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High resolution gel-dosimetry by optical-CT and MR scanning.

Publication ,  Journal Article
Oldham, M; Siewerdsen, JH; Shetty, A; Jaffray, DA
Published in: Med Phys
July 2001

The increased intricacy of Intensity-Modulated-Radiation-Therapy (IMRT) delivery has created the need for a high-resolution 3D-dosimetry (three-dimensional) system capable of measuring and verifying the complex delivery. Present clinical methods are inadequate being restricted to single points (e.g., ion-chambers) or to 2D planes (e.g., film), and are labor intensive. In this paper we show that gel-dosimetry in conjunction with optical-CT scanning can yield maps of dose that are of sufficient accuracy, resolution and precision to allow verification of complex radiosurgery deliveries, and by extension IMRT deliveries. The radiosurgery dose-distribution represents the most challenging case encountered in external beam therapy by virtue of the steep dose-gradients and high resolution of delivery. We characterize the stringent radiosurgery requirements by the RTAP (Resolution-Time-Accuracy-Precision) criteria defined as < or = 1 mm3 spatial resolution, < or = 1 hour imaging time, accurate to within 3%, and within -1% precision. The RTAP criteria is applied to an in-house laser-based optical-CT scanning system presented here, and evaluated using gel-flasks containing BANG3 gel. The same gel flasks were subsequently imaged using the MR imaging protocol recommended by the gel manufacturer, but modified to match as closely as possible the RTAP. The resulting dose-maps demonstrate the high precision (< 1.3% noise at high dose) achievable with optical CT scanning while preserving high spatial resolution (<1 mm3). Using the sequence above, the MR gel-dose maps were found to have poorer precision by a factor of 5, under the strict conditions of the RTAP. The optical CT gel-dosimetry system was further evaluated for the verification of a complex 3-isocenter radiosurgery delivery. In conclusion, this work demonstrates that gel-dosimetry and optical-CT scanning approach an important long-term goal of radiation dosimetry, as specified by the RTAP criteria, and have potential to impact the clinic by improving and facilitating clinical dose verification for the most complex external beam radiation treatments.

Duke Scholars

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

July 2001

Volume

28

Issue

7

Start / End Page

1436 / 1445

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Reproducibility of Results
  • Radiotherapy, Conformal
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Models, Statistical
  • Magnetic Resonance Imaging
  • Gels
  • Calibration
  • 5105 Medical and biological physics
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Oldham, M., Siewerdsen, J. H., Shetty, A., & Jaffray, D. A. (2001). High resolution gel-dosimetry by optical-CT and MR scanning. Med Phys, 28(7), 1436–1445. https://doi.org/10.1118/1.1380430
Oldham, M., J. H. Siewerdsen, A. Shetty, and D. A. Jaffray. “High resolution gel-dosimetry by optical-CT and MR scanning.Med Phys 28, no. 7 (July 2001): 1436–45. https://doi.org/10.1118/1.1380430.
Oldham M, Siewerdsen JH, Shetty A, Jaffray DA. High resolution gel-dosimetry by optical-CT and MR scanning. Med Phys. 2001 Jul;28(7):1436–45.
Oldham, M., et al. “High resolution gel-dosimetry by optical-CT and MR scanning.Med Phys, vol. 28, no. 7, July 2001, pp. 1436–45. Pubmed, doi:10.1118/1.1380430.
Oldham M, Siewerdsen JH, Shetty A, Jaffray DA. High resolution gel-dosimetry by optical-CT and MR scanning. Med Phys. 2001 Jul;28(7):1436–1445.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

July 2001

Volume

28

Issue

7

Start / End Page

1436 / 1445

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Reproducibility of Results
  • Radiotherapy, Conformal
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Models, Statistical
  • Magnetic Resonance Imaging
  • Gels
  • Calibration
  • 5105 Medical and biological physics