47 research outputs found
A hollow cathode arc as a high intensity beam source for ground state and metastable noble gas atoms in the eV translational energy range
Molecularâbeam sampling of a hollowâcathode discharge in argon as a plasma diagnostic and a source for fast neutrals
IsoBED: a tool for automatic calculation of biologically equivalent fractionation schedules in radiotherapy using IMRT with a simultaneous integrated boost (SIB) technique
<p>Abstract</p> <p>Background</p> <p>An advantage of the Intensity Modulated Radiotherapy (IMRT) technique is the feasibility to deliver different therapeutic dose levels to PTVs in a single treatment session using the Simultaneous Integrated Boost (SIB) technique. The paper aims to describe an automated tool to calculate the dose to be delivered with the SIB-IMRT technique in different anatomical regions that have the same Biological Equivalent Dose (BED), i.e. IsoBED, compared to the standard fractionation.</p> <p>Methods</p> <p>Based on the Linear Quadratic Model (LQM), we developed software that allows treatment schedules, biologically equivalent to standard fractionations, to be calculated. The main radiobiological parameters from literature are included in a database inside the software, which can be updated according to the clinical experience of each Institute. In particular, the BED to each target volume will be computed based on the alpha/beta ratio, total dose and the dose per fraction (generally 2 Gy for a standard fractionation). Then, after selecting the reference target, i.e. the PTV that controls the fractionation, a new total dose and dose per fraction providing the same isoBED will be calculated for each target volume.</p> <p>Results</p> <p>The IsoBED Software developed allows: 1) the calculation of new IsoBED treatment schedules derived from standard prescriptions and based on LQM, 2) the conversion of the dose-volume histograms (DVHs) for each Target and OAR to a nominal standard dose at 2Gy per fraction in order to be shown together with the DV-constraints from literature, based on the LQM and radiobiological parameters, and 3) the calculation of Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) curve versus the prescribed dose to the reference target.</p
Health profiles of 996 melanoma survivors: the M. D. Anderson experience
BACKGROUND: The incidence and survival of melanoma are increasing, but little is known about its long-term health effects in adult survivors. METHODS: A health survey was available from 996 melanoma survivors (577 treated with surgery alone, and 391 with combined treatments). Their medical/physiologic and psychosocial responses were analyzed and compared with those of the survivors from other cancers. RESULTS: The melanoma survivors were 44.8 ± 12.8 years of age at diagnosis (significantly younger than the survivors of other cancers) and 63.7 ± 12.8 years at survey. Melanoma survivors were less likely to report that cancer had affected their health than survivors of other cancers (15.8% vs. 34.9%). The 577 individuals treated with surgery alone reported arthritis/osteoporosis, cataracts, and heart problems most frequently (less often than survivors of other cancers). The 391 individuals who had undergone combined treatments reported circulation problems and kidney problems generally as often as survivors of other cancers. Health problems were not associated with number of decades since diagnosis but with age at diagnosis, treatment modality, and family relationships. CONCLUSION: We present information from a large cohort of long-term survivors of melanoma. As a group, they were less likely to report that cancer had affected their overall health than survivors of other cancers; a number of disease related and psychosocial factors appear to influence their health profiles
Re-evaluating the Quoit Brooch Style: Economic and Cultural Transformations in the 5th Century ad, with an Updated Catalogue of Known Quoit Brooch Style Artefacts
Quoit Brooch Style material, produced from the early 5th century onwards, has previously been considered mostly from a stylistic point of view, leaving much scope for further investigation. In addition, the known corpus of material has been much expanded through newly excavated and metal-detected finds. In this article, I bring together the known extant material for the first time, and document important evidence relating to contextual dating, gender associations, manufacture (including new compositional analysis of c 75 objects), repair, and reuse. The article questions previous interpretations of Quoit Brooch Style material relating to Germanic mercenaries and/or post-Romano-British political entities. It interprets the earliest material as part of wider trends elsewhere, in Britain and in Continental northwestern Europe, for the production of material imitating late Roman symbols of power. It presents new evidence for connectivity with Continental Europe via the western Channel route in the 5th century. A detailed investigation of individual artefacts shows that many Quoit Brooch Style objects were reused, sometimes being subjected to extensive repair and modification. This provides new insights into the 5th century metal economy, for instance, acute problems in the availability of new metal objects in southeastern Britain in the middle years of the 5th century. Compositional analysis contributes further to our understanding of metal supply in the 5th century and relationships with the post-Roman West. Insights are provided into wider cultural transformations in the 5th century and the gradual loss of value that occurred for Roman-style objects
Genotoxic exposure of workers creosoting wood.
In a small wood preserving industry spot samples were taken from contaminated surfaces at several places and tested for mutagenicity. The results suggest that the application of a wipe test can give a first indication of occupational exposure to mutagenic and carcinogenic substances, particularly when exposure occurs more from skin contact than from inhalation. One of the pesticide chemicals used to preserve wood is the mutagenic creosote . It was found that mutagens appeared in the urine of rats after intraperitoneal administration of creosote . Despite these results, no increase in mutagenicity could be detected in the urine of creosote workers in relation to their work
Tuning Possibilities of the Longitudinal Beam Shape of a Racetrack Microtron
The beam shape in the longitudinal phase plane at the extraction point of an RTM strongly depends on the choice of the stable phase of the accelerating cavity. This is due to the fact that the main longitudinal focusing force is the derivative of the accelerating potential with respect to time (or phase). Furthermore, this focusing force is applied to the electron beam each turn, such that the output beam shape in the longitudinal phase plane is significantly affected. This effect can for instance be used in order to minimise the bunch length or the energy spread of the output beam of the RTM. For this paper we have used the lay-out of the Eindhoven RTM for the calculations of the stable-phase variations, which have been studied in linear approximation. The stable phase area for this RTM equals 18 degrees. It will be shown that stable-phase variations in the order of 1 degree already have a significant impact on the longitudinal beam shape. Furthermore, some remarks are made on the consequences of non-linear beam dynamics in relation to stable-phase variations