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.     

Evaluation of patient and staff doses during various CT fluoroscopy guided interventions

As CT scanners are more routinely used as a guidance tool for various types of interventional radiological procedures, concern has grown for high patient and staff doses. CT fluoroscopy provides the physician immediate feedback and can be a valuable tool to dynamically assist various types of percutaneous interventions. However, the fixed position of the scanning plane in combination with high exposure factors may lead to high cumulative patient skin doses that can reach deterministic threshold limits. The staff is also exposed to a considerable amount of scatter radiation while standing next to the patient during the procedures. Although some studies have been published dealing with this subject, data of patient skin doses determined by direct in vivo dosimetry remains scarce. The purpose of this study is to quantify and to evaluate both patient and staff doses by direct thermoluminescent dosimetry during various clinical CT fluoroscopy guided procedures. Patient doses were quantified by determining the entrance skin dose with direct thermoluminescent dosimetry and by estimating the effective dose (E). Staff doses were quantified by determining the entrance skin dose at the level of the eyes, thyroid, and both the hands with direct thermoluminescent dosimetry. For a group of 82 consecutive patients, the following median values were determined (data per procedure): patient E (19.7 mSv), patient entrance skin dose (374 mSv), staff entrance skin dose at eye level (0.21 mSv), thyroid (0.24 mSv), at the left hand (0.18 mSv), and at the right hand (0.76 mSv). The maximum recorded patient entrance skin dose stayed well below the deterministic threshold level of 2 Gy. Poor correlation between both patient/staff doses and integrated procedure mAs emphasizes the need for in vivo measurements. CT fluoroscopy doses are markedly higher than classic CT-scan doses and are comparable to doses from other interventional radiological procedures. They consequently require adequate radiation protection management. An important potential for dose reduction exists by limiting the fluoroscopic screening time and by reducing the tube current (mA) to a level sufficient to provide adequate image quality.     

Occupational radiation doses to operators performing cardiac catheterization procedures

Cardiac catheterization procedures using fluoroscopy reduce patient morbidity and mortality compared to operative procedures. These diagnostic and therapeutic procedures require radiation exposure to patients and physicians. The objectives of the present investigation were to provide a systematic comprehensive summary of the reported radiation doses received by operators due to diagnostic or interventional fluoroscopically-guided procedures, to identify the primary factors influencing operator radiation dose, and to evaluate whether there have been temporal changes in the radiation doses received by operators performing these procedures. Using PubMed, we identified all English-language journal articles and other published data reporting radiation exposures to operators from diagnostic or interventional fluoroscopically-guided cardiovascular procedures from the early 1970's through the present. We abstracted the reported radiation doses, dose measurement methods, fluoroscopy system used, operational features, radiation protection features, and other relevant data. We calculated effective doses to operators in each study to facilitate comparisons. The effective doses ranged from 0.02-38.0 microSv for DC (diagnostic catheterizations), 0.17-31.2 microSv for PCI (percutaneous coronary interventions), 0.24-9.6 microSv for ablations, and 0.29-17.4 microSv for pacemaker or intracardiac defibrillator implantations. The ratios of doses between various anatomic sites and the thyroid, measured over protective shields, were 0.9 +/- 1.0 for the eye, 1.0 +/- 1.5 for the trunk, and 1.3 +/- 2.0 for the hand. Generally, radiation dose is higher on the left side of an operator's body, because the operator's left side is closer to the primary beam when standing at the patient's right side. Modest operator dose reductions over time were observed for DC and ablation, primarily due to reduction in patient doses due to decreased fluoroscopy/cineradiography time and dose rate by technology improvement. Doses were not reduced over time for PCI. The increased complexity of medical procedures appears to have offset dose reductions due to improvements in technology. The large variation in operator doses observed for the same type of procedure suggests that optimizing procedure protocols and implementing general use of the most effective types of protective devices and shields may reduce occupational radiation doses to operators. We had considerable difficulty in comparing reported dosimetry results because of significant differences in dosimetric methods used in each study and multiple factors influencing the actual doses received. Better standardization of dosimetric methods will facilitate future analyses aimed at determining how well medical radiation workers are being protected.     

