Cumulative radiation dose estimates from medical imaging in paediatric patients with non-oncologic chronic illnesses. A systematic review

Paediatric patients with non-oncologic chronic illnesses often require ongoing care that may result in repeated imaging and exposure to ionizing radiation from both diagnostic and interventional procedures. In this study the scientific literature on cumulative effective dose (CED) of radiation accrued from medical imaging among specific cohorts of paediatric, non-oncologic chronic patients (inflammatory bowel disease, cystic fibrosis, congenital heart disease, shunt-treated hydrocephalus, hemophilia, spinal dysraphism) was systematically reviewed.We conducted PubMed/Medline, Scopus and EMBASE searches of peer-reviewed papers on CED from diagnostic and therapeutic radiological examinations. No time restriction was introduced in the search. Only studies reporting CEDs accrued for a period >1 year were included.We found that the annual CED was relatively low (<3 mSv/year) in cystic fibrosis, congenital heart disease, patients with cerebrospinal fluid shunts and hemophilia, while being moderate (>3–20 mSv/year) in Crohn's patients.This extra yearly radiation exposure accrues over the lifetime and can reach high values (>100 mSv) in selected cohorts of paediatric chronic patients.     

Results of the Second Stage of the Investigation of the Radiation Mechanism of Chiral Influence (RAMBAS-2 Experiment)

Results of the second stage of the RAMBAS (RAdiation Mechanism of Biomolecular ASymmetry) experiment on investigation of the radiation mechanism of the influence on chiral molecules are presented. Optical activity of samples of racemic mixtures of amino acids with heavy metals was compared prior to and after irradiation by electron flux from a radioactive source. It is found that the irradiation results in asymmetric degradation of both complexes and amino acids and in production of chiral asymmetry of the samples under study. These results confirm the conclusions inferred from the first stage of the RAMBAS experiment and could be important for the solution of the origin-of-life and biological homochirality problems.     

Medical physics and physics in medicine in Ireland (part 1: 1600–~2000)

Medical physics and other contributions from physics to medicine are relatively well known, if not well documented in Ireland. Less well known are contributions from medicine to the development of physics, which can and do occur. This paper addresses examples of all three. The methods employed include documentary research and interviews with those who share(d) the stage in the area. Documentary evidence for historical aspects of medical physics over the last century are relatively sparse and incomplete. Notwithstanding this, they can and do enable a picture to be built up of how the arrangements in place now have come about, particularly when they are accompanied by mature recollections of the participants.Good critically assessed and accessible sources have been identified covering the seventeenth to nineteenth century material presented. Examples are presented based on the work of significant contributors, each with strong Irish connections, including Robert Boyle, Erwin Schrödinger, Fearghus O'Foghludha, and Edith Stoney the first female medical physicist. Their contributions are striking and continue to be relevant now. The findings provide a rich context and heritage for medical physics in Ireland and in the international community. They will include the contemporary period in a second paper, Part 2 of this study.     

Some phylogenetic implications of action spectra for photoreactivation of ultraviolet-inactivated yeasts

Action spectra for photoreactivation of ultraviolet-inactivated cells of representative species of five genera of yeasts indicate that the spectral requirements for photoreactivation are characteristic for individual genera and may be useful data in analyses of the systematics of yeasts.Abbreviations ATCC American Type Culture Collection - NRRL Northern Regional Research Laboratory - PR photoreactivation - UV ultraviolet radiation - H. Hansenula - K. Kluyveromyces - N. Nadsonia - S. Saccharomyces - T. Trigonopsis These studies were aided in part by a contract (AT 11-1)-1172 with the U.S. Atomic Energy Commission.     

Occupational radiation exposure in vascular interventional radiology: A complete evaluation of different body regions

PurposeTo perform a complete evaluation on radiation doses, received by primary and assistant medical staff, while performing different vascular interventional radiology procedures.Materials and methodsWe evaluated dose received in different body regions during three categories of vascular procedures: lower limb angiography (Angiography), lower limb percutaneous transluminal angioplasty (Angioplasty) and stent graft placement for abdominal aortic aneurysm treatment (A. A. A. Treatment). We positioned the dosimeters near the eye lens, thyroid, chest, abdomen, hands, and feet of the interventional physicians. Equivalent dose was compared with annual dose limits for workers in order to determine the maximum number of procedures per year that each physician could perform. We assessed 90 procedures.ResultsWe found the highest equivalent doses in the A. A. A. Treatment, in which 90% of the evaluations indicated at least one region receiving more than 1 mSv per procedure. Angioplasty was the only procedural modality that provided statistically different doses for different professionals, which is an important aspect on regards to radiological protection strategies. In comparison with the dose limits, the most critical region in all procedures was the eye lens.ConclusionsSince each body region of the interventionist is exposed to different radiation levels, dose distribution measurements are essential for radiological protection strategies. These results indicate that dosimeters placed in abdomen instead of chest may represent more accurately the whole body doses received by the medical staff. Additional dosimeters and a stationary shield for the eye lens are strongly recommended.     

