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.

Progress of photonuclear cross sections for medical radioisotope production at the SLEGS energy domain

Photonuclear reactions using a laser Compton scattering(LCS)gamma source provide a new method for producing radioisotopes for medical applications.Compared with the conventional method,this method has the advantages of a high specific activity and less heat.Initiated by the Shanghai Laser Electron Gamma Source(SLEGS),we conducted a survey of potential photonuclear reactions,(γ,n),(γ,p),and(γ,γ')whose cross sections can be measured at SLEGS by summarising the experimental progress.In general,the data are rare and occasionally inconsistent.Therefore,theoretical calculations are often used to evaluate the production of medical radioisotopes.Subsequently,we verified the model uncertainties of the widely used reaction code TALYS-1.96,using the experimental data of the^(100)Mo(γ,n)^(99)Mo,^(65)Cu(γ,n)^(64)Cu,and^(68)Zn(γ,p)^(67)Cu reactions.

Accurate Formulae for the Cross-Section Data for the Radio-Halogen I-123 from Cyclotron Production

123I is the most widely used cyclotron-produced radio-halogen in medical research. In this paper, excitation function formulae for the nuclear reactions of 123I production are introduced. 124Te (p, 2n)123I and 127I (p, 5n)123Xe → 123I nuclear reactions have been studied as a function of the energy of the neutrons. Both two formulae were created using the least squares regression of the experimental cross sections data, which were obtained from the Experimental Nuclear Reaction Data EXFOR Database version of 2023. The proposed formulae were evaluated using two statistical indicators for goodness-of-fit. High agreement was observed between the empirical and experimental results for both nuclear processes.

Localized Effects of Mechanical Wounding and Exogenous Jasmonic Acid on the Induction of Secondary Laticifer Differentiation in Relation to the Distribution of Jasmonic Acid in Hevea brasiliensis

The relationship between the effect of exogenous jasmonic acid (JA) on the induction of secondary laticifer differentiation and the distribution of JA in the seedling of Hevea brasiliensis Mull. Arg. was investigated with the aid of experimental morphological and radioisotope technique. Most radioactivity of H-3-JA sustained in treated site within one hour while no radioactivity was detected in new shoot and the radioactivity in upper leaf was much less than that in the parts below the treated site, suggesting that JA was mainly transported downwards in the shoot of H brasiliensis. Mechanical wounding hindered the entrance of exogenous JA remarkably while held back the entered JA to the regions around wounded site. The effect of exogenous JA and mechanical wounding on the induction of the secondary laticifer differentiation was limited to treated site where high level of JA was expected. Mechanical wounding reduced the effect of exogenous JA on the differentiation of secondary laticifer, which could be ascribed to the hindrance of mechanical wounding to the entrance of exogenous JA. It was concluded from the combined data that a high accumulation of JA was required for inducing the secondary laticifer differentiation in H. brasiliensis.

乳糖化修饰纳米基因载体的肝靶向性研究(英文)

Objective:To compare the targeting effects of lactosarninated alginate(AlgNP)、polyethylene glycol - coated hydroxyapatite- poly- L- lysine nanoparticles (PLL- PCHNP)and relative nonlactosaminated ones load ed with exogenous gene on liver via peripheral intravenous route. Methods:Preparation of AlgNP based on control of gelification phenomenon of algiante by calcium ions and HA- PLLNP with collosol - gel method, both further modified with lactosaminated - poly- L - lysine synthesized by reductive lactosamination . We used pEGFPCl as the reporter gene to establish receptor- mediated and positive liver targeting nanoparticles- gene model. The potential of adsorbing DNA on nanoparticles was analysed by electrophoresis and spectrophotometer. Then different complexes were transferred into the rat's body by peripheral intravenous route and their targeting characteristics in liver were investigated by using radioisotope tracing assay. Results: PCHNP presented as needle - like particles with a diameter of 20nm by TEM and could be effectively combined with PLL. The diameter of AlgNP was 280nm. Agarpse gel electrophoresis showed both nanoparticles could effectively combine with DNA and the optimal proportion of PLLPCHNP and DNA was 30:1 (w/w); DNA mixed ratio of AlgPLL was 68.3 % by spectrophotometer. The radioactivities in liver for the two lactosaminated nanoparticles were higher than the nonlactosaminated ones. No statistic difference between AlgNP and AlgLacNP could be found . Conclusions: Lactosaminated naroparticles can target to liver more effectively by peripheral intravenous route than nonlactosaminated ones, which is closely concerned with the characteritics of the nanopartide complex.