介入放射诊治中患者X射线辐射受照水平

目的 分析介入放射诊治中患者接受的X射线辐射,探讨减少辐射的方法。方法 采用Angiostar-Plus型DSA机随机配置的剂量测量系统(Diamentor K1),回顾性分析432例经血管途径介入诊治的面积剂量乘积(DAP,cGycm²)和入射剂量(ED,mGy)。结果 总体DAP值11900±10652,总体ED值679±589,摄影DAP均值为透视的3.34倍,摄影ED均值为透视的1.56倍。结论 透视时间长、摄影帧数多是DSA法介入诊治高剂量的两个主要的可控性因素,摄影剂量对总剂量的贡献大于透视,减低透视脉冲频率和减少摄影帧数可有效降低患者的X射线辐射。     

深圳市2018年数字减影血管造影（DSA）放射防护分析

目的 了解深圳市2018年数字减影血管造影（DSA）介入诊疗场所的放射防护状况,为卫生行政部门放射卫生管理提供参考。方法 根据GBZ 130—2013的方法要求,对深圳市17家医疗机构的18台DSA设备进行状态检测,检测DSA设备透视防护区测试平面上的空气比释动能率和机房外的周围剂量当量率。结果 18台DSA设备透视防护区测试平面上空气比释动能率合格率为44.4%,透视防护区测试平面上空气比释动能率第二术者位结果略高于第一术者位,经非参数Wilcoxon秩和检验分析,差异无统计学意义（P > 0.05）,第一术者位的腹部位置和第二术者位的胸部位置所受的辐射剂量值最高。DSA设备机房外周围剂量当量率合格率为88.9%,机房外介入放射工作场所处于安全水平。结论 介入放射工作人员在诊疗活动中,应重视腹部区域的防护问题,重点关注第二术者位的防护问题,介入放射工作人员应自觉规范穿戴铅橡胶围裙等个人防护用品和使用辅助防护设施。     

Capture and analysis of radiation dose reports for radiology

Radiographic imaging systems can produce records of exposure and dose parameters for each patient. A variety of file formats are in use including plain text, bit map images showing pictures of written text and radiation dose structured reports as text or extended markup language files. Whilst some of this information is available with image data on the hospital picture archive and communication system, access is restricted to individual patient records, thereby making it difficult to locate multiple records for the same scan protocol. This study considers the exposure records and dose reports from four modalities. Exposure records for mammography and general radiography are utilized for repeat analysis. Dose reports for fluoroscopy and computed tomography (CT) are utilized to study the distribution of patient doses for each protocol. Results for dosimetric quantities measured by General Radiography, Fluoroscopy and CT equipment are summarised and presented in the Appendix. Projection imaging uses the dose (in air) area product and derived quantities including the dose to the reference point as a measure of the air kerma reaching the skin, ignoring movement of the beam for fluoroscopy. CT uses the dose indices CTDIvol and dose length product as a measure of the dose per axial slice, and to the scanned volume. Suitable conversion factors are identified and used to estimate the effective dose to an average size patient (for CT and fluoroscopy) and the entrance skin dose for fluoroscopy.     

通过剂量面积乘积估算内镜逆行胰胆管造影患者的有效剂量

目的 估算内镜逆行胰胆管造影（ERCP）操作中患者的辐射剂量水平,为制定介入放射学中患者的防护标准提供科学依据。方法 以ERCP手术调查的相关参数（透视时间、点片张数及设备相关参数）为条件,测量剂量面积乘积（DAP）,并利用测量的DAP值,通过基于蒙特卡罗（Monte Carlo）计算方法剂量估算软件（Ref Dose）,估算出患者的有效剂量（Effective Dose,E）。结果 按照操作难易程度分组,患者有效剂量分别为：ERCP操作复杂组4.448 mSv、ERCP操作中等组0.715 mSv、ERCP操作简单组0.247 mSv。结论 患者有效剂量的大小与3个剂量组中透视时间及DAP值呈正相关关系。ERCP手术中,在不影响临床效果的情况下,应尽可能缩短透视时间、减少摄片帧数、缩小照射野,从而尽可能降低患者的有效剂量。     

Patient doses from neuroradiological procedures

Patient doses have been determined for a sample of 20 patients in a hospital department undergoing various interventional neuroradiological procedures. Skin entrance dose, dose-area product and effective dose have been estimated. Effective dose was estimated from published conversion factors. The highest dose on the patients body was recorded as the maximum skin entrance dose. The maximum skin entrance dose varied from 0.2 to 2.3 Gy. The largest maximum skin entrance dose is similar to the threshold for skin injuries (erythema). The effective dose varied from 2 to 34 mSv. The results of this study are compared with the results of other studies on radiation dose to patients from neuroradiological procedures.     

