Objective To determine the activities of 131I for treating differentiated thyroid carcinoma with diffuse pulmonary metastases ( DTC-DPM ) from the perspective of internal radiation dosimetry.Methods According to Medical Internal Radiation Dosimetry (MIRD) schema, the activity constraint,from which the whole bdy retention at 48 h should not exceed 2.96 GBq (2.96 GBq rule), was converted to dose-rate constraint(DRC) to lungs at 48 h ( DRCLU ·48 h ) in 131I therapy for DTC-DPM. Based on the assumption of DRCLU·48 h at 48 h in lung, the fractions of whole body activities ( F48 ), the effective half times of 131I in lungs ( TLL ) and the remainder of body ( TRB ) were 0.6-0.9, 20- 120 h, and 10- 20 h, respectively. The maximum safe activities of 131I for different human phantoms from the Organ Level Internal Dose Assessment (OLINDA) software were calculated. Results According to MIRD schema and 2.96 GBq rule, DRCLU ·48 h should not exceed 46.4 mGy/h in 131I therapy for DTC-DPM. Depending on varying F48 h,TLL and TRB, the maximum safe activities of 131I were 6.77-81.36, 5.29-56.20, 5.08-55.19 and 3.87-40. 52 GBq for the male adult, female adult, 15-year-old, and 10-year-old patients with DTC-DPM, respec tively. Conclusion Dosimetry-guided 131I therapy for DTC-DPM considers adequately the differences of 131I kinetics in individual patients and can adjust administered activities of 131I on the precondition of avoiding radiological pneumonitis and pulmonary fibrosis.

Urinary brain-derived neurotrophic factor (BDNF),an ubiquitous neurotrophin,was found to rise in patients with benign prostatic hyperplasia (BPH).We hypothesized that the urinary level of BDNF could be a potential biomarker for lower urinary tract symptoms (LUTS) in patients with BPH.Totally,76 patients with BPH-caused LUTS and 32 male control subjects without BPH were enrolled.International Prostate Symptom Score (IPSS) was applied to assess the symptom severity of LUTS.Urodynamic tests were performed for the diagnosis of underlying detrusor overactivity (DO) in the patients with BPH.Urine samples were collected from all subjects.Urinary BDNF levels were measured using enzyme-linked immunosorbent assays and normalized by urinary creatinine (Cr) levels.Seventy-six BPH patients were divided into moderate LUTS group (n=51,7＜IPSS ≤ 20) and severe LUTS group (n=25,IPSS＞20) according to the IPSS.Of the 76 BPH patients,DO was present in 34 (44.7％)according to the urodynamic test.The urinary BDNF/Cr levels were significantly higher in BPH patients with moderate LUTS (8.29±3.635,P＜0.0001) and severe LUTS (11.8±6.44,P＜0.0001) than normal controls (1.71±0.555).Patients with severe LUTS tended to have higher urinary BDNF/Cr levels than patients with moderate LUTS (11.8±6.44 vs.8.29±3.635,P=0.000).The conditions of BPH with LUTS correlated with elevated urinary BDNF levels,and urinary BDNF levels were even higher in BPH-DO patients.The results of this study have provided evidence to suggest that urinary BDNF level test could evaluate the severity of LUTS in BPH patients,and BDNF level can be used as a biornarker for the diagnosis of DO in BPH patients.