Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical radioisotopes.Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes.However,the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes.In this study,the entire process of the generation,decay,and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gamma-ray spectrometer.Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source(SLEGS),the feasibility of this measurement of production cross section for surveyed medi-cal radioisotopes was simulated,and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were provided.The feasibility of this method for high-precision measurements of the reaction cross section of medical radioisotopes was demonstrated.

Xanthogranulomatous cholecystitis mimicking gallbladder carcinoma:An analysis of 42 cases

AIM: To review and evaluate the diagnostic dilemma of xanthogranulomatous cholecystitis(XGC) clinically.METHODS: From July 2008 to June 2014, a total of 142 cases of pathologically diagnosed XGC were reviewed at our hospital, among which 42 were misdiagnosed as gallbladder carcinoma(GBC) based on preoperative radiographs and/or intra-operative findings. The clinical characteristics, preoperative imaging, intra-operative findings, frozen section(FS) analysis and surgical procedure data of these patients were collected and analyzed.RESULTS: The most common clinical syndrome in these 42 patients was chronic cholecystitis, followed by acute cholecystitis. Seven(17%) cases presented with mild jaundice without choledocholithiasis. Thirtyfive(83%) cases presented with heterogeneous enhancement within thickened gallbladder walls on imaging, and 29(69%) cases presented with abnormal enhancement in hepatic parenchyma neighboring the gallbladder, which indicated hepatic infiltration. Intra-operatively, adhesions to adjacent organs were observed in 40(95.2%) cases, including the duodenum, colon and stomach. Thirty cases underwent FS analysis and the remainder did not. The accuracy rate of FS was 93%, and that of surgeon's macroscopic diagnosis was 50%. Six cases were misidentified as GBC by surgeon's macroscopic examination and underwent aggressive surgical treatment. No statistical difference was encountered in the incidence of postoperative complications between total cholecystectomy and subtotal cholecystectomy groups(21% vs 20%, P > 0.05).CONCLUSION: Neither clinical manifestations and laboratory tests nor radiological methods provide apractical and effective standard in the differential diagnosis between XGC and GBC.

Effect of nodularity on mechanical properties and fracture of ferritic spheroidal graphite iron

Ferritic spheroidal graphite irons with nodularity from 72%to 96%were prepared.The relationship between the nodularity and the mechanical properties of the ferritic spheroidal graphite iron was investigated.The effect of nodularity on the mechanical properties and tensile fracture of the cast iron were studied.Results showed that the tensile strength Rm,yield strength Rp0.2,elongation to failure A5,and impact energy KV2 of the cast iron had a good linear relationship with its nodularity.Nodularity and annealing treatment would obviously affect the fracture characteristics of ferritic spheroidal graphite iron.The annealed ferritic spheroidal graphite iron with 93%nodularity showed a completely ductile rupture.With the decrease of nodularity from 93%to 72%,the cleavage fracture area ratio increased gradually from 0%to 8.3%.Compared with as-cast ferritic spheroidal graphite iron,annealing treatment reduced the cleavage fracture area of the ferritic spheroidal graphite iron.