A Holistic Approach to Assessment of Population Exposure to Radiation: Challenges and Initiatives of a Regulatory Authority.

A regulatory authority for radiation safety should continuously evaluate and improve the national safety framework, in line with current requirements and standards. In this context, the Greek Atomic Energy Commission initiated a series of concerted actions. The radiation dose to the population due to public and medical exposures was assessed. The assessment of dose due to public exposure was based on measurements of radon concentrations in dwellings, radionuclide concentrations in environmental samples, and air dose rates; the assessment of dose due to medical exposure was based on dose measurements for typical examinations or procedures and data on their frequency. The mean effective dose to a member of the population was found to be 4.5 mSv (1.8 mSv and 2.7 mSv from medical and public exposures, respectively). Regarding occupational exposure, aircrew dose assessment, eye lens monitoring, and the national dose registry were significantly improved. With respect to artificial tanning (sun beds), the ultraviolet radiation produced was assessed and the practices followed were observed. Results demonstrated exceedance of the 0.3 W m erythema effective irradiance limit set in European Union standards by 63.5% of the sun beds measured, along with general noncompliance with standards. An overarching activity was the upgrade of the Greek Atomic Energy Commission information system in order to collect and disseminate radiation data electronically, launch a networking strategy for interaction with stakeholders, and facilitate the process of regulatory control. In response to the above findings, regulatory actions have been initiated.

RESPONSE OF THE GREEK EARLY WARNING SYSTEM REUTER-STOKES IONIZATION CHAMBERS TO TERRESTRIAL AND COSMIC RADIATION EVALUATED IN COMPARISON WITH SPECTROSCOPIC DATA AND TIME SERIES ANALYSIS.

The Telemetric Early Warning System Network of the Greek Atomic Energy Commission consists mainly of a network of 24 Reuter-Stokes high-pressure ionization chambers (HPIC) for gamma dose rate measurements and covers all Greece. In the present work, the response of the Reuter-Stokes HPIC to terrestrial and cosmic radiation was evaluated in comparison with spectroscopic data obtained by in situ gamma spectrometry measurements with portable hyper pure Germanium detectors (HPGe), near the Reuter-Stokes detectors and time series analysis. For the HPIC detectors, a conversion factor for the measured absorbed dose rate in air (in nGy h-1) to the total ambient dose equivalent rate H*(10), due to terrestrial and cosmic component, was deduced by the field measurements. Time series analysis of the mean monthly dose rate (measured by the Reuter-Stokes detector in Thessaloniki, northern Greece, from 2001 to 2016) was performed with advanced statistical methods (Fast Fourier Analysis and Zhao Atlas Marks Transform). Fourier analysis reveals several periodicities (periodogram). The periodogram of the absorbed dose rate in air values was compared with the periodogram of the values measured for the same period (2001-16) and in the same location with a NaI (Tl) detector which in principle is not sensitive to cosmic radiation. The obtained results are presented and discussed.

Twenty-four hour intraocular pressure reduction with latanoprost compared with pilocarpine as third-line therapy in exfoliation glaucoma.

