河南省X射线摄影成年受检者入射体表剂量调查

目的 调查河南省X射线摄影致成年受检者的入射体表剂量水平,为建立适合我国国民体质特征的放射诊断受检者剂量指导水平提供技术和数据支持。方法 采用非概率抽样方法选取河南省郑州、开封和信阳3个地市14家医院,用热释光剂量测量方法调查普通X射线摄影、计算机X射线摄影（CR）和直接数字化X射线摄影（DR）不同照射部位1 404名受检者入射体表剂量水平。结果 河南省普通X射线摄影、CR摄影和DR摄影致成年受检者入射体表剂量范围分别为0.20~47.71、0.16~6.89和0.10~10.41 mGy。腹部前后位（AP）、骨盆AP、头颅侧位（LAT）、头颅后前位（PA）、胸部LAT、胸部PA、胸椎AP、胸椎LAT、腰椎AP、腰椎LAT摄影入射体表剂量范围分别为0.16~10.05、0.20~10.36、0.11~2.13、0.10~2.92、0.39~5.85、0.12~1.82、0.16~11.67、0.36~29.37、0.25~14.49和1.18~47.71 mGy。普通X射线摄影致受检者入射体表剂量高于CR和DR摄影,差异有统计学意义（Z=-8.709、-9.570,P<0.05）。普通X射线摄影胸部PA、腰椎LAT入射体表剂量高于全国“九五”期间调查结果,差异有统计学意义（Z=3.262、2.538,P<0.05）。结论 河南省普通X射线摄影和CR摄影所致受检者胸部PA和LAT入射体表剂量超过医疗照射指导水平,普通X射线摄影部分照射部位入射体表剂量较全国“九五”期间调查结果有所提高。     

Evaluation of cumulative effective dose and cancer risk from repetitive full spine imaging using EOS system: Impact to adolescent patients of different populations

ObjectiveTo evaluate the effective dose and associated cancer risk using EOS system for scoliotic adolescent patients undergoing full spine imaging at different age of exposure; to demonstrate EOS system capable of delivering less radiation dose and hence of reducing cancer risk induction when compared with conventional digital X-ray systems; to obtain cumulative effective dose and cancer risk for both genders scoliotic adolescence of US and Hong Kong population.MethodsOrgan absorbed doses of full spine exposed scoliotic adolescent patients using EOS system have been simulated with the use of patient imaging parameters input to the Monte Carlo software PCXMC. Gender specific effective dose has been calculated with the simulated organ absorbed dose using the ICRP-103 approach. The associated radiation induced cancer risk, expressed as lifetime attributable risk (LAR), has been estimated according to the method introduced in the Biological Effects of Ionizing Radiation VII report. Values of LAR were estimated for scoliotic patients exposed repetitively during their follow up period at different adolescent age for US and Hong Kong population.ResultsThe effective dose of full spine imaging with posteroanterior and lateral projection for patients exposed at the age between 10–18 years using the EOS system low dose protocol was calculated between 86 and 140 μSv. The corresponding LAR for US and Hong Kong population was ranged between 0.81 × 10⁻⁶ and 6.00 × 10⁻⁶. Cumulative effective dose and cancer risk during follow-up period can be estimated using the results and are of information to patients and their parents.ConclusionWith the use of computer simulation and analytic formulation, we obtained the cumulative effective dose and cancer risk at any age of exposure for adolescent patients of US and Hong Kong population undergoing repetitive full spine imaging using the EOS system. Female scoliotic patients would be at a statistically significant higher effective dose and cumulative cancer risk than the male patients undergoing the same EOS full spine imaging protocol.     

Estimation of lifetime attributable risks (LARs) of cancer associated with abdominopelvic radiotherapy treatment planning computed tomography (CT) simulations

Purpose: The present study attempts to calculate organ-absorbed and effective doses for cancer patients to estimate the possible cancer induction and cancer mortality risks resulting from 64-slice abdominopelvic computed tomography (CT) simulations for radiotherapy treatment planning (RTTP).

