Objective To make a rapid dose estimation for a patient exposed locally to high dose radiation exposure in early stage of 5.7 192Ir source accident in Nanjing.Methods Based on source parameters,exposure pattern,and time duration,the doses were estimated using MCNP simulations with the aid of the proper East Asia adult male voxel phantom and main physiological parameters of the exposed patient.Result Absorbed doses to 16 organs or tissues were estimated to be in the range 0.03 to 9.16 Gy.Also,the iso-dose curves for the skin of legs showed clearly the dose difference between right and left legs.Absorbed doses to patient's testicles and prostrate,about 9.16 Gy,were higher than those to other organs or tissues.The skin of both legs was exposed locally to high dose radiation exposure,for which the estimated doses were in agreement with the results obtained from infrared thermal imaging.Conclusions Monte Carlo simulation technique and common software can be used for dose estimation in early stage of radiation accidents effectively with integrating proper models.

Objective To use three different methods in attempt to estimate the biological dose of the patient partially exposed to 192Ir source at5.7 accident in Nanjing,so as to provide dosimetric information for clinical remedy of exposed patients in the emergency of a nuclear accident.Methods Peripheral blood samples were collected on days 5 after exposure.The biological dose was estimated by the yields of dicentrics plus rings ( dic + r),cytokinesis-block micronuclei (CBMN) assay and nucleoplasmic bridge plus FHC (NPB + FHC).The homogeneity of radiation exposure was examined by Poisson distribution of dicentrics.Results By using three different methods,the whole body equivalent dose was dic + r estimated to be 1.51 Gy (95％ CI 1.40-1.61),1.47 Gy (95％ CI 1.36-1.60) by CBMN and 1.30 Gy (95％ CI 1.00-1.60) by NPB + FHC,respectively.A non-poisson distribution was also detected,suggesting partial body radiation exposure.Conclusions The estimated whole body equivalent dose ot a non-uniform radiation exposure was consistent with clinical diagnosis,suggesting that the yields ofdic + r,CBMN,as well as NPB + FHC,are efficient approaches to the estimation of biological doses.

Objective To explore the natural attenuation pattern of three biological dose estimation indexes in vivo by investigating the effect on biological dosimetry of peripheral blood sampling at different time points from the victim partially exposed to 192Ir radiation source at5.7 accident in Nanjing.Methods Peripheral blood of the patient was collected on days 5,40 and 280 after exposure,respectively.The yields of dicentrics plus rings chromosomes (dic + r),cytokinesis-block micronuclei (CBMN) and nucleoplasmic bridge + fusion + horse shoe + circular(NPB + FHC) were analyzed.The dynamic reduction and dose estimation were both observed using the biomarkers mentioned above after exposure.Results Compared to the estimates on days 5 after exposure,the dose values estimated on days 40 and 280 decreased by 34％ and 49％ fordic + r method,48％ and 79％ for the CBMN assay,and 48％ and 75％ for NPN + FHC method,respectively.Conclusions Three biological dose estimation indexes show a progressive decrease in vivo,with the half-life of dic + r/cell being 40 days.The doses estimated using these three indexes on days 40 after exposure showed a relative deviation more than 20％ compared with those on days 5 after exposure.

Objective To make a summary of radiation-induced changes in ocular lens and retinal lesions based on dynamic follow-up of a patient exposed to a radiation exposure from 192 Ir source accident,in order to provide the information and experience for the clinical diagnosis and treatment of such injury in emergency of a nuclear or radiation accident.Methods The examination methods included eye lens and visual acuity,slit-lamp examination,fundus examination,automated perimetry,optical coherence tomography (OCT) examination,fundus photography,and fundus fluorescein angiography (FFA).The patient was followed-up for 20 months.Comparative analyses were made of the follow-up results.Results One month after 192Ir radiation exposure,the visual acuities in both eyes were 1.0.Mild age-related opacities were observed in peripheral cortex,but the fundus looked normal.Twenty months later,the patient was followed-up.The visual acuities reduced to about 0.6,evident powder-and punctuate-like opacities could be observed in the cortex of the right lens,and mild turbid foci in the posterior polar and capsule.Multiple scotomata appeared in the superior temporal and inferior nasal in the right eye.The macular fovea thickness was not changed significantly in the right eye.Examination with fundus photography demonstrated mild optical nerve atrophy,drusens,and pale optic discs,while FFA examination showed punctuate or flocculent leakages in both eyes.Conclusions The lens opacity could be induced or accelerated by radiation exposure.In addition to the posterior capsule and pole cataracts,punctuate opacity within cortical layer may also occur.It also suggests that cataract and fundus injuries may occur later during long-term follow-up,even though the eyes may look normal during early examination after the patient exposed to the radiation.