PURPOSE: To compare the 24 hour efficacy of latanoprost 0.005% given every evening with that of pilocarpine 4% given four times daily as third-line therapy in patients with exfoliation glaucoma receiving timolol 0.5% and dorzolamide 2% each given twice daily. METHOD: We enrolled 30 patients with exfoliation glaucoma not adequately controlled on timolol maleate 0.5% and dorzolamide 2%. Each patient underwent a baseline 24 hour intraocular pressure curve testing at 06:00, 10:00, 14:00, 18:00, 22:00 and 02:00 hours. Patients were randomised to receive either latanoprost 0.005% or pilocarpine 4% for a minimum of 8 weeks and were then crossed over to the opposite therapy. Diurnal curve testing was repeated at the end of each treatment. RESULTS: There was a significant decrease from baseline in intraocular pressure at each timepoint for both study medicines (p < 0.016). Latanoprost provided better intraocular pressure control than pilocarpine at daytime measuresments (17.4 vs 19.7 mmHg at 06:00 hours, p < 0.001; 17.8 vs 19.1 mmHg at 10:00 hours, p = 0.04). However, pilocarpine reduced the pressure more than latanoprost at 22:00 hours (18.4 vs 19.5 mmHg, p = 0.016). Overall, the diurnal intraocular pressure was reduced from a baseline of 21.5 +/- 3.7 mmHg to 18.8 +/- 3.1 mmHg on pilocarpine and to 18.0 +/- 3.0 mmHg on latanoprost (p = 0.06). In addition, mean peak pressure was similar between pilocarpine (21.0 +/- 2.9 mmHg) and latanoprost (20.5 +/- 3.8 mmHg) (p = 0.20). Side-effects were similar with the exception of blurred vision, which was only found with pilocarpine (10%). Compliance was more difficult with pilocarpine. CONCLUSION: In exfoliation glaucoma, as a third-line adjunctive therapy added to timolol and dorzolamide, latanoprost and pilocarpine have similar diurnal efficacy. However, latanoprost provides a greater morning pressure reduction.

Twenty-four hour control of intraocular pressure with dorzolamide and timolol maleate in exfoliation and primary open-angle glaucoma.

PURPOSE: To determine the efficacy and safety of adding dorzolamide 2% twice daily to timolol maleate solution 0.5% twice daily when treating exfoliation glaucoma or primary open-angle glaucoma. METHODS: This was a single-centre, crossover intra-individually controlled comparison. Sixty-two consecutive patients (31 with exfoliation glaucoma and 31 with primary open angle glaucoma) chronically treated with timolol maleate twice daily were included in this trial. Patients then had added dorzolamide 2% twice daily (08:00 and 20:00), instilled approximately 10 min after timolol maleate. Patients underwent diurnal intraocular pressure (IOP) testing (six measurements over 24 h), first on timolol maleate monotherapy and 2 months later following the addition of dorzolamide 2% as adjunctive therapy. RESULTS: On timolol monotherapy patients with exfoliation glaucoma had a higher mean IOP at 02:00, 06:00, 10:00, 14:00 and 22:00 hour time points as well as a higher maximum, minimum and range of IOP throughout the day compared with the primary open-angle glaucoma group (p < 0.05). Following the addition of dorzolamide as adjunctive therapy to timolol maleate there was a significant reduction in IOP (p < 0.05) at all time points in both glaucomas, but mean IOP at 10:00, 14:00, 18:00 and 22:00 hour time points, as well as the peak and range of IOP, remained higher in the exfoliation glaucoma group. No serious adverse events were noted with dorzolamide. Bitter taste, the most common symptom, was noted in 30% of patients. CONCLUSIONS: These data suggest that dorzolamide 2% used adjunctively with timolol maleate 0.5% solution is effective in reducing diurnal IOP in patients with primary open-angle and exfoliation glaucoma but does not alter the characteristics of higher IOP levels in the latter disease.

Comparison of 24 hour control with Timoptic 0.5% and Timoptic-XE 0.5% in exfoliation and primary open-angle glaucoma.

PURPOSE: To compare the 24 hour intraocular pressure (IOP) curve in exfoliation glaucoma (EXG) and primary open-angle glaucoma (POAG) patients treated first with timolol solution 0.5% (TS) twice daily and then with timolol maleate gel forming solution 0.5% (TXE) once daily. METHODS: We prospectively investigated age-matched, newly diagnosed EXG (n = 25) and POAG (n = 25) patients who were admitted as in-patients for 24 hour phasing first with TS and then TXE. RESULTS: Generally TS and TXE controlled both POAG and EXG patients in a similar fashion. However, a trend to lower pressures was observed in both EXG and POAG patients with TS therapy. At two time points (10:00 and 22:00) in POAG patients, TS (18.4 +/- 3.7 and 17.2 +/- 3.1 mm Hg, respectively) provided lower intraocular pressures than TXE (19.8 +/- 3.5 and 18.9 +/- 3.8 mm Hg, respectively) (p < 0.05). CONCLUSION: Both TS twice daily and TXE once daily control POAG and EXG generally to a similar extent.

