Multi-slice computed tomography (MSCT) has proven inseveral studies to have a high diagnostic accuracy for the detectionor exclusion of coronary artery disease. A major concern with coronaryMSCT, however, is the associated radiation exposure of patients.Recent studies suggest that use of a 64-slice scanner is associatedwith a non-negligible lifetime attributable risk of cancer. Severalstrategies can be used to reduce patient exposure in coronary MSCT.The purpose of this multicenter study was to investigate the effectsof the adjustment of tube voltage and current on radiation doseand image interpretability. MSCT with retrospective ECG gating was performedin 315 patients. The dose-length product (DLP) in the patients enrolledwith the dose reduction protocol resulted in a 36% overall reductionin the mean radiation dose (911 ± 289 mGy.cm) compared with thestandard protocol (1427 ± 226 mGy.cm, p < 0.001).Nevertheless, image interpretability was maintained. This studyon coronary MSCT demonstrates that the radiation dose can be significantly reducedby parameter optimization, with maintained image interpretability.

Interventional cardiology procedures (ICPs), while providing important benefits topatients, also contribute to their radiation exposure, in particular for the organssurrounding the heart. This paper addresses the issue of radiation exposure to the lungand bone marrow related to coronary interventions in terms of organ doses for coronaryangiography (CA) and percutaneous transluminal coronary angioplasty (PTCA), and riskassessment of potential radiation-induced cancer. Dosimetric information on 2095 ICPs fromFrench patients was collected. The median lung dose for CA alone was 34 mGy for men and 22mGy for women and the median bone marrow dose was 8 mGy and 4 mGy, respectively; doseswere slightly higher for CA and ad hoc PTCA and nearly twice as high forCA and elective PTCA. Based on the French national mortality registry and BiologicalEffects of Ionising Radiation VII models, spontaneous and radiation-induced lung cancersand leukaemia were estimated. For men and women aged at least 60 years old at the firstICP, excess risk of potentially fatal cancers attributable to radiation ranged from 0.4%to 4%. This study provides evidence of the potential risk of radiation-induced cancerafter an ICP. The limitations of such calculations are due to the difficulty of takinginto account patients’ possibly shorter life expectancy than in the general population,linked to their comorbidities and coronary disease. Nevertheless, risk estimates can beused to illustrate the beneficial role of optimisation of doses delivered to thepatient.

The concentrations of natural radionuclides in 6 differentcolors of volcanic tuff stones which are derived from the Cappadociaregion in Turkey were determined using gamma-ray spectroscopy witha HPGe detector, and the mineralogical composition and formula ofstones were determined by an X-ray powder diffractometer. The averageactivity concentrations of 238U, 232Th and 40Kare 50.7, 58.6 and 717.6 Bq.kg–1, which are higher thanthe world averages of 35, 30 and 400 Bq.kg–1, respectively.The radium equivalent activities (Raeq), external hazardindex (Hex), and internal hazard (Hin) associatedwith the natural radionuclides, alpha (Iα) and gammaindices (Iγ) were calculated to assess the radiationhazard of the natural radioactivity in the volcanic tuff stones.The average indoor annual effective dose equivalent is 0.1 mSv.All values of the indoor effective dose are lower than the exemptiondose value of 0.3 mSv. The calculated radium equivalent activityvalues vary from 60.31 Bq.kg–1 to 281.32 Bq.kg–1 witha mean of 189.78 Bq.kg–1. All values of radium equivalentactivity are lower than the world average. The average indoor absorbeddose rate (Din) for volcanic tuff stones, calculatedto be 21.18 nGy.h–1, is lower than the world averageof 84 nGy.h–1.

The uranium isotopes 238U, 235U and 234U are foundnaturally in the environment. 238U and 235U are parent nuclides of twoindependent decay series of isotopes, while 234U is a member of the238U decay chain. When decay series occur in a closed system the series tendsto reach, with time, the state of secular equilibrium in which the activities of all seriesmembers are equal to the activity of its first nuclide. The activity ratio234U/238U in natural uranium may vary as a consequence of decaychain disequilibrium due to alpha recoil and biogeochemical processes. A study based onmeasurement of uranium concentration and 234U/238U activity ratios insoil samples collected from Nalgonda district, Andhra Pradesh, India, a proposed miningsite, was carried out to find the spatial distribution of uranium and the state of secularequilibrium of 234U/238U to examine the possibility of applyinguranium concentration and uranium isotopic activity ratios to detect any hydrogeochemicalchanges in the environment during/post-operation. Soil samples were collected and analyzedfor uranium concentration using the conventional UV fluorimetric method, showing a uraniumconcentration in the range of 0.7 ± 0.2 ppm to 7.9 ± 0.4 ppm with an average of 3.4 ppm, and234U/238U activity ratios were estimated using the alphaspectrometry technique, showing an activity ratio in the range of 0.92 ± 0.11 to1.02 ± 0.11. The 234U/ 238U activity ratio obtained indicated thatthese two uranium isotopes are in the state of secular radioactive equilibrium. The percentactivity ratio of 238U/total U and 234U /total U is observed to varyfrom 47.94 ± 4.83 to 50.76 ± 4.87 and 45.80 ± 3.83 to 49.14 ± 3.99, respectively.

