The Experiment Of Injury To The Abdominal Tissues And Organs Of Swine In Vivo By High Intensity Focused Ultrasound Combined With Radiotherapy

Objective: to observe the injury of High Intensity Focused Ultrasound combined with radiotherapy (RT) to the abdominal tissues and organs of swine in vivo, so to access the feasibility of treating abdominal tumor in clinic by combining the HIFU and RT.Methods: 12 domestic swines entered the experiment. They were assigned into 4 groups: the control group, HIFU group, RT group and the combined group, 3 cases in each. For HIFU treatment, the emission power was 600W, emission time was 150ms, and the interval was 150ms. The number of pulse was 70. The size of focus was 3mm×3mm×3 mm, the distance of focus was 4 mm, the distance of slice was 6mm. For RT, the VARIAN 21EX linac accelerator was used, 6MV X-ray, a total dose(DT) 13Gy in a single fraction was given. The target size was 10cm×10cm in a square field. The center of RT field was the pancreatic head of swine. All the swines had laparotomy 7 days following treatment to evaluate the treatment effects and the unintended injury. After the harvesting of the pancreas, the animals were euthanized. Histologic evaluation of the pancreas and the unintended tissue was performed to access the tissue injury.Results: the gross examination indicates that in the HIFU group there was 1 swine appeared an injury to the skin immediately after the treatment and stomach injury after 7 days of the treatment. A local erythema and superficial blistering was seen, and there was a gastric ulcer without perforation in the post-wall of stomach. In each of the RT group and the combined group there were 2 cases of stomach injury respectively, which appeared erythema in the wall of stomach. It can be observed only 1 case injury in the pancreas in the HIFU group, there was no gross injury observed in the other 2 groups. The histological examination indicates that there was no statistical significance of the difference among the test groups for the gastric and the bowel wall lesion. The sum score of the three test groups of the injury to the pancreas was 3, 5, and 7 respectively, Comparison among groups, there was no statistical significance between the HIFU group (the sum score was 3) and the RT group ( the sum score was 5) ; it was same between the RT group (sum score 5) and the combined group(sum score 7). There was a significantly difference between the combined group (sum score 3) and the HIFU group (sum score 7) of the injury to the pancreas.Conclusion: HIFU combined with RT can increase the injury to the pancreas of the swine compare with HIFU alone; meanwhile there was no increase of the injury to the unintended target tissue. The main toxicity of the combination was the toxicity of RT and the animals can tolerate. If the HIFU treatment was strictly controlled, the combination of HIFU and RT was safety and feasibility.