Air-crew exposure to cosmic radiation on board of Polish passenger aircraft

To establish the need for individual monitoring of air crew, exposure of air-crew members of Polish airlines LOT to cosmic radiation has been determined and several dosimetry methods tested in flight. Passive radiation dosimetry (using thermoluminescent LiF and chemically etched CR-39 track detectors) was supported by calculations with the CARI computer code. We found that the air crew of most of the LOT aircraft studied (with the exception of those flying ATR propeller aircraft) may somewhat exceed or, in certain conditions (depending on solar activity), may considerably exceed the effective dose level of 1 mSv per year. For crew members flying regularly on B-767 aircraft, the estimated yearly effective dose ranged between 2 mSv and 5 mSv, depending mainly on flying frequency and solar activity. During periods of enhanced intensity of cosmic radiation (i.e. during minimum solar activity) the effective doses could be close to the level of 6 mSv per year

Assessment of exposure to X - rays during patient positioning at the proton eye radiotherapy facility at IFJ PAN, Kraków

At the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN, Kraków, Poland) the proton eye radiotherapy facility has recently been developed and is now fully operational. A set of two X-ay RAD-14 Varian medical systems tubes are used to obtain orthogonal images of the patient’s eyeball undergoing radiotherapy with tantalum clips already attached to its surface to delineate the tumour volume. We assessed the dose received by the patient from multiple X-ray exposures during the patient positioning procedure. Measurements of Kair were performed using various types of ionization chambers and MCP-N thermoluminescent (TL) detectors and calculated using the PCXMC code. Good agreement between measurements and calculations was found. The mean absorbed dose to the brain was measured using TL detectors placed inside the head of a Rando anthropomorphic phantom used in simulation of the patient positioning procedure. The measured maximum incident air kerma absorbed during the entire procedure of patient positioning was found not to exceed 7 mGy, while the mean absorbed dose to the brain did not exceed 2 mSv

Application of LiF : Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) for experimental verification of radial dose distribution models

In track structure theory, the radial distribution of dose, D(r), around an ion track plays a fundamental role in predicting the response of biological systems and physical detectors after a dose (or fluence) of ions. According to the formulations of D(r), the local dose at radial distances below 1 nm can reach values as high as 106 Gy. We propose a new method of verifying experimentally the radial dose distribution around alfa-particle tracks, using LiF:Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) which are able to measure gamma-ray doses in the kGy range via evaluation of their high-temperature TL glow peak structure over the temperature range of 350–550 centigrade. MCP-N detectors were irradiated with Am-241 alfa-particles at fluences ranging from 107 to 1011 particles/cm2, and by Co-60 gamma-ray doses ranging from several Gy up to the MGy. A number N of individual high-temperature TL peaks were analysed in the obtained glow curves by deconvolution, using the GlowFit code. For each of these peaks, an equation relating the intensity, A, of the TL signal obtained after alfa-particle irradiation and after gamma-ray doses, via the dose-frequency function, f alfa(D), was written in the form: A i alfa = integral A i gamma(D)x f alfa (D)dD, i 1,.., N. Using this set of N equations, where A alfa i and A gamma i(D) were known (measured), the single unknown function f alfa(D) was unfolded and converted to D(r). Parametric unfolding and the SAND-II iterative code were applied. While we were able to confirm the 1/r2 dependence of D(r) in agreement with D(r) expressions, we were unable to conclusively evaluate the dependence of D(r) at intermediate ranges of radial distance r. This preliminary result of our unique experimental approach to determine the radial dose distribution around the path of heavy charged particles in LiF detectors, requires further development

Ambient dose equivalent measurements in secondary radiation fi elds at proton therapy facility CCB IFJ PAN in Krakow using recombination chambers

This work presents recombination methods used for secondary radiation measurements at the Facility for Proton Radiotherapy of Eye Cancer at the Institute for Nuclear Physics, IFJ, in Krakow (Poland). The measurements of H*(10) were performed, with REM-2 tissue equivalent chamber in two halls of cyclotrons AIC-144 and Proteus C-235 and in the corridors close to treatment rooms. The measurements were completed by determination of gamma radiation component, using a hydrogen-free recombination chamber. The results were compared with the measurements using rem meter types FHT 762 (WENDI-II) and NM2 FHT 192 gamma probe and with stationary dosimetric system

Characterization of the HollandPTC proton therapy beamline dedicated to uveal melanoma treatment and an interinstitutional comparison

Purpose Eye dedicated proton therapy PT facilities are used to treat malignant intraocular lesions, especially uveal melanoma UM . The first commercial ocular PT beamline from Varian was installed in the Netherlands. In this work, the conceptual design of the new eyeline is presented. In addition, a comprehensive comparison against five PT centers with dedicated ocular beamlines is performed, and the clinical impact of the identified differences is analyzed. Material Methods The HollandPTC eyeline was characterized. Four centers in Europe and one in the United States joined the study. All centers use a cyclotron for proton beam generation and an eye dedicated nozzle. Differences among the chosen ocular beamlines were in the design of the nozzle, nominal energy, and energy spectrum. The following parameters were collected for all centers technical characteristics and a set of distal, proximal, and lateral region measurements. The measurements were performed with detectors available in house at each institution. The institutions followed the International Atomic Energy Agency IAEA Technical Report Series TRS 398 Code of Practice for absolute dose measurement, and the IAEA TRS 398 Code of Practice, its modified version or International Commission on Radiation Units and Measurements Report No. 78 for spread out Bragg peak normalization. Energy spreads of the pristine Bragg peaks were obtained with Monte Carlo simulations using Geant4. Seven tumor specific case scenarios were simulated to evaluate the clinical impact among centers small, medium, and large UM, located either anteriorly, at the equator, or posteriorly within the eye. Differences in the depth dose distributions were calculated. Results A pristine Bragg peak of HollandPTC eyeline corresponded to the constant energy of 75 MeV maximal range 3.97 g cm2 in water with an energy spread of 1.10 MeV. The pristine Bragg peaks for the five participating centers varied from 62.50 to 104.50 MeV with an energy spread variation between 0.10 and 0.70 MeV. Differences in the average distal fall offs and lateral penumbrae LPs over the complete set of clinically available beam modulations among all centers were up to 0.25 g cm2, and 0.80 mm, respectively. Average distal fall offs of the HollandPTC eyeline were 0.20 g cm2, and LPs were between 1.50 and 2.15 mm from proximal to distal regions, respectively. Treatment time, around 60 s, was comparable among all centers. The virtual source to axis distance of 120 cm at HollandPTC was shorter than for the five participating centers range 165 350 cm . Simulated depth dose distributions demonstrated the impact of the different beamline characteristics among institutions. The largest difference was observed for a small UM located at the posterior pole, where a proximal dose between two extreme centers was up to 20 . Conclusions HollandPTC eyeline specifications are in accordance with five other ocular PT beamlines. Similar clinical concepts can be applied to expect the same high local tumor control. Dosimetrical properties among the six institutions induce most likely differences in ocular radiation related toxicities. This interinstitutional comparison could support further research on ocular post PT complications. Finally, the findings reported in this study could be used to define dosimetrical guidelines for ocular PT to unify the concepts among institution