A Critical Review of the Clinical Effects of Therapeutic Irradiation Damage to the Brain: The Roots of Controversy

We critically examined the damaging affects of therapeutic irradiation by comparing results from cross-disciplinary studies of early- and late-delayed radiotherapy effects. Focus is attained by concentrating on clinical treatment issues (volume of brain, dose, timing of effects, age, modality types, and stereotactic treatment techniques), rather than on methodological means or problems, which is necessary to understand the mechanisms and characteristics of radiotherapy-induced behavioral dysfunction including cognition. We make observations and hypotheses about the actual risks from radiotherapy that could be informative in the treatment decision process, and which may lessen the concerns of some patients and their families about the risks they take when receiving radiation. Conditions that predispose to radiation injury are reviewed: (1) higher doses even to part of the brain versus lower doses to the whole brain, (2) combined treatment modalities, (3) malignancy itself, (4) radiation early during postnatal brain development, and (5) late-delayed effects (more than 3 years posttreatment). Current neurocognitive frameworks for understanding cognitive change over time in children and adults are summarized, along with the literature on effects of brain tumors and treatment on depression. No studies have as yet identified candidate brain regions that are more sensitive to radiotherapy. Two studies have provided early, preliminary evidence for a specific vulnerability of visual attention/memory to the early stage of late radiation damage. Furthermore, radiation effects appear severe only in a minority of patients. Risk is related to direct and indirect effects of cancer type, concurrent clinical factors, and premorbid risk factors.     

Consensus conference on environmental values in radiation protection: a report on building consensus among experts

During the fall of 2001 (October 22–25), The Norwegian Radiation Protection Authority (NRPA) and the Agricultural University of Norway arranged a consensus conference on the protection of the environment against ionising radiation. The motive for the conference was the need to study the ethical and philosophical basis for protection of nature in its own right. The conference was funded by Nordic Nuclear Safety Research (NKS), in cooperation with the International Union of Radioecology (IUR). The National Committee for Research Ethics in Science and Technology (NENT) was hired as facilitators for the consensus process. This paper will give a brief outline of the aims and method of the conference, distinguishing these from other kinds of consensus conferences. The paper ends with some general reflections on the appropriateness of seeking consensus on ethics-related issues among experts.     

Trading jobs for health: Ionizing radiation,occupational ethics,and the welfare argument

Blue-collar workers throughout the world generally face higher levels of pollution than the public and are unable to control many health risks that employers impose on them. Economists tend to justify these risky workplaces on the grounds of the compensating wage differential (CWD). The CWD, or hazard-pay premium, is the alleged increment in wages, all things being equal, that workers in hazardous environments receive. According to this theory, employees trade safety for money on the job market, even though they realize some of them will bear the health consequences of their employment in a risky occupational environment. To determine whether the CWD or hazard-pay premium succeeds in justifying alleged environmental injustices in the workplace, this essay (1) surveys the general theory behind the “compensating wage differential”; (2) presents and evaluates the “welfare argument” for the CWD; (3) offers several reasons for rejecting the CWD, as a proposed rationale for allowing apparent environmental injustice in the workplace; and (4) applies the welfare argument to an empirical case, that of US nuclear workers. The essay concludes that this argument fails to provide a justification for the apparent environmental injustice faced by the 600,000 US workers who have labored in government nuclear-weapons plants and laboratories. Shrader-Frechette is O’Neill Professor of Philosophy and Concurrent Professor of Biological Sciences. She teaches ethics, philosophy of science, quantitative risk assessment, and environmental science. The latest of her 280 articles and 14 books is her 2002 volume from Oxford University Press, Environmental Justice: Creating Equality, Reclaiming Democracy. Shrader-Frechette is grateful to the National Science Foundation, Ethics and Values Program, for research support for this article through grant SES-98-10611. All opinions are those of the author, not the NSF.     

Radiobiology and gray science: Flaws in landmark new radiation protections

The International Commission on Radiological Protection — whose regularly updated recommendations are routinely adopted as law throughout the globe — recently issued the first-ever ICRP protections for the environment. These draft 2005 proposals are significant both because they offer the commission’s first radiation protections for any non-human parts of the planet and because they will influence both the quality of radiation risk assessment and environmental protection, as well as the global costs of nuclear-weapons cleanup, reactor decommissioning and radioactive waste management. This piece argues that the 2005 recommendations are scientifically and ethically flawed, or gray, in at least three respects: first, in largely ignoring scientific journals while employing mainly “gray literature;” second, in relying on non-transparent dose estimates and models, rather than on actual radiation measurements; and third, in ignoring classical ethical constraints on acceptable radiation risk.     

