Additional Effective Dose Research Articles

Effective Radiation Dose, Time, and Contrast Medium to Measure Fractional Flow Reserve

This study sought to define the additional effective radiation dose, procedural time, and contrast medium needed to obtain fractional flow reserve (FFR) measurements after a diagnostic coronary angiogram. The FFR measurements performed at the end of a diagnostic angiogram allow the obtaining of functional information that complements the anatomic findings. In 200 patients (mean age 66 +/- 10 years) undergoing diagnostic coronary angiography, FFR was measured in at least 1 intermediate coronary artery stenosis. Hyperemia was achieved by intracoronary (n = 180) or intravenous (n = 20) adenosine. The radiation dose (mSv), procedural time (min), and contrast medium (ml) needed for diagnostic angiography and FFR were recorded. A total of 296 stenoses (1.5 +/- 0.7 stenoses per patient) were assessed. The additional mean radiation dose, procedural time, and contrast medium needed to obtain FFR expressed as a percentage of the entire procedure were 30 +/- 16% (median 4 mSv, range 2.4 to 6.7 mSv), 26 +/- 13% (median 9 min, range 7 to 13 min), and 31 +/- 16% (median 50 ml, range 30 to 90 ml), respectively. The radiation dose and contrast medium during FFR were similar after intravenous and intracoronary adenosine, though the procedural time was slightly longer with intravenous adenosine (median 11 min, range 10 to 17 min, p = 0.04) than with intracoronary adenosine (median 9 min, range 7 to 13 min). When FFR was measured in 3 or more lesions, radiation dose, procedural time, and contrast medium increased. The additional radiation dose, procedural time, and contrast medium to obtain FFR measurement are low as compared to other cardiovascular imaging modalities. Therefore, the combination of diagnostic angiography and FFR measurements is warranted to provide simultaneously anatomic and functional information in patients with coronary artery disease.

Influence of ventilation on the reduction of the radon concentration in an underground research facility

The concentration of radon in an underground research facility (URF) was measured by setting up 12 sampling points in the URF and with 3 different measurement methods. All the methods were calibrated in the radon laboratory of the No. 6 Institute of Nuclear Industry. The accumulation of radon in the URF was observed before a ventilation system was applied. The reduction of radon concentration in the URF by 1-hour ventilation was also observed. Experimental result indicates that the concentration of radon in the URF increased from 15 to 50 Bq·m−3 in 5 days without ventilation, and decreased to less than 10 Bq·m−3 with 1-hour ventilation. Applying the average working time of 4 hours per day of the workers in the URF, the additional effective dose is 0.75 msv·y−1 when 1 hour ventilation is applied before entering the URF and 13 mSv·y−1 without ventilation. These figures strongly suggest that for the health of the workers, ventilation in such underground research facilities is needed.

Dosimetry of digital panoramic imaging. Part II: occupational exposure

To measure occupational radiation dose during panoramic exposure from five digital panoramic X-ray units. Exposures were made with five different digital panoramic units, of which four were equipped with a direct digital CCD (charge coupled device, "direct digital" technique), and one used storage phosphor plates ("indirect digital" technique). An anthropomorphic phantom served as the patient. An ionization chamber recorded the scattered radiation at 1 m from the phantom at five different locations around the panoramic units, both at the level of the thyroid gland and the level of the gonads, and effective organ doses were calculated. Exposure parameters were set as recommended by the manufacturers for the particular image and patient size: tube potential settings ranged between 64 kV and 74 kV, exposure times between 8.2 s and 19.0 s, tube current values between 4 mA and 7 mA. The maximum organ equivalent dose at 1 m from the panoramic unit was 0.60 microGy, the maximum organ effective dose was 0.10 microSv. Organ equivalent doses varied between 0.18 microGy and 0.30 microGy and organ effective doses between 0.01 microSv and 0.05 microSv for the different positions around the units (average for the different panoramic units). The variations in organ doses for the various machines were 0.04-0.53 microGy organ equivalent dose and 0.01-0.08 microSv organ effective dose. Assuming that 500 panoramic radiographs per year are taken by a dental practitioner at 1 m distance from the panoramic unit, he or she will receive an annual additional organ effective dose between 5 microSv and 15 microSv for the thyroid gland and between 5 microSv and 40 microSv for the gonads, depending on the type of digital panoramic unit.

