Radiation safety of the sentinel lymph node technique in breast cancer

Many publications attest to the potential of the sentinel lymph node technique in advancing the clinical management of melanoma and, more recently, breast cancer. Whilst not yet universally regarded as the standard of care, the technique is gaining wide acceptance. Use of a radiolabelled colloidal tracer is central to optimising sensitivity, and this brings with it the need to address radiation safety issues relating to the use of radioactive materials in the operating theatre and pathology laboratory, and the generation of radioactive waste. The radiation dose to the patient should also be determined if the professional is to reassure the patient by placing this in its proper context. For the purpose of this investigation, biodistribution data were obtained from patient studies to quantify the migration of tracer beyond the injection site, thereby permitting a detailed assessment of the internal dosimetry of the tracer and the resulting radiation dose to the patient. Uptake of tracer in the sentinel nodes, reticulo-endothelial system and circulating blood was investigated. The radiation dose to surgical staff was recorded using whole-body monitors and extremity dosimeters worn at the fingers. Clinical waste in the operating theatre was monitored and the radioactive content of significantly contaminated items determined. The radiation dose to pathology staff was estimated from knowledge of the radioactive content of the specimens obtained and a study of work practices. Migration of tracer was found to be minimal, with greater than 95% retention at the injection site. The effective dose resulting to the patient was 2.1×10^–2 mSv/MBq, with a mean breast dose of 7.2×10^–1 mGy/MBq. A mean whole-body dose of 0.34 μSv was received by surgical staff per procedure, with a mean finger dose of 0.09 mSv (90 μSv). Radiation doses received by pathology staff will be predominantly below measurable levels and are likely to be negligible unless primary specimens from a large number of studies are analysed promptly upon their excision. At operation, surgical swabs can become significantly contaminated and have been found to contain up to 22% of the administered activity, dependent upon the surgical procedure performed. It is concluded that moderate activities of technetium-99m labelled tracer are administered to the patient, and the radiation risk to the patient is consequently low relative to that from many other medical exposures. The radiation doses to staff groups involved in all aspects of the technique are low, and under normal circumstances and levels of workload, routine radiation monitoring will not be required. Standard biohazard precautions prevent direct intake of radioactive contamination. Radioactive waste is created in the operating theatre, and may be generated in the pathology laboratory if specimens are not routinely stored until fully decayed. This will require special handling if the disposal of radioactive material is not permitted. Received 4 November and in revised form 14 December 1999     

Enzymatic debridement shall not modify the global strategy for mass burn events

<正>We read with interest the leer by Surowiecka et al.[1] about early burn wound excision in mass casualty events. We couldn’t agree more with their statement about the benefit of early burn wound excision. Still, we doubt whether applying this strategy to every patient during a mass burn event could be realistic. Of note, while there is an undisputed consensus that early burn wound excision is the gold standard of burn care, what"early"actually means is still debated. Depending on the aut...     

Usefulness of the Guglielmi detachable coil for embolization of a systemic venous collateral after Fontan operation: A case report

Embolization of collateral veins is often treated with rigid coils(Gianturco and interlocking detachable coils type).However,when dealing with tortuous and dilated collateral veins,there is a high risk for technical failure and coil migration due to inflexibility of the coils.To safely and successfully solve this problem,Guglielmi detachable coils(GDC) can be used for embolization.Their flexibility allows for easy navigation in tortuous veins,low risk of unintended coil release or coil migration,and safe deployment.A 12-year-old girl with a single ventricle had severe cyanosis and a low exercise tolerance 5 years after Fontan procedure.The symp-toms were caused by a tortuous and dilated collateral from the left phrenic vein into the left pulmonary vein,forming a right-to-left shunt.The collateral,which had a large diameter and high flow,and therefore a high risk of coil migration,was successfully embolized with 8 GDC.There were no complications such as coil migration or cerebral infarction.Transcatheter embolization increased her systemic oxygen saturation from 81%-84% to 94%-95%,and increased her ability to exercise.The embolization procedure using flexible GDC was low risk compared with other rigid coil embolization techniques when performing embolization of tortuous and dilated collateral veins.     

