Flat-panel Fluoroscopy Research Articles

The Importance of Digital Lung Tomosynthesis in Overcoming Computed-Tomography-to-Body Divergence During Bronchoscopic Biopsies of Peripheral Lung Nodules.

The advent of robotic bronchoscopy coupled with electromagnetic navigation bronchoscopy (EMN) and shape-sensing technology have increased diagnostic yields for peripheral pulmonary nodules compared to traditional bronchoscopy. Yet, diagnostic yields from these bronchoscopic platforms still fall short of where they should be. This shortfall is in large part due to a lack of advanced imaging during peripheral bronchoscopy and computed tomography (CT)-to-body divergence (CTBD). Digital lung tomosynthesis (DLT) is an advanced imaging modality that helps overcome CTBD during bronchoscopic biopsies of lung nodules. DLT is a quasi-3D imaging technique, which reconstructs tomographic images of the lung from a series of 2D fluoroscopic projection images. These images can be acquired either using a digital flat panel fluoroscopy machine or a fluoroscopy machine with a more traditional image-intensifier present in most standard bronchoscopy suites. This review aims to explain the mechanisms of both CTBD and DLT to help diagnose early-stage lung cancer more effectively.

Effectiveness of Flat-Panel Fluoroscopy in Direct Anterior Total Hip Arthroplasty: A Comparison to Image Intensifier Fluoroscopy With Radiopaque Grid

IntroductionThe use of traditional, image intensifier fluoroscopy with a radiopaque grid during direct anterior total hip arthroplasty (DA THA) has demonstrated reduced variability in component positioning and operative time compared to fluoroscopy without a grid. A disadvantage of image intensifier fluoroscopy is spatial distortion, particularly compared to flat-panel fluoroscopy systems. The purpose of this study is to determine whether flat-panel fluoroscopy decreases variability in component positioning during DA THA compared to the use of traditional grid fluoroscopy. MethodsWe retrospectively reviewed 70 consecutive DA THAs between February 2020 and February 2021: 36 using flat-panel fluoroscopy, and 34 using traditional fluoroscopy with a grid. Radiographs were independently reviewed by 2 authors to identify components exceeding goal parameters: cup abduction of 40 ± 10 degrees, as well as offset and limb lengths within 10 mm of the contralateral side. Binary values for goal parameter achievement were assigned for each THA. ResultsNo significant difference was observed in the number of hips that met goals for cup abduction (100% vs 97%, P = 1.00), hip offset (88% vs 88%, P = 1.00), limb length (91% vs 94% [ ±10 mm], P = .669, 65% vs 72% [±5 mm], P = .498), or for the number of hips that met all 3 component goals (79% vs 80%, P = 1.00). No significant difference in operative time was noted between the 2 groups (110.2 minutes vs 100.9, P = .76). ConclusionsWe demonstrated no significant difference in component positioning in DA THAs utilizing flat-panel fluoroscopy as compared to using traditional fluoroscopy with a grid.

Radiation Dose Exposure to Patients During Transcatheter Patent Ductus Arteriosus Closure via the Arterial Route

