Fluoroscopic Device Research Articles

Extreme left anterior oblique projection guided leadless pacemaker implantation: a pilot study

Abstract Introduction Cardiac perforation with leadless pacemakers (LPM) remains a concern. Non-septal placement seems to be the main cause, with frequent delivery in the right ventricular (RV) free wall when using standard 30-40º left anterior oblique (LAO) projections. Thus, individualized angulations might be considered, because distinguishing septal from free-wall location with standard projections has been proved to be unreliable: previous studies have shown frequent RV free wall position misclassified as septal when using 30-40º LAO. Methods This is a single-center, observational pilot study, comparing a 60º LAO approach LPM (VR or VDD) implant technique with the standard one. All consecutive patients who received LPM using non-standard LAO projections (study cohort) were compared with an immediately retrospective cohort of consecutive patients who received LPM using only standard projections in the same institution (control cohort). In the study group, sequential 30-40º and 60º LAO projections were performed, and a RV transvenous reference was also considered in cases with preexisting pacing leads or by placing an electrophysiological catheter into an apical-septum position upon implanter´s criterion. The primary endpoint was the need of repositioning the delivery catheter in the study cohort, due to unproper position in the 30-40º LAO angulation. The secondary endpoints were: 1) procedural characteristics (procedure and fluoroscopy times, final fluoroscopic device position and number of deployments); 2) procedure related complications (the composite of vascular complications, implant failure, cardiac perforation, and device dislodgement); 3) acute pacing parameters. Results Twenty-one patients who received LPM using both 30-40º and 60º LAO (study cohort) were compared with 84 patients who received LPM using only 30-40º LAO. Delivery catheter repositioning was needed in 73,7% of patients (n=16/21) in the study cohort, most of them (n=14/16, 77,5%) due to catheter towards RV free wall, distinguished with 60º LAO from 30-40º LAO. Placement in non-midseptal locations was more common in the control group compared to the study group (74.7% vs. 42.8%, p=0.006). The median number of delivery attempts was higher in the study group (1.8±1.3 vs. 1.3±0.9, p=0.010), with longer procedural times. Threshold tended to be higher in the study group (0.8±0.7Vx0.4ms vs. 0.5±0.3Vx0.4ms, p=0.063), with smaller R-wave sensing (9.2±3.7mV vs. 11.4±4.4mV, p=0.038) and impedance (757±207ohms vs. 1026±314ohms, p<0.001). Conclusion 60º LAO frequently identified catheter mislocations using 30-40º LAO, helping to avoid RV free wall LPM deployment. This intervention resulted in longer procedures, possibly due to a higher number of repositions and delivery attempts. Pacing parameters remained adequate, although there was a trend for higher threshold, meanwhile sensing and impedance were lower, maybe related to worse myocardial contact when true septal placement is achieved.Study group implant sequenceBaseline and procedural characteristics

Intraoperative imaging with the mobile C-arm : Technique, image creation and radiation protection

Imaging techniques in the discipline of orthopedics and trauma surgery are essential not only for making a diagnosis but also play a central role in the performance, documentation and monitoring of the corresponding treatment. Procedures such as open reduction and internal fixation (ORIF) and closed reduction and internal fixation (CRIF) of fractures, kyphoplasty and vertebroplasty as well as posterior stabilization of spinal fractures are carried out under X‑ray control. In the relevant operating rooms of emergency departments and operating theaters, mobile fluoroscopy devices are available, which due to their appearance are called C‑arms. These devices can be moved horizontally, vertically, and along the pivotal axis, enabling real-time imaging of joints and bones from various angles. This imaging enables minimally invasive surgical techniques as this often eliminates the need for extensive preparation and resulting in smaller wound defects compared to open surgical preparation. Additionally, surgeons can immediately assess and, if necessary, adjust the reduction outcome to achieve the best possible care and reduce the need for corrective interventions. With current C‑arms it is also possible to generate 3‑dimensional datasets, to enhance the assessment of implant positioning, particularly in complex intra-articular fractures. This availability helps avoid subsequent corrective interventions that would otherwise only be identified through postoperative computed tomography [1].