Material and methods: A group of 70 patients, who underwent 64-slice abdominopelvic CT scan for RTTP, voluntarily participated in the present study. To calculate organ and effective doses in a standard phantom of 70?kg, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator. Patient-specific organ dose and effective dose were calculated by applying related correction factors. For the estimation of lifetime attributable risks (LARs) of cancer incidence and cancer-related mortality, doses in radiosensitive organs were converted to risks based on the data published in Biological Effects of Ionizing Radiation VII (BEIR VII).

Results: The mean?±?standard deviation (SD) of the effective dose for males and females were 13.87?±?2.37 mSv (range: 9.25–18.82 mSv) and 13.04?±?3.42 mSv (range: 6.99–18.37 mSv), respectively. The mean?±?SD of LAR of cancer incidence was 35.34?±?13.82 cases in males and 34.49?±?9.63 cases in females per 100,000 persons. The LAR of cancer mortality had the mean?±?SD value of 15.38?±?4.25 and 16.72?±?3.87 cases per 100,000 persons in males and females respectively.

Conclusion: Increase in the LAR of cancer occurrence and mortality due to abdominopelvic treatment planning CT simulation is noticeable and should be considered.     

Does collimation affect patient dose in antero-posterior thoraco-lumbar spine?

IntroductionThe purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients.MethodsHigh sensitivity thermo-luminescent dosimeters (TLDs) were used to measure radiation dose to all organs of an adult male dosimetry phantom, positioned for an AP projection of the thoraco-lumbar spine. Exposures were made, first applying tight collimation and then subsequently with loose collimation, using the same acquisition factors. In each case, the individual TLDs were measured to determine the local absorbed dose and those representing each organ averaged to calculate organ dose.This information was then used to calculate the effective risk of cancer incidence for each decade of life from 20 to 80, and to compare the likelihood of cancer incidence when using tight and loose collimation.ResultsThe calculated figures for effective risk of cancer incidence suggest that the risk when using loose collimation compared to the use of tight collimation is over three times as high and this is the case across all age decades from 20 to 80.ConclusionTight collimation can greatly reduce radiation dose and risk of cancer incidence. However collimation in scoliotic patients can be necessarily limited.     

苏州市数字X射线摄影和CT医疗照射所致公众剂量负担的研究

目的 估算2017年苏州市医用数字X射线摄影（DR）和CT所致全市公众有效剂量负担。方法 利用分层随机抽样方法,通过医学影像存档与通信系统（PACS）和放射科信息系统（RIS）,采集苏州市27家医疗机构2017年DR和CT诊疗频度数据。对于DR,使用剂量面积乘积测量仪测量受检者常见投照部位的剂量面积乘积（DAP）,估算出有效剂量;对于CT,测量头部、胸部和腹部扫描时的加权CT剂量指数（CTDI_w）,结合扫描参数,估算出有效剂量。根据各部位的扫描人次和有效剂量,估算苏州市DR和CT医疗照射所致公众剂量负担。结果 DR检查中,腹部前后位、骨盆前后位、头颅侧位和后前位、胸部侧位和后前位、胸椎侧位和后前位、腰椎侧位和后前位一次检查所致受检者有效剂量分别为0.565、0.280、0.016、0.012、0.111、0.060、0.100、0.102、0.307和0.152 mSv。CT检查中,头部、胸部、腹部一次检查所致受检者有效剂量分别为1.33、5.75和7.31 mSv。2017年苏州市DR和CT医疗照射所致公众剂量为9 593.07人·Sv,人均年有效剂量为0.898 mSv。结论 CT医疗照射对公众剂量的贡献量远大于DR照射的贡献量。苏州市DR和CT医疗照射所致公众剂量负担处于高水平,需要引起相关卫生行政部门的重视。     