Objective This study aims to evaluate the radiation dose for transcatheter patent ductus arteriosus (PDA) viathe arterial route and compare it with previously published benchmarks. Background Exposure to radiation in the catheterization lab can cause skin injury and cancer in the long run, especially in pediatric patients with complex heart conditions, which necessitate serial catheterizations. Therefore, measuring the patient radiation dose and establishing a benchmark for each cardiac interventional procedure is essential. Material and methods In this prospective study, 34 patients with transcatheter patent ductus arteriosus closure via an arterial route were included. Patients who had silent PDAs, no left heart dilatation and PDA size of less than 2mm had PDA closed via an arterial route. All the study group patients received an Amplatzer duct occluder II-additional size device (St. Jude Medical Corp, St. Paul, MN) using biplane flat-panel fluoroscopy equipment adjusted in accordance with the pediatric parameters. Patients' dose area product, air kerma and fluoroscopytime were recorded in the catheterization lab and finally compared with internationally published reference data. Results Of 73 patients who had transcatheter patent ductus arteriosus closure between April 2021 to December 2021, 34patients who had a PDA closure via an arterial route were enrolled. The median age and weight were 11.5 (4-168) months and 10.5 (6-31) kg. Twenty-one (61.8%) were males, and 13 (38.2%) were males. The median radiation dose parameters were as follows: air kerma 11 (3-42) milliGray, dose area product 131 (33-443) microGray per m2, median dose area product indexed to weight 12 (1-48) microGray m2 per kg, fluoroscopy time 2 (2-4) min and frame rate 15 (7.5-15) frames per second. Due to many factors, our radiation dose parameters were less than internationally published reference values for transcatheter PDA closure. Conclusion Patient selection, detailed pre-catheterization echocardiography and procedure planning are essential for accomplishing device closure of PDA with a significant reduction in radiation dose. Hemodynamic assessment in the catheterization lab is unnecessary for most PDA patients. Additionally, a next-generation imaging platform equipped with flat-panel detectors and adjusted for pediatric settings and a fluoro recording option can be used to reduce radiation exposure.

Radiation Protection Evaluations Following the Installations of Two Cardiovascular Digital X-ray Fluoroscopy Systems

Acceptance testing and commission are essential elements of the quality assurance program for imaging equipment. We present the results of a performance evaluation of Flat Panel-Based Cardiovascular Fluoroscopy X-ray Systems as a part of acceptance testing and commissioning. Measurements were obtained using a calibrated dose rate meter, patient equivalent phantoms, and Leeds image quality test tools. The results were compared with the manufacturer and European acceptability criteria. The entrance surface air kerma (ESAK) rate ranged from 8.0 to 12.0 mGy min−1 in the continuous mode and from 0.01 to 0.04 mGy fr−1 in the pulsed mode of operation. Detector-input air kerma rates ranged from 0.29 to 0.39 mGy min−1 in continuous mode and from 0.02 to 0.07 µGy fr−1 in pulsed mode. Fluoroscopy device half-value layer (HVL) ranged from 2.5 to 3.0 mm Al, and the low resolution ranged from 0.9 to 1.3%. The spatial resolution limit was double that of the image intensifier (2.4 to 3.6) lp/mm. Flat-panel fluoroscopy demonstrated superior image quality and dose performance as compared to conventional image intensifier-based fluoroscopy. The quality assurance measurements presented are essential in the rapid evaluation of the imaging system for acceptance testing and commissioning.

A novel quantitative measure of image quality in fluoroscopy

The aim of this work is to develop a quantitative algorithm for the assessment of image quality in fluoroscopy as an alternative to the subjective Leeds Test Object TO-10. Current possible quantitative measurements such as Detective Quantum Efficiency and Modulation Transfer Function do not assess the effects of imaging processing, such as edge-enhancement and noise reduction, on the final displayed image. A standard statistical algorithm used to calculate the contrast needed to observe an object having area size (A) against background. The algorithm was developed to produce sets of Contrast-Detail and Threshold Contrast curves. Three flat panel fluoroscopy systems in our Cardiology were examined. Sequences of uniform fluoroscopy images, obtained using 1 mm of copper as an attenuator, were acquired and then analysed remotely. For each system curves were generated for (a) different dose rates at the detector, (b) different settings of magnification, & (c) different levels of edge-enhancement. For one system different levels of noise reduction were examined. Areas under contrast-detail and threshold-contrast curves reflect changes in dose rate at the detector. The algorithm is sensitive to changes in applied edge-enhancement and noise reduction. Both sets of curves for each system exhibit characteristic spatial frequency responses. This new efficient and objective algorithm measures fluoroscopic image quality using the standard Threshold Detection Index. It tracks quality changes that depend not only on input dose rate, but also the level of image processing applied. It only requires the acquisition of a few seconds of fluoroscopy to produce images for remote analysis.

