Page 78 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Chapter 4
the IR with a beam to subject distance of 20 cm. A lead plate with a rectangular recess of 2x6 cm was positioned on a foam scaffold in between the IR source and the mandible. A smaller lead shield to protect the eyes, underlying intraoral tissues and maxillary region was inserted intraorally to isolate the mandible for IR. The focus was oriented to unilateral IR to the right side of the mandible and the left side was used as a non-IR control. All animals were closely monitored during the treatment procedure after which they were transported back to their housing area where reversal of anesthesia was administered with 1 mg·kg-1 sc atipamezole.
IR protocol
All study animals were randomly divided into 4 groups (I, II, III and IV) of 2 animals each and each group received different total irradiation doses (i.e. 22.4 Gy, 26 Gy, 32 Gy and 30 Gy respectively). Groups I, II and III received 4 fractions (5.6 Gy, 6.5 Gy and 8 Gy respectively with a dose rate of 110 cGy/min) in 2 consecutive weeks on day 0, 3, 6 and 9. Group IV received the total dose (30 Gy with a dose rate of 110 cGy/min) in 1 fraction on day 0. All IR protocol procedures were performed by the same investigators (RH, HMR and NAPF).
Microvascular imaging technique
The microcirculation in the oral mucosa covering the lingual aspect of the mandible was examined and measured using a commercially available SDFI instrument, also known as MicroScan (MicroScan Video Microscope System, MicroVision Medical, Amsterdam, The Netherlands). Details on SDFI are described elsewhere.10,21 In brief, stroboscopic emission of 530-nm wavelength (green light) via LEDs placed at the tip of the lens probe epi-illuminate the tissue and partially gets scattered and absorbed by hemoglobin in red blood cells (RBCs). The difference in absorption and scattering produces clear images of dark circulating RBCs in the vascular lumen contrasted by a light background. Videoclips were captured through a 5x objective lens system (equal to 380x onscreen magnification) on a charge-coupled device (CCD) video camera with 720x576-pixel resolution. The imaged tissue segments were 1.0x0.75 mm2. DVI tapes on a Sony DSR-11 DVCAMTM recorder (Sony, Shinagawa-ku, Tokyo, Japan) were used for storage and were viewed on a 19-inch Samsung SyncMaster 932mv LCD monitor (Samsung, Seoul, South Korea) with a 1440x900-screen resolution.
76