Typical doses and dose rates in studies pertinent to radiation risk inference at low doses and low dose rates

In order to quantify radiation risks at exposure scenarios relevant for radiation protection, often extrapolation of data obtained at high doses and high dose rates down to low doses and low dose rates is needed. Task Group TG91 on 'Radiation Risk Inference at Low-dose and Low-dose Rate Exposure for Radiological Protection Purposes' of the International Commission on Radiological Protection is currently reviewing the relevant cellular, animal and human studies that could be used for that purpose. This paper provides an overview of dose rates and doses typically used or present in those studies, and compares them with doses and dose rates typical of those received by the A-bomb survivors in Japan.

Diversity of Concerns in Recovery after a Nuclear Accident: A Perspective from Fukushima

Since the 2011 Fukushima nuclear accident, tremendous resources have been devoted to recovery, and the Japanese Government is gradually lifting evacuation orders. However, public concerns remain prevalent, affecting some people's return to a normal life and threatening their well-being. This study reviews government reports, academic papers, newspaper articles and conference presentations with the aim of obtaining a better understanding of issues which relate to radiation concerns in the recovery process in the aftermath of the accident. It looks extensively at: (1) the current status of the post-accident operations and existing radiation issues in Fukushima, and (2) approaches taken to engage the public during recovery from five previous comparable nuclear and radiological events: Three Mile Island, Buenos Aires (RA-2 facility), Chernobyl, Goiânia and Tokai-mura. The findings indicate that the limitations and emerging challenges of the current recovery operations cause concerns about radiation exposure in various aspects of day-to-day life. Past experiences suggest that long-term management that take a holistic and cohesive approach is critical for restoration of sustainable livelihoods and for social re-integration. Not only actual risks but also public perceptions of risks should be carefully assessed and addressed in the process of environmental remediation.

Review of the Global Solar UV Index 2015 Workshop Report

The Global Solar UV Index was developed as an easy-to-understand measure of the amount of biologically-effective ambient solar ultraviolet radiation (UVR) at different locations on the earth's surface. Over the past few years, questions have been raised about the global applicability of the UV Index, about the evidence base for exposure risk thresholds and related protective measures, and about whether the overall impact of the UV Index could be improved with modifications. An international workshop was organized by several organizations, including the World Health Organization, to assess if current evidence was sufficiently strong to modify the UV Index and to discuss different ways it might be improved in order to influence sun-protective behavior. While some animal research suggests there may be no threshold effect, the relative importance of sub-erythemal doses of sunlight in causing skin cancer in humans remains unknown. Evidence suggests that regular use of sunscreen can prevent skin cancer and that sunglasses are an effective method of protecting the eyes from solar UVR. The UV Index as a risk communication tool continues to be useful for raising awareness and to support sun-protection behavior. Although there was agreement that guidance on the use of the UV Index could be improved, the workshop participants identified that strong health outcome-based human evidence would be needed as the basis for a revision. For the UV Index to be relevant in as many countries as possible, it should continue to be adapted to suit local conditions.

Radiation Risk to the Fluoroscopy Operator and Staff

OBJECTIVE

Recent articles discussing cases of brain cancer in interventionalists have raised concerns regarding the hazards of occupational exposure to ionizing radiation. We review the basics of radiation dose and the potential radiation effects, particularly as they pertain to the operator. Then we present the data regarding the risk of each type of radiation effect to the fluoroscopy operator and staff, with special attention on cancer induction, radiation-induced cataracts, and the pregnant operator.

CONCLUSION

Although the evidence overwhelmingly shows that exposure to higher doses of radiation carries a risk of cancer and tissue reactions, the risks of chronic exposure to low-level radiation are less clear. Many studies examining occupational exposure to radiation fail to show an increased risk of stochastic effects of radiation, but the positive results raise concern that the studies are underpowered to consistently detect the small risk. The lack of information in these studies about radiation doses and adherence to radiation protection further confound their interpretation. Large prospective studies of populations with occupational exposure to low-level radiation might clarify this issue. More clearly established are the risks of radiation to the fetus and the risk of cataracts in interventional cardiologists and interventional radiologists. Interventionalists can mitigate these risks by following established radiation safety practices.

