A survey of fluoroscopic equipment in Victoria

A survey of fluoroscopic units in the state of Victoria has been carried out. For fixed fluoroscopy equipment, routine quality assurance tests were carried out on the x-ray tube used for conventional radiographs, and factors relating to image quality and patient dose were measured for the screening tube. For the mobile image intensifiers, quality assurance tests were carried out and factors relating to image quality and patient dose were measured. There was a ratio of about 20 in the dose rates between the units with the highest and lowest screening dose rates with the same size phantom. Guidance levels based on the third quartile values of the entrance dose rates and spot film doses are recommended. The recommended guidance doses are: mobile image intensifier: dose rate: 30 mGy/min; fixed screening unit: dose rate: 42 mGy/min and spot film: 5 mGy.     

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.     

Patient and personnel exposure during extracorporeal lithotripsy

Extracorporeal shock wave lithotripsy (ESWL) has provided a nonsurgical approach to treatment of renal stones. The Dornier lithotripter uses dual image intensified x-ray systems to center the stone before treatment. Three imaging modes are offered: a fluoroscopic mode and two video spot filming modes. The average entrance exposure to the stone side of the typical patient at our facility is 2.6 X 10(-3) C kg-1 (10 R) [range: 0.5-7.7 X 10(-3) C kg-1 (2-30 R)] which is comparable and often much less than that reported for percutaneous lithotripsy. Recommendations are made for minimizing patient exposure. Scattered radiation levels in the lithotripter room are presented. We have determined that Pb protective apparel is not required during this procedure provided x-ray operation is temporarily halted should personnel be required to lean directly over the tub to attend to the patient. If the walls of the ESWL room are greater than 1.83 m (6 feet) from the tub, shielding in addition to conventional construction is not required.     

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.     

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。     

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%.     

Radiation doses during CT fluoroscopy

CT fluoroscopy (CTF) is a relatively new imaging modality that is particularly useful for performing complex biopsy procedures. Despite the obvious benefits, the potential exists to deliver considerable radiation doses to both the patients and medical staff. The purpose of our study was to quantify the radiation levels based upon typical clinical procedures. To assess the potential radiation risks, the patient radiation doses via the CT dose index (CTDI) method were measured during CTF for a GE Pro-Speed CT scanner using standardized head and body phantoms and a CT ionization chamber. The measurements were performed for a variety of kVp, mA, and slice thickness settings. To determine patient radiation doses, the CT kVp, mA, and total CTF scan times were recorded for various biopsy procedures. To determine the radiation doses to the hands of the radiologists, a radiation survey meter was used to measure the scattered radiation from standard phantoms. The effectiveness of various types of leaded gloves and shields were also determined. The measured CTDI values ranged from 20.4 cGy min(-1) to 63.1 cGy min(-1) of CTF. For a group of 78 patients, the clinically utilized imaging times varied from 13.0 to 407 s with an mean time of 96.6 s +/- 78.9 s (1 standard deviation). The scattered x-ray radiation at the position of the radiologists hands performing the biopsy procedures was measured to be 0.6 to 1.5 mGy min(-1). The thin leaded gloves provided a relatively minimal reduction in the scattered radiation to the hands between 11% and 44% dependent upon the kVp and the type of glove. However, floor mounted radiation shields reduced the scattered radiation levels to the body by 94% to 99%. In comparison to standard x-ray fluoroscopy, CTF employs much higher radiation dose rates due to the higher kVp, mA, and rotating geometry. It is important to minimize the radiation dose to patients and staff by limiting the imaging times, employing lower mA settings, and using appropriate radiation protection measures.     

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.     

Skin entrance radiation dose in an interventional radiology procedure

Monitoring of skin entrance radiation exposure in lengthy interventional procedures has been recommended because of the potential for skin injury. Fluoroscopy duration and dose-area product (DAP) are readily available real-time measurements. It would be of interest to study the correlation of these parameters and skin entrance radiation. Twenty neurological interventional procedures performed through the aortic arch were monitored. Two pieces of GafChromic XR Type R film were placed between the patient and the examination table. An observer recorded the fluoroscopy duration and DAP for each phase of the procedure. Each film was scanned post-procedure in RBG mode, and then the image was analyzed for peak skin entrance radiation dose (in air kerma). All DAP values were corrected according to a calibration with an ion chamber. With the DAP values for the respective phases of a procedure, the effective dose in a Reference Man was calculated. For these twenty cases, the means and standard deviations were 17.2+/-6.4 min for x ray on-time, 256+/-65 Gy cm (-2) for DAP, 94+/-34 cGy for peak skin entrance dose in air kerma, and 19.2+/-5.0 mSv for effective dose, respectively. The peak skin entrance dose was correlated to fluoroscopy duration, DAP, and effective dose with the r(2)-values of 0.48, 0.46, and 0.09, respectively. The correlation with DAP or fluoroscopy duration was not sufficiently strong to infer skin entrance dose from either of these parameters. Therefore, skin entrance dose should be determined directly.     

