Biogeochemical Cycling of Tc in Alkaline Sediments.

Tc will be present in significant quantities in radioactive wastes including intermediate-level waste (ILW). The internationally favored concept for disposing of higher activity radioactive wastes including ILW is via deep geological disposal in an underground engineered facility located ∼200-1000 m deep. Typically, in the deep geological disposal environment, the subsurface will be saturated, cement will be used extensively as an engineering material, and iron will be ubiquitous.

Positron emission tomography to visualise in-situ microbial metabolism in natural sediments.

Positron Emission Tomography simultaneously monitored flow dynamics and in-situ microbial activity in opaque sediment columns. An F labelled electron donor, 2-deoxy-2-[F]-fluoro-D-glucose (FDG), was added to flowing columns containing sterile sediment, microbially active sediment and quartz sand. FDG accumulated in microbially active, glucose primed, sediment (10-10 cells g) at 10 mol g (~40% of the 100 MBq spike) giving the first example of FDG uptake by indigenous microorganisms in a complex sediment system at flow rates representative of the shallow subsurface.

Quantifying Technetium and Strontium Bioremediation Potential in Flowing Sediment Columns.

The high-yield fission products Tc and Sr are found as problematic radioactive contaminants in groundwater at nuclear sites. Treatment options for radioactively contaminated land include bioreduction approaches, and this paper explores Tc and Sr behavior and stability under a range of biogeochemical conditions stimulated by electron donor addition methods. Dynamic column experiments with sediment from the Sellafield nuclear facility, completed at site relevant flow conditions, demonstrated that Fe(III)-reducing conditions had developed by 60 days.

Microbial impacts on Tc migration through sandstone under highly alkaline conditions relevant to radioactive waste disposal.

Geological disposal of intermediate level radioactive waste in the UK is planned to involve the use of cementitious materials, facilitating the formation of an alkali-disturbed zone within the host rock. The biogeochemical processes that will occur in this environment, and the extent to which they will impact on radionuclide migration, are currently poorly understood. This study investigates the impact of biogeochemical processes on the mobility of the radionuclide technetium, in column experiments designed to be representative of aspects of the alkali-disturbed zone.

Impact of point spread function modelling and time of flight on FDG uptake measurements in lung lesions using alternative filtering strategies.

Background: The use of maximum standardised uptake value (SUVmax) is commonplace in oncology positron emission tomography (PET). Point spread function (PSF) modelling and time-of-flight (TOF) reconstructions have a significant impact on SUVmax, presenting a challenge for centres with defined protocols for lesion classification based on SUVmax thresholds. This has perhaps led to the slow adoption of these reconstructions.

The assessment of time-of-flight on image quality and quantification with reduced administered activity and scan times in 18F-FDG PET.

Objectives: The last decade has seen considerable technological innovations in PET detectors with the availability, among other advances, of time-of-flight (TOF). TOF has been shown to increase the signal-to-noise ratio (SNR), which should allow for a reduction in acquired counts while maintaining image quality.

Methods: Fifty-eight patients referred for routine F-flurodeoxyglucose ((18)F-FDG) oncology PET studies were included in this study.

Apical thinning: real or artefact?

Background And Objective: Apical thinning is a well-known phenomenon in myocardial perfusion SPECT, often attributed to reduced myocardial thickness at the apex of the left ventricle. Attenuation correction processing appears to exaggerate this effect. Although currently there is agreement that reduced apical counts are not a diagnostic indicator, opinions differ over the cause of this effect; we sought to clarify this using results from a phantom study.

Evaluating the usefulness of self-reported risk factors in a skin cancer screening program.

The objective of this study was to describe the risk factor profile of skin cancer screening participants and to determine whether there is an association between the number of skin cancer/melanoma risk factors and the likelihood of diagnosis of a malignant melanoma. Seventy skin cancer screening clinics were held by the Lions Cancer Institute in predominantly rural areas of Western Australia between 1996 and 2003. Participants were self-selected and voluntary, responding to an advertisement seeking people at 'high-risk' of melanoma.

Who attends skin cancer screening in Western Australia? Results from the Lions Cancer Institute Skin Cancer Screening Program.

Objective: To examine the characteristics of persons attending a skin cancer screening clinic in Western Australia and compare the effectiveness of screening in different socio-demographic subgroups.

Methods: Questionnaires were completed by 5,950 self-selected participants who voluntarily attended the Western Australian Lions Cancer Institute's targeted skin cancer screening clinics during the period 1996-2003. A risk assessment technique was used to identify individuals at high risk of developing melanoma.

A comparison of PET imaging characteristics of various copper radioisotopes.

Purpose: PET radiotracers which incorporate longer-lived radionuclides enable biological processes to be studied over many hours, at centres remote from a cyclotron. This paper examines the radioisotope characteristics, imaging performance, radiation dosimetry and production modes of the four copper radioisotopes, ( 60)Cu,( 61)Cu,( 62)Cu and( 64)Cu, to assess their merits for different PET imaging applications.

Methods: Spatial resolution, sensitivity, scatter fraction and noise-equivalent count rate (NEC) are predicted for( 60)Cu,( 61)Cu,( 62)Cu and( 64)Cu using a model incorporating radionuclide decay properties and scanner parameters for the GE Advance scanner.