Long-Term Outcomes of Patients With Mediastinal Radiation-Associated Severe Aortic Stenosis and Subsequent Surgical Aortic Valve Replacement: A Matched Cohort Study

BACKGROUND

Cardiac disease after mediastinal radiotherapy for thoracic malignancy (chest radiotherapy [XRT]) often manifests as progressive aortic stenosis. In patients with XRT-induced severe aortic stenosis undergoing surgical aortic valve replacement (SAVR), we sought to: (1) study long-term survival and compare these patients with a matched cohort undergoing SAVR during the same time frame; and (2) identify potential predictors of long-term mortality.

METHODS AND RESULTS

We studied patients with symptomatic severe aortic stenosis undergoing SAVR at our institution, of which there were 172 mediastinal XRT patients (63±13 years, 62% women) matched in a 1:1 fashion (based on age, sex, time of surgery, and aortic valve area) with 172 non-XRT patients (comparison group). Baseline clinical and postoperative data were obtained. Society of Thoracic Surgeons score was calculated and mortality was recorded. In the XRT group, the median Society of Thoracic Surgeons score was 4% (interquartile range 2-13), while mean left ventricular ejection fraction, left ventricular stroke volume index, and mean aortic valve gradient were 54±11%, 38±14 mL/m2, and 39±11 mm Hg, respectively. In the entire cohort, 27% and 34% of patients underwent concomitant coronary artery bypass grafting and aortic surgery at the time of SAVR, respectively. Thirty-day/in-hospital deaths occurred in 4 (2%) patients in the XRT group and 0 patients in the comparison group. At 6±3 years of follow-up, on matched group analysis, there were 95 (28%) deaths (83 [48%] in the XRT group versus 12 [7%] in the comparison group (log-rank 89, P<0.001). On multivariable Cox survival analysis, in the whole cohort, higher Society of Thoracic Surgeons score (hazard ratio, 1.14; 95% CI, 1.03-1.26) and mediastinal XRT (hazard ratio, 8.12; 95% CI, 4.26-15.64) were associated with increased longer-term mortality (both P<0.01).

CONCLUSIONS

In patients with severe aortic stenosis undergoing SAVR, patients with prior mediastinal XRT have significantly worse longer-term survival versus a matched cohort.

Occupational Health Risks in Cardiac Catheterization Laboratory Workers

BACKGROUND

Orthopedic strain and radiation exposure are recognized risk factors in personnel staff performing fluoroscopically guided cardiovascular procedures. However, the potential occupational health effects are still unclear. The purpose of this study was to examine the prevalence of health problems among personnel staff working in interventional cardiology/cardiac electrophysiology and correlate them with the length of occupational radiation exposure.

METHODS AND RESULTS

We used a self-administered questionnaire to collect demographic information, work-related information, lifestyle-confounding factors, all current medications, and health status. A total number of 746 questionnaires were properly filled comprising 466 exposed staff (281 males; 44±9 years) and 280 unexposed subjects (179 males; 43±7years). Exposed personnel included 218 interventional cardiologists and electrophysiologists (168 males; 46±9 years); 191 nurses (76 males; 42±7 years), and 57 technicians (37 males; 40±12 years) working for a median of 10 years (quartiles: 5-24 years). Skin lesions (P=0.002), orthopedic illness (P<0.001), cataract (P=0.003), hypertension (P=0.02), and hypercholesterolemia (P<0.001) were all significantly higher in exposed versus nonexposed group, with a clear gradient unfavorable for physicians over technicians and nurses and for longer history of work (>16 years). In highly exposed physicians, adjusted odds ratio ranged from 1.7 for hypertension (95% confidence interval: 1-3; P=0.05), 2.9 for hypercholesterolemia (95% confidence interval: 1-5; P=0.004), 4.5 for cancer (95% confidence interval: 0.9-25; P=0.06), to 9 for cataract (95% confidence interval: 2-41; P=0.004).

