101 research outputs found
20. Setting the pace for strengthening radiotherapy in Europe: the estro esquire project
In most medical specialties the success rate and outcome of treatment coincide and can be measured immediately. This is not the case for radiotherapy where debilitating of even lethal side effects may show up as late as 18 years after treatment. To determine the outcome or therapeutic ratio of radiotherapy, it is therefore necessary to link tumour control closely to the actuarial long-term disease free survival of the patient.The therapeutic window for radiotherapy is narrow. In walking the tightrope between cure and complications, radiotherapy can put the odds at its side. As a precautionary measure, strict quality assurance measures including the monitoring of side effects need to be put in place. Recent studies have demonstrated that every gain in the accuracy of the beam output and treatment delivery is translated into important gains in the uncomplicated cure probability, thus sparing the lives of thousands of patients every year. QA will become all the more mandatory now that new technological developments allow much more precision in the delivery of the intended dose to the intended target volume, thus making an escalation of the dose and hence the improvement of the cancer cure rata possible.Europe has only half the number of treatment units of America and Japan. However, it has also its own strengths. These are exactly in the field of quality assurance and education. ESTRO has become a world leader in the provision of teaching in the field of radiotherapy. The ESTRO teaching programme commands the admiration and even the envy of the International radiation oncology community. We need to capitalise on this achievement and keep it at the cutting edge of scientific and technological progress to offset, through the development of the human potential and optima) use of capital-intensive infrastructural resources, at least partially the shortage in capital investment and the past shortfall in spending for research.For this reason ESTRO is embarking on an ambitious new project called ESQUIRE (Education, Science and Quality Assurance In Radiotherapy in Europe) which it hopes to realise with the support of EU funding. The aim of this project is to increase the confidence level of clinicians for embracing optimised RT treatment regimes by making sure they can be introduced without an increase in severe side effects. Actions proposed for this purpose: monitoring the accuracy of the dose (Talk 1:E∼UAL) and the side effects (Task 2: REACT), by stepping up education for the implementation of new technology (Task 3: EDRO,) by developing quality assurance procedures for optimised RT (Task 5: QUASIMODO) and brachytherapy (Task 6: BRAPHY∼S), and establishing a procedure-based surveillance of quality in treatment and research (Task 4:EPOQART)
The Sariçiçek Howardite Fall in Turkey: Source Crater of HED Meteorites on Vesta and İmpact Risk of Vestoids
The Sariçiçek howardite meteorite shower consisting of 343 documented stones
occurred on 2 September 2015 in Turkey and is the first documented howardite fall. Cosmogenic
isotopes show that Sariçiçek experienced a complex cosmic ray exposure history, exposed during
~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid
was launched by an impact 22 ± 2 Ma ago to Earth (as did one third of all HED meteorites). SIMS
dating of zircon and baddeleyite yielded 4550.4 ± 2.5 Ma and 4553 ± 8.8 Ma crystallization ages
for the basaltic magma clasts. The apatite U-Pb age of 4525 ± 17 Ma, K-Ar age of ~3.9 Ga, and
the U,Th-He ages of 1.8 ± 0.7 and 2.6 ± 0.3 Ga are interpreted to represent thermal metamorphic
and impact-related resetting ages, respectively. Petrographic, geochemical and O-, Cr- and Tiisotopic
studies confirm that Sariçiçek belongs to the normal clan of HED meteorites. Petrographic
observations and analysis of organic material indicate a small portion of carbonaceous chondrite
material in the Sariçiçek regolith and organic contamination of the meteorite after a few days on
soil. Video observations of the fall show an atmospheric entry at 17.3 ± 0.8 kms-1 from NW,
fragmentations at 37, 33, 31 and 27 km altitude, and provide a pre-atmospheric orbit that is the
first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data
indicate the similarity of Sariçiçek with the Vesta asteroid family (V-class) spectra, a group of
asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of
meteoroid delivery to Earth shows that the complete disruption of a ~1 km sized Vesta family
asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids ≤4
m in size to account for the influx of meteorites from this HED clan. The 16.7 km diameter Antonia
impact crater on Vesta was formed on terrain of the same age as given by the 4He retention age of
Sariçiçek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was
formed ~22 Ma ago
Optically stimulated luminescence in vivo dosimetry for radiotherapy: physical characterization and clinical measurements in (60)Co beams
A commercial optically stimulated luminescence (OSL) dosimetry system was investigated for in vivo dosimetry in radiation therapy. Dosimetric characteristics of InLight dot dosimeters and a microStar reader (Landauer Inc.) were tested in (60)Co beams. The reading uncertainty of a single dosimeter was 0.6%. The reproducibility of a set of dosimeters after a single irradiation was 1.6%, while in repeated irradiations of the same dosimeters it was found to be 3.5%. When OSL dosimeters were optically bleached between exposures, the reproducibility of repeated measurements improved to 1.0%. Dosimeters were calibrated for the entrance dose measurements and a full set of correction factors was determined. A pilot patient study that followed phantom validation testing included more than 100 measured fields with a mean relative difference of the measured entrance dose from the expected dose of 0.8% and the standard deviation of 2.5%. In conclusion, these results demonstrate that OSL dot dosimeters represent a valid alternative to already established in vivo dosimetry systems
Effects of intermittent-direct-electric-current (IDC) on polyphenols and antioxidant activity in radish (Raphanus sativus L.) during growth
In the present study the effects of intermittent-direct-electric-current (IDC; for one hour per day) on phenolic compounds and antioxidant activity in radish (Raphanus sativus L.) was studied. The radish plants were cultivated in rock wool substrate in combination with drip irrigation. Two stainless steel plates were added on the rock wool substrate and acted as electrodes to supply the currents to the plants. Three different IDC treatments (200 mA, 600 mA, and 1000 mA) were applied during growth period and passed horizontally through the nutrient solution as well as through the tissue of the radish plants. After 16 days of growth the radish plants were randomly harvested, divided into three segments (root, tuber, shoot) and were used for the determination of total phenolic content, anthocyanins, and antioxidative activity.This new technology increased the health-promoting phytochemical compounds in radish segments with no sign of damage. In radish tubers total phenol content, anthocyanins, and antioxidant activity increased with increasing IDC. The same was observed for the total phenol content in radish roots. However in contrast, the phenolic compounds of radish shoots remained unaffected by IDC. In conclusion IDC can serve as a general mean to stimulate the synthesis of phenolic compounds and associated antioxidant activity in radish tubers
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