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At least 307 records · Page 17Linked to original sources
PubMed1998

Portable fluoroscopy in the management of zygomatic arch fractures.

Operative methods that do not allow intraoperative visualization of the fracture fragments in patients with isolated zygomatic arch fractures often result in inadequate reduction. This article describes a technique using a portable, surgeon-operated fluoroscopic machine that can be used preoperatively, intraoperatively, and postoperatively in patients with isolated zygomatic arch fractures. Using the portable fluoroscopic unit, reduction of isolated zygomatic arch fractures was performed in 9 consecutive patients over a period of 1.5 years. Postoperative alignment was confirmed using computed tomography (CT). These CT images were compared with the fluoroscopic images in several of the patients. Eight of the nine fractures were reduced via an intraoral approach and one through a Gillies approach. All nine fractures were easily visualized and their reductions were confirmed with intraoperative dynamic visualization using a portable fluoroscopic unit. Postoperative CT revealed images of the reduction that were comparable with intraoperative and postoperative fluoroscopic images. The use of portable fluoroscopy intraoperatively allows for dynamic visualization of instrumentation and the immediate confirmation of the adequacy of fracture reduction. Moreover, this technique may eliminate the need for postoperative CT in isolated zygomatic arch fractures. Portable fluoroscopy may also have a place in the management of certain zygomatic complex fractures.

Cost-Benefit Analysis↗
PubMed2002

Fluoroscopy-based multiplanar image guidance for insertion of sacroiliac screws.

A prospective controlled experimental study was done to assess the value of fluoroscopy-based, computer-assisted orthopaedic surgery for the insertion of sacroiliac screws and to compare this new technology with the conventional technique, using image intensification. In a simulated surgical setup, 140 cannulated screws were placed into the S1 and S2 vertebral bodies of 35 pelvic models. The screws were inserted under fluoroscopy-based image guidance or with the conventional technique. Different drills were tested with both techniques, including a 2.8-mm guide wire and a 5-mm solid drill. The 2.8-mm guide wire proved inaccurate with the computer-assisted image guidance system because of guide wire flexibility. Using the more rigid 5-mm drill, the results of computer-assisted image guidance were comparable with the image intensifier technique. The radiation exposure during screw insertion was reduced considerably when using the image guidance system. System-specific requirements warranted adjustment of surgical technique and instruments. The major advantages of this new technology are immediate intraoperative image acquisition and provision of surgical guidance in as much as four planes simultaneously. The results of this experimental study are encouraging and have led to initiation of a clinical trial.

Bone Screws↗
PubMed2000

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.

Fluoroscopy↗
PubMedDate not supplied

Computerized fluoroscopy techniques for intravenous study of cardiac chamber dynamics.

A computerized fluoroscopy system which was recently developed in our laboratories permits image contrast increases of 8-16 relative to conventional image intensifer fluoroscopy and permits study of canine and human ventricular wall motion using peripheral intravenous injections. Two time-dependent image subtraction algorithms are illustrated in connection with observation of artificially infarcted dog hearts. The first algorithm produces a display analogous to direct ventriculography using catheterization. The second displays regions of dyskinetic motion as anomalous image grey shades.

Animals↗
PubMedDate not supplied

Percutaneous CT-guided biopsy: improved confirmation of sampling site and needle positioning using a multistep technique at CT fluoroscopy.

We describe a new multistep procedure for CT fluoroscopy-guided core biopsy, which allows confirmation of the biopsy-sampling trough and the final needle tip position prior to sampling. Twelve lesions measuring < or =2 cm or in close proximity to vital structures were biopsied using commercially available biopsy systems. Diagnostic biopsies were obtained in all cases. Mean fluoroscopy time was 11.1 +/- 2.8 s per biopsy. This technique may have the potential to improve the accuracy and safety of CT-guided biopsy.

Biopsy, Needle↗
PubMed2001

Novel computer-assisted fluoroscopy system for intraoperative guidance: feasibility study for distal locking of femoral nails.

