蒙特卡罗模拟在放射诊断辐射剂量估算和优化中的应用

放射诊断成像的频次和对公众的累积剂量不断提升, 带来的辐射风险引起广泛关注, 但人体所接受辐射剂量的准确测量很难实现。蒙特卡罗模拟作为以概率统计理论为指导的数值计算方法, 已应用于各种放射诊断成像的剂量评估、成像优化和辐射防护。本文就蒙特卡罗方法的原理、蒙特卡罗模拟的建模过程及其在放射诊断剂量估算的应用进展进行综述。     

降低螺旋CT辐射剂量策略

使用CT诊断一个临床指征其益处远多于潜在风险,但CT曝光辐射的潜在风险仍是近年来人们关注的焦点。因此有必要提醒放射医生在保证影像诊断质量的同时必须将辐射剂量降低到尽可能低水平（ALARA）。为达到ALARA标准,必须合理使用CT,并根据具体的诊断任务而进行调整。就CT辐射输出测量的概况、辐射剂量的合理使用和优化以及降低辐射剂量的策略予以综述。     

颈部先天性囊性病变的影像学表现

使用CT诊断一个临床指征其益处远多于潜在风险,但CT曝光辐射的潜在风险仍是近年来人们关注的焦点.因此有必要提醒放射医生在保证影像诊断质量的同时必须将辐射剂量降低到尽可能低水平(ALARA).为达到ALARA标准,必须合理使用CT,并根据具体的诊断任务而进行调整.就CT辐射输出测量的概况、辐射剂量的合理使用和优化以及降低辐射剂量的策略予以综述.     

Radimetrics在放射剂量管理中的研究与进展

【摘要】随着CT影像技术的不断发展与进步,CT检查应用越来越广泛,其在临床诊断中起着不可或缺的作用。 但CT的辐射剂量较大,世界各国的医疗辐射特别是CT的辐射剂量仍在持续增加,如何使CT辐射剂量得到合理的管控,同时获得更优的成像质量已经成为大家关注的重点。Radimetrics放射剂量管理软件能够很好地调控与优化剂量管理。本文就Radimetrics在放射剂量管理中的研究与进展进行阐述。     

我国CT检查成年人辐射剂量诊断参考水平的建立历程及解读

经过放射诊断专家、影像技术专家、辐射防护专家和专业技术人员10多年的探索,一项基于大规模国内调查数据而建立的CT检查成年人辐射剂量诊断参考水平(diagnostic reference level,DRL)以国家卫生行业标准(WS/T 637-2018)形式发布。其制定原则和方法符合国际惯例和我国的实际情况,基本上涵盖了我国成年人常见CT检查项目,与国外的DRL比较,整体处于一个合理或较低的剂量水平。给出的50%分位数(可能达到水平)和25%分位数(异常低剂量的提示水平)作为辐射剂量优化指导的额外工具。在日常放射诊断活动中,使辐射剂量与图像质量、临床诊断任务相匹配,降低非正当过高或过低剂量的发生频率。     

多层CT辐射剂量与防护研究进展

多层CT(MDCT)可进行快速扫描和大范围容积扫描。与单层CT(SDCT)相比,MDCT特有的参数可能增加或减少受检者剂量。早期研究表明MDCT所致受检者剂量高于SDCT,但目前越来越多的研究表明两者剂量相似甚至MDCT的剂量较低。多层CT主要依靠CT的合理使用来降低辐射剂量。CT检查正当化判断是临床医生与放射医师共同的责任。扫描参数应根据扫描指征、受检者体形、年龄及扫描范围设置,并使用自动曝光控制等降低辐射剂量的技术。对临床医生和CT工作人员进行CT辐射防护培训有助于CT检查正当化及扫描方案与辐射剂量的最优化。     

儿童CT检查辐射剂量标准中国专家共识

CT是临床常用的检查手段, 儿童生长速度快, 细胞分裂旺盛, X线会对儿童造成更严重的电离辐射损伤, 如何在保证CT诊断的同时减少辐射剂量是儿童影像学的重点问题之一, 但是目前国内尚无统一的儿童CT辐射剂量标准。为进一步规范儿童CT检查辐射剂量使用方法, 在满足临床诊断的同时减少儿童所受的电离辐射损伤, 中华医学会儿科学分会影像学组、中华医学会放射学分会儿科学组牵头组织国内相关专家, 结合国内外专家共识和参考文献, 经多次讨论, 对儿童头颅平扫、鼻窦平扫、颞部平扫、颈部平扫、胸部平扫、腹部平扫、头颅增强、胸部增强、腹部增强的辐射剂量标准达成共识, 旨在规范儿童CT检查的辐射剂量, 更好地为儿童的健康安全服务。     

