2D and 3D dose analysis of PRESAGE® dosimeter using a prototype 3DmicroHD-OCT imaging system

Abstract

The purpose of this study was to investigate the two dimensional (2D) and three dimensional (3D) radiotherapy dosimetric properties of PRESAGE® dosimeter using an in-house optical computed tomography (OCT) imaging system known as 3DmicroHD-OCT. Dosimetric properties for verification of intensity-modulated radiation therapy (IMRT) treatment technique were studied including dose linearity, dose integration, dose rate dependence and the percentage depth dose analysis. Nine cylindrical PRESAGE® of 5 cm diameter × 5 cm height were irradiated at 6 MV photon beam with different field geometry for the dose range of 0.1–15 Gy. We also irradiated PRESAGE® in the cuvette for UV–Vis analysis for the same dose range to verify the optical density value measured by the 3DmicroHD-OCT imaging system. The irradiation was repeated with EBT film dosimetry for the 2D analysis validation. The study shows that the optical density change increases as dose deposition increases on PRESAGE®, with R2 value better than 0.988. The same response was also recorded when multiple beam was integrated for the dose range investigated. The dose linearity result is consistent with the results obtained from UV–Vis spectrometry. It was also found that the dose rate variation does not affect the optical density change over the dose range investigated. PDD analysis of the PRESAGE® dosimeter investigated shows a good agreement with the ion chamber measurement. In summary, the study shows accurate 3D and 2D measurements of PRESAGE® and EBT film dosimeter were obtained using the 3DmicroHD-OCT imaging system. It shows potential for intensity-modulated radiation therapy (IMRT) treatment verification.