Flat Panel Fluoroscopy (O-Arm) Guided Percutaneous Radiofrequency Anterolateral Cordotomy

Abstract INTRODUCTION Chronic pain is a major cause of the current opioid epidemic in the United States. Cancer related intractable pain represents a challenging condition to manage medically. Most patients with this condition need increasingly higher doses of opioid analgesics due to receptor downregulation. This put patients at risk of opioid addiction, and it results in financial burden on both the patients and healthcare system. Anterolateral cordotomy is an ablative pain procedure that works through interrupting the ascending pain pathways contralateral to the pain site, namely the spinothalamic tract. Here, we present a case with unilateral cancer related somatic pain that was treated with a contralateral C1-C2 cordotomy. METHODS A 55-yr-old female with a stage 4 breast cancer that invaded her chest wall and axilla on the right side was studied. The tumor eroded through the skin of the breast. She has been having worsening chronic somatic pain that required hospital admission. She was using 60 mg of oral Methadone and 300 mg of Dilaudid delivered through patient control analgesia (PCA), with residual pain scored at 5 (1-10). She underwent a left sided C1-C2 O-arm guided percutaneous Radiofrequency cordotomy. RESULTS The patient had an immediate complete relief of her pain in the operating room that lasted throughout her hospital stay. On postop day 1 the Dilaudid was cut down by 50%. On postop day 2 it was stopped, and the patient was continued on oral protocol. She was discharged home on postop day 3. Neurologically the patient had no pain/temperature sensation on the right arm and chest, but she maintained motor strength, proprioception, vibration, and balance equally on both sides. CONCLUSION O-arm guided percutaneous Radiofrequency cordotomy is an effective minimally invasive method to treat chronic somatic pain. It results in immediate pain relief in 90% of patients with resultant reduction in opioids consumption and decrease hospital length of stay.

Urgent endovascular repair for ruptured aortic aneurysm using computed tomography image fusion

Abdominal aortic aneurysm rupture remains a cardiovascular catastrophe with strikingly high morbidity and mortality rates. Endovascular aneurysm repair management has recently emerged as a valuable treatment modality for ruptured abdominal aortic aneurysm, but better outcomes have to be reached. Image fusion may potentially improve perioperative outcomes in selected patients, guiding navigation and device implantation and limiting contrast dosage during interventions. We report an 83-year-old man presenting with an 80-mm infrarenal aortic aneurysm rupture suitable for endovascular aneurysm repair. Endovascular navigation and stent graft deployment were achieved using computed tomography image fusion for the first reported case in English.

Performance comparison of flat panel fluoroscopy systems from three vendors

Performance comparison of flat panel fluoroscopy systems from three vendors

National DRLs for adult body CT scans based on body width

National DRLs for adult body CT scans based on body width

Flat-Panel Fluoroscopy O-arm–Guided Percutaneous Radiofrequency Cordotomy

Percutaneous radiofrequency cordotomy (PRFC) involves controlled ablation of the anterolateral quadrant of the spinal cord, thereby relieving pain. Evolving from a morbid open surgery, the procedure has been modernized through the application of physiological target confirmation, well-regulated thermal ablation, and improved intraoperative imaging. To evaluate the utility in PRFC of a new high-resolution, portable flat-panel fluoroscopic imaging technology, the O-arm Imaging System. The O-arm allows traditional 2-dimensional fluoroscopy in addition to axial and 3-dimensional reconstructed computed tomography imaging. PRFC was performed using the O-arm Imaging System in 6 patients with unilateral cancer pain. Patients experienced 90% to 100% initial pain relief, with 50% to 100% sustained pain relief at the time of death at 2 to 12 months. There were no complications. Portable flat-panel fluoroscopy allows high-resolution, readily updated computed tomography and fluoroscopic image guidance during PRFC. Use of this new technology may assist neurosurgeons in providing an important analgesic intervention at centers possessing the imaging technology.