Cascade effects on the irradiation stability of amorphous SiOC

We studied the heavy ion radiation tolerance of amorphous silicon oxycarbide (SiOC) alloys by in situ Kr ion irradiation within a transmission electron microscopy. The amorphous SiOC thin films were grown via co-sputtering from SiO₂ and SiC targets on a surface-oxidized Si (100) substrate. These films were irradiated by 1 MeV Kr ions at both room temperature and 300 °C with damage levels up to 5 displacements per atom (dpa). TEM characterization shows no sign of crystallization, void formation or segregation in all irradiated samples. Our findings suggest that SiOC alloys are a class of promising radiation tolerant materials.     

Cosmology: What One Needs to Know

Cosmology, the study of the universe, has a past, which is reviewed here. The standard model—the Big Bang, or the hot, dense early universe that is still expanding—is based on observations that are basically consistent but which require additional input to improve the agreement. Out of the early universe came the galaxies and stars that shine today. The future of the universe depends on the density of matter: too much mass leads to the Big Crunch; too little leads to eternal expans ion and cooling. The dark-matter problem prevents us from knowing which will be the fate of the universe. Thelimits of what may be called "scientific" are addressed.     

MINDING QUANTA AND COSMOLOGY

The revolution in science inaugurated by quantum physics has made us aware of the role of observation in the construction of data. Eugene Wigner remarked that in quantum physics we no longer have observables (invariants), only observations. Tongue in cheek, I asked him whether that meant that quantum physics is really psychology, expecting a gruff reply to my sassiness. Instead, Wigner beamed understanding and replied "Yes, yes, that's exactly correct." David Bohm pointed out that were we to look at the cosmos without the lenses of our telescopes we would see a hologram. I extend Bohm's insight to the lens in the optics of the eye. The receptor processes of the ear and skin work in a similar fashion. Without these lenses and lenslike operations all of our perceptions would be entangled as in a hologram. Furthermore, the retina absorbs quanta of radiation so that quantum physics uses the very perceptions that become formed by it. In turn, higher-order brain systems send signals to the sensory receptors so that what we perceive is often as much a result of earlier rather than just immediate experience. This influence from inside out becomes especially relevant to our interpretation of how we experience the contents and bounds of cosmology that come to us by way of radiation.     

非小细胞肺癌放疗时机和放疗方式的临床决策

放射治疗是非小细胞肺癌的主要治疗手段之一。大约有3／4的肺癌患者在疾病的不同时期需要做放射治疗。针对不同的患者可以选择根治性放疗、姑息性放疗、术前、术后、放化疗联合治疗等不同的治疗方式。从治疗技术上还可以选择适形、调强、立体定向放疗等。临床医生需要辨证地应用循证医学证据,针对不同的患者刺定合理的个体化治疗方案,以提高疗效。     

Toward an understanding of aging in plutonium from direct measurements of stored energy

ABSTRACT

We present here the first direct measurement of the radiation-damage-induced energy stored in δ-phase plutonium. The primary mode of radioactive decay of ²³⁹Pu occurs with a time constant of τ=1.1?×?10¹²?s. Each decay imparts about 85?keV of recoil energy to the uranium byproduct, 5.2?Mev to the alpha particle, and a spectrum of mostly low energy gamma rays with the most probable at 51?keV [1]. Most of the decay energy is converted immediately to heat, releasing about 1.9?mW/g. However, some thermally-recoverable energy remains trapped. Reported here are measurements of that stored energy using differential scanning calorimetry (DSC) applied to ²³⁹Pu-2.0 at.%Ga δ-phase alloy. Retained energy of ～2 J/g saturates at about 5 months and is unchanged after 30 years. The magnitude of the stored energy agrees with a short-bond defect model that that we present here. This model treats radiation damage as a Pu impurity with shortened bond lengths. It explains the change in known properties with age and predicts that density increases with age, contrary to current thinking. The short-bond impurities proposed are expected to act like other impurities, affecting strength, phase transitions, grain boundaries and other metallurgical properties.     

Crystal growth and defect study of BiSbTe3

BiSbTe₃ single crystals have been grown by the Bridgman technique. Microscopic observations of the as-grown crystals reveal typical features, such as striations on the top free surface, which are attributed to the effect of growth conditions. A nitric-acid-based reagent capable of revealing dislocations has been developed and tested. Etch pits are produced at the dislocation sites, but some discrepancies have been observed on matched cleavage surfaces. The structural difference between the matched cleavage surfaces is discussed.