Dose optimization in cardiac CT

Rapid progress in the field of Cardiac CT is fostered by the advances in CT scanner technology as well as multiple clinical trials demonstrating its role in coronary artery disease and other indications like congenital heart disease, pulmonary vein assessment and pre transcatheter aortic valve replacement. The cardiovascular imager today is responsible for delivering diagnostic image quality while striking a balance with optimized radiation dose. Radiation dose is the result of multiple scanner and patient related factors. Achieving a justifiable radiation dose according to the ALARA principle requires an adept understanding of the factors affecting radiation dose. We review different scan factors and their effect on radiation dose and present strategies for radiation dose optimization in cardiac CT.     

Very small photoluminescent gold nanoparticles for multimodality biomedical imaging

An original synthesis method based on X-ray irradiation produced gold nanoparticles (AuNPs) with two important properties for biomedical research: intense visible photoluminescence and very high accumulation in cancer cells. The nanoparticles, coated with MUA (11-mercaptoundecanoid acid), are very small (1.4 nm diameter); the above two properties are not present for even slightly larger sizes. The small MUA-AuNPs are non-cytotoxic (except for very high concentrations) and do not interfere with cancer cell proliferation. Multimodality imaging using visible light fluorescence and X-ray microscopy is demonstrated by tracing the nanoparticle-loaded tumor cells.     

Radiation and adaptation, evolutionary biology and semantics

Radiations can be either adaptive or non-adaptive, resulting in a variety of niches occupied by sympatric species, or in hardly any niche differentiation and species showing largely mosaic distribution patterns. The terms are useful despite the fact that intermediate situations occur.     

Spatial Variability in Decomposition Rates in a Desert Scrub of Northwestern Mexico

The decomposition of leaf litter for five dominant plant species of a desert scrub in Baja California Sur, Mexico was investigated. We designed a factorial decomposition experiment using decomposition bags and the collected leaf-litter from Prosopis articulata, Jatropha cinerea, J. cuneata, Cyrtocarpa edulis, and Fouquieria diguetti. Factors, such as radiation exposure, rainfall, and the size of litter-consuming organisms were considered. The rates of litter decomposition were calculated for these plant species and the environmental conditions by using single exponential models. The initial concentration of nutrients (C, N, P, K, and Ca) and crude-fiber content of the leaf litter were determined. Our results show that the environmental heterogeneity generated by different conditions of radiation exposure and short-term rainfall patterns are the most relevant factors affecting decomposition processes in this Sonoran desert community. A species-specific pattern was observed in decay rates and mass-loss patterns. Decomposition rates varied from 0.0027 to 0.0201 depending on the species and exposure to different ecological conditions. The decay rates were higher under bare-soil conditions and during a wet year than under the shade provided by the canopy of nurse trees and during a dry year. The leaf litter of J. cuneata reincorporated to the soil more rapidly than that of P. articulata and C. edulis. Termites were the more important macroarthropods associated with litter decomposition, and their harvest distribution was independent of the resources distribution. The ecological significance of these results is discussed considering the extreme climatic conditions prevailing in this region.     

Influence of microclimate and species interactions on the composition of plant and invertebrate communities in alpine northern Norway

We assessed the effects of both biotic processes and abiotic factors on the community composition of vascular plant species and invertebrates at a site in northern Norway. Plant species were assigned to functional (woody versus herbaceous) and biogeographic (boreal versus alpine) groups. Invertebrate species were classified as either herbivore or predator. When species interactions and effects of the abiotic environment were partitioned, boreal species appeared to influence the distribution of alpine species and woody species the distribution of herbaceous species. Analysis of partial correlations indicated that facilitation was the dominant mode of interaction between the two pairs of plant groups. Among abiotic factors, the thermal environment probably influenced all components of the plant and invertebrate communities, except for predatory invertebrates, and wind appeared important in determining the composition of woody and alpine components of the plant community but not the herbaceous component. The composition of the boreal component of the plant community apparently influenced the composition of all invertebrate communities, except for predatory invertebrates. The composition of the woody component of the plant community influenced the composition of both herbivore and predator communities. The alpine plant-community composition influenced predatory invertebrate community composition. Woody plant community composition influenced the composition of both herbivore and predator communities. Our analytic approach, based on two kinds of structural equation models (d-separation and path analysis), provides a useful method for identifying the biotic as well as abiotic factors that influence community structure.