Objective To provide nutritional supportive scheme for patients with radiation injury through the treatment of the one exposed to Nanjing 192Ir source accident.Methods The reasonable nutrition treatment scheme was made on the basis of dietary survey and nutritional index monitoring during clinical stages of the patient,including body weight,body mass index(BMI),biochemical indexes,electrolyte,etc.,as well as metabolic cart determination of resting energy expenditure (REE).Results Patient on admission (days 5 post-irradiated) weighing 42.5 kg,172 days after the first irradiated (the first skin grafting) fell to a minimum of 36 kg,then gradually rise,hen rose back to normal range on days 383 before discharge.Normal admission hemoglobin was 135 g/L,172 d after irradiated to a minimum of 54 g/L,normal discharge;when lymphocytes admission low as 0.5 × 109/L,58 days back to normal after exposure,172 days after irradiated down to 0.4 × 109/L.Serum albumin was normal admission 41.2 g/L,172 days after irradiated down to 25.3 g/L.The normal level of serum prealbumin was 0.22 g/L,248 days to a minimum of 0.04 g/L,the basic return to normal at discharge was 0.17 g/L.Admission normal liver function,bilirubin index slightly higher,the all in one parenteral nutrition after about 2.5 months later,bilirubin and liver function indicators were gradually increased,the adjusted treatment and nutrition liver and gallbladder and other gradually returned to normal after treatment.REE and the body weight were determined by metabolic cart on days 294,308 and 342 for the energy requirements.Conclusions For patient with radiation injury,appropriate nutrition therapy is a key method for the clinical treatment and rehabilitation,which can maintain the nutritional status of patients and improve clinical treatment.

Objective To evaluate the radiosensitization and mechanism of DNA-dependent protein kinase catalytic subunit inhibitor NU7026 on HCT116 colorectal cancer stem cells.Methods The flow cytometry was used to determine the sub-population of cancer stem cells with the markers CD133/ CD44.The cells were divided into four groups:control group,20 μmol/L NU7926 group,2 Gy irradiation group,and 20 μmol/L NU7026 combined with 2 Gy irradiation group.Cell proliferation and survival were evaluated by colony-formation experiment.Flow cytometry was used to analyze the cell cycle distribution and apoptosis induction.γ-H2AX foci were detected with immune-fluorescence staining analysis by a laser confocal microscopy for investiating the DNA double-strand break repair.Results The flow cytometric data of CD133 +/CD44 + positive cells indicated that the sub-population of cancer stem cell (CSC) took the ratio of (88.14 ± 0.47)％ of the cultured HCT116 cells.The colony-formation efficiency of HCT116 cells was (84.75 ± 1.35) ％ in serum-free mediums in vitro culture.Compared to 2 Gy irradiation alone group,the NU7026 combined with 2 Gy irradiation group had a lower cell colony-forming ratio (t =7.21,P ＜0.01) and a lower survival ratio (t =7.22,P ＜ 0.01).The proportion of CSCs sub-population increased at 48 h post-2 Gy irradiation,suggesting that HCT116 CSCs was more resistant to ionizing radiation.Importantly,NU7026 largely decreased the proportion of CSCs sub-population in 2 Gy-irradiated cells.The difference of CSC proportion between 2 Gy irradiation alone group and 2 Gy combined with NU7026 treatment group was statistically significant (t =9.55,P ＜ 0.01).In addition,the group of NU7026 combined with 2 Gy irradiation had a higher ratio of G2/M arrest 24 h post-irradiation (t =7.67,P ＜ 0.01) and an increased induction of cell early apoptosis (t =8.24,P ＜ 0.05).48 h post irradiation as compared to 2 Gy irradiation alone group.NU7026 treatment significantly inhibited the cellular capacity of repairing DNA double-strand breaks induced by γ-ray irradiation.The γ-H2AX foci of the combined treatments group were much higher than that of 2 Gy irradiation alone group at 2,4,8,24 h postirradiation (t=19.58,11.95,7.01,9.45,P＜0.01).Conclusions DNA-dependent protein kinase catalytic subunit inhibitor NU7026 can significantly sensitize the cancer stem cells of colorectal carcinoma HCT116 cells to γ-ray irradiation.Multiple mechanisms are involved in the radiosensitization effect of NU7026,including DNA repair inhibition,elongation of G2/M arrest,and increase of radiation-induced apoptosis.