2016-2017年介入放射学工作人员职业性外照射个人剂量水平调查分析

目的 调查介入放射学工作人员的职业性外照射个人剂量水平和防护现状,为加强介入放射学工作人员的放射防护与监督管理提供科学依据。方法 采用热释光剂量测量方法监测介入放射学工作人员职业性外照射个人剂量当量H_p（10）,利用X、γ散漏射线巡测仪451P检测DSA设备透视防护区空气比释动能率。结果[HT5"SS]2016年共监测介入放射工作职业性外照射757人,有效监测536人,有效监测率为70.81%,人均年剂量当量为1.29 mSv;2017年共监测1 123人,有效监测309人,有效监测率为27.52%,人均年剂量当量为1.47 mSv;2017年不同岗位放射工作人员人均年剂量当量的差异有统计学意义（χ²=11.612,P<0.01）;第二术者位总体空气比释动能率要高于第一术者位,且头部空气比释动能值均高于其他部位。结论 2016—2017年介入放射学工作人员的外照射个人剂量处于较低剂量照射水平但有效监测率偏低;放射防护工作仍需不断完善,重点应加强对介入放射学工作人员及其管理人员的辐射防护培训。     

正确使用数字减影血管造影机减少介入手术中的辐射吸收剂量

目的:通过分析介入手术治疗中数字减影血管造影(DSA)参数,探讨减少辐射吸收剂量的途径及防护方法.方法:对随机选取的1200例各类介入手术操作时DSA机器的管电压、管电流和透视时间的资料进行统计分析,研究在介入手术治疗中影响吸收剂量的相关因素.结果:心脏冠状动脉支架术和室上速射频消融术所需透视时间最长,此时的管电流、管电压数值最大,因此应特别注意在行心脏介入手术治疗过程中的吸收剂量,并做好辐射防护.结论:合理应用DSA机器,正确使用缩光器、减少透视时间和每秒脉冲率是减少吸收剂量的有效方法     

Patient radiation exposure measurements during interventional procedures: a prospective study

This is a prospective study with the purpose of assessing patient radiation dose and stochastic risk (risk for fatal cancer) in a patient population undergoing interventional radiological (IR) procedures. Measurements were performed on 36 consecutive patients undergoing percutaneous transluminal angioplasty (PTA, n=18), transjugular intrahepatic portosystemic shunt (TIPS, n=3), diagnostic angiography (DA, n=6), arterial embolization (AE, n=3), and hepatic neoplasm chemoembolization (HCE, n=6). Kerma area product (KAP) was used as a measure of x-ray exposure to the patient. Mean KAP value per procedure was 79+/-50 Gy cm for PTA, 139+/-55 Gy cm for TIPS, 110+/-44 Gy cm for DA, 325+/-145 Gy cm for AE, and 150+/-76 Gy cm for HCE. Forty-six percent of total KAP value was attributed to fluoroscopy. In conclusion, we showed that a linear correlation between effective dose and KAP was found (r=0.84), which could be used for estimating patient effective dose using KAP measurements. Small changes to the number of digital frames acquired result in substantial change of the total KAP in interventional radiological procedures. Stochastic risk from IR procedures is quite low for the patient. Measuring KAP is a simple and accurate method, which provides the interventional radiologist with a good estimation of the patient's relative risk for stochastic effects.     

Overview of contemporary interventional fluoroscopy procedures

Interventional fluoroscopy procedures are increasingly important in medical practice. As new procedures are introduced and validated, they tend to replace the equivalent surgical procedure. There is wide variation in patient dose, both among procedures and for a specific procedure. Stochastic risk is present, but interventional fluoroscopy procedures may also present deterministic risk. Radiation risk/benefit analyses are different for interventional fluoroscopy procedures than they are for diagnostic imaging procedures. The radiation risk component of an interventional fluoroscopy procedure is substantially less than the other procedural risks, and there is always clear and measurable benefit to the patient from a successful procedure. Optimizing patient dose will require both improvements in equipment technology and greater attention from regulators, accrediting bodies and medical organizations. Ensuring adequate operator training is essential.     

