Fluoroscopic Dose Rate Research Articles

Long-term Reproducibility Evaluation of Fluoroscopy Dose Rate in Angiography Equipment

Diagnostic reference levels (DRLs) are defined as fluoroscopic dose rate measurements that are used for patient dose management in angiography. It is recommended that DRLs be measured at least once a year. This study aimed to evaluate the long-term fluctuations of fluoroscopic dose rate in an angiography system. An unconnected X-ray output analyzer was used to measure the fluoroscopic dose rate (air kerma rate) at the patient's entrance reference point for a specific angiography system. The target period was from 2015 to 2022, and four measurements per year were made. First, the fluoroscopic dose rate was measured, and the average value and standard deviation for the target period were calculated. Next, the uncertainty of the measured values and the coefficient of variation were calculated. Finally, we calculated the fluoroscopic dose rate measurement error. The average±standard deviation of the fluoroscopic dose rate was 353.29±9.11 µGy/s. The maximum uncertainty and coefficient of variation for each year were 5.41 µGy/s and 0.03, respectively. The maximum measurement error was 4.67%, where the mean measured value was taken as the true value. The fluctuation in the measured value of the fluoroscopic dose rate by an angiography system for 8 years is within ±5%, indicating stable X-ray output.

WEO Newsletter.

WEO Newsletter.

Examination of Optimization of Exposure Dose by IVR Procedure Based on DRLs 2020

DRLs 2020 has been revised, and Ka,r and PKA for each procedure have been set for IVR along with the reference fluoroscopic dose rate. The total dose of IVR includes fluoroscopic and digital acquisition (DA) doses, but in actual clinical practice, the ratio varies greatly depending on the procedure (diagnosis/treatment purpose and procedure content), and there are not many detailed data on the ratio. Therefore, we evaluated previous efforts that optimized radiation protection through examining dose for each procedure and the ratio of fluoroscopic and DA doses to total dose, and reviewing protocols. Since the ratio of fluoroscopy and DA dose differs depending on the procedure, it was suggested that the radiation dose exposed to patients can be optimized by sharing the dose information with physicians and constructing a protocol while considering the image quality for each procedure.

Simple evaluation method for radiation dose monitoring using fluoroscopic dose rate in cardiac catheterization for pediatric congenital heart disease

Simple evaluation method for radiation dose monitoring using fluoroscopic dose rate in cardiac catheterization for pediatric congenital heart disease

Multicenter Evaluation of Cine Angiography and Digital Subtraction Angiography Dose Rate for Various Angiography Programs: Comparison with Fluoroscopic Dose Rate

We conducted a nationwide multicenter survey of various interventional radiology (IVR) procedures. Data were collected from 385 X-ray systems in 126 institutions, including 432 cine programs and 380 digital subtraction angiography (DSA) programs for diagnostic catheterization, percutaneous coronary intervention (PCI), ablation, transcatheter aortic valve implantation (TAVI), neurologic IVR, thorax IVR, abdominal IVR, and endovascular therapy (EVT). Fluoroscopic and cine dose rates were 10.1 mGy/min and 110.7 mGy/min, respectively, whereas for DSA programs, the median fluoroscopic and DSA dose rates were 8.0 mGy/min and 224.8 mGy/min, respectively. The DSA dose rate was more than twice the cine dose rate. The largest difference between dose rates was for diagnostic catheterization, which had a cine dose rate of 142.6 mGy/min and a fluoroscopic dose rate of 12.6 mGy/min (by a factor of 12.5), followed by EVT, which had a DSA dose rate of 216.0 mGy/min and a fluoroscopic dose rate of 7.7 mGy/min (by a factor of 29.6). The smallest difference between dose rates was for TAVI, which had a cine dose rate of 96.8 mGy/min and a fluoroscopic dose rate of 12.0 mGy/min (by a factor of 8.9), followed by neurologic IVR, which had a DSA dose rate of 227.9 mGy/min and a fluoroscopic dose rate of 9.6 mGy/min (by a factor of 22.6). Compared with the fluoroscopic dose rates, the cine dose rates were 9-13 times higher and the DSA dose rates were 22-30 times higher; the DSA dose rates were more than double the cine dose rates.

