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Hatchwell CJ, Bergin M, Carr B, Barr MG, Fahy A, Dastoor PC. Measuring scattering distributions in scanning helium microscopy. Ultramicroscopy 2024; 260:113951. [PMID: 38471412 DOI: 10.1016/j.ultramic.2024.113951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/29/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024]
Abstract
A scanning helium microscope typically utilises a thermal energy helium atom beam, with an energy and wavelength (¡100meV, ∼0.05 nm) particularly sensitive to surface structure. An angular detector stage for a scanning helium microscope is presented that facilitates the in-situ measurement of scattering distributions from a sample. We begin by demonstrating typical elastic and inelastic scattering from ordered surfaces. We then go on to show the role of topography in diffuse scattering from disordered surfaces, observing deviations from simple cosine scattering. In total, these studies demonstrate the wealth of information that is encoded into the scattering distributions obtained with the technique.
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Affiliation(s)
- C J Hatchwell
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - M Bergin
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - B Carr
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - M G Barr
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - A Fahy
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - P C Dastoor
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
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Bergin M, Roland-Batty W, Hatchwell CJ, Myles TA, Martens J, Fahy A, Barr M, Belcher WJ, Dastoor PC. Standardizing resolution definition in scanning helium microscopy. Ultramicroscopy 2022; 233:113453. [PMID: 35030513 DOI: 10.1016/j.ultramic.2021.113453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/27/2021] [Accepted: 12/05/2021] [Indexed: 11/17/2022]
Abstract
Resolution is a key parameter for microscopy, but methods for standardizing its definition are often poorly defined. For a developing technique such as scanning helium microscopy, it is critical that a consensus-based protocol for determining instrument resolution is prepared as a written standard to allow both comparable quantitative measurements of surface topography and direct comparisons between different instruments. In this paper we assess a range of quantitative methods for determining instrument resolution and determine their relative merits when applied to the specific case of the scanning helium microscope (SHeM). Consequently, we present a preliminary protocol for measuring the resolution in scanning helium microscopy based upon utilizing appropriate test samples with sets of slits of well-defined dimensions to establish the quantitative resolution of any similar instrument.
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Affiliation(s)
- M Bergin
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - W Roland-Batty
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - C J Hatchwell
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - T A Myles
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - J Martens
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - A Fahy
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - M Barr
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - W J Belcher
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
| | - P C Dastoor
- Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia
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Ploquin N, Kertzscher G, Vandervoort E, Cygler JE, Andersen CE, Francescon P. Sci-Fri PM: Delivery - 07: Cyberknife relative output factor measurements using fiber-coupled luminescence, MOSFETS and RADPOS dosimetry system. Med Phys 2012; 39:4643. [PMID: 28516658 DOI: 10.1118/1.4740202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Novel dosimetry systems based on Al2 O3 :C radioluminescence (RL) and a 4D dosimetry system (RADPOS) from Best Medical Canada were used to measure the relative output factor (ROF) on Cyberknife. Measurements were performed in a solid water phantom at the depth of 1.5 cm and SSD = 78.5 cm for cones from 5 to 60 mm. ROFs were also measured using a mobileMOSFET system (Best Medical Canada) and EBT1 and EBT2 GAFCHROMIC® (ISP, Ashland) radiochromic films. For cone sizes 12.5-60 mm all detector results were in agreement within the measurement uncertainty. The microMOSFET/RADPOS measurements (published corrections applied) yielded ROFs of 0.650 ± 1.9%, 0.811 ± 0.9% and 0.843 ± 1.7% for the 5, 7.5 and 10 mm cones, respectively, and were in excellent agreement with radiochromic film values (averaged for EBT1 and EBT2) of 0.645 ± 1.4%, 0.806 ± 1.1% and 0.859 ± 1.1%. Monte-Carlo calculated correction factors were applied to the RL readings to correct for excessive scatter due to the relatively high effective atomic number of Al2 O3 (Z=10.2) compared to water for the 5, 7.5 and 10 mm cones. When these corrections are applied to our RL detector measurements, we obtain ROFs of 0.656 ± 0.3% and 0.815 ± 0.3% and 0.865 ± 0.3% for 5, 7.5 and 10 mm cones. Our study shows that the microMOSFET/RADPOS and optical fiber-coupled RL dosimetry system are well suited for Cyberknife cone output factors measurements over the entire range of field sizes, provided that appropriate correction factors are applied for the smallest cone sizes (5, 7.5 and 10 mm).
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Affiliation(s)
- N Ploquin
- The Ottawa Hospital Cancer Centre, Medical Physics, Ottawa, ON, Canada.,University of Ottawa, Department of Radiology, Ottawa, ON, Canada
| | - G Kertzscher
- Centre for Nuclear Technologies, Technical University of Denmark, Roskilde, Denmark
| | - E Vandervoort
- The Ottawa Hospital Cancer Centre, Medical Physics, Ottawa, ON, Canada.,University of Ottawa, Department of Radiology, Ottawa, ON, Canada
| | - J E Cygler
- The Ottawa Hospital Cancer Centre, Medical Physics, Ottawa, ON, Canada.,University of Ottawa, Department of Radiology, Ottawa, ON, Canada.,Carleton University, Department of Physics, Ottawa, ON, Canada
| | - C E Andersen
- Centre for Nuclear Technologies, Technical University of Denmark, Roskilde, Denmark
| | - P Francescon
- Ospedale Di Vicenza, Medical Physics Department, Vicenza, Italy
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