Establishment of scatter factors for use in shielding calculations and risk assessment for computed tomography facilities

The specification of shielding for CT facilities in the UK and many other countries has been based on isodose scatter curves supplied by the manufacturers combined with the scanner's mAs workload. Shielding calculations for radiography and fluoroscopy are linked to a dose measurement of radiation incident on the patient called the kerma-area product (KAP), and a related quantity, the dose-length product (DLP), is now employed for assessment of CT patient doses. In this study the link between scatter air kerma and DLP has been investigated for CT scanners from different manufacturers. Scatter air kerma values have been measured and scatter factors established that can be used to estimate air kerma levels within CT scanning rooms. Factors recommended to derive the scatter air kerma at 1 m from the isocentre are 0.36 μGy (mGy cm)(-1) for the body and 0.14 μGy (mGy cm)(-1) for head scans. The CT scanner gantries only transmit 10% of the scatter air kerma level and this can also be taken into account when designing protection. The factors can be used to predict scatter air kerma levels within a scanner room that might be used in risk assessments relating to personnel whose presence may be required during CT fluoroscopy procedures.     

脑血管介入放射诊治中患者的X射线辐射评价

目的 研究DSA方式介入性脑血管造影诊断与脑血管栓塞治疗过程中患者所受X射线辐射。方法 100例脑部病变患者,脑血管造影诊断68例、脑血管栓塞治疗32例。Siemens公司DSA机Angiostar-Plus随机配置剂量监测系统(Diamentor K1 and Diamentor ED),在线测量面积剂量乘积DAP(cGycm²)和入射表面剂量ESD(mGy)、采用Monte-Carlo转换因子估算有效剂量ED(mSv)。结果 本组病例一次IVNR的DAP、ESD、ED值分别为(11 916±7 499)cGycm²、(973±682)mGy、(12.59±9.12)mSv。其中造影诊断组的剂量分别为(9 264±3 777)cGycm²、(741±321)mGy、(10.01±6.85)mSv,血管栓塞治疗组的剂量分别为(17 553±10 027)cGycm²、(1 496±952)mGy、(18.06±10.90)mSv,两组的差异具有显著性意义。摄影剂量[DAP(mSv)、mGy]/透视[DAP(mSv)、mGy]的比值,分别为7.52±6.44、6.14±4.72。结论 在IVNR诊治过程中,患者受到大剂量X射线辐射,其摄影剂量均值数倍于透视剂量,减少摄影总帧数是降低患者辐射最有效的方法。     

Radiotherapy verification film for estimating cumulative entrance skin exposure for fluoroscopic examinations

Measurement of skin entrance exposures during fluoroscopic procedures is complicated by the use of automatic exposure control devices and the presence of contrast media. Due to variability in positioning spot films from patient to patient, standard dosimeters, such as thermoluminescent, cannot be properly placed on the skin prior to examination. Prepackaged film of the type used for portal verification in radiation therapy held next to the patient's skin in a specially modified patient examination gown was found to be useful for determining the entrance skin exposure from both fluoroscopy and spot films during air contrast barium enema exams. The usable sensitivity range of this film has been found satisfactory for exposure measurements at exposures and kVps typically used for gastrointestinal fluoroscopic procedures. Errors in exposure estimates due to changes in film speed and contrast with kVp are less than 5% for the range of kVps used. Errors from variations in beam quality due to the adjacency of scattering material are approximately 5%. Entrance exposures determined with film agreed with those determined from TLD measurements to within 21%, with an average difference of 9%.     

心血管介入手术中操作者职业照射的临床调查

目的 调查心血管介入手术中操作者的有效剂量。方法 利用热释光方法对某省属三级甲等医院进行的24例冠状动脉血管造影术(CA)或者继续行经皮穿刺腔内冠状动脉成形术(PTCA)或者继续行冠状动脉支架植入术(PICAS)和4例起搏器植入术(PT)的操作者进行了体表剂量测定和有效剂量估算。结果 在CA、PTCA、PICAS中平均手术时间为(19.2±6.3)min,操作者平均每次手术的有效剂量为(4.1±0.9)μSv,在没有铅衣防护的条件下,为(52.2±15.5)μSv;而PT平均手术时间为(14.1±4.6)min,操作者平均每次手术的有效剂量为(5.5±1.4)μSv,在没有铅衣防护的条件下,为(220±42)μSv。结论 应努力提高操作者的技术水平,缩短荧光照射时间,保证医护人员防护设施的配置,以降低操作者的受照剂量。     