Ultrasound contrast agents and their use in urogenital radiology: status and prospects

The analysis of bone structure in vivo is an important goal in osteoporosis, because the determination of bone mineral density alone is insufficient to predict whether an individual patient will eventually suffer an osteoporotic fracture or not. An additional structural analysis may significantly improve the statistical assessment of fracture risk. In this study we present a method to generate realistic although enlarged 3D phantoms of trabecular bone. These phantoms are useful in characterizing the potential of in vivo imaging procedures for the analysis of bone structure and to verify textural or structural analysis methods applied to these images. Our phantoms are based on a real trabecular bone specimen that was converted to a plastic model using the technique of stereolithography. The trabecular network is modeled by hydroxyapatite. Limitations of the stereolithographic process prevent the generation of exact 1:1 replicas of the real bone. A histomorphometric analysis of μCT scans of the phantoms showed that an excellent replication of the bone structure could be achieved in phantoms enlarged by a factor of 2.5 with "trabecular" hydroxyapatite concentrations up to 400 mg/cm³. In order to demonstrate the usefulness of our phantoms, we investigated one of them with various thin-slice CT protocols using clinical single- and multi-slice spiral CT scanners. The enlargement of the phantoms limits their use on high spatial resolution CT scanners (resolution >20 lp/cm). The limited hydroxyapatite concentration requires enhanced exposure rates for the phantoms scans to offset the larger impact of noise due to the lower contrast in the phantoms. Electronic Publication     

Inferior pancreaticoduodenal artery aneurysm treated with coil packing and stent placement

Two cases with a pancreaticoduodenal arterial aneurysm accompanied with superior mesenteric artery(SMA) stenosis were previously described and both were treated surgically.However,for interventional treatment,securing a sufficient blood supply to the SMA should be a priority of treatment.We present the case of a 71-year-old male with a 20 mm diameter pancreaticoduodenal arterial aneurysm accompanied by SMA stenosis at its origin.The guidewire traverse from SMA to the aneurysm was difficult because of the tight SMA stenosis;however,the guidewire traverse from the celiac artery was finally successful and was followed by balloon angioplasty using a pull-through technique,leading to stent placement.Thereafter,coil packing through the SMA achieved eradication of the aneurysm without bowel ischemia.At the last follow-up computed tomography 8 mo later,no recurrence of the aneurysm was confirmed.The pull-through technique was useful for angioplasty for tight SMA stenosis in this case.     

知母活性成分ZMR对慢性帕金森病模型小鼠多巴胺系统的调节

objective The significant neuropathological features of Parkinson's disease include sharp decrease of striatal dopamine (DA) and downregulation of striatal dopamine transporter (DAT) density in nigrostriatal pathway.The purpose of this research was to investigate the effects of ZMR on the DAT and DA membolism in the brain of a chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinisen's disease.Metbods C57BL/6 mice were divided into four groups:control mice,model mice,model mice treated with 10 mg/kg of ZMR(ZMR-10)and model mice treated with 26 mg/kg of ZMR(ZMR-26).All mice except control received ten doses of MPTP(15 mg/kg,subcutaneous injection)plus probeneeid(250 ms/kg,intraperitoneal injection)twice a week in five weeks.Mice in groups of ZMR10 and ZMR-26 were administrated 10mg/kg and 26 mg/kg of ZMR by oral gavage once daily for 60 d respectively.Striatal DAT was detected by autoradiography using 125I-2β-carbomethoxy-3B-(4-iodophenyl)-N-(3-fluoropropropyl) nortropane (FP-CIT).Monoamine oxidase B(MAO-B)activity was determined with a commercial kit.DA and its metabolites were determined by high performance liquid chromatography-electrochemical detection(HPLC-ECD).Staffstical analysis was performed with SAS 6.12 software,and the oneway ANOVA,grouped t-test Were used to analyze the data.Results Compared with vehicle treated model mice,ZMR-10 and ZMR-26 increased striatal DAT density from 0.212±0.012 to 0.268±0.019 and 0.281±0.018 respectively(t=2.5314,3.1124,P＜0.05 and＜0.01 respectively),raised striatal DA levels from(3.00±0.25)μg/g to(4.21±0.32)μg/g and(4.58±0.39)μg/g respectively(t=2.9879,3.4163.P＜0.05 and＜0.01 respectively).However.ZMR-10 and ZMR-26 did not affect the MAO-B activity.Conclusion ZMR raises striatal DA levels in chronic MPTP-model mice.which is closely related to the elevation of striatal DAT density but not related to catabolism of DA.     