成年受检者数字断层融合扫描有效剂量估算

目的 估算数字断层融合扫描时组织、器官吸收剂量和受检者有效剂量,为辐射剂量学提供数据参考。方法 按照受检者检查部位（主射束扫描部位）将体模实验分组,以放射科现场收集的数字断层融合扫描人体不同部位时实时显示的数据作为体模实验的条件,对体模进行扫描,计算组织、器官的吸收剂量,并估算成年受检者的有效剂量。结果 成年受检者采用数字断层融合扫描时有效剂量分别为头部组0.524 mSv、颈椎组0.736 mSv、胸椎组2.719 mSv、胸部组1.810 mSv、腰椎组1.240 mSv、腹部组2.317 mSv、骨盆组2.316 mSv。结论 数字断层融合扫描时,成年受检者有效剂量的估算结果为胸椎组最高,其次为腹部组,头部组最小,有效剂量主要相关因素为管电压、总mAs、照射野大小、主射束照射范围、扫描范围内组织或器官的数量。     

Estimated risks of radiation-induced fatal cancer from pediatric CT

OBJECTIVE: In light of the rapidly increasing frequency of pediatric CT examinations, the purpose of our study was to assess the lifetime cancer mortality risks attributable to radiation from pediatric CT. MATERIALS AND METHODS: Organ doses as a function of age-at-diagnosis were estimated for common CT examinations, and estimated attributable lifetime cancer mortality risks (per unit dose) for different organ sites were applied. Standard models that assume a linear extrapolation of risks from intermediate to low doses were applied. On the basis of current standard practice, the same exposures (milliampere-seconds) were assumed, independent of age. RESULTS: The larger doses and increased lifetime radiation risks in children produce a sharp increase, relative to adults, in estimated risk from CT. Estimated lifetime cancer mortality risks attributable to the radiation exposure from a CT in a 1-year-old are 0.18% (abdominal) and 0.07% (head)-an order of magnitude higher than for adults-although those figures still represent a small increase in cancer mortality over the natrual background rate. In the United States, of approximately 600,000 abdominal and head CT examinations annually performed in children under the age of 15 years, a rough estimate is that 500 of these individuals might ultimately die from cancer attributable to the CT radiation. CONCLUSION: The best available risk estimates suggest that pediatric CT will result in significantly increased lifetime radiation risk over adult CT, both because of the increased dose per milliampere-second, and the increased lifetime risk per unit dose. Lower milliampere-second settings can be used for children without significant loss of information. Although the risk-benefit balance is still strongly tilted toward benefit, because the frequency of pediatric CT examinations is rapidly increasing, estimates that quantitative lifetime radiation risks for children undergoing CT are not negligible may stimulate more active reduction of CT exposure settings in pediatric patients.     

数字摄影受检者辐射剂量调查

目的 了解数字摄影（DR）检查中受检者的辐射剂量水平,为数字放射摄影受检者指导水平的制定提供基础数据。方法 使用热释光剂量计TLD测量受检者不同部位、不同投照方向的入射体表剂量（ESD）;使用剂量面积乘积仪测量受检者不同部位、不同投照方向的剂量面积乘积（DAP）,并利用测量的DAP值,估算出有效剂量（E）。结果 同类检查中,kV和mAs的变化范围较大,不同部位DR检查中ESD、DAP和E的差别均具有统计学意义（F=33.47、24.68、43.19,P<0.05）。其中,ESD和DAP均以腰椎（LAT）最高,均数为4.62mGy/次和2.26Gy·cm²/次;E以腹部（AP）最高,均数为0.59mSv,高于腰椎（LAT）的0.31mSv。结论 DR在加强受检者放射防护最优化方面很有潜力,应尽快建立适合我国国民体质特征的数字放射摄影受检者辐射剂量的指导水平。     