Objective To evaluate the therapeutic effect of adipose-derived mesenchymal stem cells on radiation enteritis.Methods A total of 52 male Sprague-Dawley rats were used in the present study.Herein,46 rats were randomly selected and irradiated with a dose of 15 Gy at their abdomens.Two hours post-irradiation,23 rats were randomly selected and infused intraperitoneally with adipose-derived mesenchymal stem cells in passage 6 from young-female donor.The other 23 rats were intraperitoneally infused with PBS.The rest 6 rats were set as normal control.During the first 10 days post-irradiation,peripheral blood-samples from irradiated rats were harvested for testing the levels of IL-10 in serum using ELISA assay.Additionally,after isolating the thymic cells and peripheral blood mononuclear cells,the percentages of CD4/CD25/Foxp(3)-positive regulatory T cells in thymus and peripheral blood were tested by flow-cytometry.Finally,infiltration of inflammatory cells and deposition of collagens within irradiated small intestine were analyzed by H&E staining and Masson Trichrome staining,respectively.Based on the MPO-immunohistochemistry staining,the type of infiltrated cells was identified.The Kaplan-Meier method was used for analyzing the survival rate of irradiated rats.Results During a period of 30 days post-irradiation,the irradiated rats receiving adipose-derived mesenchymal stem cells survived longer than those receiving PBS (t =4.53,P ＜ 0.05).Compared to the irradiated rats with PBS-treatment,adipose-derived mesenchymal stem cells could elevate the level of IL-10 in serum (7 d:t =13.93,P ＜ 0.05) and increase the percentages of CD4/CD25/Foxp(3)-positive regulatory T cells in both peripheral blood (3.5 d:t =7.72,7 d:t=11.11,10 d:t =6.99,P ＜0.05) and thymus (7 d:t =16.17,10 d:t =12.12,P＜ 0.05).Moreover,infiltration of inflammatory cells and deposition of collagens within irradiated small intestine were mitigated by adipose-derived mesenchymal stem cells.Conclusions Adipose-derived mesenchymal stem cells were capable of curing radiation enteritis.

Objective To investigate the impact of gantry angles on the position accuracy of buildin multi-leaf collimator (MLC) during static (step & shoot) intensity modulated radiotherapy (IMRT).Methods The position accuracy of MillenniumTM 60 pairs multi-leaf collimator (MLC) in Varian 23EX medical linear accelerator during 10 fractions of treatments with static intensity modulated radiotherapy (IMRT) was retrospectively analyzed by resolving dynamic therapy log files and MLC planning files.The single leaf position deviation and gap deviation of each MLC pairs were compared between expected values and actual outcomes.The impact of gantry angle on MLC position accuracy was also investigated with paired t-test between vertical and horizontal beams.Results All the MLC position deviations ranged within ± 1.0 mm,while the gap deviations were at the range of ± 1.5 mm.The statistical standard deviation of MLC position deviations among fractions was less than 0.06 mm.After all the 60 pairs of MLC leaves were taken into account,the M LC position deviation in the field of 103° was smaller than in the field of 0° (t =58.74,P ＜ 0.01),but there was no significant difference between 257° and 0°,while only the moving leaves were put into consideration,the MLC position deviation in the field of 103° was still smaller than in the field of 0°,but the MLC position deviation in the field of 257° was slightly higher than in thefield of 0° (t =41.95、-4.47,P ＜ 0.01).Conclusions The MillenniumTM 60 pairs MLC in Varian 23EX medical linear accelerator meets the mechanical quality assurance requirement during static IMRT treatments.The MLC positioning showed stable repeatability among treatment fractions.Although the MLC position accuracy is slightly affected by gravity from different gantry angles,but still meets the mechanical QA requirements for medical linear accelerator.This dynamic analysis method is expected to be a novel strategy which may improve the existing QA protocols.

