Analysis of radiation scatter during angiographic procedures: evaluation of a phantom model and a modified radiation protection system

PURPOSE: To study the radiation scattering associated with the digital subtraction angiography (DSA) unit in angiographic procedures and to design an effective radiation protection shield based on these data. MATERIALS AND METHODS: The number of scattered photons was measured at three points relative to the operator's position. Anteroposterior abdominal and lateral cranial fluoroscopy were evaluated. As protective devices, a lead curtain, sliding shields, and a brim-shaped image intensifier (II) hood were designed. RESULTS: In abdominal fluoroscopy, radiation was found to scatter to the operator's lower limbs from the underside of the catheter table, to the abdomen from the side of the patient's body, and to the head and neck from the table surface adjacent to the patient. The use of protective devices reduced exposure from 2.89 to 0.058 mR/min for the operator's lower limbs, from 0.987 to 0.069 mR/min for the operator's abdomen, and from 0.696 to 0.139 mR/ min for the operator's head and neck area. With lateral cranial fluoroscopy, radiation was detected to scatter to the operator's lower limbs from the underside of the catheter table, to the abdomen from the patient's temporal area, and to the head and neck from the patient's face. The use of protective devices reduced exposure from 0.248 to 0.010 mR/min for the operator's lower limbs, from 0.129 to 0.010 mR/min for the operator's abdomen, and from 0.162 to 0.018 mR/min for the operator's head and neck area. CONCLUSIONS: The characteristic directions of scattering to the operator were identified. An effective modified radiation protection system was designed based on this information.     

CT-guided procedures: evaluation of a phantom system to teach accurate needle placement

AIM: To evaluate the use of a phantom system to help teach the basic techniques of accurate CT-guided needle placement, thereby avoiding the risks associated with teaching on patients. MATERIALS AND METHODS: Gelatine phantoms with five, 1.9 cm embedded spherical wooden targets were constructed. Four trainee operators performed 15 simulated biopsy procedures on the targets (series one) and repeated identical procedures 2 weeks later (series two). Statistical analysis of accuracy of needle placement and subject confidence were performed. RESULTS: Significant sequential improvement in axial plane angular error was noted with the average error decreasing by 0.33 degrees after every five procedures performed (95% CI: -0.58 to -0.08, p=0.01). Operator confidence indicated significant improvement both within each series and from series one to series two (95% CI: 0.08 to 1.17, p=0.025 and 95% CI: 0.00 to 0.58, p=0.05) respectively. However, variability in operator performance made statistically significant improvement in other variables unproven. CONCLUSION: Despite the study comprising a relatively small number of participants and procedures, it clearly demonstrated the effectiveness of teaching operators to perform CT-guided procedures using a phantom system. Needle placement accuracy significantly improved, with a reduction in axial angular error, and improved operator confidence without the risks associated with training on patients. Three of the operators in this study had never performed a CT-guided procedure previously, and their proficiency, after a relatively short but intense period of training, was impressive. The use of phantoms should be considered routinely for basic training of CT-guided needle placement.     

Radiation exposure of operator performing interventional procedures using a flat panel angiography system: evaluation with photoluminescence glass dosimeters

Purpose  

Using glass rod dosimeters we investigated the radiation dose to the operator performing interventional procedures in 43 patients with the aid of a monoplane flat detector-based angiography system.     

Radiation protection in interventional radiology

There is growing concern regarding the radiation dose delivered during interventional procedures, particularly in view of the increasing frequency and complexity of these techniques. This paper reviews the radiation dose levels currently encountered in interventional procedures, the consequent risks to operators and patients and the dose reduction that may be achieved by employing a rigorous approach to radiation protection.     

平板DSA介入检查治疗患者的剂量调查

目的 调查平板数字减影血管造影(DSA)介入检查治疗患者的照射剂量,分析影响患者照射剂量的因素.方法 收集2009年3至6月来本院做DSA检查治疗的患者461例,手术种类包括全脑血管造影(CEA)、颅内动脉瘤弹簧圈栓塞(CAE)、肝脏动脉造影+超选化疗(SHAC)、冠状动脉造影(COA)、冠状动脉支架植入(PISI)、心脏射频消融(RFCA)、永久起搏器安装(PCPI).通过采集所有病例的剂量面积值(DAP)、累计皮肤表面人射剂量(CAK)、透视时间,采用转换因子计算有效剂量值.结果 CEA、CAE、SHAC、COA、PIST、RFCA、PCPI的有效剂量当量分别为(0.33±0.20)、(0.49±0.35)、(6.92±4.19)、(0.76±0.91)、(2.35±1.47)、(0.50±0.74)和(0.67±0.70)Sv;461例患者中超过1 Sv的达到120人次,占26%,超过10 Sv的达到10人次,均为SHAC患者.CAK分另为(0.55±0.43)、(1.34±1.11)、(0.95±0.57)、(0.32±0.31)、(0.91±0.33)、(0.16±0.22)和(0.15±0.14)Gy,CAK值超过1 Gy共为59例,占12.8%,超过2 Gy为11例,占2.4%,有2例超过3 Gy,为4.5和6.1 Gy,分别为CEA和CAE患者.结论 各项介入手术患者所受照射剂量个体差异较大.介入检查治疗患者接受的照射剂量较高,需要进行严格的监督以保证患者照射剂量得到最佳控制.

Abstract：

Objective To investigate the radiation doses for the patients undergoing interventional radiology and to analyze the dose - influencing factors.MethodsThe clinical data of 461 patients undergoing interventional radiology,including cerebral angiography ( CEA ),cerebral aneurysm embolism ( CAE ),superselective hepatic arterial chemoembolization ( SHAG ),coronary angiography ( COA ),percutaneous intracoronary stent implantation ( PIS1 ),cardiac radiofrequency catheter ablation ( RFCA ),and permanent cardiac pacemaker implantation(PCPI) were collected to observe the cumulative air kerma (CAK),dose area product (DAP),and fluoroscopy time,and effective dose was estimated using the conversion factors.Results The effective doses for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPI were (0.33 ±0.20),(0.49 ±0.35),(6.92 ±4.19),(0.76 ±0.91),(2.35 ± 1.47),(0.50 ±0.74),and (0.67 ±0.70) Sv,respectively.In 126 of the 416 patients (26%),the effective doses were greater than 1 Sv,and the effective doses of 10 person-times were greater than 10 Sv,all of which were observed in the patients undergoing SHAG.The CAK values for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPIwere (0.55 ±0.43),(1.34 ± 1.11),(0.95 ±0.57),(0.32 ±0.31),(0.91 ±0.33),(0.16 ±0.22),and (0.15 ±0.14) Gy,respectively.The CAK values were greater than 1 Gy in 59 of the 461 patients ( 12.8% ),greater than 2 Gy in 11 cases (2.4%) ,and greater than 3 Gy in 1 CEA cases and 1 CEA case,respectively.Conclusions There is a wide variation range in radiation dose for different procedures.As most interventional radiology procedure can result in clinically significant radiation dose to the patient,stricter dose control should be carried out.     

Radiation dose in interventional fluoroscopic procedures.

Vascular interventional procedures carried out under fluoroscopic guidance often involve high radiation doses. Above certain thresholds, radiation can cause significant damage to the skin including hair loss and severe necrosis. Such damage has been reported by several investigators. Many attempts have been made to quantitate the radiation doses to the skin involved with these procedures, but dosimetry methods are often flawed. To improve the situation better monitoring of radiation doses, fluoroscopist education, and changes in technology and methods are needed.     

Radiation exposure of the interventional radiologist during percutaneous biopsy using a multiaxis interventional C-arm CT system with 3D laser guidance: a phantom study

Objective:

Evaluation of absolute radiation exposure values for interventional radiologists (IRs) using a multiaxis interventional flat-panel C-arm cone beam CT (CBCT) system with three-dimensional laser guidance for biopsy in a triple-modality, abdominal phantom.

Methods:

In the phantom, eight lesions were punctured in two different angles (in- and out-of-plane) using CBCT. One C-arm CT scan was performed to plan the intervention and one for post-procedural evaluation. Thermoluminescent dosemeters (TLDs) were used for dose measurement at the level of the eye lens, umbilicus and ankles on a pole representing the IRs. All measurements were performed without any lead protection. In addition, the dose–area product (DAP) and air kerma at the skin entrance point was documented.

Results:

Mean radiation values of all TLDs were 190 µSv for CBCT (eye lens: 180 µS, umbilicus: 230 µSv, ankle: 150 µSv) without a significant difference (p > 0.005) between in- and out-of-plane biopsies. In terms of radiation exposure of the phantom, the mean DAP was not statistically significantly different (p > 0.05) for in- and out-of-plane biopsies. Fluoroscopy showed a mean DAP of 7 or 6 μGym², respectively. C-arm CT showed a mean DAP of 5150 or 5130 μGym², respectively.

