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SU-E-T-40: Is Accurate 3D Dosimetry Possible When Using Optical-CT Readout with Low (or Without) Refractive Index Matching Fluids?

Publication ,  Journal Article
Rankine, L; Oldham, M
Published in: Med Phys
June 2013

PURPOSE: Achieving accurate optical-CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. This work evaluates various potential 'dry-scan' optical-CT configurations (including parallel, point, and converging light-ray geometries) through computer simulations. METHODS: Three surrounding refractive media were investigated: air, water, and a fluid closely matched to PRESAGE™ (n=1.00,1.33,1.49). Reconstructions performed using both filtered-back-projection (FBP) and algebraic-reconstruction-technique (ART). For each media, the efficacy of the three configurations and the two algorithms was evaluated by calculating usable radius (i.e. the outermost radius where data was accurate to within 2%), and gamma analysis. This definition recognizes that, for optical-CT imaging, errors are greatest near the edge of the dosimeter where refraction can be most pronounced. Simulations were performed on three types of dose distribution: uniform, volumetric modulated arc therapy (VMAT), and brachytherapy (Cs-137). RESULTS: Uniformly irradiated dosimeter useable radius recovered using FBP was 68% for water-matching, and 31% for air-matching (dry-scanning). ART gave useable radii of 99% for both water and dry-scanning, indicating greater recovery of useful data for the uniform distribution. FBP and ART performed equally well for a VMAT dose distribution where less dose is delivered near the edge of the dosimeter (useable radius of 86% and 53% for water and dry-scanning respectively). Brachytherapy useable radius recovered using FBP was 99% and 98% for water and dry-scanning respectively, and a major decrease was seen with ART. Point-source geometry provided 1-2% larger usable radii than parallel. Converging geometry recovered up to 10% reduced useable radii than point and parallel. CONCLUSION: For applications where dose information is not required in the periphery of the dosimeter, some dry and low-viscous matching configurations may be feasible. When dosimetry is required on the periphery, best results were obtained using close refractive matching and ART.

Duke Scholars

Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

June 2013

Volume

40

Issue

6Part11

Start / End Page

212

Location

United States

Related Subject Headings

  • Nuclear Medicine & Medical Imaging
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences
 

Citation

APA
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ICMJE
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Rankine, L., & Oldham, M. (2013). SU-E-T-40: Is Accurate 3D Dosimetry Possible When Using Optical-CT Readout with Low (or Without) Refractive Index Matching Fluids? Med Phys, 40(6Part11), 212. https://doi.org/10.1118/1.4814475
Rankine, L., and M. Oldham. “SU-E-T-40: Is Accurate 3D Dosimetry Possible When Using Optical-CT Readout with Low (or Without) Refractive Index Matching Fluids?Med Phys 40, no. 6Part11 (June 2013): 212. https://doi.org/10.1118/1.4814475.
Rankine, L., and M. Oldham. “SU-E-T-40: Is Accurate 3D Dosimetry Possible When Using Optical-CT Readout with Low (or Without) Refractive Index Matching Fluids?Med Phys, vol. 40, no. 6Part11, June 2013, p. 212. Pubmed, doi:10.1118/1.4814475.

Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

June 2013

Volume

40

Issue

6Part11

Start / End Page

212

Location

United States

Related Subject Headings

  • Nuclear Medicine & Medical Imaging
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences