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Characterization of MOSFET Dosimeter Angular Response Using a Spherical Phantom for Fluoroscopic Dosimetry.

Publication ,  Journal Article
Wang, C; Hill, K; Yoshizumi, T
Published in: Health physics
January 2016

Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) dosimeters, placed in anthropomorphic phantoms, are a standard method for organ dosimetry in medical x-ray imaging applications. However, many x-ray applications, particularly fluoroscopy procedures, use variable projection angles. During dosimetry, the MOSFET detector active area may not always be perpendicular to the x-ray beam. The goal of this study was to characterize the dosimeter's angular response in the fluoroscopic irradiation involved in pediatric cardiac catheterization procedures, during which a considerable amount of fluoroscopic x-ray irradiation is often applied from various projection angles. A biological x-ray irradiator was used to simulate the beam quality of a biplane fluoroscopy imaging system. A custom-designed acrylic spherical scatter phantom was fabricated to measure dosimeter response (in mV) in two rotational axes, axial (ψ) and normal-to-axial (θ), in 30° increments, as well as four common oblique angles used in cardiac catheterization: a) 90° Left Anterior Oblique (LAO); b) 70° LAO/ 20° Cranial; c) 20° LAO/ 15° Cranial; and d) 30° Right Anterior Oblique (RAO). All results were normalized to the angle where the dosimeter epoxy is perpendicular to the beam or the Posterior-Anterior projection angle in the clinical setup. The relative response in the axial rotation was isotropic (within ± 10% deviation); that in the normal-to-axial rotation was isotropic in all angles except the ψ = 270° angle, where the relative response was 83 ± 9%. No significant deviation in detector response was observed in the four common oblique angles, with their relative responses being: a) 102 ± 3%; b) 90 ± 3%; c) 92 ± 3%; and d) 95 ± 3%, respectively. These angular correction factors will be used in future dosimetry studies for fluoroscopy. The spherical phantom may be useful for other applications, as it allows the measurement of dosimeter response in virtually all angles in the 3-dimensional spherical coordinates.

Duke Scholars

Published In

Health physics

DOI

EISSN

1538-5159

ISSN

0017-9078

Publication Date

January 2016

Volume

110

Issue

1

Start / End Page

45 / 49

Related Subject Headings

  • Transistors, Electronic
  • Semiconductors
  • Radiometry
  • Radiation Protection
  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Humans
  • Fluoroscopy
  • Equipment Design
 

Citation

APA
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ICMJE
MLA
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Wang, C., Hill, K., & Yoshizumi, T. (2016). Characterization of MOSFET Dosimeter Angular Response Using a Spherical Phantom for Fluoroscopic Dosimetry. Health Physics, 110(1), 45–49. https://doi.org/10.1097/hp.0000000000000370
Wang, Chu, Kevin Hill, and Terry Yoshizumi. “Characterization of MOSFET Dosimeter Angular Response Using a Spherical Phantom for Fluoroscopic Dosimetry.Health Physics 110, no. 1 (January 2016): 45–49. https://doi.org/10.1097/hp.0000000000000370.
Wang, Chu, et al. “Characterization of MOSFET Dosimeter Angular Response Using a Spherical Phantom for Fluoroscopic Dosimetry.Health Physics, vol. 110, no. 1, Jan. 2016, pp. 45–49. Epmc, doi:10.1097/hp.0000000000000370.

Published In

Health physics

DOI

EISSN

1538-5159

ISSN

0017-9078

Publication Date

January 2016

Volume

110

Issue

1

Start / End Page

45 / 49

Related Subject Headings

  • Transistors, Electronic
  • Semiconductors
  • Radiometry
  • Radiation Protection
  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Humans
  • Fluoroscopy
  • Equipment Design