Conclusion:

In our setting, the radiation dose to the IR was distinctly high using CBCT. For dose reduction, it is advisable to pay attention to lead shielding, to increase the distance to the X-ray source and to leave the intervention suite for C-arm CT scans.

Advances in knowledge:

The results indicate that using modern navigation tools and CBCT can be accompanied with a relative high radiation dose for the IRs since detector angulation can make the use of proper lead shielding difficult.     

Radiation protection and procedures in the OR

The field of surgery has advanced considerably during the past decade. New and innovative surgical techniques have emerged, many involving the use of diagnostic and therapeutic radiology procedures. Although these benefit patients, adequate radiation protection for the operating room staff is still an issue. This article provides information on diagnostic and therapeutic imaging exams performed in the operating room and discusses occupational radiation hazards for operating room staff, as well as the measures that must be taken to ensure radiation safety.     

Radiation protection for patient and operator in interventional radiology

While interventional radiological procedures are minimally invasive and beneficial to patients, some complex and lengthy fluoroscopically guided procedures may cause radiation-induced skin injuries. Interventional radiologists should be aware of threshold doses, actual dose rates of specific X-ray equipment, and practical techniques to control the patient's cumulative skin dose. The International Commission on Radiation Protection recommends that the maximum dose to the skin be recorded when it approaches 1 Gy (for procedures that may be repeated) or 3 Gy (for any procedure) and that patient follow-up be provided in the latter situation. To reduce operator exposure, it is essential to avoid direct exposure of the primary beam to the hands in procedures such as transhepatic biliary drainage. During vascular interventions, the majority of operator exposure is caused by scatter radiation from the patient. Almost every effort to reduce patient dose secondarily reduces scatter radiation to the operator as well. The overcouch X-ray tube system is associated with higher exposure to the hands and eyes, and should not be used for complicated procedures. Appropriate shields help in reducing scatter to the operator.     

Radiation protection value to the operator from augmented reality smart glasses in interventional fluoroscopy procedures using phantoms

IntroductionSmart glasses can be adapted to display radiographic images to allow clinician's gaze not to be directionally fixed or predetermined by computer monitor location. This study presents an analysis of eye lens dose during interventional fluoroscopy guided procedures, comparing fixed monitor positions against the use of smart glasses.MethodsUsing a head phantom (simulating the clinician), thermoluminescent dosimeters and lead shielded glasses, the dose to the eye was measured for different head ‘rotations and tilts’ for: gaze directed towards the main scattering source (patient/primary beam) to represent potential gaze direction if smart glasses are used; gaze directed to a range of potential computer monitor positions. An anthropomorphic pelvis phantom was utilised to simulate the patient. Accumulated dose rates (μGy sˉ¹) from five 10-second exposures at 75 kV 25.2 mAs were recorded.ResultsAn average DAP reading of 758.84 cGy cm² was measured during each 10 second exposure. Whilst wearing lead shielded glasses a 6.10 – fold reduction in dose rate to the lens is possible (p < 0.05). Influence of the direction of gaze by the clinician demonstrated a wide range of dose rate reduction from 3.13% (p = 0.16) to 143.69% (p < 0.05) when the clinician's gaze was towards the main scattering source. Increased dose rate to the clinician's eyes was received despite wearing lead shielded glasses, as the angle of gaze moved 45° and 90° from 0°.ConclusionIf the clinician's gaze is directed towards the main scattering source a potential exists for reducing eye lens dose compared with fixed location computer monitors. Introduction of lead lined smart glasses into interventional radiology may lead to improvements in patient care, reducing the need for the clinician to look away from the patient to observe a radiographic image.     

三种常见介入诊疗中机房内的辐射场分布

目的 测试3种常见介入诊疗中机房内的辐射场分布,为介入放射工作人员的防护和安全操作提供基础数据。方法 在介入诊疗床周围的水平面和介入放射工作人员经常停留区域的立面,选择不同的点放置热释光剂量计,根据选定的实验条件分组照射,结束后将热释光剂量计带回实验室测量并计算辐射场剂量。结果 相同位置的数据大部分符合心血管介入诊疗>脑血管介入诊疗>肝脏介入诊疗;同种介入诊疗在相同位置的剂量大都符合高剂量组>中剂量组>低剂量组,该结果与有用线束剂量大小一致,与透视时间的长短成正比。个别不符合以上规律的数据存在测量误差或实验偏差。结论 肝脏和脑血管介入诊疗时,辐射剂量相对较低,3 m以外的辐射剂量基本可以忽略。心血管介入诊疗时,离X射线管中心点越远,剂量降低越多。辐射场中术者、第一助手和第二助手站立处的剂量较高,患者的头端、足端方向剂量较低。     