Usefulness of augmented reality in radiological protection education and training for interventional radiologists

The aim of this work is to evaluate the usefulness of using augmented reality (AR) to train medical professionals in radiological protection (RP) in fluoroscopy. A Microsoft HoloLens 2 device has been used to simulate a fluoroscopic device. The teaching scenario considers a Philips Azurion able to rotate to pre-defined gantry positions,a dorsal decubitus patient and a ceiling shield. Radiation exposures were simulated using the FLUKA Monte Carlo code. 11 radiologists were asked to reproduce their positioning as per a clinical procedure and to correctly position the ceiling shield. Then, they were presented with the radiation exposure of their choices and were able to further optimise it. After the session, they were asked to complete a questionnaire. Users rated the AR educational approach as Intuitive and relevant to RP education (35%) and inspiring to deepen their knowledge (18%). Nevertheless, a negative aspect was mainly the difficulty in dealing with the system (58%). Although the participants were radiologists, a minority recognised themselves as having accurate knowledge of the RP (18%), indicating a relevant knowledge gap. The usefulness of using AR in RP education for radiologists has been shown. The visual aid of such technology is likely to improve the consolidation of practical knowledge. The use of interactive teaching techniques has the possibility to both help radiology professionals consolidate their radiation protection training and confidence in their practices.

Use of a Lightweight Portable Fluoroscopy Device for Obtaining Weightbearing Ankle Images

Category: Ankle; Other Introduction/Purpose: Portable fluoroscopy devices provide point-of-care imaging in emergency and out-patient clinics. In patients suffering from ankle syndesmosis injuries, imaging under physiologic load can lead to more accurate diagnosis, particularly in subtle cases. In this study, we compared weightbearing images obtained using a novel lightweight portable battery-powered fluoroscopy device with a conventional radiography device regarding syndesmosis examination measurements. Methods: In this prospective study, eleven healthy participants underwent bilateral three-view weightbearing imaging of both ankles using a radiography (X-ray group) device and a portable fluoroscopy system (Smart-C group). Radiographic measurements were done by two observers on anteroposterior, mortise, and lateral views were compared between the two techniques. These measurements included talar tilt, tibiofibular clear space, tibiofibular overlap, plafond malleolar angle, medial distal tibial angle, medial clear space, lateral distal tibial angle, anterior and posterior tibiofibular distance were measured using the appropriate view. Data were compared between the two techniques; the interobserver agreement was calculated within each group. P<0.05 was considered statistically significant. Results: Comparing the two imaging modalities, there was no significant difference between the measurements in Smart-C and X- ray groups except plafond malleolar angle. The overall interobserver agreement was excellent between the two observers. There was no significant difference between the measures by the two observers and between the bilateral ankles. Conclusion: Our results support the use of weightbearing images using portable fluoroscopy device as an alternative for the conventional radiography systems, particularly in limited-resource settings.

PO095 / #613 STEREOELECTROENCEPHALOGRAPHY OF THE INSULAR CORTEX WITH INTRAOPERATIVE O-ARM. OUR EXPERIENCE AND RESULTS: E-POSTER VIEWING

Refractory epilepsy affects 30% of epileptic patients, with devastating consequences for their personal and professional development. Of those, about 40% could benefit from surgical treatment, provided there is an identifiable accessible epileptic focus. When non-invasive diagnosis is inconclusive, further study is warranted by incursive registration of electrical brain activity with either subdural, epidural or deep electrodes. The latter, known as stereoelectroencephalography (SEEG), displays a three dimensional representation of the epileptic zone and permits identification of subcortical aberrancies. Traditional frame-based or the novel robotic-based stereotactic placement of deep electrodes, though very precise, are cumbersome and expensive. Thus, we propose a frameless neuronavigation technique, combined with intraoperative imaging, as a reliable and straightforward alternative. We present our experience and results with an intraoperative 3D fluoroscopic device and an articulated passive arm for SEEG electrode placement.

Contactless Electrocatheter Tracing within Human Body via Magnetic Sensing: A Feasibility Study.

