Magnification Modes Research Articles

Comparative effectiveness between two types of head-mounted magnification modes using a smartphone-based virtual display.

This work shows the benefits of using two different magnification strategies to improve the reading ability of low-vision patients using a head-mounted technology. The aim of this study was to conduct a comparative clinical trial evaluating the effectiveness of two magnification strategies in a head-mounted virtual reality display. Eighty-eight eligible low-vision subjects were randomized into two arms: (1) the full-field magnification display or (2) the virtual bioptic telescope mode. Subjects completed baseline testing and received training on how to use the device properly and then took the device home for a 2- to 4-week intervention period. An adaptive rating scale questionnaire (Activity Inventory) was administered before and after the intervention (home trial) period to measure the effect of the system. A Simulator Sickness Questionnaire was also administered. Baseline and follow-up results were analyzed using Rasch analysis to assess overall effectiveness of each magnification mode for various functional domain categories. Both magnification modes showed a positive effect for reading, visual information, and the overall goals functional domain categories, with only reading reaching statistical significance after correction for multiple comparisons. However, there were no significant between-group differences between the two modes. The results of the Simulator Sickness Questionnaire showed that the magnification modes of the head-mounted display device were overall well tolerated among low-vision users. Both the full-field and virtual bioptic magnification strategies were effective in significantly improving functional vision outcomes for self-reported reading ability.

MP09-20 CONTRAST AGENTS FOR UROLOGIC FLUOROSCOPY: A COMPARATIVE PHANTOM STUDY

You have accessJournal of UrologyCME1 Apr 2023MP09-20 CONTRAST AGENTS FOR UROLOGIC FLUOROSCOPY: A COMPARATIVE PHANTOM STUDY Anahita Heshmat, Gene Austin, Manuel Arreola, and Benjamin Canales Anahita HeshmatAnahita Heshmat More articles by this author , Gene AustinGene Austin More articles by this author , Manuel ArreolaManuel Arreola More articles by this author , and Benjamin CanalesBenjamin Canales More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003224.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The recent international shortage of iodinated contrast agents has driven many clinicians to search for alternative agents to image a variety of urologic conditions in order to maintain clinic workflow. We sought to standardize these agents by a quantitative comparison using a phantom model. METHODS: A donut shape gel phantom with 10-mm wide plastic rods filled with Omnipaque-300, Omnipaque-350, Visipaque-270, Isovue-370, Gadavist, Eovist, and liquid water, was used to represent a patient being imaged for an urethrogram study utilizing a mobile fluoroscopy. The phantom was imaged with various acquisitions (Auto tube voltage (kVp), tube current (mA), and various dose modes, frame rates, and magnification modes) to compare and asses image quality for different contrast agents. Quantitative evaluations were performed with extracting regions of interest (ROIs) of each contrast rod to gather mean pixel values and standard deviations. These ROI measurements were then utilized to calculate contrast-to-noise ratio (CNR) as the metric appropriate for image quality evaluation. RESULTS: The mean pixel and CNR values of Omnipaque-300, Omnipaque-350, Visipaque-270, Isovue-370, and Gadavist showed no difference in visibility among these five contrast agents while using different dose modes, frame rates, and magnification modes. However, that was not the case for Eovist as its mean pixel value and CNR value were close to those of liquid water. Furthermore, changing magnification from normal to magnification 1 and magnification 2 increased the mean pixel values and CNR values at normal dose and continuous frame rate. CONCLUSIONS: With the exception of Eovist, the iodinated and gadolinium-based contrast agents we tested can be interchanged without compromising visibility or image quality based upon this comparative phantom study. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e113 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anahita Heshmat More articles by this author Gene Austin More articles by this author Manuel Arreola More articles by this author Benjamin Canales More articles by this author Expand All Advertisement PDF downloadLoading ...

