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  • 1
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    Head-to-Head Comparison of Chest X-Ray/Head and Neck MRI, Chest CT/Head and Neck MRI, and 18F-FDG PET/CT for Detection of Distant Metastases and Synchronous Cancer in Oral, Pharyngeal, and Laryngeal Cancer (2017)
    The Society of Nuclear Medicine (SNM)
    Details
    Publication Date: 2017-12-02
    Description: The purpose of this study was to determine the detection rate of distant metastasis and synchronous cancer, comparing clinically used imaging strategies based on chest x-ray + head and neck MRI (CXR/MRI) and chest CT + head and neck MRI (CHCT/MRI) with 18 F-FDG PET/CT upfront in the diagnostic workup of patients with oral, pharyngeal, or laryngeal cancer. Methods: This was a prospective cohort study based on paired data. Consecutive patients with histologically verified primary head and squamous cell carcinoma at Odense University Hospital from September 2013 to March 2016 were considered for the study. Included patients underwent CXR/MRI and CHCT/MRI as well as PET/CT on the same day and before biopsy. Scans were read masked by separate teams of experienced nuclear physicians or radiologists. The true detection rate of distant metastasis and synchronous cancer was assessed for CXR/MRI, CHCT/MRI, and PET/CT. Results: A total of 307 patients were included. CXR/MRI correctly detected 3 (1%) patients with distant metastasis, CHCT/MRI detected 11 (4%) patients, and PET/CT detected 18 (6%) patients. The absolute differences of 5% and 2%, respectively, were statistically significant in favor of PET/CT. Also, PET/CT correctly detected 25 (8%) synchronous cancers, which was significantly more than CXR/MRI (3 patients, 1%) and CHCT/MRI (6 patients, 2%). The true detection rate of distant metastasis or synchronous cancer with PET/CT was 13% (40 patients), which was significantly higher than 2% (6 patients) for CXR/MRI and 6% (17 patients) for CHCT/MRI. Conclusion: A clinical imaging strategy based on PET/CT demonstrated a significantly higher detection rate of distant metastasis or synchronous cancer than strategies in current clinical imaging guidelines, of which European ones primarily recommend CXR/MRI, whereas U.S. guidelines preferably point to CHCT/MRI in patients with head and neck squamous cell carcinoma.
    Print ISSN: 0022-3123
    Topics: Medicine
    Published by The Society of Nuclear Medicine (SNM)
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  • 2
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    A PET/CT-Based Strategy Is a Stronger Predictor of Survival Than a Standard Imaging Strategy in Patients with Head and Neck Squamous Cell Carcinoma (2018)
    The Society of Nuclear Medicine (SNM)
    Details
    Publication Date: 2018-04-03
    Description: Our purpose was to examine whether staging of head and neck squamous cell carcinoma (HNSCC) by upfront 18 F-FDG PET/CT (i.e., on the day of biopsy and before the biopsy) discriminates survival better than the traditional imaging strategies based on chest x-ray plus head and neck MRI (CXR/MRI) or chest CT plus head and neck MRI (CCT/MRI). Methods: We performed a masked prospective cohort study based on paired data. Consecutive patients with histologically verified primary HNSCC were recruited from Odense University Hospital from September 2013 to March 2016. All patients underwent CXR/MRI, CCT/MRI, and PET/CT on the same day. Tumors were categorized as localized (stages I and II), locally advanced (stages III and IVB), or metastatic (stage IVC). Discriminative ability for each imaging modality with respect to HNSCC staging were compared using Kaplan–Meier analysis, Cox proportional hazards regression with the Harrell C-index, and net reclassification improvement. Results: In total, 307 patients with histologically verified HNSCC were included. Use of PET/CT significantly altered the stratification of tumor stage when compared with either CXR/MRI or CCT/MRI ( 2 , P 〈 0.001 for both). Cancer stages based on PET/CT, but not CXR/MRI or CCT/MRI, were associated with significant differences in mortality risk on Kaplan–Meier analyses ( P ≤ 0.002 for all PET/CT-based comparisons). Furthermore, overall discriminative ability was significantly greater for PET/CT (C-index, 0.712) than for CXR/MRI (C-index, 0.675; P = 0.04) or CCT/MRI (C-index, 0.657; P = 0.02). Finally, PET/CT was significantly associated with a positive net reclassification improvement when compared with CXR/MRI (0.184, P = 0.03) but not CCT/MRI (0.094%, P = 0.31). Conclusion: Tumor stages determined by PET/CT were associated with more distinct prognostic properties in terms of survival than those determined by standard imaging strategies.
