Dosimetric analysis of thyroid doses from total cranial irradiation

The purpose was to estimate the radiation dose to the thyroid from total cranial irradiation with parallel opposed lateral fields of 1.25 MeV gamma rays of (60)Co, to represent the current treatment modality, and with 6 MV photon beams derived from a linear accelerator. The mean thyroid doses were measured using thermoluminescence dosemeters in the Rando phantom with two cranial irradiation set-ups: (1) the lateral beams were angled by rotating the collimator to avoid irradiation of the lens and healthy tissues and (2) the lateral beams were not angled, and shielding blocks were used to protect the lens and healthy tissues. For a cranial dose of 18 Gy, thyroid doses for child patients for (60)Co with the open and blocked fields were 0.27 and 0.32 Gy, respectively. With 6 MV, the thyroid dose was less than the doses for (60)Co open and blocked cranial fields by 17 and 10%, respectively. Unblocked cranial fields and a high-energy photon beam should be preferred for cranial irradiation of children.     

Sperm abnormalities in high- and low-dose-rate Gamma-irradiated Korean dark-striped field mice, Apodemus agrarius coreae

To evaluate the in vivo effects of low-dose-rate (0.7 mGy h(-1)) gamma radiation, abnormal shapes of sperm in the caudal epidydimus of Apodemus agrarius coreae (A. a. coreae) were used. The six categories of abnormal forms (amorphous heads, blunt hooks, excessive hooks, two heads and tails, folded tails and short tails) of sperm were observed eight days after gamma irradiation (0, 0.5, 1 and 2 Gy) with a high dose rate (0.8 Gy min(-1)) and a low dose rate. The frequency of total abnormal sperm gradually increased starting from 0.5 Gy after high-dose-rate radiation. Blunt hooks and short tails shaped sperm, in particular, were gradually increasing in the high-dose-rate irradiated mice. Dose rate reduction effects for the frequency of abnormal sperms in low-dose-rate irradiated mice to high-dose-rate irradiated mice were 1 at 0.5 Gy, 0.7 at 1 Gy and 0.5 at 2 Gy. Our results indicate that low-dose-rate radiation is not detrimental to spermatogenic cells.     

Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams

This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.     

Dose-rate dependent effects of ionizing radiation on vascular reactivity

This study was designed to investigate the dose-rate dependent effects of ionising radiation on endothelium- and NO-mediated reactivity of aorta and coronary vessels. Rats were exposed to acute ((137)Cs, 9 x 10(-4) Gy s(-1), 18 min) and chronic ((137)Cs, 2.8 x 10(-7) Gy s(-1), 41 days) radiation in 1 Gy dose. Acute irradiation transiently increased coronary flow in eNOS-activity-dependent manner on day 3 after exposure. In striking contrast, chronic irradiation caused a significant depression of coronary flow even on day 90 after irradiation and abolished the effects of NO-synthase inhibitor N-nitro-L-arginine methyl ester (10 micromol l(-1)). Furthermore, low intensity radiation strongly diminished the vasodilator properties of NO-donor sodium nitroprusside (5 micromol l(-1)). A similar pattern was observed in aortic rings. Endothelium-dependent vasodilation was increased on days 3 and 10 after acute irradiation, but strongly inhibited following chronic exposure for the entire post-radiation period. This was accompanied by a diminished vasodilator response to NO-donor on days 3, 10 and 30 of post-radiation but not on day 90. The data suggest that ionising radiation in 1 Gy induces changes of aortic and coronary vessels reactivity depending on the dose-rate and the interval after exposure.     

Bayesian estimation of dose thresholds

An example is described of Bayesian estimation of radiation absorbed dose thresholds (subsequently simply referred to as dose thresholds) using a specific parametric model applied to a data set on mice exposed to 60Co gamma rays and fission neutrons. A Weibull based relative risk model with a dose threshold parameter was used to analyse, as an example, lung cancer mortality and determine the posterior density for the threshold dose after single exposures to 60Co gamma rays or fission neutrons from the JANUS reactor at Argonne National Laboratory. The data consisted of survival, censoring times and cause of death information for male B6CF1 unexposed and exposed mice. The 60Co gamma whole-body doses for the two exposed groups were 0.86 and 1.37 Gy. The neutron whole-body doses were 0.19 and 0.38 Gy. Marginal posterior densities for the dose thresholds for neutron and gamma radiation were calculated with numerical integration and found to have quite different shapes. The density of the threshold for 60Co is unimodal with a mode at about 0.50 Gy. The threshold density for fission neutrons declines monotonically from a maximum value at zero with increasing doses. The posterior densities for all other parameters were similar for the two radiation types.     