During surgical procedures, real-time estimation of the current position of a metal lead within the patient’s body is obtained by radiographic imaging. The inherent opacity of metal objects allows their visualization using X-ray fluoroscopic devices. Although fluoroscopy uses reduced radiation intensities, the overall X-ray dose delivered during prolonged exposure times poses risks to the safety of patients and physicians. This study proposes a potential alternative to real-time visualization of a lead inside the human body. In principle, by making a weak current flow through the lead and measuring the related magnetic field generated outside the body, it is possible to trace the position of the lead. This hypothesis was verified experimentally via two tests: one carried out on a curved copper wire in air and one carried out on a real pacemaker lead in a saline solution. In the second test, a pacemaker lead and a large return electrode were placed in a tank filled with a saline solution that reproduced the mean resistivity of the human torso. In both tests, a current flowed through the lead, which consisted of square pulses with short duration, to avoid any neuro-muscular stimulation effects in a real scenario. A small coil with a ferrite core was moved along a grid of points over a plastic sheet and placed just above the lead to sample the spatial amplitude distribution of the magnetic induction field produced by the lead. For each measurement point, the main coil axis was oriented along the x and y axes of the plane to estimate the related components of the magnetic induction field. The two matrices of measurements along the x and y axes were further processed to obtain an estimate of lead positioning. The preliminary results of this study support the scientific hypothesis since the positions of the leads were accurately estimated. This encourages to deepen the investigation and overcome some limitations of this feasibility study.

Use of a Lightweight Portable Fluoroscopy Device for Obtaining Weightbearing Ankle Images

Portable fluoroscopy devices provide point-of-care imaging in emergency and out-patient clinics. In this prospective study, we compared weightbearing images of syndesmosis obtained using a novel lightweight portable battery-powered fluoroscopy device with those obtained with a conventional radiography device. Eleven healthy participants underwent bilateral 3-view weightbearing imaging of both ankles using a radiography (X-ray group) device and a portable fluoroscopy system (LPF group). Anteroposterior, mortise, and lateral views were compared between the 2 techniques. Radiographic measurements were done by 2 observers. These measurements included talar tilt, tibiofibular clear space, tibiofibular overlap, plafond malleolar angle, medial distal tibial angle, medial clear space, lateral distal tibial angle, anterior and posterior tibiofibular distance were measured using the appropriate view. Data were compared between the 2 techniques; the interobserver agreement was calculated within each group. P < .05 was considered statistically significant. Comparing the 2 imaging modalities, there was no significant difference between the measurements in LPF and X-ray groups except plafond malleolar angle. The overall interobserver agreement was excellent between the 2 observers. There was no significant difference between the measures by the 2 observers and between the bilateral ankles. Fluoroscopy was associated with about 50% extra radiation exposure, although the absolute amount of radiation was not clinically significant. These results support the use of weightbearing images using portable fluoroscopy device as an alternative for the conventional radiography systems.

Treating sacroiliac joint dislocation through percutaneous sacroiliac screw fixation with the aid of 2 fluoroscopes: a novel technique.

Percutaneous sacroiliac screw fixation is the standard treatment for sacroiliac joint (SIJ) dislocation. In most hospitals, the procedure is guided by a C-arm X-ray fluoroscopy system, which must be repeatedly repositioned during surgery. In this study, we investigated the feasibility of using 2 fluoroscopes simultaneously. A total of 28 consecutive patients with SIJ dislocation were included in this study. The patients were randomly allocated to groups and underwent percutaneous sacroiliac screw fixation using either 1 or 2 fluoroscopes. Total radiation exposure frequency, radiation dose, and operation time were recorded and compared. Dislocation reduction quality was assessed using the Tornetta and Matta standard, and the Majeed functional score was used to evaluate clinical, imaging, and social function following pelvic injury. Complications were also recorded. The results showed that the radiation exposure frequency was significantly less with 2 fluoroscopes than with a single fluoroscope (21.5±8.6 and 42.6±18.3 times, respectively; P<0.001). However, the radiation dose (156.3±67.2 mGy for 1 fluoroscope and 157.8±38.2 mGy for 2 fluoroscopes; P>0.05) between the 2 groups was not significantly different. The total operation time was also significantly shorter with 2 fluoroscopic devices than with a single device (35.8±12.9 and 65.5±19.7 minutes, respectively; P<0.001). The dislocation reduction quality and Majeed functional score (92.3% and 86.7% for 1 fluoroscope, 93.3% and 84.6% for 2 fluoroscopes, respectively; P>0.05) did not differ significantly between the 2 groups at the final follow-up. Complications, such as pain, superficial infection, restricted squatting, limp, and screw failure, were rarely recorded in either group. The simultaneous application of 2 fluoroscopes is highly appropriate during percutaneous sacroiliac screw fixation to treat SIJ dislocation, and can significantly reduce radiation exposure frequency and operation time.

