Comparison of the BANGkit~(TM) and the PRESAGETM Gel Dosimeters for Use with a CCD-based Optical CT Scanner

摘要

We compared the basic characteristics of two commercially-available scattering gel (BANGkit~(T M)) and non-scattering gel (PRESAGE~(T M)) dosimeters with a spectrophotometer to investigate each device's dosimetric properties. The two types of gel dosimeters were spectrophotometrically analyzed. For each gel dosimeter, the absorbance, dose linearity, reproducibility, dose rate dependency, and oxygen effect were evaluated at various wavelengths and doses. The best dose linearities of the BANGkit~(T M) and the PRESAGE~(T M) gel dosimeters gave R2values of 0.97 and 0.98 at wavelengths of 485 nm and 600 nm, respectively, over the range of doses. The BANGkit~(T M) gel showed no peak sensitivity within the studied range of wavelengths whereas the PRESAGE~(T M) gel demonstrated peak sensitivity at a wavelength of 630 nm. The reproducibilities and the dose-rate dependences of the two gel dosimeters were within the range of± 2% and± 3%, respectively. We have shown that the peak sensitivities of the two gel dosimeters were significantly different; the BANGkit~(T M) gel showed no peak sensitivity within the studied range of wavelengths whereas the PRESAGE~(T M) gel demonstrated a peak sensitivity at a wavelength of 630 nm. We have confirmed that the radiochromic gel dosimeter was appropriate for use with a CCD-based optical CT scanner.