    Print ISSN: 0022-3123
    Topics: Medicine
    Published by The Society of Nuclear Medicine (SNM)
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental characterization of a compact ECR ion source : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2556-2558 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A small ECR plasma source is experimentally evaluated. The compact, coaxial cavity source has an outer diameter of about 5.8 cm and is less than 15 cm in length, and can therefore be fitted on vacuum ports on existing MBE machines. Double- and single-Langmuir probes and an energy analyzer are used to measure ion density, electron temperature, plasma potential, and energy distributions at various downstream and cross-sectional positions in the plasma beam. The measurements are made for a variety of flow rates (2–30 sccm) and the corresponding pressures (from about 10−5 to 10−4 Torr), incident powers ranging from 80 to 164 W, and various gas types including argon and oxygen. The experimental measurements show that the ion source provides ion density of about 1011/cm3 at relatively low powers of 123 W and at sub-mTorr pressures. The ions created follow typical ambipolar diffusion out of the discharge creation region. Ions impinging downstream on a grounded substrate in an argon discharge show a narrow, peaked energy distribution that varies with pressure and power. Low-energy ion beams with energies less than 35 eV can easily be produced by varying the pressure and input power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142887
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  • 4
    Electronic Resource
    Electronic Resource
    Transitions in morphology observed in nitrogen/methane–hydrogen depositions of polycrystalline diamond films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6062-6068 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work, we report on a series of transitions in morphology and texture as 5–1000 parts per million of nitrogen were added to 2% and 1% methane–hydrogen depositions of polycrystalline diamond films. Five results are reported. (1) The threshold for transition into the {100}-faceted morphology occurred at lower parts per million nitrogen for the 1% versus the 2% methane–hydrogen series, opposite from the transition thresholds previously reported. (2) At 1000 parts per million nitrogen the film quality of both series had not yet seriously degraded. (3) A well defined sequence of intermediate texture transitions as a function of increasing parts per million nitrogen was observed for both series. (4) A pretransition morphology of large crystallites interspersed among microcrystalline material directly preceding the transitions to the {100}-faceted morphology was observed for both series. (5) A layered growth and/or etched morphology at high nitrogen concentrations was observed for both series. We discuss these observations in terms of the possible influence of our deposition conditions on the accessibility of diamond growth parameter space and chemistry, including possible dynamical effects of the temperature gradients. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1362406
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  • 5
    Electronic Resource
    Electronic Resource
    Discharge characteristics of a 5 cm multipolar electron cyclotron resonance ion sourcea) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1749-1752 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact 5-cm-diam multipolar electron cyclotron resonance (ECR) ion source is characterized. The source is experimentally studied with no grids using argon gas with 50–250 W of 2.45-GHz microwave input power. Using a microcoaxial probe it was confirmed that the exciting electromagnetic fields within the resonant cavity were indeed TE111, as expected from the critical cavity dimensions. Double Langmuir probe measurements indicate high densities of about (4–5)×1011/cm3 near the source, and 5 cm downstream from the source output the densities become very uniform with a value of about 5×1010/cm3 over a 10-cm diameter. Electron energy distribution functions (EEDF) were measured using a single Langmuir probe. Average electron energies were seen to be about 8–10 eV with an energy distribution function falling between a Maxwellian and a Druyvesteyn distribution. Ion energy distribution functions (IEDF) were measured with a multigrid energy analyzer. It was seen that the distribution functions were narrow and peaked [with a full width half maximum (FWHM) of about 5 eV] except under certain conditions. Above 200-W input power, and also below about 0.5 mTorr there is significant broadening of the ion distribution function. It is speculated that the former may be caused by gas heating, and the latter may be caused by the presence of Ar+2 ions. With its high current densities ((approximately-greater-than)10 mA/cm2) and low average ion energies (〈40 eV), it is expected that this ion/plasma source will be very useful in many etching and deposition applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144871
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  • 6
    Electronic Resource
    Electronic Resource