Radiation exposure of medical staff from interventional x-ray procedures: a multicentre study

The purpose of this study was to analyse the radiation exposure of medical staff from interventional x-ray procedures. Partial-body dose measurements were performed with thermoluminescent dosimeters (TLD) in 39 physicians and nine assistants conducting 73 interventional procedures of nine different types in 14 hospitals in Germany. Fluoroscopy time and the dose–area product (DAP) were recorded too. The median (maximum) equivalent body dose per procedure was 16 (2,500) μSv for an unshielded person; the partial-body dose per procedure was 2.8 (240) μSv to the eye lens, 4.1 (730) μSv to the thyroid, 44 (1,800) μSv to one of the feet and 75 (13,000) μSv to one of the hands. A weak correlation between fluoroscopy time or DAP and the mean TLD dose was observed. Generally, the doses were within an acceptable range from a radiation hygiene point of view. However, relatively high exposures were measured to the hand in some cases and could cause a partial-body dose above the annual dose limit of 500 mSv. Thus, the use of finger dosimeters is strongly recommended.     

Ultrasound-guided interventional procedures in the musculoskeletal system

Ultrasonography is the most appropriate tool for interventional procedures in the musculoskeletal system when the lesion is visible on ultrasonography. Procedures performed under ultrasonographic guidance include: taking biopsies; draining abscesses; bursitis; hematomas or muscle tears; treating cystic lesions; diagnostic or therapeutic arthrocentesis; injecting substances into joints or lesions; aspirating calcium deposits and extracting foreign bodies. Although some of these procedures are often carried out without imaging guidance, ultrasonographic guidance improves their efficacy. Drainage can be performed with catheters or needles and makes it possible to avoid more aggressive treatments in most cases. Urokinase is useful for draining hematomas or fibrinous collections. Injecting corticoids is useful in the treatment of synovial cysts, Baker's cyst, tendinitis, and non-infective arthritis. Calcifying tendinitis of the shoulder can be treated effectively with percutaneous calcium lavage.     

心血管病介入操作时患者受照剂量研究

目的 对心血管介入手术中患者所受辐射剂量及与辐射剂量相关的指标进行采集和分析,为改善患者的辐射防护提供依据.方法 对在省属三级甲等医院进行的26例完整的心血管介入手术的患者进行临床数据采集,按手术类别分成冠状动脉血管造影术(CA)及行冠状动脉血管造影术(CA)后继续行经皮穿刺腔内冠状动脉成形术(PTCA)两组,采用TLD个人剂量计照射野矩阵测量法,检测患者荧光照射时间、入射皮肤剂量(ESD)、最高皮肤剂量(PSD)、剂量-面积乘积(DAP)等指标,用TLD测量在模拟心血管手术条件下体模器官剂量.结果 荧光透视时间为(17.7±15.6)min,范围为0.80～42.4 min;ESD范围为(159±138)mGy,4.40～459 mGy;PSD范围为(769±705)mGy,22.6～2.43×103mGy.CA+PTCA组的荧光照射时间、ESD、PSD均大于CA组,差异有统计学意义.最大皮肤受照剂量与透视时间有较好的相关性(r=0.84,P＜0.01).结论 心血管病放射性介入操作时,可通过透视时间来估算最大皮肤受照剂量.

Abstract：

Objective To collect and analyze the radiation dose to patients in cardiovascular interventional procedures and the radiation dose-related indicators,in order to provide a basis for improving radiation protection of patients.MethodsThe clinical data of 26 cases of complete cardiovascular interventional procedures was collected in the municipal Grade A Class Three hospitals,including coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA),and the patient-received radiation doses and other related factors was studied.TLD personal dosimeter radiation field matrix method was used to measure fluorescence time,the entrance skin dose (ESD),the peak skin dose (PSD),dosearea product (DAP) and other indicators.TLD was used to measure the organ dose of the phantom under the cardiovascular interventional procedure condition.ResultsThe fluoroscopy time was (17.7 ±15.6) min during the range of 0.80-42.4 min.The average entrance skin dose (ESD) was (159 ± 138)mGy during the range of 4.40-459 mGy.The peak skin dose (PSD) was (769 ± 705) mGy during the range of 22.6 - 2.43 × 103mGy.The fluorescence time,entrance skin dose (ESD) ,peak skin dose (PSD) of the group CA + PTCA are greater than the group CA and the difference has statistical significan.The peak skin dose and the fluoroscopy time have good linear correlation (r = 0.84,P ＜ 0.01 ).Conclusion The peak skin dose the patient received in cardiovascular interventional radiological operation can be estimated through the fluoroscopy time.     