Comparison of the dose-response relationship of radiation-induced apoptosis in the hippocampal dentate gyrus and intestinal crypt of adult mice

The present study compared the dose-response curves for the frequency of apoptosis in mouse hippocampal dentate gyrus (DG) and intestinal crypt using whole-body gamma irradiation. The incidence of gamma-ray-induced apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end-labelling (TUNEL) method. TUNEL-positive apoptotic nuclei in the DG and intestinal crypt were increased in a dose-dependent pattern (0-2 Gy). The dose-response curves were linear-quadratic, with a significant relationship between the appearance of apoptosis and irradiation dose. The slopes of the dose-response curves in the DG were much steeper (~5-6-fold) than those in the intestinal crypt within the range of 0-1 Gy exposure. Hippocampal DG might be a more effective and sensitive evaluation structure than the intestinal crypt to estimate the degree of radiation exposure in damaged organs of adult mice exposed to low irradiation dose.     

快中子诱发U251神经胶质瘤细胞的生物效应研究

目的:以14 MeV快中子照射体外培养的U251(人脑胶质瘤)细胞,研究快中子诱发U251的相关生物效应;方法:快中子照射U251细胞,吸收剂量分别为1、3、5、7 Gy,辐照后检测细胞的存活率、凋亡率、生长曲线以及周期变化等相关指标;结果:随着吸收剂量的增加,细胞存活率下降,凋亡率上升,呈良好的剂量-效应关系.照射后24h,细胞生长曲线无明显变化;照射后48 h,细胞增殖速度明显变缓;结论:快中子为高LET射线,与相关文献报道的γ射线相比,快中子具有较高的相对生物效应.     

Assessment of doses to the offspring of the Techa River cohort due to intakes of radionuclides by the mother

The Techa River was contaminated as a result of radioactive releases by the Mayak plutonium production facility in 1949-1956. The residents of riverside communities were exposed to internal irradiation from radionuclides ingested mainly with river water, and also to external gamma irradiation resulting from shoreline and flood-plain contamination. The most important role in population exposure was played by (89,90)Sr and 137Cs. The persons born after the onset of the contamination have been identified as the 'Techa River Offspring Cohort' (TROC). The TROC has the potential to provide direct data on health effects in progeny that resulted from exposure of a general population to chronic radiation. This report describes the results of the calculation of fetal doses due to intakes of radionuclides by their mothers. Particular attention has been given to fetal dose from 90Sr because this nuclide is the most significant in terms of population dose for the Techa River. The comparison of the fetal bone marrow doses evaluated using different approaches proposed in the literature has shown a large dispersal in dose values. The main cause of this is the difference in model assumptions simplifying some developmental aspects of fetal haematopoiesis and bone formation. This paper presents an analysis of these basic assumptions that could be useful for further improvements in fetal dosimetry.     

Patient and endoscopist radiation doses during ERCP procedures

The aim of the study was to calculate radiation doses for patients and staff during interventional Endoscopic retrograde cholangiopancreatography (ERCP) procedures. Patient age (A), kerma-area product (KAP), fluoroscopy time (T) and total number of films (F) were collected for 157 interventional ERCP procedures. One endoscopist (>10 y of experience) monitored using a thermoluminescent dosemeter worn over the lead apron performed the ERCPs. Median (range) KAP was 3.1 Gy cm(-2) (0.1-106.7 Gy cm(-2)). Median (range) A, T and F were 72 y, 2.6 (0.2-26.0) min and 2 (1-4) images, respectively. No correlation was observed between KAP and A, T or F. Monthly endoscopist dose was negligible due to the use of lead apron, collar and two lead-articulated ceiling mounted shields. The endoscopist dose is minimal when using appropriate protective measures. Patient doses showed large variation that has to be further investigated.     