Clinical observation of 125 I labeled anti alpha fetoprotein antibody radioimmunotherapy in hepatocellular carcinoma *

AIM To observe the therapeutic effects and toxic side reactions of 125 I labeled hourse anti human AFP polyclonal antibodies in immuno targeting therapy against hepatocellular carcinoma (HCC).

Serial stimulated thyroglobulin measurements are more specific for detecting distant metastatic differentiated thyroid cancer before radioiodine therapy

Objective: Preablative stimulated thyroglobulin (ps-Tg) has the potential to be used in identifying distant metastatic differentiated thyroid carcinoma (DM-DTC), but its single level can be affected by remnant thyroid tissue and thyrotropin (TSH). The objective of this retrospective study was to evaluate the value of serial ps-Tg measurements in identifying DM-DTC specifically. Methods: A total of 317 DTC patients with serial measurements of ps-Tg, TSH and anti-Tg antibody were divided into M1 (n=72) and M0 (n=245) according to the presence of distant metastasis (DM) or not. The initial psTg measurement, with a corresponding TSH exceeding 30 mu IU/mL, was marked as Tg1, and ps-Tg measured right before radioactive iodine (RAI) therapy was defined as Tg2, with a median interval of 8 days. Delta Tg denotes Tg2-Tg1, and Delta TSH denotes TSH2-TSH1. Tg1, Tg2, Delta Tg, and Delta Tg/Delta TSH were tested for efficacy in identifying DM-DTC using receiver operating characteristic (ROC) curve analysis, and further compared with chest computed tomography (CT) and posttreatment whole-body RAI scan (RxWBS). Results: Compared with single ps-Tg measurement (Tg1 or Tg2), both Delta Tg and Delta Tg/Delta TSH were more narrowly distributed around zero in the M0 group, which made their distribution in the M1 group more distinguished in a relatively dispersed way. Delta Tg/Delta TSH manifested a higher accuracy (88.64%) and specificity (90.20%) in identifying DM-DTC than Tg1 or Tg2 measurements, with a much higher specificity than chest CT (90.20% vs. 66.00%) and a much higher sensitivity than RxWBS (83.33% vs. 61.11%). Conclusions: Serial ps-Tg measurements even over as short an interval as 8 days hold incremental value in identifying DM-DTC. Delta Tg/Delta TSH is a specific early biochemical marker for DM-DTC.

Pharmacokinetics of radioimmunotherapeutic agent of direct labeling mAb ^(188)Re-HAb18

AIM:To labed Anti-hepatoma monoclonal antibody(mAb) fragment HAb18 F(ab')_2 was labeled with 188 Re for the pharmacokinetic model of ^(188)Re-HAb18 F(ab')_2 and to evaluate its pharmacokinetic parameters in hepatoma- bearing nude mice. METHODS:HAb18 F(ab')_2 was directly labeled with ^(188)Re using 2-mercaptoethanol(2-ME)as reducing agents. Labeling efficiency and immunoreactivity of ^(188)Re-HAb18 F (ab')_2 were evaluated by Whatman 3MM paper chromatography and live cell assay,respectively. Biodistribution analysis was also conducted in nude mice bearing human hepatoma in which animals were sacrificed at different time points(1,4,18,24 and 24h)after ^(188)Re-HAb18 F(ab')_2 was injected through tail-vein into hepatoma-bearing nude mice.The blood and radioactivity of organs and mass were measured.The concentrations of ^(188)Re-HAb18 F(ab')_2 were evaluated with a pharrnacokinetic 3P97 software. RESULTS:The optimum labeling efficiency and immunoreactive fraction were 91.7% and 0.78%, respectively.The parameters of ^(188)Re-HAb18 F(ab')_2 were: T_(1/2),2.29h;Vd,1.49×10^(-9)L·Bq^(-1);AUC,20.49×10~9Bq·h· L^(-1);CL,0.45×10^(-3)L·h^(-1).^(188)Re-HAb18 F(ab')_2 could locate specially in hepatoma with high selective reactivity of HAb18 F(ab')_2.^(188)Re-HAbl8 F(ab')_2 was mainly eliminated by kidney.The maximal tumor to blood ratio was at 48h,and maximal tumor to liver ratio was at 18h. CONCLUTION:The pharmacokinetics of ^(188)Re-HAb18 F(ab')_2 fit a I-compartment model.^(188)Re-HAb18 F(ab')_2 can be uptaken selectively at the hepatoma site.

