Scavenging ability of dendritic PAMAM bridged hindered phenolic antioxidants towards DPPH˙ and ROO˙ free radicals

The intramolecular synergistic effects of two dendritic antioxidants between hindered phenol groups and tertiary amine groups were investigated using the DPPH˙ method and the oxygen uptake method.

Synthesis and oxidative stability of hyperbranched macromolecule-bridged hindered phenols

The oxidative stability of hyperbranched macromolecule-bridged hindered phenols was investigated using the DPPH method and the oxygen uptake method.

Fiducial markers vs. PET/CT for esophageal cancer GTV delineation for radiotherapy treatment planning using a standard SUV threshold and background uptake method.

70 Background: Often in esophageal targets that move with respiration, endoscopically implanted fiducial markers are placed under ultrasound guidance within 1 cm from the superior and inferior tumor border. Our group has previously reported the stability of this method. 3D 18F-FDG PET/CT is obtained for initial staging of esophageal cancer and has altered the tumor volume in many sites. The correlation of these two methods for GTV delineation is currently undefined. Methods: Twenty-one patients with esophageal cancer were selected for this retrospective, IRB-approved analysis. Each patient underwent fiducial placement (by one of six endoscopists) at the inferior and superior borders of the tumor and received PET/CT prior to Radiotherapy (RTx). PET/CT images were imported into an image analysis software system for measurements. The distance between fiducial markers and MTV defined by 2.5 SUV contour (method 1) and MTV using a threshold above mean liver uptake (method 2) was calculated. The fiducials were located on CT. The distance between the centroid and MTV border was measured. The Concordance Correlation Coefficient (CCC) was calculated to determine the correlation between results from the two methods. Results: In method 1 the median distance between MTV (2.5 SUV) and fiducials was 1.0 cm (0.0 cm - 2.8 cm) and 1.0 cm (0.0 cm - 6.9 cm) for inferior and superior borders, respectively. In method 2 median distance between MTV and fiducials was 1.14 cm (0.0 cm - 2.62 cm) and 1.64 cm (0.33 cm – 6.84 cm) for inferior and superior borders, respectively. The CCC indicated poor agreement between methods for both distances (0.57 and 0.87 for inferior fiducial distance and superior fiducial distance, respectively). There was no correlation between MTV-to-fiducial distances greater than 2 cm and the endoscopist that performed the fiducial implantation. Conclusions: Although the methods of defining the MTV had poor strength of agreement, both methods demonstrated a robust correlation between inferior fiducial marker placement and inferior PET/CT uptake. The superior fiducial marker and MTV border illustrated discordance – unrelated to the endoscopist.