我国X射线摄影程序受检者入射体表剂量调查结果与分析

目的 通过调查全国15个省市不同级别医疗机构使用数字和屏片设备开展X射线摄影时受检者的入射体表剂量（ESD）,为制定适合我国国民体质特征的X射线摄影诊断参考水平提供数据。方法 按照《医用辐射危害评价与控制技术研究》实施方案的要求,选择年龄在20~70岁的受检者,男性体重在55~80 kg,女性体重在50~70 kg;采用热释光探测器（TLD）测量不同X射线摄影程序中成人受检者ESD,每台设备同一体位患者应不少于10名受检者;测量部位包含头颅、胸部的后前位（PA）和侧位（LAT）,腹部、骨盆、腰椎、胸椎的前后位（AP）和腰椎、胸椎的LAT等。结果 共在全国15个省的342家医院调查了19 975例X射线摄影受检者,1 813台不同类型X射线摄影设备,包括屏片X射线摄影、计算机X射线摄影（CR）和直接数字化X射线摄影（DR）设备,对于这3种类型的设备,不同摄影体位时受检者ESD的平均值分别为头颅PA：1.75、1.90、1.15 mGy;头颅LAT：1.69、1.46、1.03 mGy;胸部PA：0.75、0.65、0.36 mGy;胸部LAT：1.81、1.26、0.88 mGy;腹部AP：4.37、3.77、2.15 mGy;骨盆AP：3.73、3.56、2.75 mGy;腰椎AP：5.49、5.84、4.17 mGy;腰椎LAT：12.01、9.37、6.82 mGy;胸椎AP：4.53、3.65、2.49 mGy;胸椎LAT：6.91、6.43、4.15 mGy。结论 不同照射部位X射线摄影致受检者ESD有较大的差异。DR设备致受检者的ESD均低于屏片设备;除胸椎AP外,DR设备致受检者ESD均低于CR设备。在所有检查部位中,CR和屏片设备所致受检者ESD的差异均无统计学意义。     

Worker doses and potential health effects resulting from the accident at the Fukushima nuclear power plant in 2011

Abstract

Purpose: The reliability of exposure scenarios used in the World Health Organization's Health Risk Assessment (HRA) for Fukushima workers was examined. HRA risk estimates for cancer incidence in these workers were then reviewed.

Materials and methods: The HRA constructed four exposure scenarios to estimate worker radiation doses; recent individual dosimetric data were used to assess their reliability. Risks of specified cancer types attributable to radiation exposure were estimated in the HRA by calculating Lifetime Attributable Risks (LAR) for each scenario, and comparisons of LAR are provided.

Results: The scenarios were confirmed as reliable for the purposes of the HRA. For the lowest dose scenario (Scenario 1: 69% of the workforce), the HRA found that any elevated cancer risk was insignificant. Significantly elevated cancer risks were, however, found for the three higher dose scenarios.

Conclusions: For the highest dose scenario (Scenario 4: 13 workers), LAR values for thyroid cancer up to 3.5% were estimated, but a radiation-related increase in thyroid cancer incidence is unlikely to be observed because of the small number of workers. For the two intermediate dose scenarios, a small number of cancer cases may occur, but these are unlikely to be observed because the variability in baseline rates of cancer incidence is much larger than the predicted radiation-related incidence rates.     

直接摄影检查患者的照射剂量分析

目的 通过对不同部位直接摄影(DR)检查的医学数字成像和传输(DICOM)文件信息中的患者剂量信息的统计,调查不同投照部位DR摄片的照射剂量分布范围,分析影响DR检查照射剂量的因素。方法 随机选取浙江省某三甲医院2009年1月至4月5160次DR摄片,包括胸部、胸椎及腰椎正、侧位、腹部前后位及骨盆正位。应用软件自动提取每例患者检查中DICOM信息文件中的剂量面积乘积(DAP),并结合照射野的范围,计算各部位DR检查的入射表面剂量(ESD)。结果 腹部前后位、腰椎侧位、胸椎正侧位的变异系数在60%以下;胸部正侧位、腰椎正位、骨盆正位的变异系数为60%~80%。各个部位的DAP最大值与最小值比值,除腹部前后位较小为3倍,其余部位差异较大。其中,腰椎正位最大差别为46倍、腰椎侧位30倍,胸椎侧位、胸部正位、侧位、骨盆正位、胸椎正位分别为23、23、18、16、11倍。通过计算得到ESD值选择75%分位点与现行普通摄片诊断参考水平(DRL)比较后发现,胸部正、侧位分别下降75%和73%;腰椎正侧位下降66%和77%;胸椎正侧位下降85%和84%;骨盆正位下降88%;腹部前后位下降88%。结论 DR检查中各个部位的DAP与ESD值存在较大变动,ESD值与现行的常规摄片的DRL相比有较大下降;有必要回顾分析DR摄片的患者照射剂量,对患者照射剂量与图像质量进行质量管理。     