Multicenter Survey on Radiation Dose of Cardiac Intervention

We conducted a nationwide survey of multiple institutions and collected data of various interventional procedures in the field of cardiology. Included in the analysis were 126 institutions, 381 X-ray systems, and 805 protocols. The dose values were compared with the Japanese diagnostic reference levels (DRLs) 2015. Fluoroscopy time, air kerma at the patient entrance reference point (Ka, r), and air kerma-area product (PKA ) were analyzed for various interventional procedures in 5,734 cardiology patients. The fluoroscopic dose rate (FDR) for pulmonary vein isolation (PVI) was less thanhalfthatof the 75th percentile of the Japanese DRLs 2015. The 75th percentiles of fluoroscopy time, Ka, r, and PKA for the respective interventional procedures were as follows: 11.0 min, 735 mGy, and 64 Gy･cm2 for diagnostic coronary angiography (CA); 13.2 min, 839 mGy, and 75 Gy･cm2for CA + left ventriculography; 34.4 min, 1,810 mGy, and 148 Gy･cm2for percutaneous coronary intervention (PCI) excluding chronic total occlusion; 80.1 min, 4,338 mGy, and 312 Gy･cm2 for PCI for chronic total occlusion; 74.4 min, 833 mGy, and 90 Gy･cm2 for PVI; and 34.0 min, 795 mGy, and 94 Gy･cm2for transcatheter aortic valve implantation, respectively. In assessing dose values in interventional radiology,the difficulty of the technique needs to be considered, and the DRL values for FDR, fluoroscopic time, Ka, r, and PKA for each interventional procedure are considered necessary when reassessing or updating DRLs.

Examination of Effectiveness Verification and Additional Items in Angiography and IVR of DRLs 2015

Japanese Diagnostic Reference Levels (DRLs) were released as "Japan DRLs 2015" from Japan Network for Research and Information on Medical Exposure (J-RIME) in June 2015. In "Japan DRLs 2015", DRLs in angiography and interventional procedures are set at a fluoroscopic dose rate of 20 mGy/min at the interventional reference point using a phantom. In order to achieve optimization with DRLs, then it need to be revised regularly. Therefore, we (research group to examine the effect of Japan DRLs 2015 and the necessity of additional items in angiography and vascular interventions) examined the effects of "Japan DRLs 2015" on angiography and interventional procedures. And we also investigated for DRLs revision in the future. As a result, it turned out that it is important to create DRLs in medical procedures that can be effectively used in clinical settings.

Nationwide Survey of Medical Radiation Exposure on Cardiovascular Examinations in Japan

It is very important to manage the radiation dose of cardiovascular interventional (CVI) procedures. Overseas, the diagnostic reference levels for cardiac interventional procedures were established with the air kerma at the patient entrance reference point (Ka,r) and the air kerma-area product (PKA). Although the Japan DRLs 2015 was established by the Japan Network for Research and Information on Medical Exposure (J-RIME), the Japan DRL for CVIs were established by fluoroscopic dose rates of 20 mGy/min at the patient entrance reference point with 20 cm thickness polymethyl methacrylate (PMMA) phantom. In the present our study, we performed a questionnaire survey of indicated values of angiographic parameters in CVI procedures. A nationwide questionnaire was sent by post to 765 facilities. Question focused on angiographic technology, exposure parameters and radiation doses as the displayed dosimetric parameters on the angiographic machine. The recovery rate was 22.8% at 175 out of 765 facilities. In total 1728 cases of the coronary angiography (CAG), 1703 cases of the percutaneous coronary intervention (PCI), 962 cases of the radiofrequency catheter ablation (RFCA) and 377 cases of pediatric CVI. The 75th percentile value of Ka,r, PKA, fluoroscopy time (FT) and number of cine images (CI) for CAG, PCI, RFCA and pediatric CVI were 702, 2042, 644, and 159 mGy, respectively, 59.3, 152, 81.3, and 14.9 Gy・cm2, respectively, 10.2, 35.6, 61.1, and 35.6 min, respectively and 1503, 2672, 722, and 2378 images, respectively. Our investigation showed that the angiographic parameters were different in several CVI procedures. The displayed dosimetric parameters on the angiographic machine in CVI procedures showed different values. We should classify the dosimetric parameters for each procedure.