OBJECTIVES: Orthopaedic procedures that use fluoroscopy require intraoperative mental navigation of the surgical tools in a three-dimensional space. Moreover, because of their reliance on real-time monitoring, such procedures are frequently associated with increased x-ray exposure. The goal of this study was to develop a computer-guided surgical navigation system based on fluoroscopic images that not only facilitates direction of surgical tools within anatomy, but also provides constant feedback without the need for radiologic updates. To evaluate the feasibility of the new technology, the authors used it on cases requiring distal locking of femoral nails. METHODS: The hardware components of the system include an instrumented C-arm, optoelectronic position sensor, stereotactic tools, and custom-made software. Computer integration of these devices permitted C-arm alignment assistance and real-time navigation control without constant x-ray exposure. The nails were locked in a variety of media, including plastic femurs, dry human femoral specimens, human cadavers, and one clinical case. Unreamed femoral nail sizes ranged from 9/340 to 12/400. Radiographs were taken to confirm that screws were positioned correctly, and fluoroscopic time associated with the locking procedure was recorded. RESULTS: All distal holes were locked successfully. In eight (11 percent) of seventy-six holes, the drill bit touched the canal of the locking hole, albeit with no damage to the nail and no clinical consequences. The fluoroscopy time per pair of screws was 1.67 seconds. CONCLUSIONS: The developed system enables the physician to precisely navigate surgical instruments throughout the anatomy using just a few computer-calibrated radiographic images. The total radiation time per procedure can be significantly reduced because additional x-ray exposure is not required for tool navigation.

Bone Nails↗
PubMed1998

The use of bedside fluoroscopy to evaluate the cervical spine in obtunded trauma patients.

BACKGROUND: Recognition of a cervical spine injury is important to prevent further injury and in planning for future care. The management of the patient with a possible cervical spine injury who remains unresponsive is controversial. METHODS: A retrospective evaluation of obtunded trauma patients admitted to the surgical intensive care unit who underwent bedside fluoroscopic cervical spine evaluation. Fluoroscopic findings and all complications were noted. RESULTS: Twenty obtunded patients with possible cervical spine injuries underwent bedside fluoroscopic cervical spine evaluation. All patients had at minimum a normal three-view cervical spine series before fluoroscopy. Thirteen patients (65%) had the fluoroscopic examination completed at the bedside and were cleared. The complete cervical spine could not be evaluated in six patients (30%). One patient (5%) was found to have a C4-5 subluxation in the bedside examination. None of the patients had progression of their neurologic symptoms after cervical spine flexion/extension, and none developed evidence of spinal cord injury after being cleared during their hospital course. Cervical collars remained in place for 5.7+/-1.41 days (range, 1- 26 days). Three patients (15%) were noted to have decubiti under the cervical collar. CONCLUSION: In this small study, the use of bedside fluoroscopy to evaluate the cervical spine appears safe and easy to perform. One unrecognized injury was identified. The technique is usually successful and gives reassurance that a significant cervical spine injury is not present.

Adult↗
PubMed1997

Fluoroscopy-assisted intubation of a child with an unstable subluxation of C1/C2.

Patients presenting with unstable cervical spine injuries are at risk for additional neurological injury as a consequence of airway manipulation. Techniques of awake intubation may not always be desirable or practical, particularly in the pediatric patient. We describe the use of fluoroscopy during the induction of anesthesia and intubation of a child with an unstable C1/C2 spinal subluxation. Fluoroscopy is readily available and noninvasive. This technique allows for rapid establishment and maintenance of optimal head and neck positioning during induction of general anesthesia and performance of laryngoscopy and tracheal intubation.

Accidents, Traffic↗
PubMed2004

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.

Fluoroscopy↗
PubMed1981

A new temporary atrial pacing catheter inserted percutaneously into the subclavian vein without fluoroscopy: a preliminary report.

A permanently formed "J" shaped 6F bipolar electrode catheter specially designed to facilitate temporary atrial pacing was constructed and tested in 15 patients. A pair of rigid, "orienting wings" was fixed to the catheter 28 cm from a large spherical tip electrode to establish directional orientation of the "J" while in the right atrium. Rapid percutaneous introduction is possible with a peel-away sheath via the subclavian vein. Positioning in the right atrium can be accomplished without fluoroscopy. The catheter could be inserted and positioned against the right atrial wall generally in less than three minutes and required little or no additional manipulation for capture. No instance of loss of capture was documented during subsequent continuous monitoring as the catheter remained in place from one to thirteen days. Ease of insertion of this electrode catheter, as well as stability, provided an effective method for temporary atrial pacing without fluoroscopy. This novel catheter design warrants testing in a large patient population by others and could have a potential application to other types of catheter needs.

Aged↗
PubMed2002

Phantom study to determine radiation exposure to medical personnel involved in ERCP fluoroscopy and its reduction through equipment and behavior modifications.