Clinical utility of postprocessed low-dose radiographs in skeletal imaging

Objectives:Radiography remains the mainstay of diagnostic and follow-up imaging. In view of the risks and the increasing use of ionizing radiation, dose reduction is a key issue for research and development. The introduction of digital radiography and the associated access to image postprocessing have opened up new opportunities to minimize the radiation dosage. These advances are contingent upon quality controls to ensure adequate image detail and maintenance of diagnostic confidence. The purpose of this study was to investigate the clinical applicability of postprocessed low-dose images in skeletal radiography.Methods:In our study setting, the median radiation dose for full dose X-rays was 9.61 dGy*cm2 for pelvis, 1.20 dGy*cm2 for shoulder and 18.64 dGy*cm2 for lumbar spine exams. Based on these values, we obtained 200 radiographs for each anatomic region in four consecutive steps, gradually reducing the dose to 84%, 71%, 60% and 50% of the baseline using an automatic exposure control (AEC). 549 patients were enrolled for a total of 600 images. All X-rays were postprocessed with a spatial noise reduction algorithm. Two radiologists assessed the diagnostic value of the radiographs by rating the visualization of anatomical landmarks and image elements on a five-point Likert scale. A mean-sum score was calculated by averaging the two reader’s total scores. Given the non-parametric distribution, we used the Mann-Whitney U test to evaluate the scores.Results:Median dosage at full dose accounted for 38.4%, 48 and 53.2% of the German reference dose area product for shoulder, pelvis and lumbar spine, respectively. The applied radiation was incrementally reduced to 21.5%, 18.4% and 18.7% of the respective reference value for shoulder, pelvis and lumbar spine. Throughout the study, we observed an estimable tendency of superior quality at higher dosage in overall image quality. Statistically significant differences in image quality were restricted to the 50% dose groups in shoulder and lumbar spine images. Regardless of the applied dosage, 598 out of 600 images were of sufficient diagnostic value.Conclusion:In digital radiography image postprocessing allows for extensive reduction of radiation dosage. Despite a trend of superior image detail at higher dose levels, overall quality and, more importantly, diagnostic utility of low-dose images was not significantly affected. Therefore, our results not only confirm the clinical utility of postprocessed low-dose radiographs, but also suggest a widespread deployment of this advanced technology to ensure further dose limitations in clinical practice.Advances in knowledge:The diagnostic image quality of postprocessed skeletal radiographs is not significantly impaired even after extensive dose reduction by up to 20% of the reference value.     

广西X射线诊断受检者体表入射剂量调查

目的 探讨广西X射线诊断受检者体表入射剂量。方法 分层随机抽样选取25家不同级别医院的2 236例X射线诊断受检者为调查对象,采用热释光剂量测量不同级别的医院、不同类型设备和不同照射部位受检者的体表入射剂量。结果 普通X射线摄影、计算机X射线摄影(CR)和直接数字化X射线摄影(DR)受检者体表入射剂量范围分别为0.08~31.51、0.11~4.25和0.05~35.63 mGy。腹部前后位(AP)、骨盆AP;头颅侧位(LAT)、头颅后前位(PA)、胸部PA、胸部LAT、胸椎AP、胸椎LAT、腰椎AP、腰椎LAT入射剂量范围分别为0.08~19.53、0.15~18.78、0.08~9.87、0.06~9.24、0.05~2.71、0.13~2.93、0.15~19.01、0.07~25.33、0.16~27.23和0.11~35.63 mGy。结论 广西X射线诊断受检者平均入射剂量达标,但部分DR摄影致胸部PA入射剂量超过医疗照射指导水平。     

Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: A phantom study

Objective

To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk.