Ocular Dimensions of the Chinese Adolescents with Keratoconus

Objective:The purpose of this study is to investigate the ocular dimensions in Chinese adolescents with keratoconus(KC).Methods:One hundred and six KC eyes of 53(42 boys and11 girls)KC adolescents(age 15.5±1.7 years,range 11 to18)were involved in this retrospective study.The eye with more severe KC(Severe Group)of each patient was compared to their less affected eye(Mild Group).Optical axial length(OAL)was measured by optical coherence biometry(IOL-master).Central corneal thickness,anterior chamber depth(ACD),flat keratometry value,steep keratometry value,and maximum keratometry value were assessed with an anterior segment analyzer(Pentacam HR).Anterior segment length(ASL)was manually measured from the 25 scheimp flug images captured by the Pentacam HR with the mean value recorded.The posterior segment length(PSL)was calculated with the formula"PSL=OALASL".Results:The mean ACD,OAL,ASL,and PSL values of the Severe Group were(3.51±0.32)mm,(24.76±1.24)mm,(4.01±0.30)mm and(20.76±1.15)mm.While those of the Mild Group were(3.36±0.29)mm,(24.97±1.40)mm,(3.94±0.35)mm and(21.03±1.31)mm.The Severe Group has significantly higher ACD(P0.001)value but lower OAL(P0.05)and PSL(P0.001)values when compared to those of the Mild Group.Conclusions:For adolescent KC,the more severe keratoconic eyes may be characterized by deeper ACD but shorter OAL and PSL,when compared to the less affected ones.     

Volvulus of the ascending colon in a non-rotated midgut: Plain film and MDCT findings

Colonic volvulus is a relatively uncommon cause of large bowel obstruction usually involving mobile,intraperitoneal,colonic segments.Congenital or acquired anatomic variation may be associated with an increased risk of colonic volvulus which can occasionally involve retro-peritoneal segments.We report a case of 54-year-old female who presented to our Institution to perform a plain abdominal film series for acute onset of cramping abdominal pain.Both the upright and supine films showed signs of acute colonic obstruction which was thought to be due to an internal hernia of the transverse colon into the lesser sac.The patient was therefore submitted to a multi-detector contrast-enhanced computed tomography(CT).CT findings were initially thought to be consistent with the presumed diagnosis of internal hernia but further evaluation and coronal reformatting clearly depicted the presence of a colonic volvulus possibly resulting from a retro-gastric colon.At surgery,a volvulus of the ascending colon was found and a right hemi-colectomy had to be performed.However,a non rotated midgut with a right-sided duodeno-jejunal flexure and a left sided colon was also found at laparotomy and over-looked in the pre-operative CT.Retrospective evaluation of CT images was therefore performed and a number of CT signs of intestinal malrotation could be identified.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

双探头符合线路SPECT正电子显像衰减校正实验研究

Objective The photons from the body would be attenuated in their intensity by the soft tissue before they reach the detectors. Some of them lost more intensity than others when coming from the deeper body. Attenuation of the photons would distort the image, affect the image quality, and may lead to misdiagnosis. In this research the X-ray and γ-ray were used as transmission resources for accurate assess-ment of attenuation in each part of the body. The transmission data was used to correct the emission data from the body. Iteration algorithm was used for the reconstruction of attenuation corrected tomography ima-ges. Evaluate the efficacy of attenuation correction in duel head hybrid SPECT/coincidence PET systems (SPECT/PET) and SPECT using both the Jaszczak and the myocardial phantoms. Methods For PET phantom study, the Jaszczak phantom was filled with the aqueous solution of 18F-fluorodeoxyglucose (FDG) and was scanned with two hybrid SPECT/coincidence PET systems respectively (Vertex Plus, Netherlands Philips ADAC Company and Hawkeye, USA GE Company). The PET images were acquired and reconstruc-ted. Results The "cold" lesion, which the diameter was less than 12 mm of uncorrected image, could not be identified. But it, after correction, diameter 9 mm, would be recognized clearly, less than 7 mm would not be distinguished. Noncorrected image could only identify "hot" lesions which the diameter were 9, 12, 14, 18, 22 and 38 mm, while in the corrected image, not only it was much better, but also the "hot" le-sion of 6 mm was distinguished. In Hawkeye, the same situation, the corrected image of was improved obvi-ously; the disparity of counts between surrounding and deep center less, and the counts in deep center were compensated. There were only 3 round " cold" lesions could be recognized, the diameter: 14, 18 and 20 mm; all of them which diameter were less than 12 mm could not be distinguished. One in the center was al-most as background, and could not be identified. The radioactive accounts of surrounding and center were quite different. The corrected image 5 "cold" lesions could be found, 9, 12, 14, 18 and 20 mm, but7 mm could not be found. The noncorrected image, only 12, 14, 18, 22 and 38 mm " hot" lesions could be found, and by the surrounding, there was an arc shape "hot" lesion. But it could distinguish 9, 12, 14, 18, 22 and 38 mm "hot" lesions on the corrected image, and the image was much better than noncorrected one. Conclusions The corrected image of Vertex Plus was improved obviously with the disparity of counts between surrounding and deep center less, and the counts in deep center was compensated. The result of at-tenuation with phantom showed that 137Cs was better than CT in both image quality and spatial resolution.     

