SU-E-T-53: An Investigation of the Dosimetric Characteristics of a Novel Radiochromic 3D Dosimeter.

PURPOSE: A new formulation of PRESAGE has been developed with potential for increased dose sensitivity and post irradiation temporal stability. DEA-PRESAGE differs from conventional PRESAGE by incorporating a methoxy group adjacent to the methine and N,N diethyl groups vs the N,N dimethyl groups of LMG. This work presents an evaluation of the temporal and spatial variation of dose response. METHODS: All measurements were made on cylindrical DEA-PRESAGE dosimeters of 11cm diameter and 11cm height. Dosimeters were irradiated with five small 6MV radiation beams incident on the upper flat surface. The maximum doses were 3, 6 and 9.5 Gy, with the 3 and 9.5 Gy beams being delivered at two separate locations, and the 6 Gy beam irradiating along the central axis of the dosimeter. Post irradiation, the dose distribution was imaged by optical-CT (1mm isotropic spatial resolution) at half hour intervals for the first 4 hours, then hourly for the next two hours, hourly from 20 to 24 hours, and again at 26 hours. Temporal and spatial variations in dose sensitivity were determined by tracking the radiochromic response in different regions of interest within the dosimeter at different times. RESULTS: Between 6 and 26 hours, the radiochromic response at all dose levels and spatial locations was found to be very stable, with <1% variation. In peripheral regions, an initial drop followed by a gradual rise in OD was observed. Centrally in the dosimeter, a gradual reduction in OD was observed. The dose response throughout was found initially to be ∼3.30±0.12×10-2 /cm/Gy. However larger differences were observed (up to tilde;8%) after stabilizationConclusion: The DEA-PRESAGE formulation is found to be extremely stable between 6 and 26 hours post irradiation at room temperature. However the variation in stabilized dose response will need to be accounted for in situations of delayed readout. NIH Grant No. RO1 CA 100835.

Duke Scholars

Author Mark Oldham Radiation Oncology