CONCLUSIONS

Health problems are more frequently observed in workers performing fluoroscopically guided cardiovascular procedures than in unexposed controls, raising the need to spread the culture of safety in the cath laboratory.

Molecular Breast Imaging for Screening in Dense Breasts: State of the Art and Future Directions

OBJECTIVE

The purposes of this review are to discuss the motivation for supplemental screening, to address molecular breast imaging (MBI) radiation dose concerns, and to provide an updated guide to current MBI technology, clinical protocols, and screening performance. Future directions of MBI are also discussed.

CONCLUSION

MBI offers detection of mammographically occult cancers in women with dense breasts. Although MBI has been under investigation for nearly 15 years, it has yet to gain widespread adoption in breast screening.

Radiation Protection for the Fluoroscopy Operator and Staff

OBJECTIVE

The purposes of this article are to review available data regarding the range of protection devices and garments with a focus on eye protection and to summarize techniques for reducing scatter radiation exposure.

CONCLUSION

Fluoroscopy operators and staff can greatly reduce their radiation exposure by wearing properly fitted protective garments, positioning protective devices to block scatter radiation, and adhering to good radiation practices. By understanding the essentials of radiation physics, protective equipment, and the features of each imaging system, operators and staff can capitalize on opportunities for radiation protection while minimizing ergonomic strain. Practicing and promoting a culture of radiation safety can help fluoroscopy operators and staff enjoy long, productive careers helping patients.

Physicians' Perceptions of Radiation Dose Quantity Depend on the Language in Which It Is Expressed

PURPOSE

Radiation dose information is increasingly requested by nonradiology providers, but there are no standard methods for communicating dose. The aim of this study was to compare physicians' perceptions of the amount of radiation associated with similar dose quantities expressed using different dose terms to evaluate the impact of word choice on physicians' understanding of radiation dose.

METHODS

Internal medicine and pediatric residents were surveyed online for 42 days. After obtaining demographics and training levels, respondents were asked to rank five different radiation dose quantities, each corresponding to one of the five ACR relative radiation levels (RRLs) expressed using different dose terms. Respondents ranked the choices from least to greatest (ie, from 1 to 5) or indicated if all five were equal. For the final question, the same dose quantity was expressed five different ways.

RESULTS

Fifty-one medicine and 45 pediatric residents responded (a 44% response rate). Mean differences in rankings were as follows: for chest x-rays, 0.109 (95% confidence interval [CI], -0.018 to 0.236); for cross-country flights, 0.462 (95% CI, 0.338 to 0.585); for natural background radiation, -0.672 (95% CI, -0.793 to -0.551); for cancer risk, -0.294 (95% CI, -0.409 to -0.178); and for ACR RRL, 0.239 (95% CI, 0.148 to 0.329). Statistically significant differences were found in the distributions of rankings (P < .001) and percentage of correct rankings across each radiation dose term (P < .001), with the ACR RRL having the highest percentage of correct rankings (61.2%).

CONCLUSIONS

Adult and pediatric physicians consistently over- or underestimated radiation dose quantities using different terms to express radiation dose. These results suggest that radiation dose information should be communicated using standard terminology such as the ACR RRL scale to foster consistency and improve the accuracy of physicians' radiation risk perceptions.

JOURNAL CLUB: Scatter Radiation Dose From Digital Screening Mammography Measured in a Representative Patient Population

OBJECTIVE

The purpose of this study was to quantify the amount of scatter radiation received at the skin surface overlying the thyroid gland, salivary gland, lens of the eye, sternum, and uterus during a routine screening digital mammographic examination measured in a representative patient population.

SUBJECTS AND METHODS

The subjects were 207 women without symptoms with varied body mass indexes who underwent annual screening mammography while wearing six optically stimulated luminescence dosimeters placed at the bridge of the nose, right submandibular gland, right and left thyroid lobes, mid sternum, and 2 cm caudal to the umbilicus to assess scatter radiation dose to the skin.