ERCP Room Setting: What Doctors Starting ERCP Need to Know

To date, there is no standardization of the endoscopi c retrograde cholangiopancreatography (ERCP) room setting regarding with the size, equipment or space arrangement. Therefore, the authors visited 11 tertiary hospitals that recently remodeled or newly designed the ERCP room to analyze and identify their advantages and disadvantages. The ERCP room should have enough space for equipments including fluoroscopy, endoscopy, electrosurgical unit, preparation table and for patient movement. The EUS room does not require an independent space unless it is a very large scale hospital, and the ERCP room can be shared. Considering the pros and cons of each equipment, adequate fluoroscopic device should be selected depending on the hospital circumstance. Expensive equipment for X-ray fluoroscopy system is not necessarily good, and it is necessary to install equipment suitable for each hospital situation by understanding the advantages and disadvantages of fluoroscopy. For prevention of ERCP-related radiation hazard, both endoscopist and assistants should wear radiation-blocking apron, thyroid protectors, and lead glasses. Furthermore, a shield that can block radiation between the endoscopist and the patient should be installed to protect high-energy scattered waves. One-way direction should be designed to prevent cross infection when moving the endoscopic equipment from the ERCP to the cleaning room. If possible, it is recommended to keep a cardiopulmonary resuscitation cart in the ERCP room.

Toward a priori noise characterization for real-time edge-aware denoising in fluoroscopic devices

BackgroundLow-dose X-ray images have become increasingly popular in the last decades, due to the need to guarantee the lowest reasonable patient’s exposure. Dose reduction causes a substantial increase of quantum noise, which needs to be suitably suppressed. In particular, real-time denoising is required to support common interventional fluoroscopy procedures. The knowledge of noise statistics provides precious information that helps to improve denoising performances, thus making noise estimation a crucial task for effective denoising strategies. Noise statistics depend on different factors, but are mainly influenced by the X-ray tube settings, which may vary even within the same procedure. This complicates real-time denoising, because noise estimation should be repeated after any changes in tube settings, which would be hardly feasible in practice. This work investigates the feasibility of an a priori characterization of noise for a single fluoroscopic device, which would obviate the need for inferring noise statics prior to each new images acquisition. The noise estimation algorithm used in this study was tested in silico to assess its accuracy and reliability. Then, real sequences were acquired by imaging two different X-ray phantoms via a commercial fluoroscopic device at various X-ray tube settings. Finally, noise estimation was performed to assess the matching of noise statistics inferred from two different sequences, acquired independently in the same operating conditions.ResultsThe noise estimation algorithm proved capable of retrieving noise statistics, regardless of the particular imaged scene, also achieving good results even by using only 10 frames (mean percentage error lower than 2%). The tests performed on the real fluoroscopic sequences confirmed that the estimated noise statistics are independent of the particular informational content of the scene from which they have been inferred, as they turned out to be consistent in sequences of the two different phantoms acquired independently with the same X-ray tube settings.ConclusionsThe encouraging results suggest that an a priori characterization of noise for a single fluoroscopic device is feasible and could improve the actual implementation of real-time denoising strategies that take advantage of noise statistics to improve the trade-off between noise reduction and details preservation.

