Estimation of entrance surface air kerma due to diagnostic X-ray examinations of adult patients in Uttarakhand,India and establishment of local diagnostic reference levels

It is well established that diagnostic X-ray practices must be optimised to keep patient radiation dose as low as compatible with providing the diagnostic information required. For effective optimisation of diagnostic exposures, the International Commission on Radiological Protection (ICRP) introduced the concept of diagnostic reference levels (DRLs) in 1996. The present study aimed to carry out an extensive dose survey of diagnostic radiography installations in the Uttarakhand region of India to establish local DRL Values for the different diagnostic practices. During the survey, air kerma values were measured for 297 diagnostic X-ray machines installed at 270 medical centres in the region and the entrance surface air kerma (K _a,e) was estimated for ten commonly performed radiographic projections. These included chest posterior-anterior (PA), cervical spine anterior-posterior (AP), skull PA, abdomen AP, KUB (kidney, ureter and bladder), lumbar spine AP, lumbar spine lateral (LAT), pelvis AP, thoracic spine AP, and thoracic spine LAT. Wide variations were observed in the estimated values of K _a,e for individual projections. The third quartile of the distribution of the median values of the estimated K _a,e for a given projection was calculated to establish local DRL Values. The majority of the acquired dose data were found to be comparable to or less than the proposed national and international DRLs. The local DRL Values reported in this study may be used to improve radiological practice by reducing patient doses during radiography examinations. The obtained data may also contribute to a national patient dose database for establishing future national DRLs.     

Retrospective patient dose analysis of Ghana's first direct digital radiography system

ABSTRACT: The log file generated in the flat panel detector of a direct digital x-ray machine (General Electric, Haulun Medical Systems, Serial Number 8M0392) after x-ray exposure was used to acquire data regarding the entrance surface air kerma (ESAK) for some routine x-ray examinations. The data were collected for a minimum of 10 standard adult patients undergoing each examination considered. The mean ESAK were found to be 0.25, 0.33, 0.14, 7.33, 9.76, 7.38, and 6.86 mGy for skull AP and LAT, chest AP, lumbar spine AP and LAT, pelvis AP and abdomen AP series, respectively. The mean ESAK values recorded from this study show wide variations but were below diagnostic reference levels (DRLs) of the Commission of European Communities and also compare with other recommendations. The comparisons of this study's dose levels with DRLs were undertaken as an approach to dose optimization. The study revealed that a dose audit of digital radiography systems is necessary because of the potential high doses one is likely to receive. Continuous dose evaluation in digital radiography is therefore encouraged in order to optimize doses to patients.     

Digital chest radiography image quality assessment with dose reduction

A retrospective study of digital chest radiography was performed to compare the image quality and dose parameters from two X-ray rooms in different areas of the same hospital using identical X-ray units but different local protocol for obtaining chest PA and lateral radiographs. Image quality of radiographs was assessed from the printed films using well established European guidelines and modified criteria. Patient entrance surface air kerma was calculated using technical data recorded for each radiograph and measured output of the X-ray unit. Effective dose and dose to radiosensitive organs was estimated using dose calculation software PCXMC. There was no statistical significant difference in the evaluated image quality using either technique, median entrance surface air kerma to the patient reduced significantly with added filtration technique and use of normal density setting. Phantom measurements indicated that an additional filtration of 0.1 mm Cu + 1 mm Al in the X-ray beam alone reduced the entrance surface air kerma by 35%.     

应用蒙特卡罗方法模拟诊断X射线机

目的:应用蒙特卡罗程序模拟诊断X射线机运行过程,获得其输出参数。方法:采用Geant4程序构建诊断X射线模型,得到不同管电压下的X射线能谱,利用能谱计算相应的平均能量,应用Geant4模拟相应能谱的有效能量,利用有效能量计算出标准位置的空气比释动能率值,应用试验测量的空气比释动能率验证计算值。结果:通过对比应用蒙特卡罗方法计算的空气比释动能率值和实验值,发现两者误差最大在7%,两值基本一致。结论:应用蒙特卡罗方法可以模拟诊断X射线机的管电压能谱、平均能量、有效能量和空气比释动能率值。[关键词]蒙特卡罗Geant4;空气比释动能;有效能量;平均能量;X射线     