Radiation dose in interventional cardiology procedures: urgent need for monitoring dose and establishing diagnostic reference levels

The use of fluoroscopy in interventional cardiology procedures may expose patients to levels of radiation that manifest in unintended outcomes. Such outcomes may include skin injury and cancer. Currently, there is limited understanding of the magnitude of dose administered in an individual procedure. Canada does not have a formal policy for monitoring and recording the radiation dose administered to patients. This article reviews existing American, European and international policies for both monitoring administered radiation dose and patient follow-up. As a subsequent focus, this article presents the process for setting benchmarks for optimizing administered dose in the Hamilton Health Sciences Heart Investigation Unit.     

心血管介入患者的医疗照射水平

[目的]分析心血管介入诊疗中患者的医疗照射水平,探讨相应的辐射防护对策。[方法]回顾性分析262例共4组患者（组1：单行冠状动脉造影术;组2：冠状动脉造影＋球囊预扩张和支架置入术;组3：心脏起搏器置入、更换术;组4：电生理检查＋射频消融术）,测算不同类别心血管介入诊疗的剂量与面积之积（dose-area product,DAP,mGycm2）和空气比释动能（air kerma,AK,mGy）,用Monte-Carlo转换系数从剂量与面积之积估算有效剂量。[结果]DAP值、AK值、有效剂量均以组2最高,分别为（131941.91±112242.64）mGycm2、（1131.07±635.75）mGy、（18.47±15.71）mSv;均以组3最低,分别为（32045.50±57475.17）mGycm2、（158.98±379.50）mGy、（4.49±8.05）mSv;各组中个体的辐射暴露差异均较大。透视时间以组4最长,为（17.03±3.35）min。摄影帧数以组2最多,为（787.12±316.53）帧;组4最少,仅为（3.55±6.27）帧。[结论]不同类别心血管介入诊疗,患者的医疗照射水平差异较大。患者所受辐射剂量较高,应采取适当防护措施,有效防范患者可能受到的潜在电离辐射危险。     

Skin dose measurement for patients using imaging plates in interventional radiology procedures

A method using europium-doped BaFBr imaging plates (IPs) has been developed to estimate and map values of entrance skin doses during interventional radiology (IR). IPs offer many advantages for measuring the entrance skin dose because they have a wide dynamic range (up to 100 Gy), provide high spatial resolution as a detector of two-dimensional images, and can be used repeatedly. The entrance skin dose was measured by fitting a 40x40 cm IP sheet around a patient's back using a corset in clinical studies involving IR procedures at two hospitals. The corset can minimize a geometric discrepancy in dose estimates between the IP and the patient body. The entrance skin dose was measured by using photoluminescent glass dosimeters simultaneously, and both values were compared. The spatial relative dose profiles from both dose estimates showed generally good agreement; however, the doses obtained with glass dosimeter chips were often lower than those obtained with IPs. This discrepancy comes from a radiation shielding effect for x rays by IPs and a strong angular dependence of the glass dosimeter in low energy x-ray fields. Comprehensive results of this study demonstrated that IPs were able to measure entrance skin dose in even high dose regions with steep dose gradients and to determine the peak skin dose, without missing hot spots, over all ranges used during interventional radiology procedures. Use of the corset minimized variations associated with angular dependence.     

50名CHD患儿的介入诊疗的参数和受照剂量调查

目的 了解CHD患儿主要的介入手术类型的参数和受照剂量的情况。方法 回顾性调查2016年某三甲级医院收集CHD患儿介入诊疗的患儿的人口统计学资料和辐射剂量数据信息。结果 CHD患儿介入诊疗中透视时间最长的是射频消融术（RFCA）为21.8 min,摄影帧数最多的是VSD封堵术为355帧,VSD封堵术的累计剂量（CD）和剂量面积乘积（DAP）最高为728 mGy和1 415 mGy·cm²;10岁之前的患儿比例较高,尤其是PDA封堵术,占到总数的83%。结论 应合理运用心脏介入诊疗,优化手术参数,以减少患儿的辐射剂量。