Long PFN nailing in comminuted high subtrochanteric fractures femur in lateral position on ordinary table

Introduction: Most of the hip fractures are managed in supine position on a fracture table with foot attached to foot plates and biplanar fluoroscopy supervision under c-arm. But this procedure has its own difficulties in managing especially comminuted subtrochanteric fractures, where in different fragments and segments are being pulled by strong muscles around hip, and getting good reduction and alignment is difficult due to displaced bony fragments being held in traction on fracture table and cannot be manipulated easily. This leads to prolonged operative time, opening of fracture site, increased bleeding, increased chances of infection and over all increased anaesthesia time adding up to risk factors. The purpose of this study was to report how these difficulties can be overcome by operating on a simple radioluscent top operating table in lateral position without a fracture table. Materials and Methods: 74 cases of subtrochanteric fractures with or without comminution were operated in lateral position on simple ordinary radioluscent top table with lesser attachments and adjustments to operating table during the study duration were included in the study. We used long Proximal Femur Nail (PFN) (length more than 25cms 34, 36, 38, 40cms long) to fix these fractures. Results: In the present study, age group of patients was 25yrs to 74yrs. Male patients (83.7%) were more than female patients (16.3%) An average of less than 150 ml in closed surgery. The average operative time for all cases was 80 minutes. Union time varied from 16 weeks in simple fractures to 26 weeks in comminuted fractures. Clinical function of hip and knee was excellent with full range of movements. Conclusions: Reduction and fixation of proximal femoral fractures in the lateral position with fluoroscopy or portable radiography in the anteroposterior view for small set ups and rural hospitals that lack a fracture table or advanced fluoroscopic devices may be executable and probably safe. Keywords: L

The effect of a new universal laser aiming device in C-arm fluoroscopy on the technician's accuracy.

Objectives This study aims to introduce a new low-cost universal laser aiming device (LAD) that can be used in existing C-arm fluoroscopy devices, independent of brand and model, and to determine whether this new universal LAD improves technician accuracy in locating the desired region at the midpoint of the fluoroscopic image.Materials and methods A low-priced universal LAD that is compatible with existing 12-inch C-arm fluoroscopy devices was designed. Eight radiology technicians with varied levels of experience in C-arm fluoroscopy participated in the study. A 12 mm cortical screw with a diameter of 3.5 mm was placed on proximal, diaphyseal, and distal points of femur, tibia, and humerus bones in the anteroposterior plane on L3 vertebrae and the left pubis arm in the pelvis bone model. Technicians were asked to align each screw in the image center 10 times from a distance of 30 cm in the anterolateral plane, first without the LAD and then with the LAD. The distance of the screw head to the center point was measured from the 3,520 images with the help of medical viewer software based on the X- and Y-axis.Results Each fluoroscopic image was divided into 48 equal parts and the length of a part was taken as one unit for distance measurements. The compliance between technicians without the LAD was 0.347 (95% confidence interval [CI]: 0.208-0.47, p=0.001) and with the LAD was 0.687 (95% CI: 0.621-0.741, p=0.001). The distance between the screw head and the center of the image without the LAD was 19.0±9.8 for technicians with more than 10 years of experience and 28.0±12.9 for those with less than 10 years of experience. This difference was statistically significant (p=0.001). When the LAD was used, the difference between the less experienced (3.1±1.5) and more experienced (3.3±2.0) technicians was statistically reduced, along with the distance (p=0.033).ConclusionThe use of the LAD with C-arm fluoroscopy appears to be successful in helping technicians capture the desired point in the center of the fluoroscopic image. The use of the LAD reduces the experience gap between technicians.

Real-time algorithm for Poissonian noise reduction in low-dose fluoroscopy: performance evaluation

BackgroundQuantum noise intrinsically limits the quality of fluoroscopic images. The lower is the X-ray dose the higher is the noise. Fluoroscopy video processing can enhance image quality and allows further patient’s dose lowering. This study aims to assess the performances achieved by a Noise Variance Conditioned Average (NVCA) spatio-temporal filter for real-time denoising of fluoroscopic sequences. The filter is specifically designed for quantum noise suppression and edge preservation. It is an average filter that excludes neighborhood pixel values exceeding noise statistic limits, by means of a threshold which depends on the local noise standard deviation, to preserve the image spatial resolution. The performances were evaluated in terms of contrast-to-noise-ratio (CNR) increment, image blurring (full width of the half maximum of the line spread function) and computational time. The NVCA filter performances were compared to those achieved by simple moving average filters and the state-of-the-art video denoising block matching-4D (VBM4D) algorithm. The influence of the NVCA filter size and threshold on the final image quality was evaluated too.ResultsFor NVCA filter mask size of 5 × 5 × 5 pixels (the third dimension represents the temporal extent of the filter) and a threshold level equal to 2 times the local noise standard deviation, the NVCA filter achieved a 10% increase of the CNR with respect to the unfiltered sequence, while the VBM4D achieved a 14% increase. In the case of NVCA, the edge blurring did not depend on the speed of the moving objects; on the other hand, the spatial resolution worsened of about 2.2 times by doubling the objects speed with VBM4D. The NVCA mask size and the local noise-threshold level are critical for final image quality. The computational time of the NVCA filter was found to be just few percentages of that required for the VBM4D filter.ConclusionsThe NVCA filter obtained a better image quality compared to simple moving average filters, and a lower but comparable quality when compared with the VBM4D filter. The NVCA filter showed to preserve edge sharpness, in particular in the case of moving objects (performing even better than VBM4D). The simplicity of the NVCA filter and its low computational burden make this filter suitable for real-time video processing and its hardware implementation is ready to be included in future fluoroscopy devices, offering further lowering of patient’s X-ray dose.