数字X射线摄影机房内散漏射线的空间分布

目的研究医用诊断X射线数字摄影机房内散漏射线剂量大小的空间分布情况,为新建、改建、扩建医用诊断X射线机房的屏蔽防护设计提供参考依据。方法以X射线球管为中心,分别采用水平与垂直两种照射方式,测量机房内离球管不同距离及不同方向的散漏射线空气比释动能率。结果在同一方向情况下,离球管1～2m处的散漏射线空气比释动能率处于最高水平,且保持相对稳定状态。在同样距离的情况下,当水平方向照射时,与主射线束成45°、90°、270°、315°方向的散漏射线空气比释动能率较高,180°方向最低;当垂直方向照射时,球管左右两侧的散漏射线空气比释动能率较高,球管正面略低,球管背面最低。结论机房内散漏射线的空间分布出现剂量大小与球管距离不成平方反比的衰弱现象。     

Australian diagnostic reference levels for multi detector computed tomography

The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) is undertaking web based surveys to obtain data to establish national diagnostic reference levels (DRLs) for diagnostic imaging. The first set of DRLs to be established are for multi detector computed tomography (MDCT). The survey samples MDCT dosimetry metrics: dose length product (DLP, mGy.cm) and volume computed tomography dose index (CTDI_vol, mGy), for six common protocols/habitus: Head, Neck, Chest, AbdoPelvis, ChestAbdoPelvis and Lumbar Spine from individual radiology clinics and platforms. A practice reference level (PRL) for a given platform and protocol is calculated from a compliant survey containing data collected from at least ten patients. The PRL is defined as the median of the DLP/CTDI_vol values for a single compliant survey. Australian National DRLs are defined as the 75th percentile of the distribution of the PRLs for each protocol and age group. Australian National DRLs for adult MDCT have been determined in terms of DLP and CTDI_vol. In terms of DLP the national DRLs are 1,000 mGy cm, 600 mGy cm, 450 mGy cm, 700 mGy cm, 1,200 mGy cm, and 900 mGy cm for the protocols Head, Neck, Chest, AbdoPelvis, ChestAbdoPelvis and Lumbar Spine respectively. Average dose values obtained from the European survey Dose Datamed I reveal Australian doses to be higher by comparison for four out of the six protocols. The survey is ongoing, allowing practices to optimise dose delivery as well as allowing the periodic update of DRLs to reflect changes in technology and technique.     

Use of the VIP-Man model to calculate energy imparted and effective dose for x-ray examinations

A male human tomographic model was used to calculate values of energy imparted (epsilon) and effective dose (E) for monoenergetic photons (30-150 keV) in radiographic examinations. Energy deposition in the organs and tissues of the human phantom were obtained using Monte Carlo simulations. Values of E/epsilon were obtained for three common projections [anterior-posterior (AP), posterior-anterior (PA), and lateral (LAT)] of the head, cervical spine, chest, and abdomen, respectively. For head radiographs, all three projections yielded similar E/epsilon values. At 30 keV, the value of E/epsilon was approximately 1.6 mSv J(-1), which is increased to approximately 7 mSv J(-1) for 150 keV photons. The AP cervical spine was the only projection investigated where the value of E/epsilon decreased with increasing photon energy. Above 70 keV, cervical spine E/epsilon values showed little energy dependence and ranged between approximately 8.5 mSv J(-1) for PA projections and approximately 17 mSv J(-1) for AP projections. The values of E/epsilon for AP chest examinations showed very little variation with photon energy, and had values of approximately 23 mSv J(-1). Values of E/epsilon for PA and LAT chest projections were substantially lower than the AP projections and increased with increasing photon energy. For abdominal radiographs, differences between the PA and LAT projections were very small. All abdomen projections showed an increase in the E/epsilon ratio with increasing photon energy, and reached a maximum value of approximately 13.5 mSv J(-1) for AP projections, and approximately 9.5 mSv J(-1) for PA/lateral projections. These monoenergetic E/epsilon values can generate values of E/epsilon for any x-ray spectrum, and can be used to convert values of energy imparted into effective dose for patients undergoing common head and body radiological examinations.     