Evaluation of 2D and 3D navigation for iliosacral screw fixation

Image guidance is essential in some orthopedic surgical procedures, especially iliosacral screw fixation. Currently, there is no consensus regarding the best image guidance technique. An ex-vivo study was performed to compare conventional, 2-dimensional (2D), and 3D imaging techniques and determine the optimal image guidance technique for pelvic surgery. Plastic (n = 9) and donated cadaver pelvises (n = 8) were evaluated in the laboratory. The pelvises were positioned on radiolucent operation tables in a prone position. Transiliosacral screws were inserted without or with 2D- and 3D-navigational support. A digital mobile X-ray unit with flat-panel fluoroscopy and navigation software was used to measure precision, radiation exposure, and time requirements. 2D-navigation resulted in 40% incorrect screw positioning for the cadavers, 6% for the plastic phantoms, and 21% overall. The highest accuracy was accomplished with 3D-navigation (plastic: 100%; cadavers: 83%; p<0.05). The dose-area product showed that both 2D- and 3D-navigation required increased exposure compared to the conventional technique (p<0.01). For both plastic and cadaver specimens, navigated techniques required significantly longer times for screw insertion than the conventional technique (p<0.01). 3D image guidance for transiliosacral screw fixation enabled more accurate screw placement in S1 and S2 vertebrae. However, radiation exposure in 3D-navigation was excessive; thus, we recommend avoiding 3D-navigation in young patients. A primary advantage of 3D-navigation was that the operating team could leave the room during the scan; thus, it reduced their radiation exposure. Moreover, the time required for screw insertion with 3D-navigation was similar to that required in the conventional technique; thus, 3D-navigation is recommended for older patients.

Percutaneous foot joint needle placement using a C-arm flat-panel detector CT

Image guidance is valuable for diagnostic injections in foot orthopaedics. Flat-detector computed tomography (FD-CT) was implemented using a C-arm, and the system was tested for needle guidance in foot joint injections. FD-CT-guided joint infiltration was performed in 6 patients referred from the orthopaedic department for diagnostic foot injections. All interventions were performed utilising a flat-panel fluoroscopy system utilising specialised image guidance and planning software. Successful infiltration was defined by localisation of contrast media depot in the targeted joint. The pre- and post-interventional numeric analogue scale (NAS) pain score was assessed. All injections were technically successful. Contrast media deposit was documented in all targeted joints. Significant relief of symptoms was noted by all 6 participants. FD-CT-guided joint infiltration is a feasible method for diagnostic infiltration of midfoot and hindfoot joints. The FD-CT approach may become an alternative to commonly used 2D-fluoroscopically guidance.

SU‐E‐I‐80: Dose Metrics, the Relationship, and Reduction Strategies for Interventional Procedures

Purpose: Interventional Radiological (IR) procedures result in the highest individual doses in most radiology practices. Recently FDA unveiled initiative to reduce unnecessary radiation exposure from medical imaging. To achieve this goal, the understanding of dose metrics and their relationships from IR procedures is a must. This study aims to summarize dose metrics, investigate the relationship and develop strategies for IR dose reduction and overdose alert. Methods: A Rando phantom was used to investigate entrance skin dose (ESD) in two Siemens flat panel fluoroscopy systems (Artis and Atris Biplane) using typical protocols for neuro, chest and abdominal interventional procedures. Fluoroscopy time, dose‐area product (DAP), and reference dose were recorded from consoles. Exposure rate and cumulative dose at different surface (skin) locations of the imaged areas were measured with a RadCal dosimeter and a Unfors Patient Skin Dosimeter (PSD, with 4 sensors). The relationships among dose metrics were then analyzed for different clinical settings and dose reduction/overdose alert strategies were discussed. Results: Linear relationships among different dose metrics are observed for fixed clinical setting (SID, image area, fluoroscopy mode, etc). With changes in clinical settings, the linear relationship changes accordingly, which causes difficulty in directly predicting ESD by any single dose metric. However, combining different settings may give a reasonable estimation of patient skin dose during IR procedure. Conclusions: Considering different clinical settings, ESD can be estimated from dose metrics in the current fluoroscopy systems and used as indicator of patient dose during IR procedures. This information and related strategies may potentially reduce the risk of patient overdose.