Increase in fluoroscopic radiation dose in successive sessions of multistage Onyx embolization of brain arteriovenous malformations compared with the first session

Background and purposeOnyx embolization is a treatment for brain arteriovenous malformations (AVMs). However, multistage embolization usually involves the presence of radiodense Onyx cast from the previous sessions, which may influence...

Fluoroscopic frame rates: not only dose.

AJR:203, September 2014 Selecting and using the fluoroscopic dose rate that optimizes the balance between aspects of image quality and patient dose is important to patient management. In this article, “dose” and “dose rate” are used in a generic sense. Most modern fluoroscopes provide a multitude of controls that affect the balance between images and dose. Other influences that affect imaging are the patient size, clinical task, and imaging geometry. Normal fluoroscopic dose rates are also constrained by regulatory limits. All of these factors interact with each other in complex and occasionally nonintuitive ways [1, 2]. This article discusses some of the consequences of changing the frame rate (frames per second) and dose rate (mGy/s). It also discusses aspects of image processing using recursive filtering and gap filling.

Reference levels and patient doses in interventional cardiology procedures in Greece

To present a national survey that was performed for the establishment of national reference levels (RLs) for interventional cardiology (IC) procedures and to estimate the effective dose (E) received by the patient during these procedures. Data concerning the fluoroscopy time and air kerma-area product (P KA) during coronary angiography (CA), percutaneous coronary intervention (PCI), pacemaker implantation (PMI) and radiofrequency cardiac ablation (RFCA) from 26 centres were collected. Moreover, measurements concerning the performance of X-ray systems used in IC were performed in order to set system-related reference levels. P KA to E conversion factors were also calculated. The suggested P KA RLs for CA, PCI, PMI and RFCA are 53 Gycm(2), 129 Gycm(2), 36 Gycm(2) and 146 Gycm(2), respectively, and the estimated E to the patient from these procedures is 9.7mSv, 26.8mSv, 5.5mSv and 20.4mSv, respectively. Reference levels for the fluoroscopic dose rate and dose per frame during image acquisition at the entrance of a water phantom are 29mGy/min and 0.23mGy/frame, respectively. The suggested RLs are comparable to those suggested by other studies. Additional information concerning the complexity of the procedures and patient pathology should be collected for future reevaluation of the suggested RLs. • The radiation dose imparted during fluoroscopically guided interventional procedures can be high • Understanding of reference levels might help optimise interventional cardiological procedures • Optimisation by changing the systems' settings seems feasible in some cases • Procedure complexity and the patient's clinical problem should be taken into account.