RESULTS

The average scatter radiation doses at the skin surface during digital screening mammography in the representative population of women were as follows: overlying the right lobe of the thyroid, 0.24 mGy; left lobe of the thyroid, 0.25 mGy; salivary gland, 0.2 mGy; bridge of the nose, 0.025 mGy; sternum, 0.87 mGy; and umbilicus, 0.011 mGy. The scatter radiation doses at the umbilicus and the bridge of the nose were too low to measure with statistical confidence. Scatter radiation dose increased with increasing body mass index and increasing breast compression thickness.

CONCLUSION

Scatter radiation dose at the skin overlying organs of interest is a small fraction of the entrance skin dose to the breast. The low levels of scatter radiation measured do not support delaying clinically indicated mammography during early pregnancy.

Ionizing Radiation in Craniofacial Surgery: A Primer on Dose and Risks

An understanding of radiation dose and the anticipated risk to the patient is an important aspect of ordering radiological imaging studies responsibly. It is especially true for the pediatric practitioner because children are more vulnerable to the biological effects of radiation, such as radiosensitivity, longer lifetime years, and higher cellular mitotic activity. The use of fluoroscopy and computed tomography is commonplace in the practice of craniofacial surgery, but often dose reports from varied investigations are not directly comparable, and the risk of patient harm from the investigation is unclear. This article presents the fundamentals of radiation, dose, and risk as it applies to radiological imaging and also introduces our low dose craniofacial computed tomography protocol.

Clinical imaging guidelines part 2: Risks, benefits, barriers, and solutions

A recent international meeting was convened by two United Nations bodies to focus on international collaboration on clinical appropriateness/referral guidelines for use in medical imaging. This paper, the second of 4 from this technical meeting, addresses barriers to the successful development/deployment of clinical imaging guidelines and means of overcoming them. It reflects the discussions of the attendees, and the issues identified are treated under 7 headings: ■ Practical Strategy for Development and Deployment of Guidelines; ■ Governance Arrangements and Concerns with Deployment of Guidelines; ■ Finance, Sustainability, Reimbursement, and Related Issues; ■ Identifying Benefits and Radiation Risks from Radiological Examinations; ■ Information Given to Patients and the Public, and Consent Issues; ■ Special Concerns Related to Pregnancy; and ■ The Research Agenda. Examples of topics identified include the observation that guideline development is a global task and there is no case for continuing it as the project of the few professional organizations that have been brave enough to make the long-term commitment required. Advocacy for guidelines should include the expectations that they will facilitate: (1) better health care delivery; (2) lower cost of that delivery; with (3) reduced radiation dose and associated health risks. Radiation protection issues should not be isolated; rather, they should be integrated with the overall health care picture. The type of dose/radiation risk information to be provided with guidelines should include the uncertainty involved and advice on application of the precautionary principle with patients. This principle may be taken as an extension of the well-established medical principle of "first do no harm."

Linking Gamma-H2AX Foci and Cancer in Rat Skin Exposed to Heavy Ions and Electron Radiation

This study uses acute doses of three test radiations, [Ar ions (L = 125 keVμ), Ne ions (L = 25 keVμ) and electron radiation] to examine a potential quantitative link between rat skin cancer induction and gamma-H2AX foci in rat keratinocytes exposed in vitro to radiations with comparable L values. Theory provided a testable link between cancer yield and gamma-H2AX foci yields: YCa(D,L)rat = (NF)2YAX(D,L)keratinocyte (eqn 1), where YCa(D,L) is cancers(rat) at 1.0 y, YAX(D,L) is in vitro gamma-H2AX foci(keratinocyte) , D is radiation dose, L is linear energy transfer, N is irradiated keratinocytes in vivo, and F is the error rate of end joining. An explicit expression for cancer yield was derived based on cancers arising in the ion track region in proportion to D and L (first term) and independently in proportion to D in the delta ray region in between the ion tracks (second term): YCa(D,L) = CCaLD + BCaD (eqn 1a). Parameters quantified include: CCa = 0.000589 ± 0.000150 cancers-micron[rat(kev)Gy]; BCa = 0.0088 ± 0.0035 cancers(ratGy), F = (8.18 ± 0.91) × 10; N = (8.8 ± 1.2) × 10 and (NF)2 = 0.036 ± 0.006 cancer keratinocyte(rat H2AX foci). Verification of eqns (1) and (1a) and the constancy of F support the hypothesis that end-rejoining errors play a major role in radiation carcinogenesis in rat skin. Cancer yields per rat were consistently predictable based on gamma-H2AX foci yields in keratinocytes in vitro such that 27.8 H2AXfoci(keratinocyte) predicted 1.0 cancer(rat) at 1 y.