The influence of illumination conditions in the measurement of built-in electric field at p–n junctions by 4D-STEM

Momentum resolved 4D-STEM, also called center of mass (CoM) analysis, has been used to measure the long range built-in electric field of a silicon p–n junction. The effect of different STEM modes and the trade-off between spatial resolution and electric field sensitivity are studied. Two acquisition modes are compared: nanobeam and low magnification (LM) modes. A thermal noise free Medipix3 direct electron detector with high speed acquisition has been used to study the influence of low electron beam current and millisecond dwell times on the measured electric field and standard deviation. It is shown that LM conditions can underestimate the electric field values due to a bigger probe size used but provide an improvement of almost one order of magnitude on the signal-to-noise ratio, leading to a detection limit of 0.011 MV cm−1. It is observed that the CoM results do not vary with acquisition time or electron dose as low as 24 e−/A2, showing that the electron beam does not influence the built-in electric field and that this method can be robust for studying beam sensitive materials, where a low dose is needed.

Multi-Mode Compact Microscopy for High-Contrast and High-Resolution Imaging

We report a multi-mode compact microscope (MCM) for high-contrast and high-resolution imaging. The MCM consists of two LED illuminations, a magnification lens, a lift stage, and a housing with image processing and LED control boards. The MCM allows multi-modal imaging, including reflection, transmission, and higher magnification modes. The dual illuminations also provide high-contrast imaging of various targets such as biological samples and microcircuits. The high dynamic range (HDR) imaging reconstruction of MCM increases the dynamic range of the acquired images by 1.36 times. The microlens array (MLA)-assisted MCM also improves image resolution through the magnified virtual image of MLA. The MLA-assisted MCM successfully provides a clear, magnified image by integrating a pinhole mask to prevent image overlap without additional alignment. The magnification of MLA-assisted MCM was increased by 3.92 times compared with that of MCM, and the higher magnification mode demonstrates the image resolution of 2.46 μm. The compact portable microscope can provide a new platform for defect inspection or disease detection on site.

Real-time Detection of Patient Head Position and Cephalometric Landmarks from Neuro-Interventional Procedure Images Using Machine Learning for Patient Eye-Lens Dose Prediction.

A deep learning (DL) model has been developed to estimate patient-lens dose in real-time for given exposure and geometric conditions during fluoroscopically-guided neuro-interventional procedures. Parameters input into the DL model for dose prediction include the patient head shift from isocenter and cephalometric landmark locations as a surrogate for head size. Machine learning (ML) models were investigated to automatically detect these parameters from the in-procedure fluoroscopic image. Fluoroscopic images of a Kyoto Kagaku anthropomorphic head phantom were taken at various known X (transverse) and Y (longitudinal) shifts, as well as different magnification modes, to create an image database. For each image, anatomical landmark coordinate locations were obtained manually using ImageJ and are used as ground-truth labels for training. This database was then used to train the two separate ML models. One ML model predicts the patient head shift in both the X and Y directions and the other model predicts the coordinates of the anatomical landmarks. From the coordinates, the distance between these anatomical landmarks is calculated, and input into the DL dose-prediction model. Model performance was evaluated using mean absolute error (MAE) and mean absolute percentage error (MAPE) for the head-shift and landmark-coordinate models, respectively. The goal is to implement these two separate models into the Dose Tracking System (DTS) developed by our group. This would allow the DTS to automatically detect the patient head size and position for eye-lens dose prediction and eliminate the need for manual input by the clinical staff.