Carcinogenicity of radon/radon decay product inhalation in rats--effect of dose, dose rate and unattached fraction

PURPOSE: The effects of inhalation of radon/radon decay products at different total doses, dose rates and 'unattached' fractions were investigated in a life span study in rats. MATERIALS AND METHODS: 1574 rats inhaled radon/radon decay products in a purpose-built recirculating exposure system that provided stable/reproducible exposure conditions. 501 were maintained as controls. RESULTS: Lung tumour incidences were significantly elevated in most exposed groups. The study power was insufficient to resolve the shape of the dose and dose rate response curves, but combination of this data with that from other studies demonstrated that for high cumulative exposures, the lifetime excess absolute risk increases with increasing exposure durations and for low cumulative exposures the opposite trend occurs. Exposure did not increase leukaemia incidences. A small number of non-lung tumour types including mammary fibroadenoma showed elevated incidences in some exposed groups, however not consistently across all exposure groups and showed no dose or dose rate relationship. CONCLUSIONS: Radon/radon decay product exposure caused excess lung tumours in rats along with limited non-lung effects. The results are consistent with the findings that at low cumulative exposures decreasing exposure concentrations or protracting the time over which the dose is delivered, reduces lung tumour risk. At higher levels, decreasing exposure concentrations or protracting exposure time increases lung tumour risk.     

Carcinogenicity of radon/radon decay product inhalation in rats – effect of dose,dose rate and unattached fraction

Purpose: The effects of inhalation of radon/radon decay products at different total doses, dose rates and ‘unattached’ fractions were investigated in a life span study in rats.

Materials and methods: 1574 rats inhaled radon/radon decay products in a purpose-built recirculating exposure system that provided stable/reproducible exposure conditions. 501 were maintained as controls.

Results: Lung tumour incidences were significantly elevated in most exposed groups. The study power was insufficient to resolve the shape of the dose and dose rate response curves, but combination of this data with that from other studies demonstrated that for high cumulative exposures, the lifetime excess absolute risk increases with increasing exposure durations and for low cumulative exposures the opposite trend occurs. Exposure did not increase leukaemia incidences. A small number of non-lung tumour types including mammary fibroadenoma showed elevated incidences in some exposed groups, however not consistently across all exposure groups and showed no dose or dose rate relationship.

Conclusions: Radon/radon decay product exposure caused excess lung tumours in rats along with limited non-lung effects. The results are consistent with the findings that at low cumulative exposures decreasing exposure concentrations or protracting the time over which the dose is delivered, reduces lung tumour risk. At higher levels, decreasing exposure concentrations or protracting exposure time increases lung tumour risk.     

基于EPA/BEIR-VI模型的我国居室内氡致肺癌风险估计

目的:估计我国居室内氡导致的居民肺癌归因份额。方法:利用较为权威且适用的EPA/BEIR-VI风险模型,基于我国2015年肺癌死亡率、全死因死亡率以及有代表性的吸烟率和居室内氡平均浓度,预测我国居室内氡浓度水平致肺癌死亡风险。结果:非吸烟男性人群居室内氡致肺癌死亡超额相对危险(ERR)高于吸烟人群,且达到年龄为50岁时...     