Radiation exposure from CT-guided ablation of renal masses: effects on life expectancy

OBJECTIVE. The purpose of this article is to project the effects of radiation exposure on life expectancy (LE) in patients who opt for CT-guided radiofrequency ablation (RFA) instead of surgery for renal cell carcinoma (RCC). MATERIALS AND METHODS. We developed a decision-analytic Markov model to compare LE losses attributable to radiation exposure in hypothetical 65-year-old patients who undergo CT-guided RFA versus surgery for small (≤ 4 cm) RCC. We incorporated mortality risks from RCC, radiation-induced cancers (for procedural and follow-up CT scans), and all other causes; institutional data informed the RFA procedural effective dose. Radiation-induced cancer risks were generated using an organ-specific approach. Effects of varying model parameters and of dose-reduction strategies were evaluated in sensitivity analysis. RESULTS. Cumulative RFA exposures (up to 305.2 mSv for one session plus surveillance) exceeded those from surgery (up to 87.2 mSv). In 65-year-old men, excess LE loss from radiation-induced cancers, comparing RFA to surgery, was 11.7 days (14.6 days for RFA vs 2.9 days for surgery). Results varied with sex and age; this difference increased to 14.6 days in 65-year-old women and to 21.5 days in 55-year-old men. Dose-reduction strategies that addressed follow-up rather than procedural exposure had a greater impact. In 65-year-old men, this difference decreased to 3.8 days if post-RFA follow-up scans were restricted to a single phase; even elimination of RFA procedural exposure could not achieve equivalent benefits. CONCLUSION. CT-guided RFA remains a safe alternative to surgery, but with decreasing age, the higher burden of radiation exposure merits explicit consideration. Dose-reduction strategies that target follow-up rather than procedural exposure will have a greater impact.

Radiographic screening of infants and young children with genetic predisposition for rare malignancies: DICER1 mutations and pleuropulmonary blastoma

OBJECTIVE

The purpose of this study was to compare the risks of radiation in screening strategies using chest radiographs and CT to detect a rare cancer in a genetically predisposed population against the risks of undetected disease.

MATERIALS AND METHODS

A decision analytic model of diagnostic imaging screening strategies was built to predict outcomes and cumulative radiation doses for children with DICER1 mutations screened for pleuropulmonary blastoma. Screening strategies compared were chest radiographs followed by chest CT for a positive radiographic result and CT alone. Screening frequencies ranged from once in 3 years to once every 3 months. BEIR VII (model VII proposed by the Committee on the Biological Effects of Ionizing Radiation) risk tables were used to predict excess cancer mortality for each strategy, and the corresponding loss of life expectancy was calculated using Surveillance Epidemiologic and End Results (SEER) statistics. Loss of life expectancy owing to undetected progressive pleuropulmonary blastoma was estimated on the basis of data from the International Pleuropulmonary Blastoma Registry. Sensitivity analysis was performed for all model parameters.

RESULTS

Loss of life expectancy owing to undetected disease in an unscreened population exceeded that owing to radiation-induced cancer for all screening scenarios investigated. Increases in imaging frequency decreased loss of life expectancy for the combined (chest radiographs and CT) screening strategy but increased that for the CT-only strategy. This was because loss of life expectancy for combined screening is dominated by undetected disease, whereas loss of life expectancy for CT screening is dominated by radiation-induced cancers.