Examination techniques and patient dose in paediatric barium meal procedures

The paediatric barium meal procedure is an examination that employs ionizing radiation and implies radiation exposure of children with doses that can be rather high. Radiation risk for paediatric patients is higher than for adult patients. It is possible to reduce the dose values optimizing the technical parameters of the equipment that usually is not configured for paediatric imaging. In this work, we analyse the examination techniques applied by two fluoroscopic devices during the examinations performed by the same professionals in the same hospital. The procedures were conducted using the Philips Diagnost 93 manufactured in 1993 (49 exams) and Flexavision F3 from Shimadzu manufactured in 2016 (37 exams). The patients were categorized into age groups of 0–1, 1–5, 5–10 and 10–18 years. Unlike the old device, the new equipment has pulsed exposition and removable anti-scatter grid which should ensure a reduction in dose. However, our study shows that implementation of a modern equipment with new features enabling dose reduction does not guarantee a positive result. The reduction of kVp and mAs at the new equipment is completely compensated by smaller FDD. The significant dose reduction (up to 3 times) for the youngest patients was achieved by removing of the anti-scatter grid. No positive effect of pulsed exposition was observed. Producing the radiographic images, the professionals systematically use kVp lower than that chosen by the equipment, which indicates possible source of reduction of patient dose.

Ease of doing proximal femoral nailing in lateral position in the management of peri-trochanteric femoral fractures in adults: A prospective study

Introduction: Intertrochanteric fractures are among the most common pei-trochanteric fractures encountered in orthopaedic practice. Most of the hip fractures are managed in supine position on a fracture table with foot attached to foot plates and biplanar fluoroscopy supervision under c-arm. But this procedure has its own difficulties in managing especially comminuted peri-trochanteric fractures, where in different fragments and segments are being pulled by strong muscles around hip, and getting good reduction and satisfactory alignment is difficult due to displaced bony fragments being held in traction on fracture table and cannot be manipulated easily. This leads to prolonged operative time, opening of fracture site, increased bleeding, and increased chances of infection and over all increased anaesthesia time adding up to risk factors. The purpose of this study was to demonstrate the technique of surgery as well as to report how these difficulties can be overcome by using long Proximal Femoral Nail in complex comminuted unstable trochanteric fractures in lateral position on an ordinary radiolucent top table without fracture table. Materials and Methods: 30 cases of peri-trochanteric fractures with or without comminution were operated in lateral position on simple ordinary radioluscent top table with lesser attachments and adjustments to operating table during the study duration were included in the study. We used long Proximal Femur Nail (PFN) (length more than 25cms 34, 36, 38, 40cms long) to fix these fractures. Results: In the present study, age group of patients was 60yrs to 78yrs. Male patients (60%) were more than female patients (40%) An average of less than 150 ml in closed surgery and 350 ml in Open reduction cases. The average operative time for all cases was 80 minutes. Union time varied from 14 weeks in simple fractures to 26 weeks in comminuted fractures. Clinical function of hip and knee was excellent with full range of movements. Overall excellent to good results were achieved in 90% cases. Conclusions: The lateral decubitus position provides easy identification of entry point, a shorter operation time, less of hospital stay, blood loss, number of intraoperative X-ray, incision length and out-of-bed activity time Reduction and fixation of proximal femoral fractures in the lateral position with fluoroscopy in the anteroposterior view for small set ups and rural hospitals that lack a fracture table or advanced fluoroscopic devices may be executable and probably safe.