Baculovirus vector-mediated transfer of NIS gene into colon tumor cells for radionuclide therapy

AIM:To investigate the feasibility of radionuclide therapy of colon tumor cells by baculovirus vector-mediated transfer of the sodium/iodide symporter(NIS) gene.METHODS:A recombinant baculovirus plasmid carrying the NIS gene was constructed,and the viruses(BacNIS) were prepared using the Bac-to-Bac system.The infection efficiency in the colon cancer cell line SW1116 of a green fluorescent protein(GFP) expressing baculovirus(Bac-GFP) at different multiplicities of infection(MOI) with various concentrations of sodium butyrate was determined by flow cytometry.An in vitro cytotoxicity assay was also conducted after infection of SW1116 cells with Bac-NIS.Iodine uptake of Bac-NIS infected SW1116 cells and inhibition of this uptake by sodium perchlorate was examined,and the effect of Bac-NISmediated 131 I in killing tumor cells was evaluated by cell colony formation tests.RESULTS:Infection and transgene expression in SW1116with Bac-GFP were significantly enhanced by sodium butyrate,as up to 72% of SW1116 cells were infected with the virus at MOI of 400 and sodium butyrate at 0.5 mmol/L.No obvious cytotoxicity was observed under these conditions.Infection of SW1116 with Bac-NIS allowed uptake of 131 I in these tumor cells,which could be inhibited by sodium perchlorate.The viability of SW1116 cells infected with Bac-NIS was significantly lower than with Bac-GFP,suggesting that NIS gene-mediated 131 I uptake could specifically kill tumor cells.CONCLUSION:Baculovirus vector-mediated NIS gene therapy is a potential approach for treatment of colon cancer.

Distribution and Accumulation of Neodymium and Its Effect on Secretion of Progesterone in Mice

Distribution and accumulation of Nd, and its effect on secretion of progesterone in mice were studied using radioisotope tracer ((()^(147)Nd)) technique. Following single intraperitoneal administration of neodymium traced with (()^(147)Nd) at a dose of 200 mg·kg^(-1), uneven distribution of the radioactive Nd occurred in various tissues and organs. Much amount of (()^(147)Nd) accumulates in the bone, and the residue increases with the lapse of time. Some amount of radioactivity was also detected in eyes, blood and brain, but the accumulation decreased with the time due to excretion and re-distribution in mice. In comparison with controls, concentration of progesterone is found to be significantly lower in the serum of administered mice, indicating a significantly inhibitory effect of Nd on secretion of progesterone.

Investigation of production of medical ^(82)Sr and ^(68)Ge for ^(82)Sr/^(82)Rb and ^(68)Ge/^(68)Ga generators via proton accelerator

How to operate^(82)Sr/^(82)Rb and ^(68)Ge/^(68)Ga generators used in the positron emission tomography scan process is explained, and the importance of ^(82)Sr and ^(68)Ge radionuclides for these generators is revealed. To produce medical ^(82)Sr and ^(68)Ge by means of a proton accelerator in an irradiation time of 24 h, a proton beam current of250 l A, and an energy range E_(proton)= 100 →5 MeV, the cross sections and the neutron emission spectrum curves of(p,xn) reaction processes on Rb-85, Ga-69 and Ga-71 targets were calculated, and the activities and yields of the product were simulated for the reaction processes. Additionally, the integral yields of the reaction processes were determined via the calculated cross-sectional curves and the mass stopping power obtained from the X-PMSP program. Furthermore, based on the obtained results, the appropriate reaction processes for the production of ^(82)Sr and ^(68)Ge isotopes on Rb-85, Ga-69, and Ga-71 targets are discussed.