牙科X射线诊断的受检者剂量调查研究

目的 调查牙科X射线诊断所致受检者剂量范围,为牙科X射线检查辐射剂量最优化提供参考,降低牙科X射线检查的辐射风险。方法 使用多功能X射线测量仪Raysafe X2和PTW Diamentor CX型空气比释动能面积乘积仪在北京市6家医疗机构,对口内牙科X射线机的入射空气比释动能和空气比释动能面积乘积进行了调查,对口外牙科X射线机的空气比释动能面积乘积进行了调查。结果 共调查了5台口内牙科X射线机和6台口外牙科X射线机,口内牙科X射线机的入射空气比释动能范围为0.57 mGy~2.95 mGy,KAP范围为13.2 mGy·cm²~70.8 mGy·cm²。口外牙科X射线机全景的空气比释动能面积乘积范围为54.2 mGycm²~139.4 mGy·cm²,头颅正侧位的空气比释动能面积乘积范围为24.8 mGycm²~83.6 mGy·cm²,CBCT的空气比释动能面积乘积范围为714.7 mGy·cm²~3 791.5 mGy·cm²。结论 牙科X射线应根据诊断目的合理选择辐射风险低的检查类型,对不同类型检查根据所要达到的图像质量选择合适的照射条件,通过患者剂量调查建立诊断参考水平是防护最优化的重要手段。     

江西省X射线摄影受检者入射体表剂量调查

目的 调查2017年度江西省X射线摄影所致受检者的入射体表剂量水平,阐述江西省X射线诊断的医疗照射现状。方法 随机选取南昌市、上饶市、赣州市、萍乡市、宜春市和九江市共6个地级市不同级别的20家医院,利用热释光剂量计测定1 273人次受检者不同照射部位的ESD值。结果 2017年江西省CR和DR摄影所致受检者的ESD范围分别为0.08~17.81 mGy和0.04~30.91 mGy,胸部正位和侧位、腰椎正位和侧位、颈椎正位和侧位、骨盆及髋关节的X射线摄影检查所致受检者的ESD值的范围分别为0.07~2.40 mGy、0.13~7.27 mGy、0.33~23.29 mGy、0.62~30.91 mGy、0.09~1.69 mGy、0.10~1.79 mGy、0.29~23.46 mGy。结论 江西省胸部侧位X射线摄影所致受检者的入射体表剂量75%百分位值超过医疗照射指导水平,部分照射部位ESD值较全国"九五"期间调查值有显著下降,DR摄影所致受检者剂量比CR高,应采取措施降低DR摄影所致受检者的辐射剂量。     

Benchmarking the performance of fixed-image receptor digital radiography systems. Part 2: system performance metric

This is part two of a two-part study in benchmarking system performance of fixed digital radiographic systems. The study compares the system performance of seven fixed digital radiography systems based on quantitative metrics like modulation transfer function (sMTF), normalised noise power spectrum (sNNPS), detective quantum efficiency (sDQE) and entrance surface air kerma (ESAK). It was found that the most efficient image receptors (greatest sDQE) were not necessarily operating at the lowest ESAK. In part one of this study, sMTF is shown to depend on system configuration while sNNPS is shown to be relatively consistent across systems. Systems are ranked on their signal-to-noise ratio efficiency (sDQE) and their ESAK. Systems using the same equipment configuration do not necessarily have the same system performance. This implies radiographic practice at the site will have an impact on the overall system performance. In general, systems are more dose efficient at low dose settings.     

2015年广西数字化摄影受检者入射体表剂量水平调查与分析

目的 了解广西地区数字化摄影(DR)所致受检者的入射体表剂量水平。方法 采用分层随机抽样方法,选取广西区内14家医院不同时间段进行DR检查的受检者,使用热释光剂量计测量受检者不同部位的入射体表剂量。结果 广西地区一级医院的头颅(PA)、头颅(LAT)、胸部(PA)、胸部(LAT)、胸椎(AP)、腰椎(AP)6个部位入射体表剂量的75%位值超出了国家医疗照射指导水平;二级和三级医院的胸部(PA)和胸部(LAT)两个部位入射体表剂量的75%位值超出国家医疗照射指导水平。结论 广西地区DR摄影的入射体表剂量较高,应进一步加强受检者的入射体表剂量监测。     

Paediatric dose measurements for chest X-ray examinations at Maternity and Children Hospital in Najran - Saudi Arabia

The entrance skin dose (ESD) of chest X-ray examinations for AP and PA projections of paediatric patients at Maternity and Children Hospital in Najran, Saudi Arabia have been obtained using DoseCal software. The majority of the results obtained show low measured ESD for chest X-ray examinations. The mean of ESD for the AP projection was found to be 37.5, 40.5, 41.3, and 52.3 μ Gy for age groups 0-1, >1-5, >5-10, and >10-15 years respectively. However, the ESD for PA projection was found to be 50.7 and 56.7 μ Gy for age groups >5-10, and >10-15 years respectively.     

