Objective To measure and analyze the radiation dose for patients undergoing nuclear medicine examination,and to characterize radiation exposure of patients by using the estimated effective dose.Methods Patients undergoing nuclear medicine examinations were classified and the radiation doses from radiopharmaceuticals to patients were measured and calculated.Meanwhile,radiation exposure from computed tomography (CT) procedure was calculated on the basis of CT protocols and patients' information.The effective doses to patient from both the radiopharmaceutical and CT scan radiation were calculated and the factors influencing patient radiation doses were analyzed.Results For the patients undergoing positron emission tomography-computed tomography (PET-CT) examination,the average effective doses from positron radiopharmaceutical 18F-fluorodeoxyglucose (18F-FDG),18F-fluoro-l-thymidine (18 F-FLT),11C-choline,11 C-methylmethionine (11 C-MET) and 11 C-acetate (11 C-Ac) were (5.06 ± 0.73),(4.74±1.29),(1.71 ±0.05),(3.18±0.69) and (1.08±0.19) mSv,respectively.CTscan caused average effective dose was (8.80 ± 0.58) mSv.If a full diagnostic CT investigation was performed,the effective dose might be up to 27 mSv.Whereas for emission computed tomography (ECT) examinations,the average effective dose to the patients irradiated by single photon radiopharmaceutical 99Tcm-methylenediphosphonate (99Tcm-MDP),99Tcm-macroaggregated albumin (99Tcm-MAA),99Tcm-diethylentriaminpentaacetic acid (99 Tcm-DTPA),99Tcm-methoxyisobutyl isonitrile (99 Tcm-MIBI) and 99Tcm-pyrophosphate (99Tcm-PYP) were (4.63 ± 0.01),(1.71 ± 0.01),(1.18 ± 0.01),(7.19 ± 0.03) and (4.18 ± 0.01) mSv,respectively.Conclusions Radiopharmaceutical irradiation caused effective dose to the patients undergoing nuclear medicine examinations is from 1.08 to 7.19 mSv,while CT scan cause average effective dose is 8.80 mSv in PET-CT examination.

Objective To prepare and evaluate 99Tcm radiolabeled Cetuximab (C225) for imaging of EGFR specific binding.Methods Cetuximab antibody was reduced by 2-iminothiophene (2-IT).The radiolabeling of IT-Cetuximab with 99Tcm(99Tcm-IT-Cetuximab) was analyzed by HPLC,and was tested for in vitro stability and molecular integrity.The human lung cancer line (A549)-bearing nude mouse model was prepared for biodistribution and tumor targeted study.Tumor uptake was also measured by in vivo γ imaging.Results The labeling efficiency was 93.15％.The radiochemical purity was 96.46％ after purification.The in vitro stability was good in 5％ HSA,in which the radiochemical purity maintained above 80％ at 4 ℃ for 24 h.99Tcm-IT-Cetuximab showed good specific binding to tumor with peak uptake of (3.417±0.769) ％ID/g after 4 h.The T/NT ratio of blood increased to 1.454±0.174 at 24 h.γ imaging of A549-bearing nude mice xenografts also showed high T/NT ratio.Conclusions 99Tcm-IT-Cetuximab molecular probe could be prepared with high radiolabeling yield and radiochemical purity.It has excellent in vitro and in vivo stability,and shows specific uptake in A549 tumor.

Objective To evaluate the value of 18F-FDG PET/CT in tumor staging in patients with pancreatic cancer.Methods A total 77 patients (from June 2010 to August 2015;44 males, 33 females, age range 36-83 years) who underwent 18F-FDG PET/CT examination for pancreatic cancer and confirmed with pathology were enrolled in this retrospective study.All patients had not been treated before the PET/CT scanning and received surgery or biopsy 4 weeks after the scanning.Two-sample t test and ROC curve analysis were used for data analysis.Results 18F-FDG uptake was higher in 94.8%(73/77) of pancreatic lesions than that in normal pancreatic tissue.The range of SUVmax of pancreatic lesions was 2.4-13.4(mean: 6.2±2.4).SUVmax of patients with smaller primary lesion (minor axis≤2.0 cm) was significantly lower than that of larger lesion group (minor axis >2.0 cm;t=-2.661, P<0.05).A total of 46 patients underwent lymph node excision, and the mean number of excised lymph nodes per patient was 13.8±9.2.About 56.5%(26/46)cases with lymph nodes metastases were confirmed with pathology.When the cut-off value of minor axis of regional lymph nodes was 0.45 cm, ROC curve showed that the sensitivity, specificity and AUC were 84.8%(39/46), 65.2%(30/46) and 0.788, respectively.When the cut-off value of SUVmax of regional lymph nodes was 2.05, the sensitivity, specificity and AUC were 54.3%(25/46), 80.4%(37/46) and 0.759, respectively.18F-FDG PET/CT changed 18.2%(14/77)of patients′ treatment plan.Conclusions 18F-FDG PET/CT is a useful tool in pancreatic cancer staging.Though 18F-FDG PET/CT has no significant advantages in N-staging, it really helps to make a more accurate M-staging for clinical decision.