A key-point based real-time tracking of lung tumor in x-ray image sequence by using difference of Gaussians filtering and optical flow

In radiation therapy, for accurate radiation dose delivery to a target tumor and reduction of the extra exposure of normal tissues, real-time tumor tracking is typically an important technique in lung cancer treatment since lung tumors move with patients’ respiration. To observe a tumor motion in real time, x-ray fluoroscopic devices can be employed, and various tracking techniques have been proposed to track tumors. However, development of a fast and accurate tracking method for clinical use is still a challenging task since the obscured image of the tumor can cause decreased tracking accuracy and can result in additional processing time for remedying the accuracy. In this study, a new key-point-based tumor tracking method, which is sufficiently fast and accurate, is presented. Given an x-ray image sequence, the proposed method employs a difference-of-Gaussians filtering technique to detect key points in the tumor region of the first frame which are robust against noise and outliers in the subsequent frames. In the subsequent frames, these key points are tracked using a fast optical flow technique, and tumor motion is estimated via their movement. To evaluate the performance, the proposed method has been tested on several clinical kV and MV x-ray image sequences. The experimental results showed that the average of the root mean square errors of tracking were and for kV and MV x-ray image sequences, respectively. This tracking performance was more accurate than previous tracking methods. In addition, the average processing times for each frame were and for kV and MV image sequences, respectively, and the proposed method was faster than previous methods as well as shorter than frame acquisition interval. Therefore, the proposed method has the potential for both highly accurate and fast tumor tracking in clinical applications.

P023] Estimating patient peak skin dose with fluoroscopic procedures

Purpose Deterministic radiation induced patient skin injuries may be caused by time consuming and complex fluoroscopic procedures. Post-procedure dose analysis can provide valuable feedback for optimisation of exposures in interventional radiology and follow-up of individual patients. However, lack of accuracy when estimating patient peak skin dose (PSD) can lead to inappropriate action levels and follow-up routines. It is common to use action levels entirely based on the interventional reference point (IRP) cumulative Air kerma, spatially located 15 cm from the irradiation geometry isocentre. This metric lacks influence of physical effects needed to estimate PSD, e.g., specifics of the irradiation event, conversion of Air kerma to absorbed skin dose, scattered radiation, and pre-patient attenuation. Modern radiologic equipment commonly reports irradiation event details in a radiation dose structured report (RDSR), as described by the NEMA DICOM standard. For fluoroscopy equipment the RDSR contains important information, e.g., X-ray beam field size, IRP Air kerma, number of images, X-ray beam filtration and X-ray tube voltage. The RDSR is thus a useful data source for estimation of PSD with fluoroscopic procedures. Methods Pertinent correction methods and data for PSD estimation were summarized by literature review and beam quality- and geometry dependent functions were developed in the PythonTM programming language v3.6 (Python Software Foundation). The RDSR from two different fluoroscopic devices; Siemens Artis Zee (Siemens Healthineers, Erlangen, Germany) and Philips Allura Clarity (Philips, Amsterdam, Netherlands), were examined and information required as input for the developed functions was identified. Results This work resulted in an open source Python™ script for RDSR parsing and patient PSD estimation; including table-top and mattress attenuation, Air kerma to absorbed skin dose conversion, forward and back scatter. PSD estimates were verified and compared to IRP Air-kerma. Conclusions The estimation of patient PSD with fluoroscopic procedures is greatly assisted by information found in fluoroscopy device RDSR. With refined dose metrics the specificity of patient PSD estimates may be increased, e.g., compared to the IRP Air kerma. Combining RDSR information and novel methods for refining patient dose metrics found in the literature can improve the management of patients after interventional radiology procedures.

Percutaneous Posterior Transarticular Atlantoaxial Fixation for the Treatment of Odontoid Fractures in the Elderly: A Prospective Study.

