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PURPOSE: To evaluate the influence of pulsed fluoroscopy (PF), nonpulsed fluoroscopy (NPF), and various fluoroscopic techniques on the absorbed ovarian dose (AOD) associated with uterine artery embolization (UAE) of leiomyomata. MATERIAL AND METHODS: Ovarian location was estimated from preprocedural pelvic magnetic resonance images of 23 patients previously treated by means of UAE. The AOD was measured with thermoluminescent dosimeters (TLD) placed into an anthropomorphic phantom at the determined ovarian location. The following measurements from PF and NPF were obtained: 21.89 minutes of nonmagnified posterior-anterior fluoroscopy, 10 minutes of nonmagnified oblique fluoroscopy, 10 minutes of posterior-anterior magnified fluoroscopy, 10 minutes of combined oblique magnified fluoroscopy, and 47 simulated angiographic exposures. Numbers for nonmagnified posterior-anterior fluoroscopy time and exposure numbers were chosen from the average values from previous UAE procedures. AOD from pulsed and nonpulsed nonmagnified posterior-anterior fluoroscopy was compared to measurements from oblique magnified, posterior-anterior magnified, and oblique fluoroscopy. RESULTS: AOD from NPF was, on average, 1.7 times higher than from PF. When compared with nonmagnified posterior-anterior fluoroscopy, the AOD from oblique magnified fluoroscopy was 1.9 times greater; the AOD from nonmagnified oblique fluoroscopy was 1.1 times greater. The AOD from oblique magnified fluoroscopy was 1.5 times higher on the side closer to the x-ray tube than on the contralateral side. AOD from serial angiographic exposures contributed only less than 7% to the total AOD for the average UAE procedure. CONCLUSIONS: The AOD associated with UAE can best be reduced by limiting fluoroscopy time and the use of oblique or magnified fluoroscopy. Contribution of angiographic exposures to AOD is much less significant.
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.
PURPOSE: The aim of this study was to determine in a pediatric population whether a routine chest x-ray after central venous access is necessary when the central venous catheter is placed with intraoperative fluoroscopy. METHODS: This was a retrospective review of the charts of all patients at Children's Hospital in Denver, Colorado who underwent subclavian or internal jugular central venous catheter placement from January 1, 1998 through December 31, 2001. Age, sex, primary reason for access, access site, number of venipuncture attempts, type of catheter, intraoperative fluoroscopy results, chest x-ray results, location of the tip of the catheter, and complications were analyzed. RESULTS: There were 1,039 central venous catheters placed in 824 patients, 92.6% in the subclavian vein and 7.4% in the internal jugular vein. There were 604 (58.1%) children who had both fluoroscopy and a postprocedure chest x-ray, there were 308 (29.6%) who had only fluoroscopy, there were 117 (11.3%) who had only a postprocedure chest x-ray, and there were 10 (1.0%) who had neither fluoroscopy nor chest x-ray. On completion of the procedure, there were 12 (1.1%) children with misplaced central venous catheters, only 1 (0.1%) when intraoperative fluoroscopy was used. There were 17 (1.6%) complications; 9 (0.9%) were pulmonary (pneumothorax, hemothorax, or an effusion). All children with pulmonary complications experienced clinical signs and symptoms suggestive of the complication after their central venous catheter insertion but before their postprocedure chest x-ray. CONCLUSIONS: The number of complications encountered in children who had central venous access of the subclavian vein or internal jugular central vein with intraoperative fluoroscopy was infrequent, the number of misplaced catheters was minimized with intraoperative fluoroscopy, and all children with pulmonary complications showed clinical signs suggestive of pulmonary complications before postoperative chest x-ray. Therefore, children who have had central venous access of the subclavian and internal jugular vein with intraoperative fluoroscopy do not appear to require a routine chest x-ray after catheter placement unless clinical suspicion of a complication exists.
PURPOSE: To determine the estimated absorbed ovarian dose (EAOD) and absorbed skin dose (ASD) that occurs during uterine artery embolization (UAE) using pulsed fluoroscopy and a refined procedure protocol. MATERIALS AND METHODS: The absorbed dose was measured in 20 patients who underwent UAE procedures. Radiation was limited by using low frequency pulsed fluoroscopy, bilateral catheter technique with simultaneous injections for embolization as well as pre-and postembolization exposures and focus on limitation of magnified and oblique fluoroscopy. Lithium fluoride dosimeters were placed both in the posterior vaginal fornix and on the skin at the beam entrance site. The vaginal dose was used to approximate the EAOD. Fluoroscopy time and exposures were recorded. The mean values for all patients were calculated and compared to our previous results obtained with conventional fluoroscopy and to threshold doses for the induction of deterministic skin injury. RESULTS: Mean fluoroscopy time was 10.95 min. (range 6-21.3 min.) and the mean number of angiographic exposures was 20.9 (range 14-53). The mean EAOD was 9.5 cGy (range 2.21-23.21 cGy) and the mean ASD was 47.69 cGy (range 10.83-110.14 cGy). This compares to previous results with non-pulsed fluoroscopy of an EAOD of 22.34 cGy (range 4.25-65.08 cGy) and an ASD of 162.32 cGy (range 66.01-303.89 cGy) as well as threshold doses for induction of deterministic radiation injury to the skin (400-500 cGy). CONCLUSION: When pulsed fluoroscopy is used with emphasis on dose reduction techniques, the EAOD and ASD can be substantially reduced to less than 1/2 (P = .017) and 1/3 (P < .0001) when compared to UAE performed with nonpulsed fluoroscopy. These radiation reduction tools should therefore be applied whenever possible.