Management of pediatric radiation dose using GE fluoroscopic equipment

In this article, we present GE Healthcare’s design philosophy and implementation of X-ray imaging systems with dose management for pediatric patients, as embodied in its current radiography and fluoroscopy and interventional cardiovascular X-ray product offerings. First, we present a basic framework of image quality and dose in the context of a cost–benefit trade-off, with the development of the concept of imaging dose efficiency. A set of key metrics of image quality and dose efficiency is presented, including X-ray source efficiency, detector quantum efficiency (DQE), detector dynamic range, and temporal response, with an explanation of the clinical relevance of each. Second, we present design methods for automatically selecting optimal X-ray technique parameters (kVp, mA, pulse width, and spectral filtration) in real time for various clinical applications. These methods are based on an optimization scheme where patient skin dose is minimized for a target desired image contrast-to-noise ratio. Operator display of skin dose and Dose-Area Product (DAP) is covered, as well. Third, system controls and predefined protocols available to the operator are explained in the context of dose management and the need to meet varying clinical procedure imaging demands. For example, fluoroscopic dose rate is adjustable over a range of 20:1 to adapt to different procedure requirements. Fourth, we discuss the impact of image processing techniques upon dose minimization. In particular, two such techniques, dynamic range compression through adaptive multiband spectral filtering and fluoroscopic noise reduction, are explored in some detail. Fifth, we review a list of system dose-reduction features, including automatic spectral filtration, virtual collimation, variable-rate pulsed fluoroscopic, grid and no-grid techniques, and fluoroscopic loop replay with store. In addition, we describe a new feature that automatically minimizes the patient-to-detector distance, along with an estimate of its dose reduction potential. Finally, two recently developed imaging techniques and their potential effect on dose utilization are discussed. Specifically, we discuss the dose benefits of rotational angiography and low frame rate imaging with advanced image processing in lieu of higher-dose digital subtraction.

SU-FF-I-64: X-Ray Micro-Angiographic and Fluoroscopic Image-Guided Localization of Asymmetric Endovascular Stents (AES): Study of Accuracy Versus Exposure

Purpose: Image-guided neuro-endovascular interventions, such as treatment of intracranial aneurysms using asymmetric endovascular stents (AES), can be lengthy procedures with high patient dose, yet the treatment success may be highly dependent upon the accuracy of placement of the AES at the aneurysm to occlude the orifice. We investigated the variation of AES localization accuracy for angiographic to fluoroscopic exposures using a high-resolution micro-angiographic (MA) system described previously. Method and Materials: We acquired a sequence of images of a simulated AES placed in a head-equivalent phantom for different calibrated orientations every two degrees. We tracked the 150 μm gold-sphere AES markers with images acquired using the MA detector with 43 μm pixels in angiographic mode and a detector exposure of 1.2 mR/frame. The MA detector uses a fiber-optic taper to optically couple an x-ray converter phosphor to a high performance 1024×1024 matrix CCD camera to enable imaging over a region of interest at the interventional site. Lower dose acquisitions corresponding to fluoroscopy were simulated by adding various amounts of Gaussian noise to achieve a SNR range from ∼80 to 8 corresponding to a 100X reduction in dose. The AES marker position determined by software image analysis was plotted vs. known rotation angle. An inverse function was fit, and the fit residuals calculated in degrees to gauge localization inaccuracy. Results: The results indicated that the accuracy of the stent placement was maintained within 6 degrees for an SNR between 79 and 22. However, for a SNR below 10, the stent localization accuracy deteriorated to 30 – 40 degrees. Conclusion: Intervention using AES with radio-opaque markers can be done at fluoroscopic dose rates during the initial part of the procedure followed by higher exposures to accurately guide the final stent orientation during deployment. (Partial support from NIH grants R01EB002873 and R01NS43924)

Evaluation and estimation of entrance skin dose in patients during diagnostic and interventional radiology procedures

