Characterization of the optical properties and stability of Presage™ following irradiation with photons and carbon ions

Acta Oncol. 2011 Aug;50(6):829-34. doi: 10.3109/0284186X.2011.565368.

Abstract

Background: The on-going development of both intensity-modulated radiotherapy (IMRT), including the more recent intensity-modulated arc therapy, as well as particle beam therapy, has created a clear need for accurate verification of dose distributions in three dimensions (3D). Presage™ is a new 3D dosimetry material that exhibits a radiochromic response when exposed to ionizing radiation. In this study we have 1) developed an improved optical set-up for measurements of changes in OD of Presage™ point dosimeters, 2) investigated the dose response of Presage™ for photons and carbon ions in the therapy range, 3) investigated the dose response of Presage™ for photons in the kGy range and 4) investigated the fading (i.e. bleaching) of Presage™ postirradiation.

Materials and methods: Presage™ was examined in 1 × 1 × 4.5 cm(3) optical cuvettes; a cuvette holder assured accurate repositioning, and the optical setup included a reference detector to take into account laser intensity fluctuations. The cuvettes were measured pre- and postirradiation for a two week period.

Results: A linear response was observed between dose and optical response between 0 Gy and 100 Gy for γ-radiation from Co-60 and for carbon ions (both plateau and SOBP) from 0 to 20 Gy. The dosimeter was found to have a saturation dose of approximately 100 Gy for photons. A linear energy transfer (LET) effect was not observed in the dose response of different LET radiation. The postirradiation change in optical fading was found to be 0.5% ΔOD/day.

Conclusions: Our study shows that Presage™ remains a dosimeter of interest for radiation therapy with other particles as well as photons in the therapy dose range.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon*
  • Cobalt Radioisotopes
  • Dose-Response Relationship, Radiation
  • Humans
  • Optics and Photonics*
  • Phantoms, Imaging*
  • Photons*
  • Radiation Monitoring / instrumentation*
  • Radiometry
  • Water

Substances

  • Cobalt Radioisotopes
  • Water
  • Carbon