Materials and methods

Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data.

Results

The effective doses for head, thorax, abdomen and pelvis CT, were 0.7 mSv, 3.5 mSv, 3.0 mSv, 1.3 mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33 mGy); for thorax CT, breast (7.89 mGy); for abdomen CT, colon (6.62 mGy); for pelvis CT, bladder (4.28 mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%).

Conclusion

The effective doses from these common pediatric CT examinations ranged from 0.7 mSv to 3.5 mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs.     

Significant but reasonable radiation exposure from computed tomography-related medical imaging in the ICU

Admission to an intensive care unit (ICU) is associated with increased medical imaging and radiation exposure, yet few studies have estimated the risk of cancer associated with these examinations. The purpose of this study was to review computed tomography (CT) scans performed on patients admitted to two urban academic ICUs, predict their radiation exposure, and calculate their estimated lifetime attributable risk of cancer (LAR). An electronic chart review was performed on all CT scans performed between January 2007 and December 2011. The estimated effective dose of radiation was calculated for each CT, and the LAR for each patient was predicted. Mean radiation exposure was 22.2?±?25.0 mSv with a mean LAR of 0.1?±?0.2 % and a median of 0.6 % with a range of <0.001 to 3.4 %. Our cohort received radiation doses higher than recommended by guidelines; however, the critical nature of their admission may have warranted these imaging studies. Estimated risk of cancer in this population was overall low.     

Optimisation of the lateral lumbar spine projection using an air-gap technique

IntroductionLumbar spine radiography is considered as having a high radiation dose compared to other planar radiography examinations. The aim of this study was to investigate the feasibility of replacing an antiscatter grid with an air gap technique to achieve dose reduction for lateral lumbar spine radiography while maintaining image quality on a direct digital radiography (DDR) system.MethodsIn phase 1, an experimental study using an anthropomorphic phantom identified the optimal airgap technique. In phase 2, lateral projections of the lumbar spine were performed on 50 patients randomly assigned equally into a control group (using the antiscatter grid) and an experimental group (using the airgap technique). The dose area product (DAP) was recorded, keeping other variables constant. Image quality evaluation was performed by 5 radiologists performing Absolute Visual Grading Analysis (VGA) using an image quality score tool, with resultant scores analysed using Visual Grading Characteristics (VGC).ResultsA 10 cm airgap in conjunction with a source to image distance (SID) of 121 cm was found as the optimal airgap technique. The clinical application of this technique resulted in a statistically significant (p < 0.05) reduction in DAP of 72%. Image quality scores were higher for the antiscatter grid but variation between the two techniques was not significant (p > 0.05).ConclusionReplacing the antiscatter grid with an airgap technique in lateral lumbar spine digital radiography, provides a significant dose reduction whilst still maintaining diagnostic image quality.Implications for practiceThe airgap technique is a simple and easy technique to implement and radiographers should find no difficulties in applying it, as It involves no additional cost and no additional equipment.     

Patient absorbed doses in digital grey-scale fluorography

This article describes a preliminary comparison between the levels of patient dose used in digital grey-scale fluorography (DGF) and screen-film radiography. Patient doses were measured in three common radiographic examinations, postero-anterior chest, antero-posterior lumbar spine and lateral lumbo-sacral junction, using thermoluminescent dose-meters and an anthropomorphic phantom. Within the limitations of the image quality currently available in DGF, the findings indicate that digital radiography with the large-field X-ray image intensifier promises significant savings in patient dose compared with conventional radiography.     