Gene expression profiles for monitoring radiation exposure.

Previous demonstrations that the dose, dose rate, radiation quality, and elapsed time since ionising radiation exposure result in variations in the response of stress genes suggest that gene expression signatures may be informative markers of radiation exposure. Defining sets of genes that ate specific for different outcomes of interest will be key to such an approach. A generalised post-exposure prolile may identify exposed individuals within a population, while more specific fingerprints may reveal details of a radiation exposure. Changes in gene expression in human cell lines occur after as little as 0.02 Gy rays, and in peripheral blood lymphocytes alter as little as 0.2 Gy. Diverse genes are also elevated in vivo in mice 24 h after 0.2 Gy irradiation. Ongoing microarray analyses meanwhile continue to identify large numbers of potential biomarkers from varied irradiation protocols. Development of computation-intensive informatics analysis methods will be needed for management of the complex gene expression profiles resulting from such experiments. Although the preliminary data are encouraging, significant work remains before meaningful correlations with risk or practical assessment of exposure can be made by gene expression profiling.     

Preliminary study of using imaging plates to map skin dose of patients in interventional radiology procedures

A method using europium-doped BaFBr imaging plates (IPs) has been studied for mapping entrance skin doses during interventional radiology (IR); the mapping is useful for detecting overlap between irradiation fields and determining the most exposed skin areas. IPs, which are two-dimensional radiation sensors made of photostimulated luminescence materials, have a linear dose response up to approximately 100 Gy, can accurately measure doses from 1 microGy to 10 Gy and can be used repeatedly. Because the energy dependence of IPs is rather high, the IPs were characterised in this study and a sensitivity variation of approximately 13% was observed for effective energies of 32.7 to 44.7 keV, which are used in IR procedures. Simulation of actual interventional cardiology procedures showed that the variation of sensitivity was within 5%, meaning that IPs are practical for measuring skin doses during IR. Moreover, the patient data can be stored online and easily called up when IR procedures must be repeated, helping to prevent radiation injuries.     

Dosimetric calculations for uranium miners for epidemiological studies

Epidemiological studies on uranium miners are being carried out to quantify the risk of cancer based on organ dose calculations. Mathematical models have been applied to calculate the annual absorbed doses to regions of the lung, red bone marrow, liver, kidney and stomach for each individual miner arising from exposure to radon gas, radon progeny and long-lived radionuclides (LLR) present in the uranium ore dust and to external gamma radiation. The methodology and dosimetric models used to calculate these organ doses are described and the resulting doses for unit exposure to each source (radon gas, radon progeny and LLR) are presented. The results of dosimetric calculations for a typical German miner are also given. For this miner, the absorbed dose to the central regions of the lung is dominated by the dose arising from exposure to radon progeny, whereas the absorbed dose to the red bone marrow is dominated by the external gamma dose. The uncertainties in the absorbed dose to regions of the lung arising from unit exposure to radon progeny are also discussed. These dose estimates are being used in epidemiological studies of cancer in uranium miners.     

Low dose hypersensitivity and induced resistance of V79 cells after charged particle irradiation using 100 MeV/u carbon ions

This work aimed to study the effects of low dose irradiation in order to detect possible deviations from the linear-quadratic dose dependence of survival after charged particle irradiation. Survival of V79 cells at low doses was studied using a semi-automated cell detection system similar to the DMIPS system. With such a technique, the precision of survival measurements is improved by avoiding the stochastic uncertainties of the conventional dilution assay. A significant hypersensitivity at low doses (0.1 Gy) has been detected for 100 MeV/u carbon ions, whereas for higher doses (up to 0.5 Gy) a transition to a plateau-like region is observed, which is consistent with the assumption of induced resistance. These results are apparently in contrast to earlier studies using high-LET radiation like, e.g. neutrons or negative pions, where the effect of induced resistance has been reported to be at least significantly reduced for single exposure experiments.     