    Discharge characteristics of a 5 cm multipolar electron cyclotron resonance ion source (abstract)a) : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1310-1310 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact 5-cm-diam multipolar electron cyclotron resonance (ECR) ion source is characterized. The source is experimentally studied with no grids using argon gas with 50–250 W of 2.45-GHz microwave input power. Using a microcoaxial probe it was confirmed that the exciting electromagnetic fields within the resonant cavity were indeed TE111, as expected from the critical cavity dimensions. Double Langmuir probe measurements indicate high densities of about (4–5)×1011/cm3 near the source, and 5 cm downstream from the source output the densities become very uniform with a value of about 5×1010/cm3 over a 10-cm diameter. Electron energy distribution functions (EEDFs) were measured using a single Langmuir probe. Average electron energies were seen to be about 8–10 eV with an energy distribution function falling between a Maxwellian and a Druyvesteyn distribution. Ion energy distribution functions (IEDF) were measured with a multigrid energy analyzer. It was seen that the distribution functions were narrow and peaked [with a full width half maximum (FWHM) of about 5 eV] except under certain conditions. Above 200-W input power, and also below about 0.5 mTorr there is significant broadening of the ion distribution function. It is speculated that the former may be caused by gas heating, and the latter may be caused by the presence of Ar+2 ions. With its high current densities ((approximately-greater-than)10 mA/cm2) and low average ion energies (〈40 eV), it is expected that this ion/plasma source will be very useful in many etching and deposition applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144990
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  • 7
    Electronic Resource
    Electronic Resource
    The study of a 2.45 GHz plasma source as a plasma generator for the SCECR electron cyclotron resonance ion source : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1135-1137 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The 2.45 GHz plasma source is a multicusp electron cyclotron resonance source with a tuned single mode microwave cavity. This is a bright plasma source with a well characterized operating mode and plasma parameters [A. K. Srivastava, et al., Rev. Sci. Instrum. 63, 2556 (1992); A. K. Srivastava and J. Asmussen, J. Vac. Sci. Technol. A 11, 1307 (1993)]. The superconducting electron cyclotron resonance (SCECR) is a fully superconducting, hexapole stabilized tandem mirror ion source with a multimode microwave cavity. It is a high charge state ion source with extensive beam diagnostics [T. A. Antaya, Nucl. Instrum. Methods B 40/41, 1024 (1989)]. The coupling of these two sources permits a number of fundamental studies important to both classes of ion sources. The 2.4 GHz plasma source will be used to study the effects of ion or electron (or both) density enhancement on the charge state distribution, total extracted current, and ion energy distributions of the SCECR. The SCECR in turn will be used as a test stand to measure directly the ion distribution and beam characteristics of the 2.45 GHz plasma source. The first results with this hybrid ion source will be presented at this conference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145038
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  • 8
    Electronic Resource
    Electronic Resource
    Modeling the electromagnetic excitation of a compact ECR ion/free radical source (abstract)a) : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1312-1312 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The electromagnetic excitation of a discharge inside a microwave plasma source has been numerically modeled in the time domain. The source is a cylindrical, single-mode microwave-excited cavity. The time-varying electromagnetic fields inside the resonant cavity, both inside and outside the discharge region, are obtained by applying a finite-difference time-domain method to solve Maxwell's equations. The electromagnetic properties of the discharge load are described using a conductivity model. The spatial electric field patterns, natural frequencies, stored energy, and quality factor of a plasma-loaded, microwave-resonant cavity are simulated. Additionally, the simulated results for a simplified plasma source structure are compared to a known analytical solution to verify the simulation technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144993
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  • 9
    Electronic Resource
    Electronic Resource
    Dual-side contact formation on isolated diamond films (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2461-2463 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is described for transferring deposited diamond films to a second substrate, thereby providing access to the diamond film back surface and also allowing post-deposition contact formation to both surfaces of the film. The availability of both sides of the diamond film allows increased experimental control and flexibility for investigation of electrical properties and contact phenomena. The films are deposited in a microwave plasma disk reactor onto silicon substrates and transferred to epoxy substrates. Also presented is a comparison of the roughness of the top and bottom film surfaces, a Raman spectrum of the transferred film, and current-voltage characteristics of samples with dual-side contacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103851
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  • 10
    Electronic Resource
    Electronic Resource
    Neutral gas temperatures in a multipolar electron cyclotron resonance plasma (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2473-2475 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical emission measurements of the Doppler broadening of argon (549.6 nm) and helium (501.6 nm) neutral lines in the unmagnetized regions of an electron cyclotron resonance plasma show that the gas temperature ranges from 300 to 900 K. After compensation for Zeeman splitting, Doppler widths are found to be constant across the radius of the plasma. Plasma heating of the argon gas (0.77 mTorr) is shown to increase from 300 to 500 K as microwave power absorption increases from 80 to 330 W. Long neutral residence times are observed to increase the argon gas temperature to ≈900 K. Helium and argon neutral temperatures decrease as the neutral mean free path increases indicating that the gas may be heated by ion-neutral collisions including charge exchange.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105232
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