Radiation dose in severe periodontitis assessment

Objective Radiographic assessment of patients with generalised severe periodontitis may be undertaken with a panoramic view and supplementary periapicals. The purpose of this study was to estimate the effective radiation dose from this form of radiographic assessment, and to compare it with an estimate of the dose from a series of periapicals of all the affected teeth. Design Cross-sectional observational study. Setting Departments of Periodontology and Radiology, Glasgow Dental Hospital and School. Method Fifty consecutive patients with sufficiently widespread advanced periodontitis to require at least seven periapical radiographs were recruited. Following new local guidelines, a panoramic view was taken. The adequacy of the image of every affected tooth and the number of supplementary periapicals required was determined by a panel of four examiners who also calculated the number of periapicals which would have been taken if panoramic radiography had not been available. An effective dose of 0.001 mSv for one periapical and 0.007 mSv for a panoramic view was assumed. Results The panoramic-plus-periapicals approach delivered an estimated additional effective dose to 86% of patients, in the order of 0.001 – 0.007 mSv. Conclusions Within the parameters of this investigation, the anticipated effective radiation dose from a series of periapical radiographs of all selected teeth would, for the great majority of patients, have been less than the dose from a panoramic-plus-periapicals approach.

A comparison of two radiographic assessment protocols for patients with periodontal disease

Radiographic assessment of patients with generalised severe periodontitis may be undertaken with a panoramic view and supplementary periapicals. The purpose of this study was to estimate the effective radiation dose from this form of radiographic assessment, and to compare it with an estimate of the dose from a series of periapicals of all the affected teeth. Cross-sectional observational study. Departments of Periodontology and Radiology, Glasgow Dental Hospital and School. Fifty consecutive patients [were recruited] with sufficiently widespread advanced periodontitis to require at least seven periapical radiographs. [Following new local guidelines, a panoramic view was taken.] The adequacy of the image of every affected tooth and the number of supplementary periapicals required was determined by a panel of four examiners who also calculated the number of periapicals which would have been taken if panoramic radiography had not been available. An effective dose of 0.001 mSv for one periapical and 0.007 mSv for a panoramic view was assumed. The panoramic-plus-periapicals approach delivered an estimated additional effective dose to 86% of patients, in the order of 0.001-0.007 mSv. Within the parameters of this investigation, the anticipated effective radiation dose from a series of periapical radiographs of all selected teeth would, for the great majority of patients, have been less than the dose from a panoramic-plus-periapicals approach.

Evaluation of the radiological consequences of14C due to contaminated Ignalina NPP graphite incineration

After decommissioning of Unit 1 of the Ignalina Nuclear Power Plant, the problem of the radioactive waste management emerged. Among radioactive waste there is an inventory of about 1700 tons of the graphite containing 14 C radioisotope as an activation product. The estimates show that the maximal total inventory of 14 C in graphite from Unit 1 is around 7 � 10 14 Bq. One of the possible ways for utilization of the graphite is its incineration in the radioactive waste processing plant. Unfortunately, in this case a significant amount of the radionuclide would be released into the atmosphere in the form of CO2 and the released radiocarbon would cause additional exposure of the population. Possible radiological consequences for the Lithuanian inhabitants are evaluated using the model of radiocarbon dispersion in the environment and considering several scenarios of the graphite incineration. Dispersion of the incineration gas is modelled using the Gaussian dispersion model. Assimilation of CO2 by the vegetation due to photosynthesis as well as washout of CO2 from the atmosphere by rain, uptake of the deposited 14 C by the plants from soil, and the eventual contamination of food products are considered. An estimated additional exposure effective dose to the critical group of the local population due to continuous releases of the total inventory of 14 C from the incinerator is of the order of 2.7 mSv. The consumption of the contaminated locally produced food products is the main contribution to the dose. Such continuous incineration of graphite would be acceptable if it were extended

Low-dose unenhanced multidetector CT of patients with suspected renal colic.