放射性介入操作中辐射剂量与防护措施

由放射性介入操作所导致的辐射剂量已引起人们越来越多的关注,尤其是考虑到该项操作的频率不断增加和日趋复杂化。现有研究的主要集中于三个方面:目前放射性介入操作中的剂量水平、操作人员和患者的辐射危险以及辐射防护措施。     

CT引导介入操作中患者有效辐射剂量的研究

目的探讨CT引导下各类介入操作中患者接受的有效辐射剂量。方法回顾性分析近2年来我科CT引导下介入诊断和治疗259例次患者的检查资料。介入操作包括穿刺活检、引流、射频消融、经皮瘤内无水乙醇注射术、放射性¹²⁵Ⅰ粒子植入术、腹腔神经丛阻滞术等6种方法。浏览PCAS系统上的医学信息和图像,并记录患者所接受的介入诊疗方式、扫描时间、扫描次数、总毫安秒、CT剂量指数、剂量长度乘积。有效辐射剂量根据国际放射防护委员会（ICRP）制定的蒙特卡罗有效剂量转换公式进行计算。结果放射性¹²⁵Ⅰ粒子植入术、经皮瘤内无水乙醇注射术、射频消融术、腹腔神经丛阻滞术、引流、活检平均有效辐射剂量分别是（25.62±10.43）mSv、（19.02±7.35）mSv、（18.69±6.39）mSv、（16.22±5.60）mSv、（10.66±4.51）mSv和（9.67±3.81）mSv,粒子植入术的有效辐射量明显高于其他介入操作,差异有统计学意义。结论 CT引导下单次介入操作有效辐射剂量相对较小,引起辐射损伤及后续并发症的危险小,但多次介入治疗累积的有效辐射剂量可能会较大,需要引起一定的重视。     

An animal model for radiologic biliary interventional procedures

Procedural development, in vivo evaluation, and professional training in interventional biliary radiology require an animal model that provides easy and safe access to the gallbladder and bile ducts. A porcine model was used successfully for catheterization of the biliary system under fluoroscopic control. Permanent access to the gallbladder of ten pigs was achieved with a large-bore cholecystostomy catheter. Catheterization of the common bile duct through the cystic duct was feasible in all animals. Repeated interventional radiologic procedures were performed with intramuscular sedation of the animals, which made this model particularly useful for studies requiring multiple procedures or serial follow-up over several weeks. This article describes the technical aspects of the animal model and the radiographic anatomy of the extrahepatic biliary system in 27 domestic pigs.     

Radiation doses in interventional radiology procedures: the RAD-IR Study. Part III: Dosimetric performance of the interventional fluoroscopy units

PURPOSE: To present the physics data supporting the validity of the clinical dose data from the RAD-IR study and to document the performance of dosimetry-components of these systems over time. MATERIALS AND METHODS: Sites at seven academic medical centers in the United States prospectively contributed data for each of 12 fluoroscopic units. All units were compatible with International Electrotechnical Commission (IEC) standard 60601-2-43. Comprehensive evaluations and periodic consistency checks were performed to verify the performance of each unit's dosimeter. Comprehensive evaluations compared system performance against calibrated ionization chambers under nine combinations of operating conditions. Consistency checks provided more frequent dosimetry data, with use of each unit's built-in dosimetry equipment and a standard water phantom. RESULTS: During the 3-year study, data were collected for 48 comprehensive evaluations and 581 consistency checks. For the comprehensive evaluations, the mean (95% confidence interval range) ratio of system to external measurements was 1.03 (1.00-1.05) for fluoroscopy and 0.93 (0.90-0.96) for acquisition. The expected ratio was 0.93 for both. For consistency checks, the values were 1.00 (0.98-1.02) for fluoroscopy and 1.00 (0.98-1.02) for acquisition. Each system was compared across time to its own mean value. Overall uncertainty was estimated by adding the standard deviations of the comprehensive and consistency measurements in quadrature. The authors estimate that the overall error in clinical cumulative dose measurements reported in RAD-IR is 24%. CONCLUSION: Dosimetric accuracy was well within the tolerances established by IEC standard 60601-2-43. The clinical dose data reported in the RAD-IR study are valid.