Assessment of computed tomography radiation doses for paediatric head and chest examinations using paediatric phantoms of three different ages

IntroductionWith the rapid development of computed tomography (CT) scanners, the assessment of the radiation dose received by the patient has become a heavily researched topic and may result in a reduction in radiation exposure risk. In this study, radiation doses were measured using three paediatric phantoms for head and chest CT examinations in Najran, Saudi Arabia.MethodsThirteen scanners were included in the study to estimate the CT radiation doses using three phantoms representing three age groups (1-, 5-, and 10-year-old patients).ResultsThe volume CT dose index (CTDI_vol) estimated for each phantom ranged from 6.56 to 41.12 mGy and 0.292 to 11.10 mGy for the head and chest examinations, respectively. The estimation of lifetime attributable risk (LAR) indicated that the cancer risk could reach approximately 0.02–0.16% per 500 children undergoing head and chest CT examinations.ConclusionThe comparison with the published data of the European Commission (EC) and countries reported in this study revealed that the mean CTDI_vol for the head examinations was within the recommended dose reference levels (DRLs). Meanwhile, chest results exceeded the international DRLs for the one-year-old phantoms, suggesting that optimisation work is required at a number of sites.Implications for practiceThe variation among CT doses reported in this study showed that substantial standardisation is needed.     

Estimated radiation risks potentially associated with full-body CT screening

PURPOSE: To estimate the radiation-related cancer mortality risks associated with single or repeated full-body computed tomographic (CT) examinations by using standard radiation risk estimation methods. MATERIALS AND METHODS: The estimated dose to the lung or stomach from a single full-body CT examination is 14-21 mGy, which corresponds to a dose region for which there is direct evidence of increased cancer mortality in atomic bomb survivors. Total doses for repeated examinations are correspondingly higher. The authors used estimated cancer risks in a U.S. population derived from atomic bomb-associated cancer mortality data, together with calculated organ doses from a full-body CT examination, to estimate the radiation risks associated with single and multiple full-body CT examinations. RESULTS: A single full-body CT examination in a 45-year-old adult would result in an estimated lifetime attributable cancer mortality risk of around 0.08%, with the 95% credibility limits being a factor of 3.2 in either direction. A 45-year-old adult who plans to undergo annual full-body CT examinations up to age 75 (30 examinations) would accrue an overall estimated lifetime attributable risk of cancer mortality of about 1.9%, with the 95% credibility limits being a factor of 2 in either direction. CONCLUSION: The authors provide estimates of lifetime cancer mortality risks from both single and annual full-body CT examinations. These risk estimates are needed to assess the utility of full-body CT examinations from both an individual and a public health perspective.     

Organ doses and lifetime attributable risk evaluations for scoliosis examinations of adolescent patients with the EOS imaging system

Purpose

The goal of this work is to evaluate organ doses and lifetime attributable risk of cancer incidence and mortality in scoliosis examinations of adolescent patients performed with EOS imaging system, in order to optimize patient dose and protocols.

Methods

An anthropomorphic phantom of a normal patient, with thermoluminescent dosimeters in correspondence with the main organs at risk, was imaged with both EOS and computed radiography (CR). For each modality, effective dose was calculated from the measured organ doses. Lifetime attributable risk was computed accordingly to the Committee on the Biological Effects of Ionizing Radiation (BEIR VII) and Public Health England (HPA) publications.

Results

Except for testes and eyes, which were excluded from the scan in CR protocol, for all the other organs the doses delivered with CR examination were higher than these delivered by EOS system. The effective dose in EOS examination (0.43 ± 0.04 mSv) is about two times less than the dose in computed radiography with anti-scatter grid examination (0.87 ± 0.09 mSv), and, consequently, also the cancer probability is lower (5.4 vs 9.7 number of any cancers induction cases per 100,000 person examined, for a 20-year-old male patient).

Conclusions

The EOS system is efficient in limiting patient dose. The shielding of testes and the exclusion of eyes from the scan could allow to further reduce the dose.