This study is designed to assess the intraobserver and interobserver agreements and the diagnostic performances of low-dose unenhanced multidetector CT (MDCT) in patients with suspected renal colic. The study included 106 patients who underwent unenhanced MDCT with 4 x 2.5 mm collimation, 120 kVp, 30 mAs, and, if necessary, additional focused acquisitions at 60 or 120 mAs on areas with an equivocal ureteral stone or with significant image noise. The effective radiation dose was computer-simulated with software based on the Monte Carlo model and International Commission on Radiological Protection recommendations. CT scans were archived and independently reviewed by three radiologists during two interpretation sessions on a workstation with three dimensions functions. Intraobserver and interobserver agreements were calculated with the kappa statistics. Accuracy for detection of ureteral stone on low-dose MDCT was calculated by comparison with combined clinical (stone passage), surgical (stone retrieval, extracorporeal shock wave lithotripsy), biologic (urinalysis, urine culture), and other imaging (excretory urography, standard-dose MDCT, follow-up sonography, and abdominal radiography) findings or by evidence for an alternative diagnosis. Ureteral stones were present in 38 (36%) of 106 patients. Thirty-six of 38 ureteral stones were detected by low-dose MDCT. From reviewer to reviewer, the number of true-positive, false-positive, true-negative, and false-negative findings ranged, respectively, from 34 to 36, 1 to 4, 64 to 68, and 2 to 4. The corresponding sensitivity, specificity, and accuracy ranged from 89.5% to 94.7%, from 94.1% to 100%, and from 93.4% to 98.1%, respectively. The intraobserver and interobserver agreements were excellent, with kappa values ranging from 0.87 to 0.98. In 13 patients, an alternative diagnosis explaining the patient's symptoms was proposed by all reviewers using images obtained at 30 mAs. No additional or alternative diagnosis was found at standard dose. At 30 mAs, the mean effective dose was 1.2 mSv in men and 1.9 mSv in women. Additional acquisitions at 60 mAs, all focused on the lower pelvis, were acquired in 20 patients, but the corresponding images were needed by the reviewers for only six of them. The acquisitions at 60 mAs were responsible for an additional mean effective dose of 0.5 in men and 0.8 mSv in women. Our study shows that low-dose unenhanced MDCT is appropriate for the diagnosis of ureteral stones, and that it provides excellent intraobserver and interobserver agreements and does not obscure alternative diagnoses.

Environmental Radon and Thoron Progeny Concentrations in Fujan Province of China

Surveys of environmental radon and thoron progeny concentrations were carried out with the filter method in Fujian Province of China, where very high concentrations of 238 U and 232 Th in soil had been reported. The mean values of equilibrium-equivalent radon and thoron concentrations (EEC Rn and EEC Tn ) were 12.9 Bq.m -3 and 0.87 Bq.m -3 indoors, 9.7 Bq.m -3 and 0.39 Bq.m -3 outdoors in the general living environment. Very high concentrations of both radon and thoron progeny were observed in underground places and railway tunnels. The mean additional effective doses due to the inhalation of radon and thoron and their progeny were estimated to be 7.75 mSv.a -1 and 22.2 mSv.a -1 for workers in those places mentioned above. Furthermore, the diurnal/seasonal variations and height distributions of radon and thoron progeny were also studied.

Is the incidence of congenital heart defects influenced by the radioactive contamination of the environment due to the accident in chernobyl? — Results from an epidemiological survey on congenital malformations in the South‐German State of Bavaria

AbstractThe accident in the nuclear power plant at Chernobyl led to a fall‐out and wash‐out of radionuclides, especially radiocesium, with a broad geographic variation in the South‐German State of Bavaria. For a younger adult, the additional effective lifetime dose from external exposure and ingestion of radiocesium varies between 1.2 mSv and 8.7 mSv, depending on the region. This is about 2%, respectively 16%, of the natural lifetime gamma dose. In none of the Bavarian regions with different levels of radiation exposure has the incidence of congenital heart defects in Bavarian children increased since the time of the accident. The results indicate that geographically no effects on such malformations can be attached to the additional radiation exposure resulting from the Chernobyl accident.