STUDY DESIGN: Human cadaveric. OBJECTIVES: Compare the accuracy of electromagnetic field (EMF)-based image-guided thoracic pedicle screw insertion to conventional techniques using anatomic landmarks and fluoroscopy. BACKGROUND: Image-guided surgical systems that aid in spinal instrumentation seek to minimize radiation exposure and improve accuracy. EMF image guidance was developed as an alternative to optical tracking to eliminate potential line of sight issues. MATERIALS AND METHODS: Four fresh-frozen human cadavers were randomly allocated into two groups. Pedicle screws were inserted from T1 to T12 using anatomic landmarks and fluoroscopy in group 1 and image guidance in group 2. Insertion and fluoroscopy time were recorded. Anatomic dissections were performed to assess screw placement. RESULTS: Image guidance placed 92% of thoracic pedicle screws safely, and conventional fluoroscopy placed 90% safely. The average degree of perforation was 2.4 mm with conventional fluoroscopy and 1.7 mm with image guidance (P = 0.055). Fluoroscopic time per screw was 5.9 seconds for conventional fluoroscopy and 3.6 seconds for image guidance (P = 0.045). Insertion time per screw was 4.35 minutes for conventional fluoroscopy and 2.98 minutes for image guidance (P = 0.007). However, when set-up time and image capture time were taken into account, the total insertion time per screw was not significantly different between the two groups. CONCLUSIONS: Our study has shown that EMF image-guided thoracic pedicle screw placement results in a similar incidence of safely placed screws as does conventional fluoroscopy. When set-up time and image-capture time were factored in for image guidance, the average time to insert a pedicle screw was equal for both techniques. The use of EMF image guidance significantly reduced fluoroscopic time and thus radiation exposure per screw compared with conventional fluoroscopic techniques.
OBJECTIVES: (1) To assess reproducibility of medial knee joint space width (JSW) measurement in healthy subjects and osteoarthritic (OA) patients. (2) To define minimal relevant radiological change in knee JSW based on the reproducibility of its measurement. PATIENTS AND METHODS: (1) Healthy volunteers: in the first part of the study, 20 knees of healthy adult volunteers were radiographed in the weightbearing, anteroposterior extended view, twice, two weeks apart, using three different radiographic procedures: (a) without guidelines, (b) with guidelines and without fluoroscopy, (c) with guidelines and fluoroscopy. (2) Knee OA patients: in the second part of the study, 36 knees of OA patients were radiographed twice with guidelines and without fluoroscopy. JSW was measured blindly using a graduated magnifying glass. Based on the Bland and Altman graphic approach, cut off points defining minimal relevant radiological change are proposed. RESULTS: Standard deviation (SD) of differences in JSW measurement between two sets of knee radiographs in healthy subjects were 0.66 mm for radiography performed without guidelines, 0.37 mm for radiography performed with guidelines and without fluoroscopy, and 0.31 mm for radiography with guidelines and fluoroscopy. SD of differences in JSW measurement in OA patients were 0.32 mm for radiography performed with guidelines and without fluoroscopy. A minimal relevant change in JSW between two radiographs performed in healthy subjects can be defined by a change of at least 1.29 or 0.59 mm when radiographs are taken without guidelines, and with guidelines and fluoroscopy, respectively. When radiographs are taken with guidelines and without fluoroscopy, the change must be at least 0.73 mm. A similar figure, 0.64 mm was observed in knee OA patients. CONCLUSION: Definition of radiological progression varies greatly according to the radiographic procedure chosen. Use of guidelines reduces the threshold of progression required to consider that change between two measures is relevant.
BACKGROUND: Radiographic technology plays an integral role in interventional cardiology. The number of interventions continues to increase, and the associated radiation exposure to patients and personnel is of major concern. This study was undertaken to determine whether a newly developed x-ray tube deploying grid-switched pulsed fluoroscopy and extra beam filtering can achieve a reduction in radiation exposure while maintaining fluoroscopic images of high quality. METHODS AND RESULTS: Three fluoroscopic techniques were compared: continuous fluoroscopy, pulsed fluoroscopy, and a newly developed high-output pulsed fluoroscopy with extra filtering. To ascertain differences in the quality of images and to determine differences in patient entrance and investigator radiation exposure, the radiated volume curve was measured to determine the required high voltage levels (kVpeak) for different object sizes for each fluoroscopic mode. The fluoroscopic data of 124 patient procedures were combined. The data were analyzed for radiographic projections, image intensifier field size, and x-ray tube kilovoltage levels (kVpeak). On the basis of this analysis, a reference procedure was constructed. The reference procedure was tested on a phantom or dummy patient by all three fluoroscopic modes. The phantom was so designed that the kilovoltage requirements for each projection were comparable to those needed for the average patient. Radiation exposure of the operator and patient was measured during each mode. The patient entrance dose was measured in air, and the operator dose was measured by 18 dosimeters on a dummy operator. Pulsed compared with continuous fluoroscopy could be performed with improved image quality at lower kilovoltages. The patient entrance dose was reduced by 21% and the operator dose by 54%. High-output pulsed fluoroscopy with extra beam filtering compared with continuous fluoroscopy improved the image quality, lowered the kilovoltage requirements, and reduced the patient entrance dose by 55% and the operator dose by 69%. CONCLUSIONS: High-output pulsed fluoroscopy with a grid-switched tube and extra filtering improves the image quality and significantly reduces both the operator dose and patient dose.