Anna Louizi

Radon survey in Greece—risk assesment

A large scale radon survey using track etch detectors has been carried out from 1995 to 1998 in Greece in order to estimate the radon concentrations in Greek dwellings and the exposure of the Greek population to radon. The total data set consisted of 1,277 samples. Residential potential alpha energy concentration values ranged between (0.024 +/- 0.009) and (8 +/- 1) WLM per year (P < 0.05) and effective doses between (0.09 +/- 0.04) and (28 +/- 4) mSv (P < 0.05). The mean lifetime risk for the Greek population due to radon was found to be 0.4%.

Self-organised critical features in soil radon and MHz electromagnetic disturbances: Results from environmental monitoring in Greece

This paper addresses the issues of self-organised critical behaviour of soil-radon and MHz-electromagnetic disorders during intense seismic activity in SW Greece. A significant radon signal is re-analysed for environmental influences with Fast Fourier Transform and multivariate statistics. Self-organisation of signals is investigated via fractal evolving techniques and detrended fluctuation analysis. New lengthy radon data are presented and analysed accordingly. The data did not show self-similarities. Similar analysis applied to new important concurrent MHz-electromagnetic signals revealed analogous behaviour to radon. The signals precursory value is discussed.

Investigation of breast dose in five screening mammography centres in Greece

The objectives of this study were to investigate the techniques currently used for screening mammography in Greece, to estimate the mean glandular dose (MGD) for establishing a baseline radiation dose database, to analyse the effects of various factors on MGD, and to compare the results with others in the literature. Five mammographic facilities and 250 women having as a routine screening mammogram one craniocaudal (CC) and one mediolateral oblique (MLO) projection in each breast were included in the study. The parameters recorded were age, weight, compressed breast thickness (CBT), tube potential (kV), tube loading (mA s) and MLO projection angle. Large differences were observed among the different mammography facilities, mainly in terms of the tube potential setting and the MLO angle used. The average MGD per exposure was 1.4 +/- 0.6 mGy while the respective averages separately for the CC and MLO projections were 1.2 +/- 0.5 and 1.5 +/- 0.7 mGy, respectively. The average MGD values recorded in this study were below the limit of 2 mGy established for the reference medium-sized breast of 4.5 cm CBT. However, the variety of techniques observed revealed the need for a nationwide survey concerning screening mammography in Greece.

Investigation of the exposure to radon and progeny in the thermal spas of Loutraki (Attica-Greece): Results from measurements and modelling

Radon and progeny ((218)Po, (214)Pb, (214)Bi and (214)Po) in thermal spas are well known radioactive pollutants identified for additional radiation burden of patients due to the activity concentration peaks which appear during bath treatment or due to drinking of waters of high radon content. This burden affects additionally the working personnel of the spas. The present paper has focused on the thermal spas of Loutraki (Attica-Greece). The aim was the investigation of the health impact for patients and working personnel due to radon and progeny. Attention has been paid to radon and progeny transient concentration peaks (for bath treatment) and to radon of thermal waters (both for bath treatment and drinking therapy). Designed experiments have been carried out, which included radon and progeny activity concentration measurements in thermal waters and ambient air. Additionally, published models for description of radon and progeny transient concentration peaks were employed. The models were based on physicochemical processes involved and employed non linear first order derivative mass balance differential equations which were solved numerically with the aid of specially developed computer codes. The collected measurements were analysed incorporating these models. Results were checked via non linear statistical tests. Predictions and measurements were found in close agreement. Non linear parameters were estimated. The models were employed for dosimetric estimations of patients and working personnel. The effective doses of patients receiving bath treatment were found low but not negligible. The corresponding doses to patients receiving potable treatment were found high but below the proposed international limits. It was found that the working personnel are exposed to considerable effective doses, however well below the acceptable limits for workers. It was concluded that treatment and working in the Loutraki spas leads to intense variations of radon and progeny and consequently additional health impact both to patients and working personnel.

Long-range memory patterns in variations of environmental radon in soil

This paper addresses issues of long-range memory and self-organisation in variations of radon in soil in Greece. The methods of rescaled-range, roughness-length, variogram, fractal dimension and block entropy were employed through lumping. Sliding was utilised with the wavelet spectral fractal technique. Antipersistent Hurst exponents in the range 0 < H < 0.5 were mainly identified. Persistent exponents (0.5 < H < 1) were also detected. Switching between persistency and antipersistency was observed and considered consistent with an underlying geo-environmental long-memory self-organisation. Fractal dimensions were in the range 1.2 < D < 2. The anomalous parts of the 2008 radon signal presented significantly lower fractal dimensions. Value ranges of Shannon, Shannon-per-letter, conditional, Tsallis and normalised Tsallis block entropies were 0.67 ≤ H(n) ≤ 2.73, 0.2 ≤ h(n) ≤ 0.7, 0.2 ≤ h(n) ≤ 0.6, 0.36 ≤ Sq ≤ 1.11, 0.50 ≤ Ŝq ≤ 9.55 respectively. The entropy values were affected by the block-size n. The entropic index values of the radon anomalies were significantly lower indicating long-memory underlying patterns. Underlying sources are discussed. The asperity-model is proposed.

