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Optical-CT gel-dosimetry I: basic investigations.

Publication ,  Journal Article
Oldham, M; Siewerdsen, JH; Kumar, S; Wong, J; Jaffray, DA
Published in: Med Phys
April 2003

Comprehensive verification of the intricate dose distributions associated with advanced radiation treatments is now an immediate and substantial problem. The task is challenging using traditional dosimeters because of restrictions to point measurements (ion chambers, diodes, TLD, etc.) or planar measurements (film). In essence, rapid advances in the technology to deliver radiation treatments have not been paralleled by corresponding advances in the ability to verify these treatments. A potential solution has emerged in the form of water equivalent three dimensional (3D) gel-dosimetry. In this paper we present basic characterization and performance studies of a prototype optical-CT scanning system developed in our laboratory. An analysis of the potential role or scope of gel dosimetry, in relation to other dosimeters, and to verification across the spectrum of therapeutic techniques is also given. The characterization studies enabled the determination of nominal operating conditions for optical-CT scanning. "Finger" phantoms are introduced as a powerful and flexible tool for the investigation of optical-CT performance. The modulation-transfer function (MTF) of the system is determined to be better than 10% out to 1 mm(-1), confirming sub-mm imaging ability. System performance is demonstrated by the acquisition of a 1 x 1 x 1 mm3 dataset through the dose distribution delivered by an x-ray lens that focuses x rays in the energy range 40-80 KeV. This 3D measurement would be extremely difficult to achieve with other dosimetry techniques and highlights some of the strengths of gel dosimetry. Finally, an optical Monte Carlo model is introduced and shown to have potential to model light transport through gel-dosimetry systems, and to provide a tool for the study and optimization of optical-CT gel dosimetry. The model utilizes Mie scattering theory and requires knowledge of the variation of the particle size distribution with dose. The latter was determined here using the technique of dynamic-light-scattering.

Duke Scholars

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

April 2003

Volume

30

Issue

4

Start / End Page

623 / 634

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Tomography, Optical
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Radiometry
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Models, Biological
 

Citation

APA
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MLA
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Oldham, M., Siewerdsen, J. H., Kumar, S., Wong, J., & Jaffray, D. A. (2003). Optical-CT gel-dosimetry I: basic investigations. Med Phys, 30(4), 623–634. https://doi.org/10.1118/1.1559835
Oldham, Mark, Jeffrey H. Siewerdsen, Sai Kumar, John Wong, and David A. Jaffray. “Optical-CT gel-dosimetry I: basic investigations.Med Phys 30, no. 4 (April 2003): 623–34. https://doi.org/10.1118/1.1559835.
Oldham M, Siewerdsen JH, Kumar S, Wong J, Jaffray DA. Optical-CT gel-dosimetry I: basic investigations. Med Phys. 2003 Apr;30(4):623–34.
Oldham, Mark, et al. “Optical-CT gel-dosimetry I: basic investigations.Med Phys, vol. 30, no. 4, Apr. 2003, pp. 623–34. Pubmed, doi:10.1118/1.1559835.
Oldham M, Siewerdsen JH, Kumar S, Wong J, Jaffray DA. Optical-CT gel-dosimetry I: basic investigations. Med Phys. 2003 Apr;30(4):623–634.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

April 2003

Volume

30

Issue

4

Start / End Page

623 / 634

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Tomography, Optical
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Radiometry
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Models, Biological