CONCLUSION

Even for a rare disease such as pleuropulmonary blastoma, radiographic screening of infants and young children with cancer-predisposing mutations may result in improved life expectancy compared with the unscreened population. The benefit of screening will be greater for diseases with a higher screening yield.

Imbalance of opinions expressed on Twitter relating to CT radiation risk: an opportunity for increased radiologist representation

OBJECTIVE

The purpose of this study was to assess perspectives and information relating to CT radiation risk on Twitter, a popular microblogging social network.

MATERIALS AND METHODS

Publicly available posts on Twitter ("tweets") containing both the words "CT" and "radiation" were identified from the 1st week of each month in 2013. Type of user posting and source of linked articles were recorded. Two reviewers assessed the content of tweets and links regarding CT's benefit-to-risk ratio (favorable, unfavorable, etc.).

RESULTS

Six hundred twenty-one relevant tweets were tweeted by 557 unique users, of whom 90 (16%) were physicians (17 of these were radiologists), 30 (5%) were medical practices or hospitals, 34 (6%) were patients, 8 (1%) were physicists or technologists, and 395 (71%) were other types of users. Two hundred twenty-seven tweets included user commentary regarding CT's benefit-to-risk ratio, of which 134 (59%) were unfavorable or concerned, 65 (29%) were neutral, 22 (10%) were informative regarding CT dose reduction strategies, and only 6 (3%) were favorable. Four hundred seventy-two tweets (76%) included links to a total of 99 unique articles, of which 25 (25%) were unfavorable or concerned, 10 (10%) were favorable, 25 (25%) were neutral, and 39 (39%) were informative regarding CT dose reduction. Article types were non-peer-reviewed medical sources (n = 50), lay press (n = 15), peer-reviewed medical journals (n = 13), blogs (n = 12), advertisements (n = 5), and informational websites (n = 4).

CONCLUSION

The large majority of content on Twitter was either unfavorable or concerned regarding CT radiation risk. Most articles were not peer-reviewed and were posted by nonphysicians; posts by physicians were largely by nonradiologists. More active engagement on Twitter by radiologists and physicists and increased dissemination of peer-reviewed articles may achieve a more balanced representation and alleviate concerns regarding CT radiation risk on social networks.

Are Risks From Medical Imaging Still too Small to Be Observed or Nonexistent?

Several radiation-related professional societies have concluded that carcinogenic risks associated with doses below 50-100 mSv are either too small to be detected, or are nonexistent. This is especially important in the context of doses from medical imaging. Radiation exposure to the public from medical imaging procedures is rising around the world, primarily due to increased utilization of computed tomography. Professional societies and advisory bodies consistently recommend against multiplying small doses by large populations to predict excess radiation-induced cancers, in large part because of the potential for sensational claims of health impacts which do not adequately take the associated uncertainties into account. Nonetheless, numerous articles have predicted thousands of future cancers as a result of CT scanning, and this has generated considerable concern among patients and parents. In addition, some authors claim that we now have direct epidemiological evidence of carcinogenic risks from medical imaging. This paper critically examines such claims, and concludes that the evidence cited does not provide direct evidence of low-dose carcinogenicity. These claims themselves have adverse public health impacts by frightening the public away from medically justified exams. It is time for the medical and scientific communities to be more assertive in responding to sensational claims of health risks.

Radiation exposure of patients undergoing whole-body FDG-PET/CT examinations: an update pursuant to the new ICRP recommendations

AIM

Reinvestigation of the radiation exposure of patients undergoing whole-body [18F]FDG-PET/CT examinations pursuant to the revised recommendations of the ICRP.

METHODS

Conversion coefficients for equivalent organ doses were determined for realistic anthropomorphic phantoms of reference persons. Based on these data, conversion coefficients for the effective dose were calculated using the revised tissue-weighting factors that account for the different radiation susceptibilities of organs and tissues, and the redefinition of the group 'remainder tissues'.

RESULTS

Despite the markedly changed values of the equivalent organ doses estimated for FDG and of the tissue-weighting factors, the conversion coefficient for the effective dose resulting from FDG administration decreases only slightly by 10 %. For whole-body CT scans it remains even unchanged.

CONCLUSION

The updated dose coefficients provide a valuable tool to easily assess the generic radiation risk of patients undergoing whole-body PET/CT (or PET/MRI) examinations and can be used, amongst others, for protocol optimization.

Mitigating the risk of radiation-induced cancers: limitations and paradigms in drug development

The United States radiation medical countermeasures (MCM) programme for radiological and nuclear incidents has been focusing on developing mitigators for the acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE), and biodosimetry technologies to provide radiation dose assessments for guiding treatment. Because a nuclear accident or terrorist incident could potentially expose a large number of people to low to moderate doses of ionising radiation, and thus increase their excess lifetime cancer risk, there is an interest in developing mitigators for this purpose. This article discusses the current status, issues, and challenges regarding development of mitigators against radiation-induced cancers. The challenges of developing mitigators for ARS include: the long latency between exposure and cancer manifestation, limitations of animal models, potential side effects of the mitigator itself, potential need for long-term use, the complexity of human trials to demonstrate effectiveness, and statistical power constraints for measuring health risks (and reduction of health risks after mitigation) following relatively low radiation doses (<0.75 Gy). Nevertheless, progress in the understanding of the molecular mechanisms resulting in radiation injury, along with parallel progress in dose assessment technologies, make this an opportune, if not critical, time to invest in research strategies that result in the development of agents to lower the risk of radiation-induced cancers for populations that survive a significant radiation exposure incident.

Radiation risk factors in incidence and mortality among exposed individuals of East Kazakhstan

Introduction

Lengthy clinical and epidemiological studies at the Research Institute of Radiation Medicine and Ecology have discovered basic patterns of long-term effects from ionizing radiation in population groups exposed to radiation risk. Methodology for calculating injury from radiation risk factors has been developed and implemented to minimize the effects of the Semipalatinsk nuclear test site (SNTS).

Material and methods

We analyzed materials from the database of the Scientific Medical Register that were exposed to radiation as a result of SNTS. We analyzed both male and female populations of the Abay, Beskaragai and Zhanasemei, Kokpekti (control) areas of East-Kazakhstan region (EKR) from 2008–2012. These populations were split into three groups allocated by the generation. The first group represented persons born from the period of 01/01/1930–08/01/1949 and their children born from the period of 10/09/1949–12/31/1962. The second group were persons born after 01/01/1963. The third group served as the control and were persons who immigrated to these areas after 1990.

Results

There was an increased incidence of cancer (21.5%, p < 0.000734), cardiovascular diseases (10.2%); respiratory problems (9.6%), gastrointestinal issues (9.1%, p < 0.00371–0.00679) in the first group. The effect of the radiation dose has not been fully stuided among the subjects in the second group.

The major causes of excess mortality in the first group were neoplams (30.6%), hypertension (23.8%), and myocardial infarction (22.6%). The effects of radiation influenced mortality in the second group were 2–2.5 times lower than the first group.

Conclusion

There is a correlation between the size of the radiation dose, the risk profile, and age at the moment of radiation exposure with trends of morbidity and mortality in the radiation exposed areas.

Probing lymphoma infiltration in spleen of AKR/J mice chronically exposed to electromagnetic fields for risk assessment--toward noninvasive modeling

Using the AKR/J mouse model, the potential of Raman spectroscopy for monitoring lymphoma in predisposed subjects is demonstrated by discriminating lymphoma infiltration in spleens; the relevance of different excitation profiles is shown. Under green excitation with optimal fluorescence bleaching, stronger DNA bands, intensity variations at amide-III and phenylalanine bands, and the behavior of the 1606/1639 cm(-1) doublet correlate with tumorigenesis. Under red excitation, Raman fingerprints with multivariate models help to discriminate AKR/J-mouse histological subtypes: Lymphoblastic lymphoma (LB) is found significantly distant from both separated lymphocytic lymphoma (LL) and healthy spleen; this agrees with histology since LB has well differentiated large lymphoma cells, while LL, with smaller cells similar to normal lymphocytes, usually cannot be discriminated from normal tissue without histoimmunoassays.

