Influence of nonuniform activity distribution on cellular dosimetry.

Dosimetry of nonuniformly distributed 210Po,67Cu, and 123I was evaluated for a single cell, modeled as a homogeneous unity-density sphere with a radius of 7.7 mum, which is typical of a B-cell lymphoma cell. A Visual Basic program was used to calculate S factors and radial absorbed dose-rate profiles for these radionuclides, taking into account their individual radiation energy spectra. The resulting absorbed doses were compared with those for uniform activity distributions of the respective radionuclides. It was shown that detailed radiation energy spectra are required for accurate cell-level dosimetry, especially for Auger-electron emitters. Nonuniform intracellular activity distributions do not affect the cell-to-cell S factor (i.e., S(C <-- C)) dramatically but greatly influence the cell-to-nucleus S factor (i.e., S(C <-- N)).

General situation of radiation accidents in China.

Information on radiation accidents in China compiled by the health authorities was collected. About 468 accidents were reported in 1988-2004. Detailed data from 1988 to 1998 were analysed. As to the 332 accidents reported in 1988-98, 77.7% of the cases are related to lost sources, 84.64% are liability accidents and five persons died owing to the cases occurring in the application of gamma irradiators. It is essential to improve the data bank to manage radiation sources, and to make sure that the relevant laws, together with professional theory and technical knowledge, are disseminated well and learned by professionals.

Dose estimation by EPR spectroscopy of tooth enamel in Chinese medical diagnostic X-ray workers.

Individual accumulated doses were determined by electron paramagnetic resonance spectroscopy of tooth enamel in Chinese medical diagnostic X-ray workers. Dose determination was performed using a specially developed automatic spectrum processing procedure. The determined dose values owing to X rays for the three workers with entry year (the year they began their career as medical diagnostic X-ray workers) in the 1950s ranged from 435 to 903 mGy, the converted effective doses ranged from 91 to 190 mSv.

Study on Anti-tumor Activities & Tumor Radio-sensitivity of 17a?-D-Homo-Ethynylestradiol-3-Acetate / 医学研究杂志

Objective The paper reports anti-tumor activities and tumor radio-sensitivity research of the novel Estrogen compound 17a?-D-Homo Ethynylestradiol-3-Acetate to U_ 14 and S_ 180 sarcomas;and overall test high-activity and low toxicity traits of 17a?-D-Homo Ethynylestradiol-3-Acetate by the indexes of thymus gland,spleen,etc.Methods The mouse cervical cancer U_ 14 was selected and implanted in IRM-2 mice for anti-tumor assay,and sarcoma S_ 180 was selected for tumor radio-sensitivity assay,the drug was administered to all mice by i.v.way.Results 17a?-D-Homo Ethynylestradiol-3-Acetate has obvious anti-tumor activity to U_ 14 tumor,the best inhibitory rates is U_ 14 64.3%,and17a?-D-Homo Ethynylestradiol-3-Acetate has hardly any influence to hematogenous system(spleen index),immune system(thymus index);Nevertheless,the positive control drug CCP has obvious damage to spleen index and thymus index(P

Occupational exposures of Chinese medical radiation workers in 1986-2000.

Data on occupational exposures from medical uses of radiation in China during 1986-2000 are presented. Individual dose monitoring results in the reports of monitoring centres in different provinces in China during 1986-2000 were collected as the basic data. These data were summarised and then analysed. From 1986 to 2000, in diagnostic radiology, nuclear medicine and radiotherapy, the annual collective effective doses varied within the range 122.4-206.6, 5.4-9.3 and 4.1-10.3 man Sv, respectively; the average annual effective dose in these categories varied within the range 1.5-2.2, 1.2-1.6 and 1.0-1.5 mSv, respectively. Almost all the average annual effective doses in medical uses of radiation were <3 mSv in 1986-2000, and no monitored workers were found to have received an occupational exposure >50 mSv in a single year or >100 mSv in a 5-y period. After 1990, the protection status of medical radiation workers in China was sufficient.

Effect on dose owing to source displacement in coronary endovascular brachytherapy / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the effect on the dose distribution of source position displacement with the target region margin in catheter-based 192Ir line source endovascular brachytherapy.</p><p><b>METHOD</b>Dose rate distribution along longitudinal axes was estimated by the formula recommended by AAPM No.60 and No. 43.</p><p><b>RESULTS</b>In the two cases of source displacement (1.1 and 5 mm) doses of target region margin was decreased dramatically (at most 53.9% and 565.8% respectively) were compared to that of no source displacement, and the affected range was 6 mm and 9 mm respectively.</p><p><b>CONCLUSION</b>Source displacement will lead to the decrease of dose in target region margin.</p>

Mean absorbed dose calculation at cellular level for targeted radiotherapy using Auger-electron-emitters / 中华放射医学与防护杂志

Objective To calculate the mean absorbed doses at celluar and subcellular levels for uniformly and non-uniformly distributed Auger electron emitters. Methods The energy deposited in cell or nucleus by Auger electrons was analytically calculated using the polynomial representation of energy loss.S-values were subsequently computed for several target-source combinations.The absorbed dose and dose distribution were calculated for spherically symmetric radionuclide distributions depending linearly and exponentially on the radial position.The dose profile as a function of the source radial coordinate was also evaluated for typical cell sizes.The contributions of photon radiation to absorbed dose in cells were ignored. Results The mean absorbed dose and dose distribution depend largely on the size of target cells,the radiation spectrum and intracellular localization and distribution of radionuclides.The contribution of intranuclear radionuclides to mean absorbed dose was larger than that of extranuclear ones. Conclusion Auger electrons can produce high local energy deposition in cells because of their very low energies and extremely short ranges.Our dose calculation method is simple.The results are reliable and can be used in many fields.