内蒙古自治区X射线放射诊断所致受检者辐射剂量的研究

目的 通过对1 247例X射线放射诊断致受检者入射体表剂量（ESD）的测量与计算,掌握内蒙古自治区放射诊断受检者所受辐射剂量的实际水平。方法 采用多阶段抽样的方法对不同地区、不同级别医院的X射线放射诊断所致受检者辐射剂量进行采样。采用专用热释光剂量计对辐射剂量的相关指标进行测量,通过相关公式或标准直线对辐射剂量的表征量进行计算并建立数据库,用SPSS 13.0软件对数据进行分析。结果 三级医院各部位ESD的P₇₅值均未超过指导水平参考值;除腹部平片外,其他部位的受检者ESD值在不同级别医院的差异均有统计学意义（H=6.32~11.91,P<0.05）。DR照射下,受检者ESD的P₇₅值明显低于CR和普通X射线照射;除腰椎正位、腰椎侧位以及腹部摄影外的其他部位的ESD值在不同类型设备的差异均有统计学意义（H=7.24~13.16,P<0.05）。 结论 内蒙古自治区部分放射诊断检查受检者所受辐射剂量高于国标中医疗照射指导水平值。     

胸部CT扫描所致儿童癌症风险估算研究

目的 估算1、5及10岁儿童胸部CT检查所受辐射剂量致肺癌、胃癌、肝癌、甲状腺癌、乳腺癌和白血病的终生归因风险（LAR）。方法 在医院影像归档和通信系统（PACS）中选取儿童胸部CT检查图像,在CT工作站上读取感兴趣区域（ROI）的平均CT值和面积,根据美国医学物理师协会（AAPM）推荐方法计算每个受检者的水当量直径,再结合容积CT剂量指数（CTDI_vol）计算体型特异性评估剂量（SSDE）,将SSDE转换为不同年龄不同性别儿童胸部CT检查时肺、胃、肝、甲状腺、乳腺和血液的平均器官剂量。以各器官剂量为基础,采用美国科学院电离辐射生物效应报告（BEIR）的癌症风险预测模型预测上述肿瘤的终生归因风险,其中白血病、肺癌、肝癌和胃癌是先经平均器官剂量计算出超额相对危险度后再计算肿瘤终生归因风险;甲状腺癌和女性乳腺癌是先计算出超额相对危险度再经平均器官剂量求得肿瘤终生归因风险。结果 由不同性别1、5及10岁儿童CT检查所受平均器官剂量可知,年龄对儿童CT检查SSDE值有显著影响（t=24.28,P<0.05）,性别对儿童胸部CT检查SSDE值的影响无统计学意义（P>0.05）。不同性别1、5及10岁儿童胸部CT检查所受辐射剂量致肺癌、胃癌、肝癌、甲状腺癌、乳腺癌和白血病的终生归因风险表明,肺癌和女性乳腺癌的终生归因风险较高,女性乳腺癌1、5及10岁组的LAR分别为10.9/10万人、30.8/10万人和34.5/10万人。结论 随着新技术的引进,儿童胸部CT检查受到的辐射剂量逐渐减小,但CT检查辐射剂量相对于普通放射诊断仍然不容忽视,其引起的癌症风险仍需持续关注并应在放射诊断的正当性判断中得到充分考虑。     

生物剂量估算技术在核与辐射事故医学救援中的应用

核与辐射事故医学救援中,对事故人员进行分类诊断可使医疗资源得以充分利用,从而大大提高救援效率。生物剂量估算技术是目前判断外照射放射损伤程度的有效方法。利用生物剂量估算技术进行受照人员的分类诊断,对核与辐射事故医学救援的高效、有序具有重要意义。该文针对现有生物剂量估算技术的特点及其在核与辐射事故医学救援分类诊断中的应用进行了分析讨论。     