Bone marrow dose estimates from work-related medical x-ray examinations given between 1943 and 1966 for personnel from five U.S. nuclear facilities

Inclusion of dose from work-related medical x-ray examinations with occupational external dose in an epidemiological study may reduce misclassification of exposures and provide more accurate assessment of leukemia risk from occupational exposure to ionizing radiation. In a multi-site leukemia case-control study, annual bone marrow doses due to work-related x-ray examinations given between 1943 and 1966 were estimated for cases and controls employed at five nuclear facilities. Only active bone marrow dose from photofluorographic chest and routine lumbar spine x rays were included. Bone marrow dose assigned for a single exposure ranged from 1.0 to 1.4 mGy. Mean and median cumulative bone marrow doses for each of the five sites from work-related x-ray examinations ranged from 2.0 to 14 mGy and 2.1 to 8.8 mGy, respectively. Results suggest that bone marrow dose from work-related photofluorographic and lumbar spine x-ray examinations given during the time period of this study may be significant compared to occupational bone marrow dose.     

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。     

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.     

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%.     

模拟后装放射源卡源处置时放射工作人员受照剂量研究

目的 估算放疗技师在应急处理后装放射源卡源过程中的受照剂量。方法 使用仿真人体盆腔模型替代宫颈癌患者,填充石蜡的假人替代放疗技师,模拟放射源在患者的子宫口位置发生卡源事故的场景,采用热释光剂量仪测量假人的4个敏感器官（晶体、甲状腺、乳腺、睾丸）表面不同时长内的受照剂量,并计算穿戴0.35 mm铅当量的防护用品的防护效果。结果 按¹⁹²Ir源强370 GBq计,无防护情况下各敏感器官在不同处理时间的受照剂量均小于0.12 mGy。在穿戴防护用品之后,各敏感器官的受照剂量减少1.7%~19.8%。结论 放疗技师在没有穿戴防护用品,¹⁹²Ir源强为370 GBq,应急处理时间35 s内的入射体表剂量不超过0.12 mGy,只相当于做一次X线摄影检查的受照剂量。     

Monte Carlo estimation of radiation doses in red bone marrow and breast in common pediatric x-ray examinations

Radiation exposure was investigated for children undergoing various common radiographies in three dedicated pediatric hospitals in Greece. Kerma in air at the entrance of the beam (Ka,e) was measured with thermoluminescent dosimeters. Ka,e values ranged from 0.09 mGy to 5.52 mGy and were found to be greater in Hospital C, because of the increased high voltage and time-current product used by the radiation technologists. Equivalent doses in red bone marrow and breast were estimated with Monte Carlo simulation by PCXMC code. Values ranged from 2 microSv to 204 microSv for red bone marrow and from 0 to 817 muSv for breast. Variation in doses occurred due to field size, high voltage setting, and Ka,e.     

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%.     

Estimation of adult patient doses for common diagnostic X-ray examinations in Wad-madani,Sudan: derivation of local diagnostic reference levels

The objectives of this study were to estimate patient dose in some common diagnostic X-ray examinations. Radiation doses were estimated for 307 patients in six public hospitals comprising 7 X-ray units in Wad-madani, Sudan. Entrance surface air kerma (ESAK) was estimated in a three step protocol: First, X-ray unit output Y(d) was measured at a distance, d for different peak tube voltages and tube loadings (mAs). Next, incident air kerma (K_i) was calculated from Y(d) using inverse square law combined with patient exposure factors. ESAK was calculated from K_i using backscatter factor, B. Mean ESAK values are comparable to those reported in other countries and are below reference dose levels. The estimated mean ESAK values are: 0.3, 2.2, 2.2, 2.9, 2.8, 3.1, and 7.5 mGy for chest PA, Skull AP/PA, Skull LAT, Abdomen, Pelvis AP, Lumbar Spine AP and Lumbar Spine LAT examinations, respectively. The results are used for dose optimization, and to propose local diagnostic reference levels.     

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.     

广东省MDCT机所致受检者剂量水平初探

目的 了解广东省MDCT机所致受检者辐射剂量水平。方法 采用分层随机抽样方法,选取广东省24台MDCT机进行医疗照射剂量水平调查,分析广东省MDCT检查所致受检者的辐射剂量水平。结果 成人头部、成人胸部、成人腹部、成人脊柱、成人四肢、成人冠脉的加权CT剂量指数的均值分别为44.5、15.4、20.0、23.4、16.9、38.2 mGy,而相应的剂量长度乘积的均值分别为776、482、693、691、539、1056 mGy·cm;儿童头部、儿童胸部、儿童腹部的加权CT剂量指数的均值分别为20.9、9.6、15.1 mGy,而相应的剂量长度乘积的均值分别为257、167、472 mGy·cm。结论 调查数据可以促进对受检者的剂量控制,以更好推动辐射防护最优化。