Recent Development-1 of CADTEL Software: The Resolution and Focusing Parameters Affecting at the Properties of Electron Magnetic Lenses

Computer Aided Designing Tools of Electron Lenses (CADTEL) is a software packages cares about design, compute and plot simultaneously of the objective and projector properties of electron magnetic lenses. The developments in CADTEL software leads to contain a large fields and methods, adding to previous publish in 2013. The current improvement is inserting of some important parameters which are the resolution and focusing parameters. These parameters are angular semi-angle (α), focusing power (β), resolution limit (δ), image rotation (θ), spherical aberration (Cs), defocus (ΔZ), wave aberration (Χwab), depth of field (Dfld), and depth of focus (Dfoc) at certain magnification conditions. Thus, user can easily compute and plot, according to relations and forms, the effect of these parameters at the lens properties of four magnification conditions; zero, infinite and finite (low and high) magnification modes. This work introduces a new development for CADTEL software which is an interactive visual interface in electromagnetic lenses.Whereas, it reflects a substantial reduction of time and resources desired for training new users and researchers in electron optics field. The results and curves representations appear with visual interfaces which are coded in visual basic programing language. In addition, the computations and figures which were plotted appeared that complete identification between these results which are obtained from CADTEL and that from other software’s and direct computations methods.

Comparison of two adhesive systems of various polyetheretherketone (PEEK) composites on the shear bond strength

Aim: In this in vitro study, the effect of two adhesive systems applied to surfaces of different polyether-ether-ketone (PEEK) composites on the shear bond strength (SBS) of a composite resin was compared.
 Methodology: Eighty PEEK specimens were divided into four groups (n=20): Unfilled PEEK (UF), carbon-fiber-reinforced PEEK (CFR), glass-fiber-reinforced PEEK (GFR), and ceramic-reinforced PEEK (CR). Each group was further divided into two subgroups (n=10): Visio.link (VL) and Single Bond Universal (SB). The specimens with 8-mm diameter and 5-mm thickness were prepared. SBS was examined using a universal testing machine. Results were statistically analyzed by multivariate analysis of variance and Tukey’s post-hoc test. Failure modes were analyzed using a stereomicroscope at 20× magnification. Surface properties were examined by scanning electron microscopy. The surface properties of the specimens were examined by scanning electron microscopy (SEM). 
 Results: Effect of different PEEK and adhesive systems on SBS was found to be statistically significant (p<0.05). SBS values for CFR-VL and UF-VL groups were statistically more significant than those for CFR-SB and UF-SB groups (p=0.001). SBS values for the GFR-VL group were statistically more significant than that for the UF-VL group (p=0.001). SBS values for the CF-SB group were statistically more significant than those for CFR-SB and CFR-SB groups (p=0.001). Failure modes were examined using a stereomicroscope at 20× magnification, and adhesive and mixed failure modes were observed.
 Conclusion: PEEK composites with different contents and properties can be used in fixed prosthetic restorations. However, additional experimental and clinical studies are required to investigate different PEEK frameworks and composite veneers.
 
 How to cite this article: Demirci F, Tekin S. Comparison of two adhesive systems of various polyetheretherketone (PEEK) composites on the shear bond strength. Int Dent Res 2021;11(2):54-61. https://doi.org/10.5577/intdentres.2021.vol11.no2.1
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Computer-Aided Diagnosis With Monochromatic Light Endoscopy for Scoring Histologic Remission in Ulcerative Colitis

Computer-Aided Diagnosis With Monochromatic Light Endoscopy for Scoring Histologic Remission in Ulcerative Colitis

Synthesis of Asymmetrical Charged Particle Lens Using Analytical Potential Model

In the present work, the optimization by synthesis approach in the field of charged particle optics has been followed, where a modified analytical function has been proposed to represent the axial magnetic scalar potential distribution of the charged particle lens. Thereby, the corresponding axial field distribution can be deduced which is necessary to determine the paraxial ray trajectories and the aberration coefficients. Indeed, the present work deals with asymmetrical distributions of the lens field, accordingly, the first order properties and third order aberrations of the charged particle lens have been evaluated under zero and infinite magnification modes taken into account the effect of some geometrical parameters. The present work aims to reconstruct the shape of the pole piece of the magnetic lens that produced the proposed target function. The results have shown that, the pole piece shape of the lens and the field distributions have new irregular configurations as well as the objective properties of the lens are of acceptable values, according to the constraints that are imposed in the design process.

Effects of magnification modes and location cues on visual inspection performance.

