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At least 1,135 records · Page 63Linked to original sources
PubMed1998

Dose-area product readings for fluoroscopic and plain film examinations, including an analysis of the source of variation for barium enema examinations.

This paper contains the results of an investigation undertaken between 1994 and 1996 using dose-area product (DAP) meters for monitoring radiation doses from six types of simple examinations and seven types of complex examinations. Mean hospital DAP levels have been compared with National Reference Levels (NRL), with most departments producing levels lower than NRLs. DAP readings have allowed the proposal of provisional Reference Levels (RL) to be set for simple and complex examinations. The results were also compared with recently published data from the National Radiological Protection Board (NRPB), highlighting those hospitals which need to make changes in radiographic technique. The study of DAP reference doses also confirms that dose levels for complex investigations are clearly related to technique, in terms of screening time and number of films. Although the use of increased screening tube kilovoltage may be relevant, the overall effect is small. The results suggest that there is still a need to optimize the protocols for these examinations. The use of digital equipment has been shown to have a complex effect on dose, particularly in the case of investigations involving both films and fluoroscopy.

Barium↗
PubMed2003

Short communication: time of day influences patient radiation exposure from percutaneous cardiac interventions.

The objective of this study was to investigate the influence of time of day on patient radiation exposure due to cardiac interventions. The elective interventional workload of one experienced cardiologist documented over the course of 4 months amounted to 325 diagnostic catheterizations and 145 percutaneous coronary interventions (PCI). All radiation parameters documented during diagnostic coronary angiography remained constant throughout the entire day. In contrast, for PCI measurements made from 7:00 a.m. to 1:00 p.m., our study revealed a mean overall dose-area product (DAP) of 11.8+/-6.8 Gy cm(2) (n=115). These radiation exposure levels increased significantly later in the afternoon (n=30) by 28% to a level of 15.0+/-11.1 Gy cm(2) (p<0.045). Cinegraphic DAP increased from 3.7+/-2.7 Gy cm(2) to 5.0+/-3.2 Gy cm(2) (p<0.033). The number of cinegraphic runs and frames rose from 7.9+/-2.9 to 9.1+/-3.1 (p<0.025), and from 136+/-63 to 164+/-70 (p<0.014), respectively. The following conclusion is warranted by our data and should now be confirmed in a wider multicentre study: radiation protection of the patients could be influenced by the fatigue of the cardiologist conducting the procedure. To enhance patient radiation safety, elective percutaneous angioplasty should be scheduled for the first 6 h of the interventionalist's occupational workload. Diagnostic interventions may be safely scheduled later.

Angioplasty, Balloon, Coronary↗
PubMed2004

Experiences of a proactive IR(ME)R inspection in radiotherapy.

The Ionizing Radiation (Medical Exposure) Regulations 2000, IR(ME)R, apply to the safety of the patient referred for a medical exposure to ionizing radiation. In Scotland, the Scottish Executive (Department of Health) is responsible for carrying out inspections of compliance with these regulations. IR(ME)R specifically addresses issues concerned with Employer's duties, responsibilities of the Practitioner, Operator and Referrer, justification of individual medical exposures for diagnosis and treatment, optimization of all procedures, clinical audit and adequate training of all duty holders. A proactive IR(ME)R inspection of the Clinical Oncology Department, Raigmore Hospital, Inverness, was carried out in November 2001 by inspectors based at the Department of Health, London, and seconded by the Scottish Executive, Department of Health. The aim of the inspection was to assess the degree of compliance with the regulations. In this case study the experiences of a proactive inspection are described in detail and some of the important elements of implementing IR(ME)R in a department that operates an ISO 9000-2000 Quality Management System addressed. The identification of IR(ME)R Duty Holders' responsibilities is one important aspect which may be inadequately described by the existing Quality Management System documentation. Other key elements of the inspection include the methods of authorizing the justification, the importance of the treatment prescription sheets in the demonstration of compliance with IR(ME)R, patient identification and pregnancy questions and dose recording procedures. The integration of the standard operating procedures as described in Schedule 1 of the regulations is also important. Where the existing Quality Management System documentation is written to include the IR(ME)R requirements of duty holder's responsibilities and the allocation of all the important tasks, then there is no need to re-badge these documents for IR(ME)R purposes. IR(ME)R encourages departments to focus on the safety of the patient and to document good practice. In order to comply, departments will have to show evidence of optimization of their procedures and must address the clinical governance issues associated with delivery of treatment.

Humans↗
PubMed2006

Occupational exposure in the electrophysiology laboratory: quantifying and minimizing radiation burden.