Review of translocations detected by FISH for retrospective biological dosimetry applications

Several European laboratories have combined their research efforts to arrive at a consensus view on using fluorescence in situ hybridisation (FISH) for retrospective dosimetry. The aim of this review is to report these views and to highlight some areas where further work is needed. Translocations in the stable cells should be measured only in the cells that contain the full complement of the painted material. Two-way and one-way translocations should be combined with equal weight. The control level of translocations has a strong dependence on age, which has now been measured and the system has been calibrated. In conclusion, the technique works and a lifetime dose to the bone marrow from low-linear energy transfer radiation of 0.5 Gy above normal background levels can be measured for any individual. The main application is considered to provide an independent verification of lifetime doses to individuals who might form a part of an epidemiological study.     

Investigation of occupational radiation exposure during interventional cardiac catheterisations performed via radial artery

The purpose of this study was to determine the thyroid, sternum and hand radiation doses of radiologists who perform angiographies and angioplasties via the radial artery. Staff radiation dose was estimated for 21 cardiac interventional catheterisations. Thermoluminescence dosemeters (TLDs) were used to determine radiation dose for each procedure at the right and left wrist, at the sternum and the thyroid. A dose area product (DAP) meter was also attached to give a direct value in Gy cm2 for each procedure. Staff radiation doses varied between 34 and 235 microGy per procedure at the left wrist, 28 and 172 microGy at the right wrist, 16 and 106 microGy at the level of the thyroid and 16 and 154 microGy at the level of the sternum. The DAP values varied between 25 and 167 Gy cm2. Radiation doses in this study are comparable to those reported in previous studies. Moreover, good correlation was found between the DAP values and the occupational dose measured with TLDs.     

Chromosome aberration analysis in radiotherapy patients and simulated partial body exposures: biological dosimetry for non-uniform exposures

Chromosome aberration analysis was carried out in peripheral blood lymphocytes of cancer patients following radiotherapy of lungs, cervix and spine. Radiotherapy in the pelvic region involving large doses (6 Gy) showed an overdispersed distribution of dicentrics. However, when the doses were fractionated (three fractions of 2 Gy) distribution was found to be near Poisson. Spine irradiation covering almost all the lymphocytes pools, indicated a Poisson distribution. The data show that depending on the sites of exposure, the distribution of dicentrics in cells varies and hence there is a non-uniform distribution of lymphocytes in the body. The average dose to the lymphocytes was found to be one sixth of the partial body dose. Based on the non-Poisson distribution of aberrations, the fraction of lymphocytes irradiated, mean dose to the fraction and part of the body exposed was calculated in a case of acute 6 Gy pelvic irradiation. The fraction of cells irradiated was calculated to be 4.11% and the portion of the body exposed was approximately 16.8%. The dose to the irradiated fraction was found to be 5.4 Gy, which is in agreement with the given dose of 6 Gy. In simulated exposures the u values increased systematically with the decrease in fraction of irradiated cells and the calculated dose to the fraction was also in good agreement with the true dose.     

Radiation doses to patients undergoing barium meal and barium enema examinations

The radiation doses received by patients during 41 barium meal (BM) and 42 barium enema (BE) examinations in two Greek hospitals are presented. Radiation dose was measured in terms of the dose area product (DAP). The effective dose and doses to certain organs were estimated using the ODS-60 software. Mean total DAP values were found to be 25 +/- 11 Gy cm2 for BM and 60 +/- 35 Gy cm2 for BE examinations, whereas the estimated mean values of effective dose were 8.6 +/- 4.0 and 24 +/- 16 mSv respectively. DAP to effective dose conversion coefficients were estimated to be 0.34 mSv per Gy cm2 for BM and 0.41 mSv per Gy cm2 for BE.     