AAPM/RSNA Physics Tutorial for Residents: Physics of Flat-Panel Fluoroscopy Systems

This article reviews the design and operation of both flat-panel detector (FPD) and image intensifier fluoroscopy systems. The different components of each imaging chain and their functions are explained and compared. FPD systems have multiple advantages such as a smaller size, extended dynamic range, no spatial distortion, and greater stability. However, FPD systems typically have the same spatial resolution for all fields of view (FOVs) and are prone to ghosting. Image intensifier systems have better spatial resolution with the use of smaller FOVs (magnification modes) and tend to be less expensive. However, the spatial resolution of image intensifier systems is limited by the television system to which they are coupled. Moreover, image intensifier systems are degraded by glare, vignetting, spatial distortions, and defocusing effects. FPD systems do not have these problems. Some recent innovations to fluoroscopy systems include automated filtration, pulsed fluoroscopy, automatic positioning, dose-area product meters, and improved automatic dose rate control programs. Operator-selectable features may affect both the patient radiation dose and image quality; these selectable features include dose level setting, the FOV employed, fluoroscopic pulse rates, geometric factors, display software settings, and methods to reduce the imaging time.

Three-dimensional C-arm Cone-beam CT: Applications in the Interventional Suite

C-arm cone-beam computed tomography (CT) with a flat-panel detector represents the next generation of imaging technology available in the interventional radiology suite and is predicted to be the platform for many of the three-dimensional (3D) roadmapping and navigational tools that will emerge in parallel with its integration. The combination of current and unappreciated capabilities may be the foundation on which improvements in both safety and effectiveness of complex vascular and nonvascular interventional procedures become possible. These improvements include multiplanar soft tissue imaging, enhanced pretreatment target lesion roadmapping and guidance, and the ability for immediate multiplanar posttreatment assessment. These key features alone may translate to a reduction in the use of iodinated contrast media, a decrease in the radiation dose to the patient and operator, and an increase in the therapeutic index (increase in safety-vs-benefit ratio). In routine practice, imaging information obtained with C-arm cone-beam CT provides a subjective level of confidence factor to the operator that has not yet been thoroughly quantified.

WE‐E‐332‐01: A Unified Dose Indicator for Tomographic Acquisition Modalities

Introduction : Tomographic techniques in diagnostic and interventional radiology or radiation therapy are in rapid development. The CTDI formalism that is currently used to assess dose has been challenged by several groups. The goal of this contribution is to evaluate the required scan length to reach equilibrium on various MDCT units and estimate the average dose delivered within a slice when using systems having a cone beam geometry.Method and Materials: Measurements were performed on three MDCT systems (GEMS 8, 16 and 64‐row), a flat panel fluoroscopy (Allura — Philips), an IGRT (Synergy, Elekta ltd) and on a tomotherapy (TomoTherapy Inc.) using two standard CTDI phantoms and a home made phantoms (PMMA cylinder of 30 cm filled with water) with a conventional small volume ion chamber (0.6 cc Farmer type) and a standard pencil ion chamber. Dose profiles were also recorded at various positions within the slice to study the impact of scatter as a function of the distance between the centre of the phantom and its periphery. Results: For CT units a theoretical length of 400 mm is required to reach the equilibrium at the center of the phantom. The measurements show that a dose plateau was reached after 420 mm. The average dose within a slice measured in our home made phantom for standard abdominal CT (120 kV, 210 effective mAs) was 15.3 mGy; 26.9 mGy for the fluoro‐CT (122kV, 274mAs, 20.7s); 39.0mGy for IGRT system (120kV, 219mAs, 27×27cm2 field size, one rotation) and 13.1 mGy for the Tomotherapy system (3.5 MV, pitch=0.8). Conclusion: The CTDI concept should be replaced by a more generic methodology, such as the one presented here, that could be used in all cone beam geometries. Measurements should be done using water equivalent phantoms.