Fetus radiation doses from nuclear medicine and radiology diagnostic procedures. Potential risks and radiation protection instructions

Although in pregnancy it is strongly recommended to avoid diagnostic nuclear medicine and radiology procedures, in cases of clinical necessity or when pregnancy is not known to the physician, these diagnostic procedures are to be applied. In such cases, counseling based on accurate information and comprehensive discussion about the risks of radiation exposure to the fetus should follow. In this article, estimations of the absorbed radiation doses due to nuclear medicine and radiology diagnostic procedures during the pregnancy and their possible risk effects to the fetus are examined and then discussed. Stochastic and detrimental effects are evaluated with respect to other risk factors and related to the fetus absorbed radiation dose and to the post-conception age. The possible termination of a pregnancy, due to radiation exposure is discussed. Special radiation protection instructions are given for radiation exposures in cases of possible, confirmed or unknown pregnancies. It is concluded that nuclear medicine and radiology diagnostic procedures, if not repeated during the pregnancy, are rarely an indication for the termination of pregnancy, because the dose received by the fetus is expected to be less than 100 mSv, which indicates the threshold dose for having deterministic effects. Therefore, the risk for the fetus due to these diagnostic procedures is low. However, stochastic effects are still possible but will be minimized if the radiation absorbed dose to the fetus is kept as low as possible.     

2014-2018年江西省医用放射工作人员外照射个人剂量监测结果分析

目的 分析江西省医疗机构放射工作人员的外照射个人剂量情况,为放射防护工作提供参考.方法 以2014-2018年江西省医疗机构不同工种放射工作人员为调查对象,工种包括诊断放射学、放射治疗、核医学和介入放射学,统计分析江西医用放射工作人员的受照剂量水平.结果 本次共调查23 833人次,平均人均年有效剂量为0.316 mS...     

Paediatric computed tomography radiation dose: A review of the global dilemma简

Computed tomography (CT) has earned a well-deserved role in diagnostic radiology, producing cross-sectional and three-dimensional images which permit enhanced diagnosis of many pathogenic processes. The speed, versatility, accuracy, and non-invasiveness of this procedure have resulted in a rapid increase in its use. CT imaging, however, delivers a substantially higher radiation dose than alternative imaging methodologies, particularly in children due to their smaller body dimensions. In addition, CT use in children produces an increased lifetime risk of cancer, as children’s developing organs and tissues are inherently more vulnerable to cellular damage than those of adults. Though individual risks are small, the increasing use of CT scans in children make this an important public health problem. Various organizations have recommended measures to minimize unnecessary exposures to radiation through CT scanning. These include elimination of multiple or medically unnecessary scans, development of patient-specific dosing guidelines, and use of alternative radiographic methodology wherever possible. Another important factor in excessive CT exposures, however, is a documented lack of awareness among medical practitioners of the doses involved in CT usage as well as its significant potential dangers. This review examines the effects of paediatric CT radiation, discusses the level of medical practitioner awareness of these effects, and offers recommendations on alternative diagnostic methods and practitioner education.     

The physician should benefit, not harm the patient

Six hundred years before Christ, Hippocrates said that physicians on exercising their medical duties, should benefit but not harm their patients. Seventy years ago increased medical radiation caused radiologists in the US an excess risk of leukemia, lymphoma and multiple myeloma. Now medical radiation is rather safe for the physician but the question remains if proper prophylactic measures are being taken to make it safe for the subjects examined. Roughly, first trimester of pregnancy radiography has a much greater fatal cancer risk than that of exposures taken later in pregnancy. It is suggested that women should be administered the minimum activity consistent with achieving the desired clinical information, whether or not they are known to be pregnant. The best available risk estimates suggest that pediatric CT diagnostic procedures will induce significantly increased lifetime radiation risk in children. Professor Roger Clarke wrote that there may be a need to reduce or prevent doses of medical radiation up to 3 mSv if there is no benefit to the individual. 30 mSv is described as "a dose which should not be exceeded" and can be approached only if there is a benefit to individuals and the dose is difficult to reduce or prevent. In WHO Category III a) Static brain imaging with technetium-99m pertechnetate, b) Gated cardiac imaging c) Bone imaging with technetium-99m MDP, c) Quantitative haemodynamics with technetium-99m pertechnetate, d) myocardial imaging with thallous-201 chloride and e) abscess imaging with gallium-67 citrate, induce an effective dose equivalent of 5-9 mSv. A CT scan commonly gives 25 mSv to the subject examined. BEIR VI indicated that a 10 mSv single population dose is associated with a lifetime attributable risk for developing a solid cancer or leukemia in 1:1000. Multiple CT examinations have administered to some patients with renal colic a dose of 19.5-153.7 mSv. One may suggest that there should be "justification" and informed written patients' consent for nuclear medicine examinations administering to the patient doses greater than 5 mSv, especially doses around or above 30 mSv / year.     