OBJECTIVE: The aim of this work is to evaluate the potential radiation exposure to medical personnel by comparing results from phantom studies of two different fluoroscopic units used for ERCP, and to determine which equipment or behavior modification can reduce radiation exposure. METHODS: Radiation exposures using an opaque tissue equivalent chest phantom with an abdominal insert were performed on a stationary dedicated fluoroscopy unit and a mobile C-arm unit, comparing varying equipment manipulations. Scatter radiation was recorded at 1) the patients' head, 2) where the endoscopist stands, and 3) where the equipment personnel stands. RESULTS: Radiation exposures were significantly higher for the mobile C-arm unit, revealing a 4160-times greater dosage increase for head and neck and a 8660-times increase for body than the fixed unit. Tower position and vertically stationed lead shields facilitated exposure reduction by means of equipment manipulation. The positioning of the endoscopist away from the right corner of the units also decreased exposure. CONCLUSIONS: Dedicated stationary fluoroscopy units provide significantly less radiation exposure. Equipment and behavior modification including tower positioning down and vertical shielding are essential for reduction in radiation exposure to medical personnel.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1993

Oral versus intravenous premedication for small bowel biopsy in children: effect on procedure and fluoroscopy times.

Oral alimemazine and cisapride, or diazepam and cisapride, or iv midazolam and metoclopramide were given as premedication for small bowel biopsy to three groups of children from a total population of 185 individuals. The biopsy procedures were performed under intermittent fluoroscopy and times for both were recorded. The median biopsy procedure time was significantly shorter in children given iv midazolam and metoclopramide (6 min) compared to those given oral premedication (10 min) (p < 0.001). The median fluoroscopy time was very short in all groups, ranging between 3 and 6 s. It is concluded that iv premedication is superior to oral premedication for small bowel biopsy in children because more effective sedation is obtained.

Administration, Oral↗
PubMedDate not supplied

Image magnification in digital fluoroscopy.

Image magnification is inherent in radiography. In digital fluoroscopy, the three components of magnification are geometric, electronic and photographic. In this study, the total magnification factor of a digital imaging system was determined by two methods, 1) comparison of measurements of a known object to its image and 2) calculation of geometric, electronic and photographic magnification from the imaging system specifications. Both methods were employed for various focal-film distances, image intensifier tube modes and laser printer formats. Results of these two methods were different due to the detrimental effect of penumbra on image quality with increasing magnification. If a radiographic image is to be used to approximate object size, then a technique should be used that will minimize magnification. In digital fluoroscopy this is achieved with the shortest object-film distance (assuming a fixed focal-object distance), largest image intensifier mode and greatest number of images per sheet of film.

Animals↗
PubMedDate not supplied

Radiography and image-intensified fluoroscopy of barium passage through the gastrointestinal tract in six healthy Amazon parrots (Amazona aestiva).

Gastrointestinal contrast studies were performed in six clinically healthy blue-fronted Amazon parrots (Amazona aestiva) using radiography and image-intensified fluoroscopy. During examination, the birds were confined in a perspex cage. The quality of the lateral radiographs was adequate for assessment of the contrast medium-filled gastrointestinal tract. Thirty minutes after administration of 20 mL/kg of a 25% barium sulphate suspension directly in the crop, in all birds the ventriculus was totally outlined by barium. After 60 min, the small intestine was filled in five of six birds. After 180 min, the crop was empty in all birds. The barium-outlined ventriculus had differences in shape on radiographs of individual birds and also between birds. The colon and cloaca had further filling after 120 to 300 min. With image-intensified fluoroscopy, gastrointestinal motility was evaluated. Contractions of the crop were seen, and boluses of contrast medium passing through the esophagus toward the proventriculus were easily identified. Proventricular contractions were rarely noted, but ventriculus motility was present and clearly defined. The ventriculus had a mean of 3.7 contraction cycles/min. In the duodenum and small intestine, rapid antegrade and retrograde peristaltic movements in combination with segmental contractions were seen. In the colon, occasionally very slow peristaltic activity, mainly of segmental nature, was present. During the examinations, no defeacation was recorded. Confinement in a small perspex cage provides an adequate and handy radiological set-up for evaluation of gastrointestinal passage and motility in birds, minimizing the influences of stress and anesthesia.

Animals↗
PubMed2002

Integration of digital fluoroscopy with CT-based radiation therapy planning of lung tumors.