Risk coefficient of radon-induced lung cancer and combined effect of arsenic in miners of Yunnan tin mine of China

Ｒｉｓｋｃｏｅｆｉｃｉｅｎｔｏｆｒａｄｏｎ－ｉｎｄｕｃｅｄｌｕｎｇｃａｎｃｅｒａｎｄｃｏｍｂｉｎｅｄｅｆｅｃｔｏｆａｒｓｅｎｉｃｉｎｍｉｎｅｒｓｏｆＹｕｎｎａｎｔｉｎｍｉｎｅｏｆＣｈｉｎａＳｕｎＳｈｉｑｕａｎＯｂｊｅｃｔｉｖｅＴｏｉｄｅｎｔｉｆｙｔｈ...     

室内氡与肺癌关系研究

目的 直接调查居室水平氡浓度对居民肺癌危险度的影响，并与由矿工受照结果推导的结论相比较。方法 在甘肃省平凉、庆阳两地区进行病例－对照研究。该地区居民稳定而室内氡水平较高。肺癌病例必须是在1994年1月至1998年4月期间诊断，年龄在30－75岁之间，居住在平凉和庆阳两地区的居民。根据人口调查资料随机选取对照，对照要在年龄、性别、地区方面与病例相匹配。在过去5－30年期间，凡住过两年以上的房间都布放了氡探测器。氡测量涵盖了77％的照射周期。结果 病例居室的平均氡浓度为230．4Bq/m^3(n=768)，对照为222．2Bq/m^3(n=1659)。居民肺癌危险度随室内氡水平的增高有所上升（P＜0．001）。根据线性模型，对全部研究个体而言，在100Bq/m^3情况下，附加比值比（EOR）为0.19(95% CI:0.05,0.47)。对测量涵盖了100％照射周期的个体，为0．31（95％CI：0．10，0．81）。在对照射的不确定度进行调整后，估算值可增加70％。结论 研究结果证明室内水平氡照射会增加肺癌危险度，增加值等于或超过从矿工数据外推的结果。     

Adaptive response and human benefit: Part I. A microdosimetry dose-dependent model

PURPOSE: It is important to evaluate how adaptive response may be of human benefit from the risks of ionizing radiation. The purpose of this work is to develop and apply a microdosimetric dose response model capable of explicitly determining, for broad beam exposures, the threshold and progressive activation of natural spontaneous and radiation damage protective mechanisms associated with adaptive response and other cellular negative response behavior. MATERIALS AND METHODS: A biophysical model was developed quantifying the accumulation of Poisson distributed microdose specific energy hits to cell critical nucleus volumes. The model was applied to the adaptive response data of Wiencke et al., Redpath et al., Azzam et al. and Pohl-Ruling et al. The model was also applied to non-adaptive response data showing dose response reductions below the zero dose natural spontaneous level and to data exhibiting mid-range non-monotonic dose response plateaus. RESULTS: We find good fits of the model to all data. For adaptive response, a significant result is, that only one or two specific energy hits of low linear energy transfer (LET) radiation in the cell nucleus activates the protective mechanisms for both the natural spontaneous and radiation damage. Several data support a dose plateau for radon progeny alpha production of chromosome aberrations in human lymphocytes. Using the model, a bystander factor of about 30 is obtained with the model for high dose rate, in vitro alpha particle data. For low dose rate in vivo, the bystander effect is minimal suggesting for alphas that the bystander effect may be dose rate dependent. There is no evidence of bystander effects in the low LET adaptive response data analysis. CONCLUSIONS: The microdosimetry model allows concise determinations of specific energy hits within the cell critical nucleus volume to activate both protective and damage mechanisms. One or two low LET hits can result in reduction of both zero dose natural spontaneous and radiation-induced, carcinogenic causing damage. The model should be useful in comparing in vitro and in vivo broad beam to single track microbeam exposure data. The model is capable of determining, to an accuracy of +/- one specific energy hit, the minimum threshold for induction of radioprotective mechanisms--crucial to assessing the potential human benefit of adaptive response and other negative dose response behavior.     

Internal exposure from building materials exhaling 222Rn and 220Rn as compared to external exposure due to their natural radioactivity content

The main scope of this paper is to point out the importance of introducing radon and thoron exhalation measurements from building materials in the regulating frame. Currently (2009), such a regulation of this kind of exposure is not explicitly included in the Serbian regulating network. To this end, this work reports concentration measurements of ²²⁶Ra, ²³²Th and ⁴⁰K and radon and thoron exhalation rates from building materials used in Serbia. Following detailed analysis, it was noticed that both internal exposures to radon and/or thoron exhaling from building materials may exceed external exposures to their precursors contained therein.     

