title: Effects of single-dose irradiation in tumor blood flow studied by 15O decay after proton activation in situ.
abstract: A noninvasive technique employing photon activation of tissue oxygen in situ and detection of subsequent 15O positron decay was used to study the effects of single-dose 60Co irradiation on capillary blood flow in transplanted rat rhabdomyosarcomas. Tumor blood flow was measured before irradiation with 16.5, 38.5, or 60.5 Gy and at several intervals afterward (0-72 hr.). Pre-irradiation values of volume-averaged blood flow in the tumor ranged from 7 to 44 ml/min./100 g. Several hours after irradiation, blood flow fell by up to 50% for 60.5 Gy and up to 35% for 16.5 Gy. However, 24 hours after irradiation, tumor blood flow had recovered completely in the 16.5-Gy group and substantially in the others. For smaller doses such as the fractions typically employed in radiotherapy, no changes in tumor blood flow were observed.
mesh_terms: D000818:Animals; D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D005260:Female; D006207:Half-Life; D008297:Male; D009368:Neoplasm Transplantation; D010104:Oxygen Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow; D012208:Rhabdomyosarcoma / Q000098:blood supply* / Q000532:radiotherapy
chemical_list: D003037:Cobalt Radioisotopes; D010104:Oxygen Radioisotopes