses (P = 0.039). No homogeneity index differences for left-sided radiotherapy (P = 1.00) and right-sided radiotherapy (P = 0.598) were seen. Significant organ at risk exposure differences were found on left-sided radiotherapy whole-lung V20, as well as D50 (both P = 0.008). Higher contralateral lung and ipsilateral kidney exposures were found with VMAT plans for both treatment sides. CONCLUSION: Adjuvant radiotherapy after pleurectomy/decortication in malignant pleural mesothelioma patients, with a VMAT- or helical tomotherapy-based platform, is dosimetrically feasible. Lung sparing was mostly improved with helical tomotherapy. Technique selection must be carried out according to availability and clinical criteria.

Short-term effects of green tea chronotherapy on the metabolic homeostasis of mice on different diets.

Biological rhythms can be defined as changes in physiological or behavioral variables that repeat at certain time intervals. Rhythms that last approximately 24 h are referred to as circadian rhythms. Modern lifestyles have drastically affected human habits, as well as the population's eating habits. These changes have generated an epidemic of metabolic syndromes, such as obesity and diabetes. In an attempt to combat obesity, populations have attempted to use many different herbal remedies and plant-based drugs, the most common of which is Camellia sinensis, or green tea. Most of the studies on the effects of C. sinensis on maintaining body weight have reported the involvement of this substance in lipid oxidation. The objective of this study was to evaluate how the administration of C. sinensis at different times of day influenced changes in body weight, blood glucose levels, and food intake of mice kept under different diet conditions. The structural organization of abdominal adipose tissue was also evaluated, as were certain aspects of lipid metabolism and overall synthetic activity in the liver, adipose tissue, and ovaries. The results obtained suggest that the intake of green tea in the light phase of the day stimulates weight loss, regardless of the diet ingested. Neither glucose levels nor the structural organization of adipose tissue was found to be altered in any of the experimental groups. Neither diet nor the time at which the green tea was administered was found to have any effects on the amount of food the mice consumed. The time at which green tea was consumed and the type of diet both influenced LXRαß nuclear receptor expression, as well as the expression of fibrillarin in the liver and ovaries, although this influence was tissue specific.

Bud Rot Caused by Phytophthora palmivora: A Destructive Emerging Disease of Oil Palm.

Oomycetes from the genus Phytophthora are among the most important plant pathogens in agriculture. Epidemics caused by P. infestans precipitated the great Irish famine and had a major impact on society and human history. In the tropics, P. palmivora is a pathogen of many plant species including cacao (Theobroma cacao), citrus (Citrus sp.), durian (Durio zibethines), jackfruit (Artrocarpus heterophyllus), rubber (Hevea brasiliensis), and several palm species including coconut (Cocos nucifera), and the African oil palm (Elaeis guineensis) as determined recently. The first localized epidemics of bud rot in oil palm in Colombia were reported in 1964. However, recent epidemics of bud rot have destroyed more than 70,000 ha of oil palm in the Western and Central oil palm growing regions of Colombia. The agricultural, social, and economic implications of these outbreaks have been significant in Colombia. Identification of the pathogen after 100 years of investigating the disease in the world enabled further understanding of infection, expression of a range of symptoms, and epidemiology of the disease. This review examines the identification of P. palmivora as the cause of bud rot in Colombia, its epidemiology, and discusses the importance of P. palmivora as a major threat to oil palm plantings globally.

Long-term follow-up of radiation accident patients in Peru: review of two cases.

Overexposure to radioactive sources used in radiotherapy or industrial radiography may result in severe health consequences. This report assesses the initial clinical status and the medical and psychological long-term follow-up of two radiation accident patients from Peru during the mid-to-late 1990s: one patient exposed to a radiotherapy (60)Co source in Arequipa, the other patient to a (192)Ir source in Yanango. Commonalities and differences are described. The main causes in both accidents were human error and the failure to apply appropriate safety guidelines and standard operating procedures. Education and training of the personnel working with radiation sources are essential to prevent accidents. The experience gained from the medical management of the two patients is valuable for future treatment of such patients.

First Report of Bud Rot Caused by Phytophthora palmivora on African Oil Palm in Colombia.

