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Biomedical subjects

G R Stevenson

Publications and source records attributed to G R Stevenson.

14 recordsLinked to original sources
PubMed2001

Radiation protection at high energy proton accelerators.

The radiological problems associated with proton accelerators having maximum energies higher than a few GeV are discussed. Examples are given from accelerators where the authors have had practical experience for a number of years. The main focus will be on those problems which are unique to high energy proton accelerators, and which may not be necessarily associated with the proton beam operation itself.

Humans↗
PubMed2001

Shielding high energy accelerators.

After introducing the subject or shielding high energy accelerators, point source, line-of-sight models, and in particular the Moyer Model, are discussed. Their use in the shielding of proton and electron accelerators is demonstrated and their limitations noted, especially in relation to shielding in the forward direction provided by large, flat walls. The limitations of reducing problems to those using a cylindrical geometry description are stressed. Finally the use of different estimators for predicting dose is discussed. It is suggested that dose calculated from track-length estimators will generally give the most satisfactory estimate.

Electrons↗
PubMed2001

Induced activity in accelerator structures, air and water.

A summary is given of several rules of thumb' which can be used to predict the formation and decay of radionuclides in the structure of accelerators together with the dose rates from the induced radioactivity. Models are also given for the activation of gases (air of the accelerator vault) and liquids (in particular cooling water), together with their transport from the activation region to the release point.

Air↗
PubMed1999

Caring attributes, professional self concept and technological influences in a sample of Registered Nurses in eleven countries.

Caring, the theoretical foundation of nursing, is identified as one of the core values by Hospital Authorities world-wide to be actualised in clinical practice. Exactly how caring attributes relate to nurses' professional self image and quality nursing service in the context of a contemporary technological environment have yet to be operationalised. In total, 1957 Registered Nurses from 11 different countries were involved in the study which aimed to: develop an understanding of and compare the responses to items relating to caring, professional self concept and technological influences. To collect data an instrument containing 104 Likert items was administered to RNs working in general hospitals. The instrument contained sections which examined professional self concept, technological influences and caring attributes. Descriptive and inferential statistics revealed that many of the Asian nurses in the sample were younger, had less experience yet were more qualified than their 'western' colleagues. The mean scores for the caring attributes for nurses from the Philippines, Sweden and South Africa were significantly higher than those from China (Beijing), Korea, China (Hong Kong) and Scotland. The Korean sample demonstrated the lowest mean score for professional self concept while the New Zealand sample the highest. The Australian, Canadian, NZ, Scotland and Swedish samples were strongly of the opinion that the increase in technology has not brought about the any more spare time in nursing and generally had a more negative opinion about the influence of technology when compared to those from China (Beijing), Philippines, China (Hong Kong) and Singapore. The results are discussed in the light of the cultural differences in the sample and recommendations for future research are considered.

Adult↗
PubMed1996

Experimental verification of particle distributions in proton-induced cascades.

Predictions of shielding requirements, levels of induced radioactivity and of radiation damage around high-energy accelerators require accurate simulation of the physics of proton-induced cascades from energies above the TeV to energies below the eV region. Experimental studies of cascades using activation detector, dosimeter and counter techniques provide valuable data for validating simulation procedures and for extrapolating the required accelerator design parameters directly. Such studies include the yields of low-energy secondary neutrons in proton-nucleus interactions, the spatial distribution of hadrons, low-energy neutrons and energy deposition close to the core of proton cascades and measurements at large lateral depths in shields. This paper describes some of these measurement and compares them with the predictions made by Monte-Carlo simulations.

Calorimetry↗
PubMed1984

The estimation of dose equivalent from the activation of plastic scintillators.

It is shown that the dose equivalent to be attributed to the fluence measured by the activation of 11C in a plastic scintillator when exposed outside the shielding of a high-energy proton accelerator is close to the value of 28 fSv m2 in current use at the European Organization for Nuclear Research (CERN) when the neutron component of the field alone is considered. However the presence of significant numbers of pions and protons in stray fields would raise this conversion factor to approx. 45 fSv m2.

Carbon Radioisotopes↗