Vol.20,

In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module's acceptance test at Shanghai Synchrotron Radiation Facility (SSRF), the Venturi tube is used to measure the quality factor of SRF cavity at 4.2 K. During the test, the venturi tube is be calibrated by increasing heat load with internal heater. In this paper, the horizontal test principle and venturi effect are briefly introduced. The authors find out a correct way to calibrate the venturi tubes, the calibration results are presented here. From the calibration results, one can deduce the static loss of each module, the source of static loss is also analyzed.

417

An S-band cavity BPM is designed for a new injector for HLS (Hefei Light Source). It consists of two cavities that work on 2448 MHz: a re-entrant position cavity tuned to TM110 mode and a reference cavity tuned to TM010 mode. Cut-through waveguides are used as pickups to suppress the monopole signal. Simulations with different assumption of dimension change are performed to evaluate errors caused by mechanical error and give general tolerance. Design of electronics is given. Theoretical resolution of this design is 31 nm.

445

Beach rocks samples were collected from South East Coast of Tamilnadu, India. The mineralogical composition was determined using FT-IR and XRD. The natural radioactive measurements to detect radioactive elements were determined by gamma ray spectrometer. The multi-element analyses were carried out by INAA (Instrumental neutron activation analysis), with the standard Estuarine Sediment as reference material. The geochemical behavior of elements in the region is discussed. The occurrence of the radioactive and non-radioactive elements is discussed for their geological significance. The results were used to assess environmental toxicity of heavy metals and radiation hazard in the study area.

480

The study is to investigate the feasibility and advantages of heavy ion beams on radiotherapy. The cellular cycle and apoptosis, cell reproductive death and p53 expression evaluated with flow cytometry, clonogenic survival assays and Western blot analysis were examined in lung carcinoma cells after exposure to 89.63 MeV/u carbon ion and 6 MV X-ray irradiations, respectively. The results showed that the number colonyforming assay of A549 was higher than that of H1299 cells in two radiation groups; A549 cellular cycle was arrested in G₂/M in 12 h and the percentage of apoptosis ascended at each time point of carbon ion radiation with doses, the expression of p53 upregulated with doses exposed to X-ray or carbon ion. The cell number in G₂/M of H1299 and apoptosis were increasing at all time points with doses in ¹²C⁶⁺ ion irradiation group. The results suggested that the effects of carbon ions or X rays irradiation on lung carcinoma cells were different, ¹²C⁶⁺ ion irradiation could have more effect on upregulating the expression of p53 than X-ray, and the upregulated expression of p53 might produce the cellular cycle G₂/M arrested, apoptosis increasing; and p53 gene might affect the lung cancer cells radiosensitivity.

579

A Fricke-PVA-xylenol orange (FPX) hydrogel dosimeter, in good transparency, was prepared by physical crosslinking for three-dimensional dose measurements. The process of mixing the chemical dosimeter with the PVA solution was carried out at room temperature, which reduced the influence of auto-oxidation rate. Gradation in color was obviously observed with different distance from the radiation source after 6 MeV electron beam irradiation for radiotherapy. The effects of irradiation dose and three components of the FPX gel dosimeter, i.e. ferrous ions, xylenol orange (XO) and sulphuric acid on sensitivity and stability of dose response were investigated by UV-vis spectrophotometric measurement. The dose response of the FPX gel dosimeter was linear in the range 0~2.0 Gy. The orthogonal test was employed to find the optimal composition of the gel dosimeter with a sensitivity of about 0.095 cm^-1·Gy^-1. It was found that XO concentration greatly affected the sensitivity of dose response and lower concentrations of the ferrous ion and XO gave higher sensitivity within the range 0~2.0 Gy.

425

This work was conducted for radiolabeling of an anticancer antibiotic, i.e. doxorubicin with ⁶¹Cu for production of possible tracer used in PET oncology. ⁶¹Cu was prepared with natural zinc target and 22 MeV150 µA protons via ^natZn(p, xn)⁶¹Cu reaction with a yield of 123.2 MBq·µA^–1·h^–1. Optimization reactions were performed for pH, temperature and concentration. Biodistribution of the tracer was studied in normal and fibrosarcoma bearing mice. At the optimized conditions, ITLC showed that radiochemical purity was over 97% with a specific activity of 2.22×10³MBq ·mmol^-1·L^-1. This was kept unchanged even with presence of human serum as well as room temperature for 5 h. Biodistribution of the tracer in fibrosarcoma bearing mice demonstrated significant tumor uptake after 2 h. This tracer can be used in the detection of various tumors responding to doxorubicin chemotherapy using PET scan and/or determination of tumor therapy response to doxorubicin chemotherapy.