Organ-specific external dose coefficients and protective apron transmission factors for historical dose reconstruction for medical personnel

While radiation absorbed dose (Gy) to the skin or other organs is sometimes estimated for patients from diagnostic radiologic examinations or therapeutic procedures, rarely is occupationally-received radiation absorbed dose to individual organs/tissues estimated for medical personnel; e.g., radiologic technologists or radiologists. Generally, for medical personnel, equivalent or effective radiation doses are estimated for compliance purposes. In the very few cases when organ doses to medical personnel are reconstructed, the data is usually for the purpose of epidemiologic studies; e.g., a study of historical doses and risks to a cohort of about 110,000 radiologic technologists presently underway at the U.S. National Cancer Institute. While ICRP and ICRU have published organ-specific external dose conversion coefficients (DCCs) (i.e., absorbed dose to organs and tissues per unit air kerma and dose equivalent per unit air kerma), those factors have been published primarily for mono-energetic photons at selected energies. This presents two related problems for historical dose reconstruction, both of which are addressed here. It is necessary to derive conversion factor values for (1) continuous distributions of energy typical of diagnostic medical x-rays (bremsstrahlung radiation), and (2) energies of particular radioisotopes used in medical procedures, neither of which are presented in published tables. For derivation of DCCs for bremsstrahlung radiation, combinations of x-ray tube potentials and filtrations were derived for different time periods based on a review of relevant literature. Three peak tube potentials (70 kV, 80 kV, and 90 kV) with four different amounts of beam filtration were determined to be applicable for historic dose reconstruction. The probabilities of these machine settings were assigned to each of the four time periods (earlier than 1949, 1949-1954, 1955-1968, and after 1968). Continuous functions were fit to each set of discrete values of the ICRP/ICRU mono-energetic DCCs and the functions integrated over the air-kerma weighted photon fluence of the 12 defined x-ray spectra. The air kerma-weighted DCCs in this work were developed specifically for an irradiation geometry of anterior to posterior (AP) and for the following tissues: thyroid, breast, ovary, lens of eye, lung, colon, testes, heart, skin (anterior side only), red bone marrow (RBM), and brain. In addition, a series of functional relationships to predict DT Ka-1 values for RBM dependent on body mass index [BMI (kg m-2) ≡ weight per height] and average photon energy were derived from a published analysis. Factors to account for attenuation of radiation by protective lead aprons were also developed. Because lead protective aprons often worn by radiology personnel not only reduce the intensity of x-ray exposure but also appreciably harden the transmitted fluence of bremsstrahlung x-rays, DCCs were separately calculated for organs possibly protected by lead aprons by considering three cases: no apron, 0.25 mm Pb apron, and 0.5 mm Pb apron. For estimation of organ doses from conducting procedures with radioisotopes, continuous functions of the reported mono-energetic values were developed, and DCCs were derived by estimation of the function at relevant energies. By considering the temporal changes in primary exposure-related parameters (e.g., energy distribution), the derived DCCs and transmission factors presented here allow for more realistic historical dose reconstructions for medical personnel when monitoring badge readings are the primary data on which estimation of an individual's organ doses are based.     

Reconstruction of doses from occupationally related medical x-ray examinations

Many nuclear weapons complex workers were required to undergo medical x-ray examinations as a condition of their employment. To ensure that their dose reconstructions are complete, it is necessary to include the contributions from these examinations. X-ray procedures that must be evaluated include: (1) posterior-anterior and lateral radiography, and/or photofluorography, of the chest; (2) anterior-posterior, lateral and oblique lumbar, cervical and thoracic radiography of the spine; and (3) radiography of the pelvis. Each is discussed in the context of conditions that existed during the time the worker was employed. For purposes of dose reconstruction, the x-ray beam size is especially important because the dose conversion factors (DCFs) for each specific body organ depend on whether it was in, or on the periphery of, the primary beam. The approach adopted was to use the DCFs, combined with the entrance kerma, to estimate the organ doses. In cases in which beam output data or information on the primary factors influencing the dose are not available, methods to provide conservative (i.e., claimant-favorable) entrance kerma and dose estimates are adopted. These include specific default values for chest radiography. To account for uncertainties, the estimated doses due to x-ray examinations are increased by 30%.     