In the present paper, we estimated backscattering factors for the TLD and active personaldosimeters using 662 keV gamma-ray photons on a PMMA surface, which are, for the TLD,1.12; Dosicard, 1.116; DRD, 0.99; and Saphydose, 1.073, and on a water slab phantomsurface; for the TLD, 1.115; Dosicard, 1.112; DRD, 1; and Saphydose, 1.059. Thebackscattering factor contribution for the Saphydose is nearly half that of the TLD andDosicard, whereas it is zero for the DRD. The DRD underestimates Hp(10)by 10.3–11.6%, whereas for the Saphydose it is 3.4–5% compared with the TLD or Dosicard.The response of the DRD to Hp(10) is nearly independent of the phantom,whereas the TLD, Dosicard and Saphydose require phantoms for calibration for personalmonitoring. It is observed that the PMMA phantom contributes slightly higherbackscattering compared with the water slab phantom. The backscattering factor of theselected dosimeters is comparable with ICRU tissue already reported.

Nous avons évalué l’intérêt des gants de radioprotectionde radiologie interventionnelle pour de la manipulation de radionucléidesdans un service de médecine nucléaire. Des mesures d’atténuationfaites par des dosimètres thermo-luminescents placés à l’intérieurde gants au contact des flacons ont montré une augmentation significativede la dose aux extrémités dans le cas d’un émetteur γ, et une réductionde dose pour un émetteur β. Des mesures complémentaires faites aumoyen d’un irradiateur X (150 kV) ont montré qu’il existe une productiond’électrons secondaires dans le gant, dont le parcours dans l’airest estimé à 6 cm. Étant donné que l’utilisation d’un gant radio-atténuateurdans une boîte à gants de médecine nucléaire doit être compatibleavec l’ensemble des radionucléides utilisés, notre équipe n’utiliserapas de tels gants dans la pratique quotidienne.

During an accidental release of tritium, mechanisms of hydrogen transferfrom air to man are very numerous, dependent on multiple climate,physiological and biological parameters, and the kinetic is highlyvariable from one environmental compartment to another. To evaluatethe impact of an acute tritium release requires either an overallassessment of the state of the environment during the release and thefollowing hours from a number of restricted data, or the establishmentof a significant data bank, a complex model and a system of dataacquisition in real time whose potential for daily purposes is veryhypothetical. To facilitate the first approach, this paper discussesthe key elements of the mechanisms to guide the choice of parametersfor a rapid assessment of the situation, and to clarify the typesof measurements to carry out and their interpretation.

We used CR-39 detectors to evaluate radon activity concentrations in several habitationsof Bamako. The calibration factor of the dosimeters was determined experimentally withknown radon activity concentrations inside a radon chamber, and was also simulated withMCNPX. The experimental and simulated calibration factors are, respectively,kexp = 0.119 ± 0.017 and ksim= 0.126 ± 0.007 tr.cm-2.d-1.Bq-1.m3. Indoorradon activity concentrations in Bamako were found to vary from 70 ± 18 to 154 ± 35Bq.m-3. No significant differences were observed in the mean radon activityconcentrations compared with five other African countries. Taking into account anoccupancy factor of 0.8 and an equilibrium factor of 0.4 for radon indoors, the effectivedose rate ranges from 1.77 to 2.35 mSv.y-1. In all cases the radon activityconcentrations measured were below the action limits recommended by the InternationalCommission on Radiological Protection (ICRP) Statement on Radon.

The mass concentration of uranium in water samples collected from the Bathinda districtof Punjab state, India, was estimated using the laser fluorimetric technique. The studyregion has shown a pronounced number of cancer cases in the recent period. The study aimsto calculate the human radiological risk and chemical toxicity associated with uraniumconsumption through drinking water. The mass concentration of uranium was found to varyfrom 0.48 to 571.7 μg/l with a mean value of 84.70 μg/l. The radiological risk due toconsumption of uranium through contaminated drinking water was observed to be in the rangeof 1.34 × 10-6 to 1.60 × 10-3 with a mean value of2.37 × 10-4. The chemical toxicity was found to vary from 0.04–43.11µg.kg-1.day-1 with a mean value of 6.38µg.kg-1.day-1.