Objective To analyze the impact of parotid's position and volume changing on radiation dose for head and neck cancer treated with TomoTherapy.Methods Totally 12 patients with head and neck cancer were treated with TomoTherapy.Before the treatment,the dose distribution was recalculated with MVCT images,which would obtain the parameters of position,volume and actual radiation dose for parotids.Results The volume of parotids in Plan2 was significantly lower than in Plan1,and the percentage reduction was 29.06％ and 31.78％ for left and right parotid,respectively (Z =6.77,3.06,P ＜ 0.05).Distance between the COM (center of mass) of parotids and the midline of body was significantly smaller in Plan2 than in Plan1,and the percentage reduction was 6.72％ and 6.19％ (t =5.14,5.80,P ＜ 0.05) at left and right side,respectively.Average dose and V26 for both parotids were higher than those in Plan1,increasing by an average of 37.74％,25.08％ (Z =-6.03,-5.31,P ＜ 0.05) for left parotid and 30.45％,19.33％ (Z =-5.43,-3.26,P ＜0.05) for right parotid,respectively.Conclusions The actual radiation dose to parotids was significantly increased during the radiation therapy for patients with head and neck cancer.There was a linear correlation between the decrease of distance between the COM of parotids and the midline of body and the percentage increase of parotids' radiation dose.No correlation between the reduction of parotids' volume and dose to parotids.In order to reduce the parotids' radiation dose,modification of treatment plan at the appropriate time is essential.

Objective To study the effects of internal exposure of 18F-FDG (18F-2-deoxy-2-fiuoroD-glucose) on the protein expressions of P53,XIAP (X-linked inhibitors of apoptosis protein) and GADD (growth arrest and DNA damage)45 in Lewis lung carcinoma,and to explore the possibility of applying 18F-FDG as a radiotherapy drug in vivo.Methods Lewis lung cancer transplanted tumor models were established via subcutaneous injection of 0.2 ml of 2 × 107/ml Lewis lung carcinoma cells at left hind limbs of 48 C57BL/6 mice that were randomly divided into high dose group,low dose group and control group with 16 mice each.After 7 d of cancer cell inoculation,18.5 × 107 Bq and 9.25 × 107 Bq of 18F-FDG in 0.2 ml saline or equal volume of physiological saline was intraperitoneally injected into three group mice,respectively.22 d post inoculation,the protein expressions of P53,XIAP and GADD45 were immuohistochemically detected by using SP approach.Results There was significant difference among the protein expressions in each group (x2 =8.30,16.02,7.68,P ＜0.05).The mean integral optic density of protein expression increased from 0.089 ± 0.033 in control group to 0.315 ± 0.028 in high dose group for P53,and from 0.126 ± 0.023 to 0.383 ±-0.035 for GADD45,but it decreased from 0.422 ± 0.034 to 0.149 ± 0.055 for XIAP.There was significantly difference of these protein expressions in each group (P53:F=5.26,P＜0.05;XIAP:F=4.29,P ＜0.05;GADD45:F=5.98,P ＜0.05).Conclusions 18F-FDG can up-regulate the expressions of P53 and GADD45 proteins and down-regulate the expression of XIAP protein in tumor cells,and it inhibits tumor growth by promoting cell apoptosis in the Lewis lung carcinoma tissue with a P53-dependent manner.