Investigation of the practical aspects of an additional 0.1 mm copper x-ray spectral filter for cine acquisition mode imaging in a clinical care setting

Minimizing the x-ray radiation dose is an important aspect of patient safety during interventional fluoroscopy procedures. This work investigates the practical aspects of an additional 0.1 mm Cu x-ray beam spectral filter applied to cine acquisition mode imaging on patient dose and image quality. Measurements were acquired using clinical interventional imaging systems. Acquisition images of Solid Water phantoms (15-40 cm) were acquired using x-ray beams with the x-ray tube inherent filtration and using an additional 0.1 mm Cu x-ray beam spectral filter. The skin entrance air kerma (dose) rate was measured and the signal difference to noise ratio (SDNR) of an iodine target embedded into the phantom was calculated to assess image quality. X-ray beam parameters were recorded and analyzed and a primary x-ray beam simulation was performed to assess additional x-ray tube burden attributable to the Cu filter. For all phantom thicknesses, the 0.1 mm Cu filter resulted in a 40% reduction in the entrance air kerma rate to the phantoms and a 9% reduction in the SDNR of the iodine phantom. The expected additional tube load required by the 0.1 mm Cu filter ranged from 11% for a 120 kVp x-ray beam to 43% for a 60 kVp beam. For these clinical systems, use of the 0.1 mm Cu filter resulted in a favorable compromise between reduced skin dose rate and image quality and increased x-ray tube burden.     

数字减影血管造影系统性能检测和质量控制

为保证数字减影血管造影（DSA）系统的安全性和有效性,必须定期进行性能检测和质量控制。本文按照JJG 1067-2011《医用诊断数字减影血管造影（DSA）系统X射线辐射源国家计量检定规程》,介绍了对数字减影血管造影系统的空气比释动能率、HVL（辐射输出的质）、X射线管电压、模拟血管最小尺寸、空间分辨力、低对比度分辨力、对比度线性和减影性能影响等的检测方法。     

Comparison of dose from radiological examination for scoliosis in children among two pediatric hospitals by Monte Carlo simulation

The radiation exposures of children undergoing full spine radiography were investigated in two pediatric hospitals in Greece. Entrance surface kerma (Ka,e) was assessed by thermoluminescence dosimetry and patient's effective dose (E) was estimated by Monte Carlo simulation. All required information regarding patient age and sex, the irradiation geometry, the x-ray spectra, and other exposure parameters (tube voltage and current) were registered as well. Values of Ka,e were measured to range from 0.22 mGy to 2.12 mGy, while E was estimated to range from 0.03 mSv to 0.47 mSv. In general, all values were greater in one of the two hospitals, as higher tube currents and exposure times were used in the examinations because of the difference in radiographers' training and practice. Moreover, dose to red bone marrow was found to be between 0.01 to 0.23 mSv and dose to breast ranged between 0.02 and 1.05 mSv depending on the age, projection, and hospital. These values are comparable with literature sources.     

A survey of radiation doses to adults from diagnostic radiology in Victoria.

This study examines doses to adult patients from diagnostic radiology. Measurements were made at 37 hospitals and private radiology centres in the state of Victoria. Skin entrance doses in air were measured for the exposure factors used by the radiographer for an average size patient for the following procedures: abdomen AP; pelvis AP; lumbar spine AP, lat, LSJ; and skull AP, lat. There was a large range of doses observed for each particular procedure. Factors contributing to the range of doses were identified. Guidance levels for adult radiography based on the third quartile values of the skin entrance dose have been adopted for use in Victoria.     

The abdominal radiation doses for paediatric patients undergoing X-ray examinations at southern Saudi Arabia

This study aims to estimate radiation doses for paediatric patients undergoing abdominal X-ray examinations in Najran, Saudi Arabia, through evaluation of the entrance surface doses using DoseCal software. Two X-ray units were used at a paediatric referral hospital. A total of 216 patients were examined with an age range between 0 and 7 years. The mean ESDs were found to be 0.042 and 0.101 mGy, for abdomen anteroposterior (AP) and posteroanterior (PA) respectively. The results are useful to the National Centre for Radiation Protection in Saudi Arabia and other professional organizations elsewhere, to set up safety protocols to prevent paediatric patients from needless radiation and to establish diagnostic reference levels (DRLs).     

某工业探伤工作场所验收检测与分析

目的为了解某蛇形管生产线直管对接焊缝X射线检测系统工作场所的防护情况,评估该系统在运行过程中对放射工作人员和公众健康与安全的影响。方法按照（GBZ 117-2006）《工业X射线探伤卫生防护标准》的要求进行检测。结果铅房进出管孔以远,辊道北区及南区边界处位置所测的空气比释动能率在〈0.10～3.79μGy/h之间,铅房周围其余位置所测的空气比释动能率在〈0.10～0.52μGy/h之间。结论该工业探伤工作场所防护情况良好,其防护效果达到了辐射防护的要求,该系统在正常运行条件下,不会对放射工作人员和公众的健康与安全造成影响。