Image magnification often results in disorientation through loss of orientation and location during inspection. This study investigated the effects of three different magnification modes viz. full screen, circular, and fixed-area on visual inspection performance. Also, to improve participants’ global orientation with respect to the original product, location cues in the form of halftone landmarks were introduced as a job aid and their effectiveness on inspection performance was examined. Twenty-eight undergraduates participated in the experiment. Significant magnification mode effect was found, but the location cue effect was found non-significant. The results suggested that the presentation of content/contextual information on one single screen should be considered together with the nature of the visual task and participants’ search behaviors, and that the aid of location cues might be useful when the visual task demanded a high level of search memory and/or an unsystematic search strategy was employed by inspectors.

Influence of exposure and geometric parameters on absorbed doses associated with common neuro-interventional procedures

PurposeThe purpose of this study was to investigate the effects of routine exposure parameters on patient’s dose during neuro-interventional radiology procedures. MethodsWe scrutinized the routine radiological exposure parameters during 58 clinical neuro-interventional procedures such as, exposure direction, magnification, frame rate, and distance between image receptor to patient’s body and evaluate their effects on patient’s dose using an anthropomorphic phantom. Radiation dose received by the occipital region, ears and eyes of the phantom were measured using MOSkin detectors. ResultsDSA imaging technique is a major contributor to patient’s dose (80.9%) even though they are used sparingly (5.3% of total frame number). The occipital region of the brain received high dose largely from the frontal tube constantly placed under couch (73.7% of the total KAP). When rotating the frontal tube away from under the couch, the radiation dose to the occipital reduced by 40%. The use of magnification modes could increase radiation dose by 94%. Changing the image receptor to the phantom surface distance from 10 to 40cm doubled the radiation dose received by the patient’s skin at the occipital region. ConclusionOur findings provided important insights into the contribution of selected fluoroscopic exposure parameters and their impact on patient’s dose during neuro-interventional radiology procedures. This study showed that the DSA imaging technique contributed to the highest patient’s dose and judicial use of exposure parameters might assist interventional radiologists in effective skin and eye lens dose reduction for patients undergoing neuro-interventional procedures.

A Phantom Study and a Retrospective Clinical Analysis to Investigate the Impact of a New Image Processing Technology on Radiation Dose and Image Quality during Hepatic Embolization

PurposeTo investigate changes in radiation dose and image quality using phantoms and hepatic embolization procedures performed with a new image processing technology (ClarityIQ) for a single-plane flat-detector–based interventional fluoroscopy system. Materials and MethodsPhantom study was performed using acrylic sheets simulating different patient sizes. Air kerma rates (AKRs) were compared for different fluoroscopy modes and magnification modes without and with ClarityIQ. Repeat hepatic embolization procedures performed on the same lobe of the liver in the same patient by the same interventional radiologist between January 2013 and July 2014 without and with ClarityIQ were evaluated retrospectively. This included treatment of 33 hepatic lobes in 26 patients. Cumulative air kerma (CAK), kerma–area product (KAP), and factors affecting radiation dose were extracted from study metadata and compared. Blinded randomized image quality review was performed on arteriograms using a five-point scale. ResultsThe phantom study revealed a significantly lower AKR (P < .005) with ClarityIQ. Repeated-measures analysis revealed a significant effect of ClarityIQ (P ≤ .001) on CAK and KAP, with reductions ranging between 9% and 85% (median, 67%) and between 5% and 89% (median, 75%), respectively, on a case-by-case basis. Mean reductions in CAK and KAP were 279 mGy and 134,030 mGy·cm2, respectively. Image quality review scores were significantly lower (P ≤ .001) with ClarityIQ, effecting visualization of tumor vasculature and appearance of noise texture. ConclusionsClarityIQ resulted in radiation dose reduction in the phantom study and in the hepatic embolization procedures, but with a decrease in subjective perceptions of image quality.