Comparison of 24-hour intraocular pressure reduction with two dosing regimens of latanoprost and timolol maleate in patients with primary open-angle glaucoma.

PURPOSE: To compare the 24-hour diurnal ocular hypotensive efficacy of two dosing regimens of latanoprost, once daily (8 AM or 10 PM), vs timolol maleate, twice daily. METHODS: We measured six diurnal intraocular pressure curves (6 AM, 10 AM, 2 PM, 6 PM, 10 PM, and 2 AM) in one randomly selected eye of 34 Greek patients newly diagnosed with primary open-angle glaucoma. The first diurnal curve was an untreated baseline. Patients began taking timolol 0.5%, twice daily, for 2 months. Patients were randomly assigned to latanoprost 0.005% given at 8 AM or 10 PM for 1 month and then changed to the other dosing regimen for 1 month. A diurnal curve was performed after each dosing period. RESULTS: The baseline diurnal pressure for all 34 subjects was 23.1 +/- 3.7 mm Hg. The average intraocular pressures at 6 AM for patients who were given latanoprost in the evening (17.9 +/- 2.9 mm Hg) was statistically lower than that in patients given timolol solution (20.1 +/- 2.5 mm Hg, P = .003); however, patients who were given timolol demonstrated a similar diurnal intraocular pressure (19.1 +/- 2.8 mm Hg) to both morning (18.8 +/- 3.7 mm Hg) and evening doses (18.8 +/- 3.6 mm Hg) of latanoprost (P =.329). When the two latanoprost dosages were compared directly, evening administration provided a statistically lower intraocular pressure at 10 AM (P = .0001) and morning administration at 10 PM (P = .0001). This study had an 80% power to exclude a 1.2-mm Hg difference between groups. CONCLUSIONS: This study indicates that in a small population, both latanoprost and timolol are effective in lowering intraocular pressure throughout a 24-hour period; however, latanoprost is most effective in the 12-hour to 24-hour period after administration.

The comparative ocular hypotensive effect of apraclonidine with timolol maleate in exfoliation versus primary open-angle glaucoma patients.

PURPOSE: To compare the effect of adding apraclonidine 0.5% to timolol maleate 0.5% in patients with exfoliation versus primary open-angle glaucoma. Since exfoliation glaucoma is known to demonstrate higher pressures than primary open-angle glaucoma on timolol maleate therapy alone, the authors wished to determine whether apraclonidine equalised the intraocular pressure (IOP) between these two glaucomas when added to timolol maleate. METHODS: We age-matched 30 consecutive exfoliation and 30 primary open-angle glaucoma patients who had an IOP > or = 22 mmHg on timolol maleate alone. Patients underwent IOP diurnal curve testing on timolol maleate twice daily alone and, 2 months later, following the addition of apraclonidine 0.5% three times daily. Statistical analysis of the IOP at each time point was by an unpaired t-test between groups. A paired t-test was used to evaluate the reduction in IOP from baseline within groups after the addition of apraclonidine. RESULTS: On timolol maleate alone, exfoliation patients had a higher mean IOP at 06:00 and 10:00 hours as well as a higher peak, range and standard deviation of the IOP compared with primary open-angle glaucoma patients (p < 0.05). Following the addition of apraclonidine the mean, peak and range of IOP were statistically similar between groups and only the standard deviations remained higher in the exfoliation glaucoma group (p < 0.001). The mean diurnal IOP after apraclonidine was added was 20.5 +/- 7.0 mmHg in the exfoliation glaucoma group and 20.0 +/- 3.4 mmHg in the primary open-angle glaucoma group, which was not significantly different between groups (p = 0.73). CONCLUSIONS: This study suggests that apraclonidine 0.5% used adjunctively with timolol maleate 0.5% solution is associated generally with similar IOP control in exfoliation and primary open-angle glaucoma patients.