Short-term effectiveness of radiochemoembolization for selected hepatic metastases with a combination protocol

AIM： To introduce the combination method of radio- chemoembolization for the treatment of selected he- patic metastases. METHODS： Twenty patients with biopsy proven hepat- ic metastases were selected from those who underwent transarterial radiochemoembolization, a novel combina- tion protocol, between .lanuary 2009 and July 2010. Patients had different sources of liver metastasis. The treatment included transarterial administration of three chemotherapeutic drugs （mitomycin, doxorubicin and cisplatin）, followed by embolization with large （50-150 μm） radioisotope particles of chromic 32R Multiphasic computer tomography or computer tomography stud- ies, with and without contrast medium injections, were performed for all patients for a short-term period before and after the treatment sessions. The short-term effec- tiveness of this procedure was evaluated by modified response evaluation criteria in solid tumors （mRECIST）, which also takes necrosis into account. The subjective percentage of necrosis was also assessed. The re- sponse evaluation methods were based on the changes in size, number, and the enhancement patterns of the lesions between the pre- and post-treatment imaging studies. RESULTS： Patients had liver metastasis from colorectal carcinomas, breast cancer, lung cancer and carcinoid tumors. The response rate based on the mRECIST criteria was 5% for complete response, 60% for par- tial response, 10% for stable disease, and 25% for progressive disease. Regarding the subjective necrosis percentage, 5% of patients had complete response, 50% had partial response, 25% had stable disease, and 20% had progressive disease. Based on traditional RECIST criteria, 3 patients （15%） had partial response, 13 patients （65%） had stable disease, and 4 patients （20%） had disease progression. In most patients, colorectal carcinoma was the source of metastasis （13 patients）. Based on the mRECIST criteria, 8 out of these 13 patients had partial responses, while one remained stable, and 5 showed progressive disease. We also had 5 cases of breast cancer metastasis which mostly remained stable （4 cases）, with only one partial response after the procedure. Six patients had bilobar involvement; three of them received two courses of radiochemoembolization. The follow up imaging study of these patients was performed after the second ses- sion. In the studied patients there was no evidence of extrahepatic occurrence, including pulmonary radioac- tive deposition, which was proven by Bremsstrahlung scintigraphy performed after the treatment sessions. For the short-term follow-ups for the 2 mo after the therapy, no treatment related death was reported. The mostly common side effect was post-embolization syndrome, presented as vomiting, abdominal pain, and fever. Nineteen （95%） patients experienced this syndrome in different severities. Two patient had asci- tes （with pleural effusion in one patient） not related to hepatic failure. Moreover, no cases of acute liver failure, hepatic infarction, hepatic abscess, biliary necrosis, tu- mor rupture, surgical cholecystitis, or non-targeted gut embolization were reported. Systemic toxicities such as alopecia, marrow suppression, renal toxicity, or cardiac failure did not occur in our study group. CONCLUSION： Radiochemoembolization is safe and effective for selected hepatic metastases in a short- term follow-up. Further studies are required to show the long-term effects and possible complications of this approach.

Exploratory study of betavoltaic battery using ZnO as the energy converting material

Third-generation-semiconductor zinc oxide is utilized as an energy converting material in a betavoltaic battery, where 0.06 Ci^(63) Ni and 8 Ci^(147) Pm are used as the beta sources. Based on a Monte Carlo simulation, the full scales of the devices are derived as 17 and 118 lm,respectively, for both sources. The influences of semiconductor doping concentrations on the electrical properties of the devices are analyzed. For a typical doping concentration N_A= 10^(17) cm^(-3), N_D= 10^(16) cm^(-3), the conversion efficiencies are 7.177% and 1.658%, respectively, using63 Ni and147 Pm sources. The calculation results of energy deposition in materials for the two sources show that the doping concentrations drop to 1 × 10^(13)–5×10^(14) cm^(-3) and 1 × 10^(12)–5×10^(13), and accordingly, the energy conversion efficiencies rise to 14.212% and 18.359%, respectively.