A prospective study of 20 multimorbid patients older than 65 years undergoing minimally invasive surgical treatment for odontoid fracture. To analyze the results of percutaneous transarticular atlantoaxial screw fixation as a new minimally invasive treatment modality in this high risk group of patients. Odontoid fractures are a common injury pattern in the elderly. These fractures typically present significant challenges as geriatric patients often have multiple comorbidities that may adversely affect fracture management. Despite numerous publications on this subject, with a trend toward primary operative stabilization, the appropriate treatment for this frequent and potentially life threatening injury remains controversial. Between January 2013 and December 2015, 20 consecutive patients underwent posterior percutaneous transarticular atlantoaxial screw fixation for odontoid fracture type II. The two main inclusion criteria were age 65 years or older and ASA score of III or IV. The screws were inserted percutaneously with the help of two fluoroscopy devices. Clinical and radiological examinations were regularly performed for a minimum of 18 months postoperatively. The mean age was 81 years, all of them with multiple comorbidities. Reduction of the fracture and screw insertion was possible in all cases. The mean operative time was 51.75 minutes and mean blood loss was 41.7 mL. Three patients died in the first 3 months after surgery. Healing of the fracture occurred in 15 patients (88.2%). Revision surgery was not necessary in any of the patients. Mean visual analogue scale (VAS) at the final follow-up was 2.4, and mean patient satisfaction score was 7.1. Percutaneous transarticular atlantoaxial fixation in elderly patients offers a good minimally invasive operative treatment in this multimorbid group of patients. This new technique with short operative time is well tolerated by the geriatric patients leading to a healing rate up to 88%. 4.

The Effect of C-Arm Mobility and Field of Vision on Radiation Exposure in the Treatment of Proximal Femoral Fractures: A Randomized Clinical Trial.

Objectives To examine the effect of fluoroscopy devices with different sizes of image intensifier and C-arm maneuverability on operating time, fluoroscopy time, radiation dose and reduction, and fixation quality at intertrochanteric femoral fractures. Design Single-center, randomized, prospective study. Setting Academic Level I trauma hospital. Patients and Intervention 34 patients treated with cephalomedullary nailing for a stable, intertrochanteric proximal femur fracture (OTA A1). Main Outcome Measurement The total working time of the fluoroscopy device, the dose-area product (DAP), operating time, reduction quality (cortical continuity, symmetrical collodiaphyseal angle, and shortness), and fixation quality (Bosworth quadrants, the tip-apex distance, TAD). Results There were no cases of poor reduction; also the placement of the blade was optimal for 14 patients and suboptimal in 3 patients in each group. Superior-posterior placement of the blade or TAD > 25 mm was not seen in any patient. Total operating time was significantly shorter when using device A compared to the use of device B (20.1 ± 3.4 mins versus 25.3 ± 5.4 mins, p < 0.001). Total radiation time was significantly shorter with device A compared to the use of device B (58.1 ± 19.4 secs versus 98.9 ± 55.4 secs, p = 0.008). The measured radiation dose was lower with the use of device A compared to device B (3.5 ± 1.2 Gy·cm2 versus 7.3 ± 4.5 Gy·cm2, p = 0.002). Conclusion Physical properties of fluoroscopy devices used during the fixation of intertrochanteric fractures could yield significant differences in operating times and the radiation dose while having comparable clinical results.

Reducing Radiation Exposure in an Electrophysiology Lab with Introduction of Newer Fluoroscopic Technology.

The use of fluoroscopic devices exposes patients and operators to harmful effects of ionizing radiation in an electrophysiology (EP) lab. We sought to know if the newer fluoroscopic technology (Allura Clarity) installed in a hybrid EP helps to reduce prescribed radiation dose. We performed radiation dose analysis of 90 patients who underwent various procedures in the EP lab at a community teaching hospital after the introduction of newer fluoroscopic technology in June of 2016. Watchman device insertion, radiofrequency ablation procedures, permanent pacemaker (PPM)/implantable cardioverter defibrillator (ICD) placement and battery changes were included in the study to compare radiation exposure during different procedures performed commonly in an EP lab. In all cases of watchman device placement, radiofrequency ablation procedures, PPM/ICD placement and battery changes, there was a statistically significant difference (<0.05) in radiation dose exposure. Significant reduction in radiation exposure during various procedures performed in an EP lab was achieved with aid of newer fluoroscopic technology and better image detection technology.