434

In order to prepare a specific melanocortin type 2 receptor (MC2R) ligand, β^1-24-corticotrophin was prepared in one-step reaction with [¹⁸F] SFB and β-1-24-corticotrophin pharmaceutical solution (1 mg/mL, pH=6.5). [¹⁸F]SFB was prepared in a semi-automated module in two steps with an overall radiochemical yield of 47% to EOB (not-decay corrected) in 90 min. The ¹⁸F-labeled intermediates and ¹⁸F-labeled peptide was checked by RTLC and HPLC. The results show that the radiochemical purity is >95% and the yield to EOB (not-decay corrected) is 29% for final ¹⁸F-labeled peptide at optimized conditions. Preliminary in vivo studies in normal mice were performed to determine biodistribution of the ¹⁸F-labeled peptide for 150 min. The results show that the major tracer uptake is consistent with the natural distribution of MC2R receptors in mammals. Testes/blood and testes/muscle ratios for ¹⁸F-labeled peptide at 150 min were 184 and 1.56, respectively, and adipocyte/blood and adipocyte/muscle ratios at 120 min were 221 and 142, respectively. The data support the specific receptor binding of the radiolabeled peptide as reported for MC2R receptor accumulation in adipocytes and testes and demonstrates the retention of biological activity of the peptide. This tracer can be used in detection of MC2R distribution in malignancies and sex organ diseases.

509

This work is to demonstrate feasibility of imaging the expression of herpes simplex virus 1-thymidine kinase (HSV1-tk) reporter gene in rabbits myocardium by using the reporter probe ¹³¹I-2’-fluoro-2’-deoxy-1-β-_D- arabinofuranosyl-5-iodouracil (¹³¹I-FIAU) and SPECT. Rabbits of the study group received intramyocardial injection of Ad5-tk and control group received aseptic saline injection. Two sets of experiments were performed on the study group. Rabbits of the 1^st set were injected with ¹³¹I-FIAU 600 µCi at Day 2 after intramyocardial transfection of Ad5-tk in 1×10⁹, 5×10⁸, 1×10⁸, 5×10⁷ and 1×10⁷ pfu, and heart SPECT imaging was done at different hours. Rabbits of the 2^nd were transferred various titers of Ad5-tk (1×10⁹, 5×10⁸, 1×10⁸, 5×10⁷, 1×10⁷ pfu) to determine the threshold and optimal viral titer needed for detection of gene expression. Two days later, ¹³¹I-FIAU was injected and heart SPECT imaging was performed at 6, 24 and 48 h, before killing them for gamma counting of the hearts. Reverse transcription-polymerase chain reaction (RT-PCR) was used to verify the transferred HSV1-tk gene expression. Semi-quantitative analysis derived of region of interest (ROI) of SPECT images and RT-PCR images was performed and the relationship of SPECT images with ex vivo gamma counting and mRNA level were evaluated. SPECT images conformed ¹³¹I-FIAU accumulation in rabbits injected with Ad5-tk in the anterolateral wall. The optimal images quality was obtained at 24~48 h for different viral titers. The highest radioactivity in the focal myocardium was seen at 6 h, and then declined with time. The threshold was 5×10⁷ pfu of virus titer. The result could be set better in 1~5×10⁸ pfu by SPECT analysis and gamma counting. ROI-derived semi-quantitative study on SPECT images correlated well with ex vivo gamma counting and mRNA levels from RT-PCR analysis. The HSV1-tk/¹³¹I-FIAU reporter gene/reporter probe system is feasible for cardiac SPECT reporter gene imaging. The optimal Ad5-tk titer is 1~5×10⁸ pfu and optimal imaging time is 24~48 h after transferred Ad5-tk in rabbit. The imaging of transgene expression in heart might be used for noninvasive imaging of gene therapy in cardiac diseases in human.

407

The clinical trials of tumor therapy using heavy ions beam ¹²C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy ¹²C beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy ¹²C beam in active pencil beam scanning mode.

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486

In this study, the variation of the temperature distribution of the fuel plate in Tehran Research Reactor core was studied in case of coolant channels blockage. While the experimental method is not possible, both the analytical and simulation methods were used to obtain the more reliable data. The results show that one channel blockage will increase the fuel temperature to about 100%, but it does not lead to clad melt down still. With further calculation and simulation it is understood that if the coolant velocity drops to 90% of its nominal value, it may causes the clad melting down. At least two channels with complete blockage even at the positions far from the core center can also melt down the clad.

441

Contamination of soil, water or air, due to a failure of containment or disposal of high level nuclear wastes, can potentially cause serious hazards to the environment or human health. Essential elements of the environment and radioactivity dangers to it are illustrated. Issues of high level nuclear waste disposal are discussed with a focus on thermodynamic equilibrium and environment ethics. Major aspects of the issues are analyzed and described briefly to build a perception of risks involved and ethical implications. Nuclear waste containment repository should be as close as possible to thermodynamic equilibrium. A clear demonstration about safety aspects of nuclear waste management is required in gaining public and political confidence in any possible scheme of permanent disposal. Disposal of high level nuclear waste offers a spectrum of environment connected challenges and a long term future of nuclear power depends on the environment friendly solution of the problem of nuclear wastes.

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