Random telegraph-signal noise in junctionless transistors

Random telegraph-signal noise (RTN) is measured in junctionless metal-oxide-silicon field-effect transistors (JL MOSFETs) as a function of gate and drain voltage and temperature. It is shown that the RTN in JL MOSFETs increases significantly when an accumulation layer is formed. The amplitude of RTN is considerably smaller in JL devices than in inversion-mode MOSFET fabricated using similar fabrication parameters. A measurement technique is developed to extract the main parameters of the traps, including the average charge capture and emission time from the traps. (C) 2011 American Institute of Physics. (doi:10.1063/1.3557505

Field-effect mobility extraction in nanowire field-effect transistors by combination of transfer characteristics and random telegraph noise measurements

A technique based on the combined measurements of random telegraph-signal noise amplitude and drain current vs. gate voltage characteristics is proposed to extract the channel mobility in inversion-mode and accumulation-mode nanowire transistors. This method does not require the preliminary knowledge of the gate oxide capacitance or that of the channel width. The method accounts for the presence of parasitic source and drain resistance effect. It has been used to extract the zero-field mobility and the field mobility reduction factor in inversion-mode and junctionless transistors operating in accumulation mode. (C) 2011 American Institute of Physics. (doi:10.1063/1.3626038

Reduced electric field in junctionless transistors

The electric field perpendicular to the current flow is found to be significantly lower in junctionless transistors than in regular inversion-mode or accumulation-mode field-effect transistors. Since inversion channel mobility in metal-oxide-semionductor transistors is reduced by this electric field, the low field in junctionless transistor may give them an advantage in terms of current drive for nanometer-scale complementary metal-oxide semiconductor applications. This observation still applies when quantum confinement is present. (C) 2010 American Institute of Physics. (doi:10.1063/1.3299014

Early Metabolic Flare in Squamous Cell Carcinoma after Chemotherapy is a Marker of Treatment Sensitivity In Vitro

PURPOSE: Early metabolic response with a decrease in glucose demand after cytotoxic treatment has been reported to precede tumor volume shrinkage. However, preclinical studies report of a very early rise in metabolism, a flare, following treatment. To elucidate these observations, we performed an experimental study on early metabolic response with sequential analysis of metabolic changes. METHODS: Three squamous cell carcinoma cell lines and one nontumorigenic cell line were exposed to cisplatin. The uptake of the fluorescent glucose analogue 2-NBDG was examined at days 1-6 using fluorescence microscopy. The relation between 2-NBDG-uptake and cell survival was evaluated. RESULTS: The tumor cells exhibited a high uptake of 2-NBDG, whereas the uptake in the nonmalignant cells was low. The more cisplatin sensitive cell lines exhibited a more pronounced metabolic flare than the less sensitive cell line. CONCLUSION: A metabolic flare was a very early sign of treatment response and potentially it could be used as an early marker of treatment sensitivity

Dose escalation to high-risk sub-volumes based on non-invasive imaging of hypoxia and glycolytic activity in canine solid tumors:a feasibility study

INTRODUCTION: Glycolytic activity and hypoxia are associated with poor prognosis and radiation resistance. Including both the tumor uptake of 2-deoxy-2-[(18) F]-fluorodeoxyglucose (FDG) and the proposed hypoxia tracer copper(II)diacetyl-bis(N(4))-methylsemithio-carbazone (Cu-ATSM) in targeted therapy planning may therefore lead to improved tumor control. In this study we analyzed the overlap between sub-volumes of FDG and hypoxia assessed by the uptake of (64)Cu-ATSM in canine solid tumors, and evaluated the possibilities for dose redistribution within the gross tumor volume (GTV). MATERIALS AND METHODS: Positron emission tomography/computed tomography (PET/CT) scans of five spontaneous canine solid tumors were included. FDG-PET/CT was obtained at day 1, (64)Cu-ATSM at day 2 and 3 (3 and 24 h pi.). GTV was delineated and CT images were co-registered. Sub-volumes for 3 h and 24 h (64)Cu-ATSM (Cu3 and Cu24) were defined by a threshold based method. FDG sub-volumes were delineated at 40% (FDG40) and 50% (FDG50) of SUV(max). The size of sub-volumes, intersection and biological target volume (BTV) were measured in a treatment planning software. By varying the average dose prescription to the tumor from 66 to 85 Gy, the possible dose boost (D( B )) was calculated for the three scenarios that the optimal target for the boost was one, the union or the intersection of the FDG and (64)Cu-ATSM sub-volumes. RESULTS: The potential boost volumes represented a fairly large fraction of the total GTV: Cu3 49.8% (26.8-72.5%), Cu24 28.1% (2.4-54.3%), FDG40 45.2% (10.1-75.2%), and FDG50 32.5% (2.6-68.1%). A BTV including the union (∪) of Cu3 and FDG would involve boosting to a larger fraction of the GTV, in the case of Cu3∪FDG40 63.5% (51.8-83.8) and Cu3∪FDG50 48.1% (43.7-80.8). The union allowed only a very limited D( B ) whereas the intersection allowed a substantial dose escalation. CONCLUSIONS: FDG and (64)Cu-ATSM sub-volumes were only partly overlapping, suggesting that the tracers offer complementing information on tumor physiology. Targeting the combined PET positive volume (BTV) for dose escalation within the GTV results in a limited D( B ). This suggests a more refined dose redistribution based on a weighted combination of the PET tracers in order to obtain an improved tumor control

Imaging tumour hypoxia with positron emission tomography.

