Specific features of the influence of high-energy electron beams on the luminescent properties of undoped and Nb, Fe-doped Al2O3 crystals.

The influence of 10 MeV high-current electron beams accelerated by the M-30 microtron on the luminescent properties of the α-Al2O3, Al2O3:Nb and Al2O3:Fe crystals has been studied. The effect of the long-term phosphorescence at room temperature has been found that can be used to monitor electron and gamma accelerator beams.

Poster - Thur Eve - 20: Serial FDG 4DPET imaging during radiotherapy in advanced lung cancer patients.

The availability of respiratory synchronized PET (4DPET) imaging has enabled more accurate analysis of metabolic response since motion blur is minimized. We present our preliminary analysis of serial FDG 4DPET images acquired at weeks 0, 2, 4, and 7 during radiotherapy of seven stage II-III NSCLC patients. The tumor and nodal PTV of the week 0 images restrained a 4DPET image thresholding algorithm to automatically contour SUV levels ranging from 20 to 80% of the maximum SUV, creating an intensity volume histogram (IVH) for each week. These contours allowed analysis of PET volumes and standard PET metrics such as SUVmax and SUVmean . We found a trend for decreasing SUVmax and SUVmean over a treatment course in both the tumor and nodal regions. On average, the SUVmax within the tumor decreased by 17±13% (1 SD) after 2 weeks, 30±13% after 4 weeks, and 39±19% after 7 weeks of radiotherapy. Decreasing volume trends were also observed in the 20 to 80% max SUV autocontours, ranging from 26±29% to 50±40% respectively, over 7 weeks of treatment. Only one patient demonstrated an increase in FDG uptake within the tumor volume between week 0 and week 2 of treatment, and was also the only patient to recur locally at 3 months following treatment. Changes in tumor metabolism over the course of advanced NSCLC radiotherapy are quantifiable with serial FDG 4DPET imaging. Preliminary analysis suggests that variations in these trends could be useful in identifying non-responding patients that may require an alternative radiotherapeutic approach.