A bud rot disease, referred to as "pudricion del cogollo" or PC (for its name in Spanish), is a major disease of oil palm in four production areas of Colombia. Even though the disease has been studied for more than 40 years in Central and South America, the causal agent remained unknown (1). Infection first develops in the palm heart (cogollo) above the meristematic zone. Initial external symptoms appear as necrotic lesions on the sides of the spear leaf (youngest, unexpanded leaf) and the sizes of the lesions remain static as tissues emerge, expand, and mature. Under favorable environmental conditions (temperature around 26°C and relative humidity above 80%), further rotting of the heart eventually destroys the bud. A baiting technique with papaya and cocoa fruits was successfully used to trap the causal agent from symptomatic spear leaf tissue collected from the provinces of Nariño and Santander (2), where the disease is severe. Small, triangular-shaped pieces were removed from healthy fruits that had been surface sterilized, and a corresponding piece of diseased oil palm tissue was inserted into the hole and sealed with the removed fruit tissue. The whole fruit was wrapped with plastic and incubated at 25°C. Once the fruit traps showed initial necrotic symptoms, fruit tissue from the advancing point of the lesions was plated on Phytophthora-selective media. Four isolates of Phytophtora palmivora, all A2 mating type, were obtained during this study and each presented similar white and depressed mycelium when grown on oatmeal agar (OMA) medium. Papillated, ellipsoidal sporangia with short pedicels had an average size of 37.1 (breadth) × 52.8 µm (length). Chlamydospores averaged 35.1 µm in diameter and were similar to those observed in diseased palm tissue. DNA from the Phytophthora isolates was used as a template for PCR using ITS1/ITS4 primers. BLASTn analysis of the ITS sequences (GenBank Accession No. GQ398157) showed 99.9% homology with P. palmivora. The sequences of the four isolates were identical. For pathogenicity testing, cultures were grown on OMA. Two milliliters of distilled water containing 40,000 sporangia were injected into the base of the spear leaf of 105 nursery palms; the same number of palms was injected with 2 ml of distillated water as controls. Initial PC symptoms were observed 3 to 4 days after inoculation on 85% of inoculated palms and 15% of these palms developed typical bud rot symptoms under favorable conditions. No symptoms were observed on the controls. The presence of Phytophthora was confirmed by light microscopy and P. palmivora was reisolated from symptomatic palms with the fruit-baiting technique. The presence of Phytophthora in the four Colombian growing areas was also confirmed using Agdia (Elkhart, IN) immunostrips followed by DNA extraction from the Immunostrip wick and ITS sequencing to confirm the species. To our knowledge, this is the first report of P. palmivora causing PC on oil palm in Colombia. References: (1) H. de Franqueville. Exp. Agric. 39:225, 2003. (2) G. Sarria et al. Rev. Palmas, Colombia. 29(3):31, 2008.

Clonación y transcripción del gen EBER-1 del virus Epstein-Barr: estudio de su expresión genética por hibridación in situ / Cloning and transcription of gene EBER-1 of Epstein-Barr virus: study of its genetic expression by hybridization in situ

La capacidad de virus de Eptein Barr (VEB) de inducir transformación e inmortalización de linfocitos y su alta prevalencia en algunas neoplásias linfoides ha motivado intensa investigación de su biología y comportamiento. Describimos la hibridación in situ (HIS), para la identidicación de transcriptos del virus de Epstein-Barr, desarrollado en la Unidad de Biología Molecular del Centro de Investigación en Cáncer Maes Heller, en biopsias de linfoma incluidas en parafina.El gen EBER-1 (Epstein Barr-encoded RNA) fue clonado y transcrito, el ARN transcrito fue evaluado con óptimos resultados en las líneas celulares Raji y Daudi que expresan EBER. Este transcrito marcado fue usado como sonda para determinar la expresión genética del virus en 159 especimenes biológicos en estudio y en controles positivos y negativos conocidos empleando la HIS.La actividad transcripcional del virus fue observada en 44 de los casos estudiados. Concluimos que la HIS en tejido incluido en parafina es una buena alternativa para detectar actividad del VEB y la presencia o ausencia de EBER puede ser considerada como marcador biológico en la etiopatología de estos linfomas