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Introduction An increasing number of pacemaker patients are receiving radiotherapy in various sites in our department. The need hence arises to accurately determine the radiation burden of pacemaker devices for radiotherapy patients, given the limited tolerance of such devices reported by manufacturers and select the best treatment parameters during the design of their treatment plan. Purpose This study aims to investigate the dependence of pacemaker dose on the type of wedge filter implemented in the radiotherapy machine, comparing the effect of dynamic wedges of various angles to the effect of the universal motorized wedge. Materials and methods In this study two different linear accelerators were used. All measurements were performed with 6 MV photon beams, at a range of distances from the field centre, for wedged and open beams. Dose was measured for dynamic wedges 15°, 30°, 45° and 60° and corresponding motorized wedge angles, for various wedge orientations. Moreover, the above estimated doses were compared with the data from two different treatment planning systems. Results The effect of the wedge filter can elevate the pacemaker dose significantly compared to that of an open field. Comparing the wedge designs measured in this study, the use of a dynamic wedge decreases the pacemaker burden. The pacemaker estimated dose from treatment planning systems diverged from the measured values. Conclusion This study provides data about the pacemaker exposure for different wedge systems. Furthermore, the treatment planning system’s dose estimation errors can not be neglected.

Introduction As new treatment advances are implemented in a radiotherapy department, the QA workload increases requiring more resources. Unplanned maintenance work in the middle of the daily linac schedule also demands quick methods to check beam parameters without sacrifices in the quality of measurements. New measurement modalities that can simplify procedures are thus of great value. Purpose To investigate the reliability of a detector array when beam adjustments are carried out by the linac engineer or QA work is being undertaken. Detector arrays provide an attractive alternative to water phantoms due to their compactness and ease of setup. Materials and methods A multi-axis ion chamber array (IC PROFILER™, SUN NUCLEAR) was used to collect reference data for clinical linac beams. Energies measured were photons of 6, 15 and 18 MV and electrons in the range 6 to 18 MeV. The data were compared to corresponding scans and point measurements obtained using the PTW MP3 (Freiburg, Germany) water phantom for the respective beams. Parameters checked were output constancy, dose rate dependence, energy constancy, beam profiles in cardinal and diagonal directions, beam flatness and symmetry and electron applicator output constancy. The array allowed also a quick check of beam startup characteristics and the verification of beam parameter stability at various gantry angles. Results All parameters (constancy, output factors, energy dependence, dose rate, beam symmetry and flatness), measured with the multi-axis chamber array and the water phantom for the various beams, were in accordance within 1% at most. The detector array provides comparable results and combines the reliability of a water phantom with the advantage of reduced linac time taken up by solid phantom setups. Conclusion The detector array has shown to have the reliability needed to substitute the water phantom for acquiring linac beam data. This is particularly useful for QA measurements and checking linac parameters during and after unplanned technical interventions.

Changes in solar ultraviolet radiation (SUVR) have many different effects on global biogeochemistry. Nowadays, there is an increasing interest in the interactions and feedbacks between climate change and surface UV radiation. The amount of the UV radiation reaching the ground depends on a number of atmospheric and surface parameters such as the atmospheric ozone variability, the time of the day, the latitude, the season, the cloud cover, the meteorological conditions, the aerosol and gases concentrations. Ground-based and airborne measurements of the SUVR were carried out with various instruments in Athens, Greece to study the solar ultraviolet irradiance as a function of height and the influence of the air pollution and forest fires on the UV doses reaching the ground. Additionally, the relationship between SUVR at the Earth’s surface and total ozone content during the summertime period has been investigated. To perform the above-mentioned studies a recently developed theoretical algorithm for the calculation of the UV irradiance at the Earth’s surface was also employed. Finally, implications to the adverse human health effects will be discussed.