Optical-CT imaging of complex 3D dose distributions

Mark Oldham, Leonard Kim, Geoffrey Hugo

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations

Abstract

The limitations of conventional dosimeters restrict the comprehensiveness of verification that can be performed for advanced radiation treatments presenting an immediate and substantial problem for clinics attempting to implement these techniques. In essence, the rapid advances in the technology of radiation delivery have not been paralleled by corresponding advances in the ability to verify these treatments. Optical-CT gel-dosimetry is a relatively new technique with potential to address this imbalance by providing high resolution 3D dose maps in polymer and radiochromic gel dosimeters. We have constructed a 1st generation optical-CT scanner capable of high resolution 3D dosimetry and applied it to a number of simple and increasingly complex dose distributions including intensity-modulated-radiationtherapy (IMRT). Prior to application to IMRT, the robustness of optical-CT gel dosimetry was investigated on geometry and variable attenuation phantoms. Physical techniques and image processing methods were developed to minimize deleterious effects of refraction, reflection, and scattered laser light. Here we present results of investigations into achieving accurate high-resolution 3D dosimetry with optical-CT, and show clinical examples of 3D IMRT dosimetry verification. In conclusion, optical-CT gel dosimetry can provide high resolution 3D dose maps that greatly facilitate comprehensive verification of complex 3D radiation treatments. Good agreement was observed at high dose levels (>50%) between planned and measured dose distributions. Some systematic discrepancies were observed however (rms discrepancy 3% at high dose levels) indicating further work is required to eliminate confounding factors presently compromising the accuracy of optical-CT 3D gel-dosimetry.

Original languageEnglish
Article number19
Pages (from-to)138-146
Number of pages9
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume5745
Issue numberI
DOIs
StatePublished - 2005
Externally publishedYes
EventMedical Imaging 2005 - Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 13 2005Feb 15 2005

Keywords

  • 3D
  • Computed tomography
  • Dosimetry
  • Imaging
  • Optical

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