云锡矿工肺癌病因学研究的概况

本文简要回顾了近３０年来云锡矿工肺癌病因学研究的概况，介绍了“氡砷复合，以氡为主”的病因学观点的现场研究与实验室研究的证据，提出矿工肺癌病因中氡／砷相对贡献的比值，提出利用该比值制定氡砷复合暴露时井下氡－砷空气浓度限值的办法及供肺癌矿工职业赔偿使用的计算病因概率的参数。作者认为由于存在一些技术上的问题，目前很难根据现有的流行病学研究资料计算云锡矿工的氡致肺癌危险系数。     

The influence of uncertainties of radon exposure on the results of case-control epidemiological study

Abstract

Purpose: Simulation of large-scale epidemiological study to identify the influence of uncertainties of radon exposure assessment on the excess relative risk of lung cancer.

Materials and methods: Analysis of sources of uncertainties arising during radon epidemiologic case-control studies. Assessment of the uncertainties due to influence of long-term variations of radon concentration, exposure to radon in other places of human presence, except dwellings, quality of radon concentration measurements etc. Simulation by Monte Carlo technique of radon epidemiologic study, comparable to the pooled European radon case-control study, and assessment of uncertainties, which affect the evaluation of dose-effect dependence.

Results: The uncertainties of personal exposure to radon are generally caused by the combined effect of long-term variations of radon concentration and the differences in the levels of radon concentration in homes and other places of human presence. The logarithmic standard deviation of this uncertainty is from 0.70 to 0.90. This value is ～2 times higher than the uncertainty, applied for correction of the results in the pooled European radon case-control study. It is shown that for σ_err?<?1.0 regression calibration technique allows to make full correction of the uncertainty. The error in assessment of uncertainties of the exposure to radon concentration in the pooled European radon case-control study has led to an underestimation of excess relative risk of lung cancer incidence at least by 1.5 times.

Conclusion: The error in an assessment of uncertainties of radon exposure in the pooled European radon case-control study has led to an underestimation of relative risk of lung cancer incidence at least by 1.5 times.     

Development of a method for assessing non-targeted radiation damage in an artificial 3D human skin model

Purpose : Radon risks derive from exposure of bronchio-epithelial cells to high-linear energy transfer (LET) α -particles. α -particle exposure can result in bystander effects, where irradiated cells emit signals resulting in damage to nearby unirradiated bystander cells. This can result in non-linear dose-response relations, and inverse dose-rate effects. Domestic radon risk estimates are currently extrapolated from miner data, which are at both higher doses and higher dose-rates, so bystander effects on unhit cells could play a large role in the extrapolation of risks from mines to homes. Therefore, we extend an earlier quantitative mechanistic model of bystander effects to include protracted exposure, with the aim of quantifying the significance of the bystander effect for very prolonged exposures. Materials and methods : A model of high-LET bystander effects, originally developed to analyse oncogenic transformation in vitro, is extended to low dose-rates. The model considers radiation response as a superposition of bystander and linear direct e It attributes bystander effects to a small subpopulation of hypersensitive cells, with the bystander contribution dominating the direct contribution at very low acute doses but saturating as the dose increases. Inverse dose-rate effects are attributed to the replenishment of the hypersensitive subpopulation during prolonged irradiation. Results : The model was fitted to dose- and dose-rate-dependent radon-exposed miner data, suggesting that one directly hit target bronchio-epithelial cell can send bystander signals to about 50 neighbouring target cells. The model suggests that a naïve linear extrapolation of radon miner data to low doses, without accounting for dose-rate, would result in an underestimation of domestic radon risks by about a factor of 4, a value comparable with the empirical estimate applied in the recent BEIR-VI report on radon risk estimation. Conclusions : Bystander effects represent a plausible quantitative and mechanistic explanation of inverse dose-rate effects by high-LET radiation, resulting in non-linear dose-response relations and a complex interplay between the effects of dose and exposure time. The model presented provides a potential mechanistic underpinning for the empirical exposure-time correction factors applied in the recent BEIR-VI for domestic radon risk estimation.