A study was performed to evaluate the total entrance skin dose (ESD) of patients during diagnostic and interventional radiology procedures (IVR) and to estimate ESD with body mass index (BMI) and fluoroscopy time. The study included 26 cases of transcatheter arterial embolization therapy (TAE) for hepatocellular carcinoma (HCC) and 19 cases of diagnostic digital subtraction angiography (DSA) for HCC. The ESD of patients was evaluated with a zinc-cadmium sensor linked to a digital counter (SDM: skin dose monitor). Exposure doses were measured with SDM attached to the front of the X-ray beam-limiting device like a dose area product monitor. ESD was calculated from the measured exposure dose. In 26 TAE for HCC, ESD was 1793.7+/-739.1 mGy, with the mean fluoroscopic time of 23.5 minutes and 4.4 DSA acquisitions. The fluoroscopic dose rate was 52.4+/-11.5 mGy/min. In 19 diagnostic DSA for HCC, ESD was 962.9+/-375.2 mGy, with the mean fluoroscopic time of 11.1 minutes and 4.0 DSA acquisitions. The fluoroscopic dose rate was 32.7+/-12.7 mGy/min. Although 33.2% of ESD was from fluoroscopy in diagnostic procedures, the figure was 68.8% in TAE procedures. It was demonstrated that the increase in ESD during IVR was caused by the rise of fluoroscopy dose rate caused by high-magnification fluoroscopy and the extension of fluoroscopy time. In order to reduce ESD, it is necessary to use a low fluoroscopy dose rate with low-rate pulse fluoroscopy, in addition to shortening fluoroscopy time. Fluoroscopy time was a poor predictor of risk because it did not correlate well with ESD during IVR (diagnostic procedures r(2)= 0.897, IVR r(2)= 0.594). However, ESD correlated well with the product of BMI and fluoroscopy time (diagnostic procedures r(2)= 0.910, IVR r(2)= 0.783). The linear relationship between ESD and the product of BMI and fluoroscopy time provides a simple monitoring mechanism of the ESD delivered to the patient during interventional radiology procedures. This linear relationship needs to be established for other types of interventional procedures.

Management of Patient Skin Dose in Fluoroscopically Guided Interventional Procedures

To simulate dose to the skin of a large patient for various operational fluoroscopic conditions and to delineate how to adjust operational conditions to maintain skin dose at acceptable levels. Patient entrance skin dose was estimated from measurement of entrance air kerma (dose to air) to a 280-mm water phantom for two angiographic fluoroscopes. Effects on dose for changes in machine floor kVp, source-to-skin distance, air gap, electronic magnification, fluoroscopic dose rate control settings, and fluorographic dose control settings were examined. Incremental changes in operational parameters are multiplicative and markedly affect total dose delivered to a patient's skin. For long procedures, differences in doses of 8 Gy or more are possible for some combinations of operational techniques. Effects on skin dose from changes in operational parameters are multiplicative, not additive. Doses in excess of known thresholds for injury can be exceeded under some operating conditions. Adjusting operational parameters appropriately will markedly reduce dose to a patient's skin. Above all other operational factors, variable pulsed fluoroscopy has the greatest potential for maintaining radiation exposure at low levels.

Reference Dose Rates for Fluoroscopy Guided Interventions

The wide diversity of fluoroscopy guided interventions which have become available in recent years has improved patient care. They are being performed in increasing numbers, particularly at departments of cardiology and radiology. Some procedures are very complex and require extended fluoroscopy times, i.e. longer than 30 min, and radiation exposure of patient and medical staff is in some cases rather high. The occurrence of radiation-induced skin injuries on patients has shown that radiation protection for fluoroscopy guided interventions should not only be focused on stochastic effects, i.e. tumour induction and hereditary risks, but also on potential deterministic effects. Reference dose levels are introduced by the Council of the European Communities as an instrument to achieve optimisation of radiation protection in radiology. Reference levels in conventional diagnostic radiology are usually expressed as entrance skin dose or dose-area product. It is not possible to define a standard procedure for complex interventions due to the large inter-patient variations with regard to the complexity of specific interventional procedures. Consequently, it is not realistic to establish a reference skin dose or dose-area product for complex fluoroscopy guided interventions. As an alternative, reference values for fluoroscopy guided interventions can be expressed as the entrance dose rates on a homogeneous phantom and on the image intensifier. A protocol has been developed and applied during a nationwide survey of fluoroscopic dose rate during catheter ablations. From this survey reference entrance dose rates of respectively 30 mGy.min-1 on a polymethylmethacrylate (PMMA) phantom with a thickness of 21 cm, and of 0.8 µGy.s-1 on the image intensifier have been derived.