2015-2019年内蒙古地区部分医学应用放射工作人员职业性外照射个人剂量监测结果与分析

目的 了解、分析2015-2019年内蒙古地区医学应用放射工作人员职业外照射个人剂量水平,为放射工作人员健康管理和辐射防护管理提供数据基础和科学依据.方法 通过国家个人剂量登记系统采集内蒙古地区医学应用放射工作人员个人剂量监测数据,并进行统计与分析.结果 2015-2019年各年度医学应用放射工作人员人均年有效剂量依次...     

Deoxyribonucleic acid damage-associated biomarkers of ionising radiation: current status and future relevance for radiology and radiotherapy

Diagnostic and therapeutic radiation technology has developed dramatically in recent years, and its use has increased significantly, bringing clinical benefit. The use of diagnostic radiology has become widespread in modern society, particularly in paediatrics where the clinical benefit needs to be balanced with the risk of leukaemia and brain cancer increasing after exposure to low doses of radiation. With improving long-term survival rates of radiotherapy patients and the ever-increasing use of diagnostic and interventional radiology procedures, concern has risen over the long-term risks and side effects from such treatments. Biomarker development in radiology and radiotherapy has progressed significantly in recent years to investigate the effects of such use and optimise treatment. Recent biomarker development has focused on improving the limitations of established techniques by the use of automation, increasing sensitivity and developing novel biomarkers capable of quicker results. The effect of low-dose exposure (0–100 mGy) used in radiology, which is increasingly linked to cancer incidences, is being investigated, as some recent research challenges the linear-no-threshold model. Radiotherapy biomarkers are focused on identifying radiosensitive patients, determining the treatment-associated risk and allowing for a tailored and more successful treatment of cancer patients. For biomarkers in any of these areas to be successfully developed, stringent criteria must be applied in techniques and analysis of data to reduce variation among reports and allow data sets to be accurately compared. Newly developed biomarkers can then be used in combination with the established techniques to better understand and quantify the individual biological response to exposures associated with radiology tests and to personalise treatment plans for patients.Research into the identification of biomarkers of radiation exposure is an emerging and developing area with multiple possible benefits for patients, doctors and the general public. A radiation biomarker is a biological entity that changes after exposure to radiation, allowing exposed individuals to be identified and, with some biomarkers, a dose to be estimated. There are different types of biomarkers, including chromosome aberrations, protein expression or gene expression. Some can measure accurately the dose received, while others can only indicate if a dose was received. Biomarkers can help clinicians manage treatment for a patient exposed accidentally to the wrong radiation dose or on purpose through radiotherapy. They may be able to predict the treatment response of a tumour and estimate the risk of acute or late effects in normal tissues. Biomarkers can also identify the dose received by the patient in a full or partial body exposure. Such information can help inform the necessary medical treatment plan for the patient, and it may also identify patients with a high likelihood of developing cancer in the future so that regular monitoring can be set up.     