Hypoxia, a hallmark of most solid tumours, is a negative prognostic factor due to its association with an aggressive tumour phenotype and therapeutic resistance. Given its prominent role in oncology, accurate detection of hypoxia is important, as it impacts on prognosis and could influence treatment planning. A variety of approaches have been explored over the years for detecting and monitoring changes in hypoxia in tumours, including biological markers and noninvasive imaging techniques. Positron emission tomography (PET) is the preferred method for imaging tumour hypoxia due to its high specificity and sensitivity to probe physiological processes in vivo, as well as the ability to provide information about intracellular oxygenation levels. This review provides an overview of imaging hypoxia with PET, with an emphasis on the advantages and limitations of the currently available hypoxia radiotracers.Cancer Research UK (CRUK) funded the National Cancer Research Institute (NCRI) PET Research Working party to organise a meeting to discuss imaging cancer with hypoxia tracers and Positron Emission Tomography. IF was funded by CRUK and is also supported by the Chief Scientific Office. ALH is supported by CRUK and the Breast Cancer Research Foundation. RM is funded by NIHR Cambridge Biomedical Research Centre.This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/bjc/journal/vaop/ncurrent/full/bjc2014610a.html

Imaging with non-FDG PET tracers: outlook for current clinical applications

Apart from the historical and clinical relevance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG), various other new tracers are gaining a remarkable place in functional imaging. Their contribution to clinical decision-making is irreplaceable in several disciplines. In this brief review we aimed to describe the main non-FDG PET tracers based on their clinical relevance and application for patient care

Molecular imaging of hypoxia with radiolabelled agents

Tissue hypoxia results from an inadequate supply of oxygen (O2) that compromises biological functions. Structural and functional abnormalities of the tumour vasculature together with altered diffusion conditions inside the tumour seem to be the main causes of tumour hypoxia. Evidence from experimental and clinical studies points to a role for tumour hypoxia in tumour propagation, resistance to therapy and malignant progression. This has led to the development of assays for the detection of hypoxia in patients in order to predict outcome and identify patients with a worse prognosis and/or patients that would benefit from appropriate treatments. A variety of invasive and non-invasive approaches have been developed to measure tumour oxygenation including oxygen-sensitive electrodes and hypoxia marker techniques using various labels that can be detected by different methods such as positron emission tomography (PET), single photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), autoradiography and immunohistochemistry. This review aims to give a detailed overview of non-invasive molecular imaging modalities with radiolabelled PET and SPECT tracers that are available to measure tumour hypoxia

Multislice CT angiography in the selection of patients with ruptured intracranial aneurysms suitable for clipping or coiling

Introduction We sought to establish whether CT angiography (CTA) can be applied to the planning and performance of clipping or coiling in ruptured intracranial aneurysms without recourse to intraarterial digital subtraction angiography (IA-DSA). Methods Over the period April 2003 to January 2006 in all patients presenting with a subarachnoid haemorrhage CTA was performed primarily. If CTA demonstrated an aneurysm, coiling or clipping was undertaken. IA-DSA was limited to patients with negative or inconclusive CTA findings. We compared CTA images with findings at surgery or coiling in patients with positive CTA findings and in patients with negative and inconclusive findings in whom IA-DSA had been performed. Results In this study, 224 consecutive patients (mean age 52.7 years, 135 women) were included. In 133 patients (59%) CTA demonstrated an aneurysm, and CTA was followed directly by neurosurgical (n=55) or endovascular treatment (n=78). In 31 patients (14%) CTA findings were categorized as inconclusive, and in 60 (27%) CTA findings were negative. One patient received surgical treatment on the basis of false-positive CTA findings. In 17 patients in whom CTA findings were inconclusive, IA-DSA provided further diagnostic information required for correct patient selection for any therapy. Five ruptured aneurysms in patients with a nonperimesencephalic SAH were negative on CTA, and four of these were also false-negative on IA-DSA. On a patient basis the positive predictive value, negative predictive value, sensitivity, specificity and accuracy of CTA for symptomatic aneurysms were 99%, 90%, 96%, 98% and 96%, respectively. Conclusion CTA should be used as the first diagnostic modality in the selection of patients for surgical or endovascular treatment of ruptured intracranial aneurysms. If CTA renders inconclusive results, IA-DSA should be performed. With negative CTA results the complementary value of IA-DSA is marginal. IA-DSA is not needed in patients with negative CTA and classic perimesencephalic SAH. Repeat IA-DSA or CTA should still be performed in patients with a nonperimesencephalic SAH