Radiation dose escalation may be a means to increase the local control rate of inoperable lung tumors. Treatment plans involve the creation of a uniform planning target volume (PTV) to ensure proper coverage despite patient breathing and setup error. This may lead to unnecessary radiation of normal tissue in shallow breathers or target underdosing for patients with excess internal motion. Therefore, the nature of tumor motion for each patient should be measured in 3D, something that cannot be done with CT alone. We have developed a method that acquires 2D real-time fluoroscopic images (loops) and coregisters them with 2D digitally reconstructed radiographs (DRR) formed from the CT scan. The limitations of CT to encompass motion can be overcome by merging the two modalities together. The accuracy of the coregistration method is tested with a stationary grid of radio-opaque markers at various spatial positions. The in-plane (at-depth) displacement between markers on the fluoroscopic image versus the DRR varies with position across the image due to slight misalignments between the x-ray source used in fluoroscopy and the virtual source used for the DRR relative to the test object. At clinically relevant positions, the maximum, measured in-plane displacement, is 1.1 mm. The method is applied to the thorax of an anthropomorphic phantom and a good fit is observed between the appearances of the bony anatomical structures on the coregistered image. Finally, a series of motion measurements are carried out on two oscillating cylindrical objects. The degree of motion as measured by fluoroscopy is accurate to within 1.0 mm, whereas the DRR is inconsistent in predicting motion. The coregistration of fluoroscopic loops with the DRR shows at what point within the oscillation the DRR fails to encompass motion. For any treatment site involving target motion, this real-time imaging is a useful asset in the planning stage.

Fluoroscopy↗
PubMedDate not supplied

A method for time domain filtering using computerized fluoroscopy.

A new computerized fluoroscopy technique for isolating low image contrast, which results during the flow of an intravenously administered bolus of iodinated contrast materials, is proposed. The technique requires the application of one of a family of imaging algorithms which have been designed to isolate time varying image contrast. This family of imaging algorithm is described, as is the way in which each isolates a particular range of temporal frequency components associated with the bolus's flow through various cardiovascular structures. The implementation of these algorithms in real time using appropriate digital recursive filtering techniques is described. The architecture of a dedicated hardwired computerized fluoroscopy apparatus which would incorporate these algorithms is also presented.

Computers↗
PubMedDate not supplied

A study of motion in gastrointestinal x-ray fluoroscopy.

Studying motion in the gastrointestinal (G.I.) tract is the first step towards our goal of designing a digital algorithm for real-time noise and motion blurring reduction by temporal and spatial averaging in x-ray fluoroscopy. The present work concerns the types of motion relevant to G.I. fluoroscopy (e.g., motion of the walls of the oesophagus, the stomach, the small intestine, and the colon), and measurement of the range of velocities in different parts of the G.I. tract from tape recorded fluoroscopic sequences. The relationship between image contrast and velocity, the effects of motion on system response, and in particular the influence of these parameters on the evaluation of velocities will also be discussed.

Adolescent↗
PubMed1999

Moving segments region of interest attenuator for x-ray fluoroscopy.

Region of interest (ROI) imaging has previously been proposed as a means of reducing x-ray fluoroscopy radiation dose. Previous ROI attenuators made of partially attenuating metal plates change beam quality, which may lead to uncertainty in image restoration procedures. The design and construction of a prototype moving segments ROI attenuator (MS-ROI), which maintains beam quality across the whole field of view is described. The x-ray beam intensity is halved by 36 lead segments which are rapidly rotated between the x-ray tube and patient, with a central hole projecting a circular ROI at full intensity. Image processing techniques with automatic detection of the ROI boundary were used to homogenize image brightness across the whole image. Images restored using these techniques were judged to be visually acceptable, with a good match between pixel values inside and outside the ROI. Image contrast within the ROI was improved by 18% due to reduced scatter and veiling glare from the periphery. The introduction of the MS-ROI attenuator also results in a 48% increase in statistical noise in the area outside the ROI, with no significant change in object contrast. The patient entrance dose measured using the dose area product (DAP) method was reduced by 53.4% under manual exposure control, with the dose to operators reduced by 48.4% under automatic brightness control. Further work is needed to determine whether the attenuator can be used with pulsed fluoroscopy, and to reduce vibrational effects on the ROI boundary. The MS-ROI attenuator provides a more constant ratio of central-to-peripheral image intensity, and maintains uniform beam quality and image contrast across the whole image in comparison to simple metal plate attenuators.

Contrast Sensitivity↗