Development of a CCD array imaging system for measurement of dose distributions in doped agarose gels

An imaging system for agarose gel sections has been investigated for applications in rapid two-dimensional radiation dosimetry. The imaging system, with white light illumination and CCD camera detection, was designed for measurement of the radiation-induced optical density changes in iron- and xylenol orange dye-doped agarose gels. The performance of the imaging system was compared with that of a laser scanning system for the gels and with the accepted dosimetry standard, the ionization chamber. In measurement of beam profiles of two therapeutic radiation fields, relative dose values from the CCD camera imaging system were on average within 3% ranging from 0.005% to 7.5%) of values recorded with a parallel plate ionization chamber. In comparison with the laser scanner, the CCD camera imaging system provided comparable spatial resolution and an increased rate of data acquisition, although a consistently reduced signal to noise ratio was observed. Suggestions for improving the camera imaging technique include noise reduction through camera cooling and further frame averaging.