Three-dimensional rotational X-ray acquisition technique is reducing patients' cancer risk in coronary angiography

OBJECTIVES

The purpose of this study was to assess patient-specific organ doses and cancer risk with 3D-rotational acquisitions versus the current standard of multiple single-plane coronary angiography (CA).

BACKGROUND

Catheter-based CA remains one of the most commonly performed diagnostic invasive procedures delivering a relatively high radiation dose to the patient. With the introduction of flat-panel technology, three-dimensional rotational angiography became an alternative for the conventional two-dimensional angiography. However, limited information is available on the difference in patient radiation exposure with both acquisition techniques.

METHODS

Eighty adult patients (45 males, age 38-93 years) were randomly assigned to the rotational or standard angiography group. Exposure parameters were registered and skin dose distribution was measured during the procedure. Patient-specific organ doses and related cancer risks were assessed with dedicated software.

RESULTS

Rotational angiograms were associated with 33% lower KAP-values (decrease from 49.99 Gycm(2) to 33.37 Gycm(2), P < 0.001). A significant (P < 0.001) lower peak skin dose was measured with rotational acquisitions (80 mGy, median) versus planar imaging (172 mGy, median). Moreover, the skin dose was smoothed over the whole chest of the patient. Contrast medium consumption decreased from 104 mL to 73 mL (P < 0.001) with the use of 3D-imaging. The reduction in radiation exposure resulted in a corresponding decrease of organ doses. The latter contributed to an overall cancer risk reduction of 21% for males and 50% for females.

CONCLUSIONS

The current study demonstrates that in CA radiation risk reduction is feasible by using a rotational acquisition technique.

Independent analysis of the radiation risk for leukaemia in children and adults with mortality data (1950-2003) of Japanese A-bomb survivors

A recent analysis of leukaemia mortality in Japanese A-bomb survivors has applied descriptive models, collected together from previous studies, to derive a joint excess relative risk estimate (ERR) by multi-model inference (MMI) (Walsh and Kaiser in Radiat Environ Biophys 50:21-35, 2011). The models use a linear-quadratic dose response with differing dose effect modifiers. In the present study, a set of more than 40 models has been submitted to a rigorous statistical selection procedure which fosters the parsimonious deployment of model parameters based on pairwise likelihood ratio tests. Nested models were consequently excluded from risk assessment. The set comprises models of the excess absolute risk (EAR) and two types of non-standard ERR models with sigmoidal responses or two line spline functions with a changing slope at a break point. Due to clearly higher values of the Akaike Information Criterion, none of the EAR models has been selected, but two non-standard ERR models qualified for MMI. The preferred ERR model applies a purely quadratic dose response which is slightly damped by an exponential factor at high doses and modified by a power function for attained age. Compared to the previous analysis, the present study reports similar point estimates and confidence intervals (CI) of the ERR from MMI for doses between 0.5 and 2.5 Sv. However, at lower doses, the point estimates are markedly reduced by factors between two and five, although the reduction was not statistically significant. The 2.5 % percentiles of the ERR from the preferred quadratic-exponential model did not fall below zero risk in exposure scenarios for children, adolescents and adults at very low doses down to 10 mSv. Yet, MMI produced risk estimates with a positive 2.5 % percentile only above doses of some 300 mSv. Compared to CI from a single model of choice, CI from MMI are broadened in cohort strata with low statistical power by a combination of risk extrapolations from several models. Reverting to MMI can relieve the dilemma of needing to choose between models with largely different consequences for risk assessment in public health.