Estimation of Organ and Effective Doses for Neonate and Infant Diagnostic Cardiac Catheterizations.

Radiation exposure to neonates and infants during cardiac catheterizations is an important issue. Smaller patient size and higher heart rate in these patients result in a greater need for magnification modes and higher frame rates, all of which contribute to a significant increase in radiation doses. The aims of our study were to evaluate organ and effective doses for neonates and infants during diagnostic cardiac catheterizations on the basis of in-phantom dosimetry and conversion factors from dose-area product (DAP) to the effective dose. Organ doses for 0- and 1-year-old children during diagnostic cardiac catheterizations were measured by radiophotoluminescence glass dosimeters implanted in neonate and infant anthropomorphic phantoms. The effective doses were evaluated according to recommendations of the International Commission on Radiologic Protection (ICRP) publication 103. The mean effective doses evaluated according to ICRP 103 were 7.7 mSv (range, 0.1-18.4 mSv) for a neonate and 7.3 mSv (range, 1.9-18.6 mSv) for an infant. Conversion factors from DAP to the effective dose were 2.2 and 4.0 in posteroanterior and lateral cine angiography, respectively, for a neonate and 1.4 and 2.7 in posteroanterior and lateral cine angiography, respectively, for an infant. The dose data and conversion factors evaluated in this study could be useful for the estimation of radiation exposure in neonates and infants during diagnostic cardiac catheterization.

Time to take the gloves off: the use of radiation reduction gloves can greatly increase patient dose.

Sterile radiation reduction gloves have been widely used over the past several decades in an effort to reduce hand doses during fluoroscopically guided procedures. While multiple studies have quantified the potential dose reduction to the fluoroscope operator from the use of such gloves, possible effects on the patient have not yet been quantified. The aim of this study was to examine the impact on patient dose when radiation reduction gloves are used. The impact on patient dose when using radiation reduction gloves in the field of view (FOV) was evaluated by measuring patient entrance surface dose rates (ESDR) using three C‐arm fluoroscopes for a range of patient sizes and different operating and magnification modes. Multiple measuring fields were used in combination with both peripheral and central glove placement. ESDR were measured with no glove in the FOV, with one radiation reduction glove, and with double gloves in the FOV, to replicate the actions of some fluoroscope operators. Compared to an ungloved hand, the use of a single radiation reduction glove in the measuring field resulted in up to a 2.8‐fold increase in ESDR. The use of double radiation reduction gloves resulted in up to a 4.9‐fold increase in ESDR. In both cases, the increase in ESDR was dependent on the size of the patient and on the operating and magnification modes used, and ranged from no increase up to the aforementioned maximum. When used in the FOV, and particularly within the measuring field, radiation reduction gloves can substantially increase ESDR. This increase in dose, when considered against the relatively small published reduction in dose to the operator's hands, may mean that the increased risks from the use of radiation reduction gloves outweigh the benefits. In any case, hands should not be placed in the FOV if not required by the goals of the procedure.PACS number: 87.59.C‐

SU‐E‐I‐26: When Is High Level‐Control Fluoroscopy Not High Dose‐Rate Fluoroscopy?

Purpose: To examine the logic of the current use of high level control (HLC) mode as set up on many fluoroscopic systems. Methods: Use of HLC requires special means of activation and a continuous audible alarm and implies a higher dose rate of fluoroscopy. To examine if this implication is true in practice, we performed a survey of the entrance air kerma to an abdomen phantom as well as the maximum air kerma for a number of fluoroscopic machines operated under automatic exposure‐rate control using standard (non‐HLC) fluoroscopy and HLC fluoroscopy modes. Measurements were made using the abdomen phantom of the ACR Radiography / Fluoroscopy Accreditation Program with the ionization chamber placed either 15 cm from isocenter or at the FDA compliance point. For the maximum dose rate determination a 3 mm thick sheet of lead was placed over the phantom. The results presented are for 7 different mobile and fixed c‐arm units operated in available protocol and magnification modes. Results: For the abdomen phantom, the machines showed widely different entrance air kerma rates and response to changes in exposure mode and protocols. Our survey found: c‐arm units which gave a lower dose rate under HLC fluoroscopy than standard fluoroscopy when used with the abdomen phantom; units for which the HLC dose rate for some protocols was less than for standard fluoroscopy with other protocols; and units which did not exceed 88 mGy/min for some protocols even with lead in the beam when operating under HLC. In all cases, the audible alarm signaled HLC fluoroscopy with the implication of high dose rate. Conclusion: The audible alarm activated by HLC can be misleading and counterproductive since dose rates under HLC can be lower than standard fluoroscopy on the same machine. HLC does not always mean high doserate fluoroscopy. JP was supported by the Fulbright Scholar Program.