Fluoroscopically guided procedures in the electrophysiology room, such as radiofrequency catheter ablation and implantation of cardiac resynchronization devices, may result in high radiation exposure of electrophysiologists and assisting staff. Our aim was to provide accurate and applicable data on occupational doses to the electrophysiology laboratory personnel. We exposed fluoroscopically an anthropomorphic phantom at three projections common in electrophysiology studies. For each exposure, scattered radiation was measured at 182 sites of the cardiology room at four body levels. Effective dose values, eye lens, skin and gonadal doses to the laboratory staff were calculated. Our study has shown that a procedure requiring 40 min of fluoroscopy yields a maximum effective dose of 129 microSv and a maximum value of gonadal dose of 56.8 microSv to staff using a 0.35 mm lead-equivalent apron. A conservative estimate of the electrophysiologist's annual maximum permissible workload is 155 procedures. Staff effective dose values vary by a factor of 40 due to positioning during fluoroscopy and by a factor of 11 due to radiation protection equipment. Undercouch protective shields may reduce gonadal doses up to 98% and effective dose up to 25%. Consequently, radiation levels in the electrophysiology room are not negligible. Mitigation of occupational exposure is feasible through good fluoroscopy and working practices.

Electrophysiology↗
PubMed1991

Radiation safety and quality assurance in US dental hygiene programmes, 1990.

A 1990 survey of US dental hygiene programmes indicated substantial advances in radiation safety and quality assurance techniques since 1985. None the less, further improvements are possible to minimize operator and patient exposure to ionizing radiation from dental radiography. Conversion to faster receptor speed, the use of rectangular collimation and more frequent performance of quality assurance tests represent possible improvements for some establishments.

Dental Hygienists↗
PubMed2005

Quality control and diagnostic reference levels in intraoral dental radiographic facilities.

OBJECTIVES: A quality control program in intraoral radiographic equipment was conducted aiming to verify compliance with the latest legal requirements and to measure radiation dose in order to contribute to the establishment of appropriate diagnostic reference levels. METHODS: This study was performed in 191 intraoral radiographic facilities in Northern Greece. The quality control program included visual inspection of the unit, registration of its characteristics, measurement and calculation of several radiological parameters, including entrance surface dose, and overall compliance with legislation requirements. RESULTS: Most units (61.8%) were found to perform within their corresponding specifications. Exposure timer accuracy was the parameter that the dental units showed the poorest performance. Inadequate beam filtration was found in almost half of the older 50 kVp units. Entrance surface dose showed significant discrepancies, varying from 0.30 mGy to 16.09 mGy with a third quartile value of 3.37 mGy. CONCLUSIONS: A diagnostic reference level of 3.5 mGy is considered to be a realistic value for all intraoral equipment currently operating in Greece. However, for newly installed units, a value of 2.8 mGy is considered to be more appropriate.

Filtration↗
PubMed2006

Effects of sunlight exposure on the human tooth enamel ESR spectra used for dose reconstruction.

The effects of solar radiation on the ESR signals in human tooth enamel were investigated. Enamel samples were exposed to the sunlight in Hiroshima, Japan, on sunny days for a total of about 228 hours over one year. The intensity of the illuminating sunlight was measured with a light meter, which then was converted to the intensity of the solar radiation. Three types of signals caused by the solar radiation were identified. The signal named S1 is identical to the gamma ray radiation-induced axially symmetrical signal and contains two signals S1( perpendicular) and S1(//) corresponding to the perpendicular and parallel components of the g-tensor characterized by g( perpendicular) = 2.0018 and g(//) = 1.9975 respectively. In addition, two other peaks named S2 and S3 are induced by the solar radiation. S2 is very near the inherent signal with g = 2.0052, possibly created by the same paramagnetic centers as the natural signal, and S3 is a weaker signal with g = 2.010. On increasing the amount of solar radiation S1 increases linearly, but S2 and S3 reach saturation. The average effect of the solar radiation on the S1( perpendicular) signal is estimated by dose equivalent gamma ray irradiation as 7.8 +/- 0.5 mGy (MJ m(-2))(-1), which corresponds to 19.6 +/- 1.3 mGy h(-1) at the latitude of Hiroshima. Signals S2 and S3 may be used to recognize the effect of solar radiation on the enamel.

Dental Enamel↗
PubMed1999

Neutron yields from 155 MeV/nucleon carbon and helium stopping in aluminum.

Neutron fluences have been measured from 155 MeV/nucleon 4He and 12C ions stopping in an Al target at laboratory angles between 10 and 160 deg. The resultant spectra were integrated over angle and energy above 10 MeV to produce total neutron yields. Comparison of the two systems shows that approximately two times as many neutrons are produced from 155 MeV/nucleon 4He stopping in Al and 155 MeV/nucleon 12C stopping in Al. Using an energy-dependent geometric cross-section formula to calculate the expected number of primary nuclear interactions shows that the 12C + Al system has, within uncertainties, the same number of neutrons per interaction (0.99 +/- 0.03) as does the 4He + Al system (1.02 +/- 0.04), despite the fact that 12C has three times as many neutrons as does 4He. Energy and angular distributions for both systems are also reported. No major differences can be seen between the two systems in those distributions, except for the overall magnitude. Where possible, the 4He + Al spectra are compared with previously measured spectra from 160 and 177.5 MeV/nucleon 4He interactions in a variety of stopping targets. The reported spectra are consistent with previously measured spectra. The data were acquired to provide data applicable to problems dealing with the determination of the radiation risk to humans engaged in long-term missions in space; however, the data are also of interest for issues related to the determination of the radiation environment in high-altitude flight, with shielding at high-energy heavy-ion accelerators and with doses delivered outside tumor sites treated with high-energy hadronic beams.