Factors Affecting Indoor Radon Concentrations of Greek Dwellings through Multivariate Statistics - First Approach

A large scale nationwide radon survey was conducted in Greek dwellings between 1994 and 2000. Twelve hundred passive CR-39 detectors were distributed and collected along with 963 filled in questionnaires. These were rechecked during 2012-13 to evaluate factors that potentially affect indoor radon concentrations, namely the factors (i) area (environment), (ii) building level-floor, (iii) ground type, (iv) basement, (v) building type, (vi) construction year, (vii) building walls contact, (viii) wall materials and (ix) floor materials. The questionnaires were prepared by the research team according to international standards. One-way and multivariate statistical methods were applied for the analysis, in specific (I) Linear Regression Analysis, (II) One way or multiway ANOVA, (III) General MANOVA, (IV) Stepwise Regression Analysis and (V) Principal Components Analysis. The results revealed that approximately 0.1% of the dwellings exhibited outlier radon concentrations. Noteworthy statistical correlations were detected between the measured mean annual indoor radon concentration levels and the factors (ii) (building level-floor) and (viii) (wall materials). Weak evidence was provided for the corresponding correlation with the factors (v) (building type) and (vii) (building walls contact). Minor was the association with the factors (iv) (construction year) and (ix) (floor materials). Significant differences were detected in the results of the applied statistical methods.

Accuracy of CT dose monitor values: a multicentric study

Four hundred and ninety-five adult patients in 16 medical centres participated in this study aiming to investigate the congruence between the volume CT dose index (CTDIvol) monitor values and measured ones during common CT procedures, performed by 20 systems. Tube output CTDIair measurements were carried out on single and multislice scanners for any kV, slice thickness, mA and FOV combination used. The maximum/minimum ratio of measured CTDIvol values found to be 3.1, 3.5, 7.4, 7.5, 4.2, 11.3 and 5.5 for head base, head cerebrum, thorax, abdomen, pelvis, cervical spine and lumbar spine protocols, respectively. The mean divergence between the measured and displayed CTDIvol values was 4.2, 3.5, -1.0, 2.7, 4.9, -3.9 and -2.8 % for protocols as mentioned above, respectively. From the perspective of the number of detector rows of the scanners, the mean divergence was -6.7, -6.0, 0.8, -1.1, -0.4, -1.9, -5.3, 5.2 and 10.1 % for single, dual, 4, 6, 16, 24, 64, 128 and dual source 256-slice systems, respectively.

Radon exposure of the Greek population

Publisher Summary This chapter supports the recommendation of testing mainly ground floor or first floor dwellings, since there were not found to be significant differences in radon concentrations among the dwellings of the upper floors. In addition, the radon estimates have shown geographical differences, leading to support for the strategy of focusing on areas with high radon potential. The survey is still in progress, because on the one hand, different results may be obtained elsewhere and on the other hand, a better estimation of the national average should be determined. Moreover, geological and other relevant data are being collected by MPD-UOA. They combine with the questionnaire data, to investigate the factors that affect indoor radon concentrations in Greece. The calculations of the mean nation-wide annual risk due to residential radon were based only on broad area sampling because the use of data from local sampling may have introduced a systematic error if these had represented over- or under-estimations of the mean radon concentration of each surveyed area. Nevertheless, elevated residential radon concentrations may be found in the non-broadly surveyed part of Greece.

Preliminary study of two high radon areas in Greece

Publisher Summary In dwellings with maximum radon concentration, active measurements using two modern monitors (ALPHA GUARD, Genitron Instruments & EQF3023, Sarad Instruments) were performed, estimating the variation of indoor radon and daughter nuclei concentrations with time and other parameters. The measurements were performed for a 1-month period in the case of Arnaia and a 10-day period in the case of Vrisses Apokoronou. Reported soil gas concentrations may be considered to be elevated according to our database for Greece but lie in the intermediate range according to the literature. According to our database, commonly measured soil gas concentration values in Greece lie in the range 5–15 kBqm −3 . Radon content in drinking waters in Arnea Chalkidikis may also be considered as elevated. The areas of Arnaia Chalkidikis and Vrisses Apokoronou require further investigation.