Establishing diagnostic reference levels for interventional procedures in Kenya

PurposeTo quantify ionizing radiation exposure to patients during interventional procedures and establish national diagnostic reference levels (NDRLs) for clinical radiation exposure management.MethodsThe cumulative reference point air kerma, kerma area product, fluoroscopy time and other operational parameters were monitored for 50 children and 261 adult patient procedures in five catheterization medical laboratories in Kenya. To estimate the risk associated with the exposure, effective doses were derived from the kerma area product using conversion factors from Monte Carlo models.ResultsAbout 3% of the measured cumulative reference point air kerma for the interventional procedures approached the threshold dose limit with the potential to cause deterministic effects such as skin injuries. In interventional cardiology, the results obtained for both children and adults indicated 33% were below the diagnostic reference levels (DRLs). In adult interventional radiology, 29% for cumulative reference point air kerma, and 43% for kerma area product and fluoroscopy time respectively were below the diagnostic reference levels. NDRLs were proposed for routine use in the procedures considered and for the non-existent DRLs situations in paediatric interventional cardiology.ConclusionThe measured patient doses were above the DRLs available in the literature indicating a need for radiation optimization through, continuous monitoring and recording of patient dose. To promote radiation safety, facilities performing interventional procedures need to establish a radiation monitoring notification threshold for possible deterministic effects, in addition to the use of the newly established national diagnostic reference levels, as a quality assurance measure.     

河北省医疗照射应用频度调查

目的 了解河北省2016年放射诊疗机构基本情况和医疗照射应用频度。方法 采用普查的方式,以行政文件形式下发调查表格,了解河北省2016年医用X射线诊断、介入放射学、放射治疗、临床核医学的基本情况和诊疗人次。将调查的各类型放射诊疗人次数除以2016年全省常住人口数,得出不同放射诊疗类型的应用频度。结果 2016年全省有放射诊疗机构2 951家,放射诊疗设备6 966台,医用X射线诊断应用频度为379.25人次/千人口,介入放射学应用频度2.31人次/千人口,放射治疗应用频度0.55例/千人口,临床核医学应用频度1.65人次/千人口。CT应用频度136.39人次/千人口,占全省医用X射线诊断应用频度的36.0%,年均增长率达12.4%。各地各类医疗照射应用频度中,临床核医学应用频度最高的石家庄是最低的衡水的11倍;三级医疗机构虽然只占机构总数的2.3%,但其开展25.5%的医用X射线诊断和35.3%的CT检查,开展介入放射学和放射治疗超过了全省的70%,临床核医学更是高达全省的97.7%。结论 初步掌握了河北省2016年放射诊疗机构基本情况和医疗照射应用频度,医疗照射将保持较长时间的增长趋势且各地各级医疗机构开展情况很不平衡,要加强宏观调控和医疗照射防护管理力度,合理应用各种放射诊疗,保护患者和受检者健康和安全,促进放射诊疗事业健康可持续发展。     

广东省放射诊疗工作人员个人剂量监测调查水平的探讨

目的 探讨广东省放射诊疗工作人员个人剂量监测调查水平.方法 采用方便抽样方法,以2016-2019年委托广东省职业病防治院个人剂量监测室进行个人剂量监测的广东省放射诊疗工作人员为调查对象,对其个人剂量进行监测与分析.结果 2016-2019年分别监测诊断放射学、牙科放射学、核医学、放射治疗、介入放射学和其他应用工作人员...     

Awareness of radiation protection and dose levels of imaging procedures among medical students,radiography students,and radiology residents at an academic hospital: Results of a comprehensive survey

PurposeTo evaluate the awareness of radiation protection issues and the knowledge of dose levels of imaging procedures among medical students, radiology residents, and radiography students at an academic hospital.Material and methodsA total of 159 young doctors and students (including 60 radiology residents, 56 medical students, and 43 radiography students) were issued a questionnaire consisting of 16 multiple choice questions divided into three separated sections (i.e., demographic data, awareness about radiation protection issues, and knowledge about radiation dose levels of common radiological examinations).ResultsMedical students claimed to have at least a good knowledge of radiation protection issues more frequently than radiology residents and radiography students (94.4% vs 55% and 35.7%, respectively; P < 0.05), with no cases of perceived excellent knowledge among radiography students. However, the actual knowledge of essential radiation protection topics such as regulations, patient and tissue susceptibility to radiation damage, professional radiation risk and dose optimisation, as well as of radiation doses delivered by common radiological procedures was significantly worse among medical students than radiology residents and radiography students (P < 0.05). Those latter significantly outperformed radiology residents as to knowledge of radiation protection issues (P < 0.01). Overall, less than 50% of survey respondents correctly answered all questions of the survey.ConclusionsRadiology residents, radiography students and medical students have a limited awareness about radiation protection, with a specific gap of knowledge concerning real radiation doses of daily radiological examinations. Both undergraduate and postgraduate teaching needs to be effectively implemented with radiation safety courses.