Altitude↗
PubMed2001

Direct-Sun column ozone retrieval by the ultraviolet multifilter rotating shadow-band radiometer and comparison with those from Brewer and Dobson spectrophotometers.

A methodology for direct-Sun ozone retrieval using the ultraviolet multifilter rotating shadow-band radiometer (UV-MFRSR) is presented. Total vertical column ozone was retrieved in three stations: Mauna Loa, Hawaii, in the U.S., and Regina, Saskatchewan, and Toronto, Ontario, in Canada, from direct solar irradiances of the UV-MFRSR at 325-, 305-, 332-, and 311-nm channels (2-nm FWHM). The total uncertainty of ozone retrievals in this study is +/-2.0%. For Mauna Loa the mean ratios of the UV-MFRSR column ozone retrievals to the collocated Dobson and Brewer were 0.998 and 0.986 between May and September of 1999. The mean ratio of UV-MFRSR retrievals to the collocated Brewer retrievals was 1.012 in Toronto between April and August of 1999, and the mean ratio of retrievals of the UV-MFRSR to the collocated Brewer was 0.988 in Regina between June and September of 1999. Total vertical column ozone values for solar zenith angles of >70 degrees were not considered, because of the signal-to-noise ratio and the angular response of the instruments, and were not used in the evaluation. The advantages of total vertical column ozone retrieval using UV-MFRSR include relatively low cost, computer-controlled operation, automated calibration stability checks, and minimal maintenance. It allows for the real-time measurement of total vertical column ozone. The UV-MFRSR is being used at 28 sites across the United States and 2 sites in Canada that form the U.S. Department of Agriculture UV-B Radiation Monitoring and Research Program. This constitutes a unique network of total vertical colunm ozone measurement.

Journal Article↗
PubMed2004

Effects of radiation on the environment: a need to question old paradigms and enhance collaboration among radiation biologists and radiation ecologists.

A historical perspective is given of the current paradigm that does not explicitly protect nonhuman biota from radiation but instead relies on the concept that if dose limits are set to protect humans, then the environment is automatically protected as well. We summarize recent international questioning of this paradigm and briefly present three frameworks for protecting biota that are being considered by the U.S. Department of Energy, the Canadian Nuclear Safety Commission, and the International Commission on Radiological Protection. We point out a controversial component in each of the three frameworks and suggest topics that need additional research. We emphasize that to properly address radiation protection of the environment, we need to understand how effects are integrated across different levels of biological organization. We caution that the proposed use of molecular end points to estimate ecological risks from radioactive contamination is applicable only if we understand the extent of the impact that molecular damage has on individual organisms and populations of exposed biota. To accomplish the latter, enhanced collaborations are required among the traditionally separate disciplines of radiation biology and radiation ecology.

Conservation of Natural Resources↗
PubMed2006

FISH chromosome analysis of plutonium workers from the Sellafield nuclear facility.

Chromosome analysis using a single-color FISH technique to paint three pairs of chromosomes was undertaken on a group of 46 retired plutonium workers with assessed bone marrow doses >60 mSv, 34 of whom were categorized as having robust dosimetry and 12 for whom internal doses were considered less reliable. Comparisons were made with a group of 34 workers with negligible radiation exposure and a group of 34 workers with similar recorded external gamma-ray doses but negligible internal dose. The simple translocation frequency of 17.65 +/- 1.96 x 10(-3) per genome equivalent for the 34 plutonium workers with robust dosimetry was significantly increased in comparison with that of 10.06 +/- 1.16 x 10(-3) per genome equivalent for the unirradiated control group (P = <0.001) and that of 13.55 +/- 1.43 x 10(-3) per genome equivalent for the group with similar external gamma-ray exposure (P = 0.012). Thus, although in vitro studies have indicated that the majority of alpha-particle-irradiated cells suffer complex non-transmissible chromosome damage, in vivo a significant proportion survive with simple exchanges that can be passed on to descendant cells. In contrast, the three groups demonstrated no significant differences in stable complex aberrations. No evidence of an increase in dicentrics or unstable complex aberrations associated with plutonium exposure was observed, and it can therefore be assumed that there is little, if any, ongoing irradiation of mature lymphocytes. The translocation frequency of 12.08 +/- 1.92 x 10(-3) per genome equivalent for the group of 12 plutonium workers with less reliable internal dosimetry could adequately be accounted for by age and external dose and indicates that the internal bone marrow doses are likely to have been overestimated. Cytogenetic analysis can therefore make a valuable contribution to the validation of internal doses from plutonium deposition.

Aged↗