Tc-99m ciprofloxacin imaging in diagnosis of chronic bacterial prostatitis

Aim: To investigate the value of Tc-99m ciprofloxacin imaging in the differential diagnosis of chronic bacterial prostatitis. Methods: The study included 4 normal subjects as the negative controls, 2 patients with acute prostatitis or cystourethritis as the positive controls and 59 patients diagnosed as chronic bacterial prostatitis or chronic pelvic pain syndrome by traditional laboratory tests. In every subject, the single photon emission computerized tomography images were obtained 3 h after intravenous injection of Tc-99m Ciprofloxacin. The results of the imaging were compared with those of laboratory tests. Results: On the images, negative uptake was observed in all normal subjects, while strong hot uptake, in the whole prostate of acute prostatitis patients and in the whole urethra of acute cystourethritis patients. In 13 (68 %) of 19 patients categorized as chronic bacterial prostatitis by standard laboratory tests, hot uptake with less intensity than that of acute prostatitis was observed in the prostate area around the prostatic urethra. Negative uptake in the prostate was observed in 6 of 19 patients (32 %) categorized as chronic bacterial prostatitis. Interestingly, hot uptake in the prostate was exhibited in 28 (70 %) of the 40 patients categorized as chronic pelvic pain syndrome. Conclusion: Tc-99m ciprofloxacin imaging is helpful in the differential diagnosis of prostatitis syndrome.

Man-made plutonium radioisotopes in the salt lakes of the Crimean peninsula

Investigations of ^(239+240)Pu and ^(238)Pu in the surface layer(0–5 cm) of bottom sediment in the Crimean 10 salt lakes from 4 geographical groups were carried out for the first time. The ^(239+240)Pu varied widely between regional geographical groups of lakes as well as within groups too and ranged from 11±4 to 451±43 mBq^(239+240)Pu/kg. The highest levels of ^(239+240)Pu—419±27, 443±24 and 451±43 mBq/kg were observed in the Yevpatoriya(Lake Kyzyl-Yar), the Tarkhankut(Dzharylhach) and the Kerch group(Tobechik), respectively. The lowest values of ^(239+240)Pu were identified in three lakes of the Perekop group and were 20±12, 24±6 and 48±6 mBq/kg. In all lakes ^(238)Pu was an order of magnitude lower than 239+240 Pu and varied from 4.8±2.6 to 30.7±5.5 mBq/kg. The ^(238)Pu activity was decay-corrected to 1986. The characteristic ratio of the ^(238)Pu/239+240 Pu activities in the sediment and percentage of the Chernobyl-derived Pu was calculated. The largest percentages of the Chernobyl-derived Pu were observed in the Evpatoriya group(Lake SasykSivash)—16.2%±8.26%, the Tarkhankut group(Dzharylhach)—8.4%±2.10% and the Kerch group(Aktash)—10.5%±5.56%. The study of the depth distribution of plutonium in the Lake Kyzyl-Yar bottom sediment core(0–25 cm) was fulfilled. It was shown that 239+240 Pu was high enough in all studied layers of bottom sediment, but the highest activity ratio ^(238)Pu/239+240 Pu(0.062±0.020) was found in the deepest layer of 15–20.5 cm and the percentage of Chernobyl-derived Pu was estimated at 6.8%±2.85% in this layer.

^(99)Tc^m direct labeling of angiostatin

Objective: To explore the method of 99 Tc m direct labeling of angiostatin (AS) and investigate the stability and bioactivity of the 99 Tc m labeled AS in vitro . Methods: AS was extracted, validated, and then labeled with 99 Tc m after having been reduced by 2 ME or SnCl 2. The best labeling condition was screened by cross design. The labeling efficiency was measured by TLC and column chromatography. The stability of 99 Tc m AS was observed and compared when BSA, saline and different molar ratios of Cys∶AS were separately added. The bioactivity of 99 Tc m AS was observed in human umbilical vein endothelial cell (CEV304). Results: The labeling efficiency can reach (97±1 5)% for the 2 ME reducing approach. Its best experimental condition was as follows: AS 100 μg,PB(0 5 mol/L, pH 7 3)1 ml, 2 ME 100 μg, MDP (dissolved in 1 ml saline) 10 μl, and 99 Tc mO 4 - 185 MBq. The labeling efficiency using SnCl 2 reducing method can reach (90±3 0)%. The best experimental procedure was as follows: AS 100 μg,boric acid buffer(0 1 mol/L, pH 9 0)1 ml, 2%SnCl 2 (dissolved in 1 mol/L hydrochloric acid) 20 μl, was added into MDP, which was diluted with 1 ml deoxygenized water, and then 20 μl, 99 Tc mO 4 - 185 MBq was added. The product of 99 Tc m labeled AS was stable in vitro and had the same bioactivity as AS. Conclusion: 99 Tc m direct labeling of AS is simple and efficient. And the bioactivity of 99 Tc m AS has no significant change compared with AS.

