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Comparing and evaluating the efficacy of the TOR18FG Leeds test X-ray phantom for T-rays

Journal Article


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Abstract


  • The commercially available X-ray fluoroscopy quality assurance phantom, the Leeds test object TOR18FG, was found to be suitable to assess T-ray image quality in the range (0.1-0.4) THz at a depth of

    0.5 cm. Previous to this only custom made phantoms, made especially for the T-ray region, assessed T-ray spatial resolution. However, if sub-wavelength techniques are used, the Leeds test phantom may be implemented to measure the T-ray systems spatial resolution, allowing us to directly compare X-ray and T-ray spatial resolution. The systems compared include a Gulmay Orthovoltage machine (X-ray), the On Board Imager (OBI) of a Varian linear accelerator (X-ray), a two-colour system (T-ray) and Terahertz Time Domain Spectroscopy (THz-TDS) system. X-rays were found to have a spatial resolution of 1.25 lp/mm using the On Board Imager of a Varian Linear Accelerator whilst T-rays imaged using a broadband source imaged through a spatial pinhole had a spatial resolution of 0.56 lp/mm. The TOR18FG background material was found to block, 90% and 99% of the broadband T-rays emitted from a THz-TDS photo-conductive emitter, at 0.4 THz and 0.53 THz respectively. Contrast sensitivity was found to be 3% for 25 cm × 25 cm X-ray field at 65 kV, whilst this value could not be established for T-rays using the TOR18FG. All contrast circles were found to be the same for T-rays i.e. all 40% at 0.1 THz. Images of the same leaf were taken with diagnostic X-rays and both broadband and continuous wave (CW) T-ray systems. T-rays proved superior in providing image contrast, for a hydrated leaf, over X-rays.

Publication Date


  • 2013

Citation


  • Pogson, E. M., Macnamara, J., Metcalfe, P. & Lewis, R. A. (2013). Comparing and evaluating the efficacy of the TOR18FG Leeds test X-ray phantom for T-rays. Quantitative Imaging in Medicine and Surgery, 3 (1), 18-27.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2304&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1295

Number Of Pages


  • 9

Start Page


  • 18

End Page


  • 27

Volume


  • 3

Issue


  • 1

Abstract


  • The commercially available X-ray fluoroscopy quality assurance phantom, the Leeds test object TOR18FG, was found to be suitable to assess T-ray image quality in the range (0.1-0.4) THz at a depth of

    0.5 cm. Previous to this only custom made phantoms, made especially for the T-ray region, assessed T-ray spatial resolution. However, if sub-wavelength techniques are used, the Leeds test phantom may be implemented to measure the T-ray systems spatial resolution, allowing us to directly compare X-ray and T-ray spatial resolution. The systems compared include a Gulmay Orthovoltage machine (X-ray), the On Board Imager (OBI) of a Varian linear accelerator (X-ray), a two-colour system (T-ray) and Terahertz Time Domain Spectroscopy (THz-TDS) system. X-rays were found to have a spatial resolution of 1.25 lp/mm using the On Board Imager of a Varian Linear Accelerator whilst T-rays imaged using a broadband source imaged through a spatial pinhole had a spatial resolution of 0.56 lp/mm. The TOR18FG background material was found to block, 90% and 99% of the broadband T-rays emitted from a THz-TDS photo-conductive emitter, at 0.4 THz and 0.53 THz respectively. Contrast sensitivity was found to be 3% for 25 cm × 25 cm X-ray field at 65 kV, whilst this value could not be established for T-rays using the TOR18FG. All contrast circles were found to be the same for T-rays i.e. all 40% at 0.1 THz. Images of the same leaf were taken with diagnostic X-rays and both broadband and continuous wave (CW) T-ray systems. T-rays proved superior in providing image contrast, for a hydrated leaf, over X-rays.

Publication Date


  • 2013

Citation


  • Pogson, E. M., Macnamara, J., Metcalfe, P. & Lewis, R. A. (2013). Comparing and evaluating the efficacy of the TOR18FG Leeds test X-ray phantom for T-rays. Quantitative Imaging in Medicine and Surgery, 3 (1), 18-27.

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2304&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1295

Number Of Pages


  • 9

Start Page


  • 18

End Page


  • 27

Volume


  • 3

Issue


  • 1