Increased indoor Rn levels due to actinide containing mineral collections displayed in living areas.

Collection of crystals ranging from quartz to U or Th containing minerals is a widespread spare time activity in Switzerland. Radon emanation from stones displayed in showcases in the living area may contribute considerably to elevated Rn levels in the indoor air. Time-averaged Rn gas measurements in 35 homes of subscribers to a journal for mineral collectors showed an unexpected statistically significant increase of 98 Bq m-3 in the Rn level of the room containing the collections compared to the levels measured in a control room on the same floor. Using ICRP Publication 50 conversion factors for indoor exposure to Rn decay products, the additional effective dose equivalent contracted was estimated to amount to an average of 2.7 mSv y-1. Although the 220Rn emanation rate, as measured in the display cases, was considerable in several cases, the dose from 220Rn decay products in the living area remained always a small fraction of the Rn dose. Remedial actions for crystal collections containing considerable amounts of U- or Th-based minerals are suggested.

Radiation dose to various age groups from radionuclide impurities in 99mTc-pertechnetate (fission product 99Mo generator) radiopharmaceutical preparations.

Radionuclide impurities of radiopharmaceuticals do not provide any diagnostic information, but contribute to the radiation dose to the patient. For 99mTc, even small amounts of long lived radionuclide impurities may contribute significantly to the dose from 99mTc itself. In this preliminary study, estimates have been made for the radiation dose to specific organs and for the effective dose equivalent from impurities in 99mTc-sodium pertechnetate prepared from fission product 99Mo. In addition to 99Mo, 131I, 103Ru, 89Sr and 90Sr at maximum permissible levels as stipulated in the European Pharmacopoeia, 110mAg and 239Pu were taken as representative nuclides for beta-gamma emitters and alpha emitters. Using all of these radionuclides at such maximum permissible levels of impurity as stated in the European Pharmacopoeia, the total contribution from the impurities to the effective dose equivalent is approximately 30% of the effective dose equivalent from 99mTc-pertechnetate. In terms of specific organs, the liver and kidneys can receive doses of 3-4 times and 1-3 times the dose from 99mTc-pertechnetate itself. Although these are worst case calculations, a consistent approach should be reconsidered to limit the additional effective dose equivalent from impurities to e.g. 10% of the effective dose equivalent from 99mTc itself.

An estimation of radiation exposure and risk from airtightening of homes in an alpine area with elevated radon source strength

In large areas of the Swiss Alps, the high radium content of rocks and soil, which results in high source terms for radon from the ground, may produce considerable indoor levels of radon in dwellings with low air exchange rates. During the winter of 1982/1983, a sample of 32 conventional homes showed an arithmetic mean average radon concentration in living quarters and cellars of 307 Bq/m 3 (8.3 pCi/L) and 1410 Bq/m 3 (38.1 pCi/L), respectively. Based on a matched pair analysis of Swiss single family dwellings, it is assumed that weatherstripping will produce an average increase in the radon level in the living quarters of 50% or 155 Bq/m 3 (4.2 pCi/L) in the sample studied. Using UNSCEAR82 conversion factors, this results in an additional annual effective dose equivalent of 4.6 mSv (460 mrem). A comparison with the energy saved per year by the lower air infiltration alone leads to an additional exposure of about 0.01 mSv (1 mrem) per kWh saved. The estimated lung cancer risk from this exposure is orders of magnitude higher than the projected total risks from the production of a kWh in a large-scale power plant. Since soil gas is the most important source of radon in dwellings with critical levels of radon decay products, changes in the source term concomitant with weatherstripping or new building technologies may both dampen or enhance the increase in the indoor radon levels with lower air exchange rates. Several such parameters influencing radon source strength are considered qualitatively.