Innovative Use of Light-Weight Radioisotopes in Therapeutics and the Engineering of Light-Power Generators

Light weight radioisotope (LWR) 89Sr and 90Sr could be obtained from used rods in fission atomic plants. The economics of the disposal of nuclear bars indicate the convenience to develop added value applications. The difference in t1/2 allows 89Sr to deliver its energy at a rate 200 times higher than 90Sr. A large emission number of low penetrating power particles in a short time characterize 89Sr, which allows that these highly radioactive LWR involves a rather limited danger. Chemical similitude of calcium and strontium uptake has led to the use of 89Sr in treatment of bone cancer metastasis. 89Sr damages animal tissues because ionize water, but penetrates through the skin about: 5 to 8 mm. Hence, to obtain it in insoluble form, like obtaining 89Sr silicate, could make possible its wider use. Purifying 89Sr from contaminant 90Sr allows that after one year do not leave any contamination. LWR could be covered with scintillators substances, which by subtracting kinetic energy from beta-radiation, emit light and function as a major source of shielding. This treatment engineers Radioisotope Light Generators (RLG). Their light could activate photovoltaic cells (PV), which could lead to nano-devices without moving parts RLG-PV.

The progress of radioisotope technology and application in China

The inception of radioisotope and its application in China are introduced. The research,development, production, application progress and the future development prospect of radioisotope and its products are described.

Simulating the Production of Medical Radioisotopes in a Fast Thorium-Cycle ADS with SERPENT

Radiopharmaceuticals are used in nuclear medicine for diagnostic or therapeutic acts. The short decay half-lives of medical radioisotopes, especially those used for diagnostics, imply that they should be produced continuously and transported as quickly as possible to the medical units where they are used. Neutron-rich medical radioisotopes are generally produced in research reactors, like technetium-99m, lutetium-177, holmium-166 and iodine-131. On the other hand, proton-rich radioisotopes are produced via reactions with charged particles from accelerators like fluorine-18, gallium-67, iodine-123 and thallium-201. Beside this, innovative nuclear reactors are advocated as solutions to the issues of nuclear waste production and proliferation threats. Fast neutron, thorium-cycle and accelerator-driven subcritical (ADS) reactors are some of the most promising of them, proposed as safer fuel breeders and “waste burners”. This article examines the use of a fast thorium-cycle ADS with liquid lead-bismuth eutectic coolant for the production of molybdenum-99/technetium-99m and lutetium-177. Burnup simulation has been made with the Monte-Carlo (MC) code SERPENT. It is demonstrated that MC codes can advantageously be used to determine the optimal irradiation time for a given radioisotope in a realistic reactor core. It is also shown that fast thorium-cycle ADS is an economical option for the production of medical radioisotopes.

INVESTIGATIONS OF NATURAL AND ARTIFICIAL RADIOACTIVE ISOTOPES IN SEAWATER AND SEDIMENTS IN THE YELLOW SEA AND ADJACENT SOUTHEAST AREA

Investigations of natural and artificial radioisotopes including 90Sr,137Cs, gross B and U carried out in the Yellow Sea and adjacent southeast area in 1963. 1964, 1975 and 1978 showed that radioactive pollution by 90Sr and 137Cs from atmospheric fallout had gradually decreased with time due to the cessation of atmospheric nuclear weapons tests in the 70s. The distributions of natural and artificial radioactive isotopes (U, Ra, Th. 40K and 137Cs) in sediments southwest of Jizhou Island were uniform. The more uniform may be related to the soluble species of U[Uo2(CO3)4] in the seawater.The high value of Th at stations 3 and 6 was related to the sandy clay sediment; the low value at station 8 was related to sandy sediment. The content of 137Cs in the eddy area being less than about half of that in the China inshore area showed that the source of Cs may be insufficient orthat the conditions for enriching " Cs in the circulation eddy area were not favorable.