Microdosimetric interpretation of the photon energy response of LiF:Mg,Ti detectors

Photon energy response of MTS-N (LiF:Mg,Ti) detectors (TLD Poland) and of MTS-N detectors sensitised with 200 Gy of 60Co gamma rays, followed by UV irradiation (sMTS-N), has been determined using X rays with narrow energy spectra, in the energy range from 20 to 300 keV. The over-response of LiF:Mg,Ti detectors for X rays (relative TL efficiency eta = 1.1) can be explained as an ionisation density effect. Low energy X rays produce short electron tracks, which locally deposit a high radiation dose and, consequently, lead to an enhanced (supralinear) response. This over-response has not been observed in sensitised MTS-N where supralinearity in the response after gamma ray doses above 1 Gy is not seen. Using the dose-response curves measured for MTS-N detectors after 137Cs gamma ray irradiation and local doses calculated using Monte Carlo generated electron tracks, it was possible to predict the relative TL effectiveness for different X ray energies. The calculation procedure can be applied to predict the photon energy response of LiF:Mg,Ti detectors in an arbitrary photon field.     

Effects of silver nanoparticles coated with anti‐HER2 on irradiation efficiency of SKBR3 breast cancer cells

Breast cancer is the second cause of death in the world. Ionising radiation is a potent mutagen that can cause DNA damage, chromosomes breakage, and cell death. In the present study, radiotherapy and nanoparticle‐antibodies (ABs) have been combined to enhance the efficacy of cancer cell treatment. Silver nanoparticles (SNP) were synthesised, coated with anti‐HER2, and then characterised with different techniques such as X‐ray diffraction, dynamic light scattering, transmission electron microscopy, Fourier transform infrared, and UV–Vis spectroscopy. SKBR3 cells were irradiated with cobalt‐60 in the presence of nanoparticle‐AB as the drug. Cell viability was measured using the diphenyltetrazolium bromide assay, and the cellular status was assessed by Raman spectroscopy. Irradiation considerably decreased cell viability proportionate to the dose increase and post‐irradiation time. The surface‐enhanced Raman spectroscopy increased the signal in the presence of SNP. Increasing the dose to 2 Gy increased the irradiation resistance, and higher dose increases (4 and 6 Gy) enhanced the irradiation sensitivity. Moreover, the cellular changes induced by irradiation in the presence of the drug were stable after 48 h. The authors results introduced the combination of the drug with radiation as an effective treatment for cancer and Raman spectroscopy as a suitable tool to diagnose effective irradiation doses.Inspec keywords: ultraviolet spectra, X‐ray diffraction, tumours, nanofabrication, silver, cellular biophysics, nanomedicine, cancer, drugs, DNA, light scattering, toxicology, biomagnetism, radiation therapy, Raman spectra, transmission electron microscopy, infrared spectra, nanoparticles, gynaecologyOther keywords: higher dose increases, irradiation sensitivity, drug, effective treatment, effective irradiation doses, silver nanoparticles, irradiation efficiency, SKBR3 breast cancer cells, ionising radiation, potent mutagen, DNA damage, cell death, nanoparticle‐antibodies, cancer cell treatment, SNP, different techniques, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, UV–Vis spectroscopy, SKBR3 cells, nanoparticle‐AB, diphenyltetrazolium bromide assay, cell viability proportionate, dose increase, post‐irradiation time, surface‐enhanced Raman spectroscopy, irradiation resistance, time 48.0 hour, size 60.0 inch, Ag     

External radiation exposure of personnel in nuclear medicine from 18F, 99mTC and 131I with special reference to fingers, eyes and thyroid

The radiation exposure of fingers, thyroid and eyes of workers handling radiopharmaceuticals during various nuclear medicine procedures was measured using thermoluminescent dosemeters. Dosemeters were placed on the finger tips of 19 workers on several different occasions for various procedures. Additionally, the routinely determined whole-body doses to various groups of workers were analysed. The finger dose measurements demonstrated clear differences between the various tasks, from 0.0012 μGy MBq(-1) (unpacking and installing (99)Mo/(99m)Tc-generator) to 3.0 μGy MBq(-1) (syringe withdrawal, injection and waste handling of (18)F-FDG). As long as the worker was handling (99m)Tc, the dose to the fingers was well below the ICRP dose limits, even when the activity was high. Special concern should, however, be devoted to the handling of (18)F, since the dose to the fingers could easily reach the dose limits. The estimated dose to eyes and thyroid was well below the dose limits. Since the introduction of the positron emission tomography/computed tomography facility, the annual whole-body dose has increased for those directly involved in the handling of (18)F. The annual whole-body dose of 0.2-2.5 mGy was, however, well below the dose limits.