Surgeon education decreases radiation dose in complex endovascular procedures and improves patient safety

Complex endovascular procedures such as fenestrated endovascular aneurysm repair (FEVAR) are associated with higher radiation doses compared with other fluoroscopically guided interventions (FGIs). The purpose of this study was to determine whether surgeon education on radiation dose control can lead to lower reference air kerma (RAK) and peak skin dose (PSD) levels in high-dose procedures. Radiation dose and operating factors were recorded for FGI performed in a hybrid room over a 16-month period. Cases exceeding 6 Gy RAK were investigated according to institutional policy. Information obtained from these investigations led to surgeon education focused on reducing patient dose. Points addressed included increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance. Procedural RAK doses and operating factors were compared 8 months pre- (group A) and 8 months post- (group B) educational intervention using analysis of variance with Tukey pairwise comparisons and t-tests. PSD distributions were calculated using custom software employing input data from fluoroscopic machine logs. Of 447 procedures performed, 300 FGIs had sufficient data to be included in the analysis (54% lower extremity, 11% thoracic endovascular aneurysm repair, 10% cerebral, 8% FEVAR, 7% endovascular aneurysm repair, 5% visceral, and 5% embolization). Twenty-one cases were investigated for exceeding 6 Gy RAK. FEVAR comprised 70% of the investigated cases and had a significantly higher median RAK dose compared with all other FGIs (P < .0001). There was no difference in body mass index between groups A and B; however, increasing body mass index was an indicator for increased RAK. PSD calculations were performed for the 122 procedures that focused on the thorax and abdomen (group A, 80 patients; group B, 42 patients). Surgeon education most strongly affected table height, with an average table height elevation of 10 cm per case after education (P < .0001). The dose index (PSD/RAK ratio) was used to track changes in operating practices, and it decreased from 1.14 to 0.79 after education (P < .0001). These changes resulted in an estimated 16% reduction in PSD. There was a trend toward a decrease in patient to detector distance, and the use of collimation increased from 25% to 40% (P < .001) for all cases; however, these did not result in a decrease in PSD. The number of cases that exceeded 6 Gy RAK did not change after education; however, the proportion of non-FEVAR cases that exceeded 6 Gy decreased from 40% to 20%. Surgeon education on the appropriate use of technical factors during FGIs improved operating practice, reduced patient radiation dose, and decreased the number of non-FEVAR cases that exceeded 6 Gy. It is essential that vascular surgeons be educated in best operating practices to lower PSD; nonetheless, FEVAR remains a high-dose procedure.

The Risk of Elevated Radiation Dose in Complex Endovascular Procedures: Surgeon Education Improves Patient Safety

Complex endovascular procedures (CEP), such as fenestrated endovascular aneurysm repair (FEVAR), are associated with higher radiation doses compared with other fluoroscopically guided interventions (FGI). The purpose of this study was to determine whether surgeon education on radiation dose control can lead to lower reference air kerma (RAK) and peak skin dose (PSD) levels in high-dose procedures. Radiation dose and operating factors were recorded for FGI performed in a hybrid room over a 17-month period. Cases exceeding 6 Gy RAK were investigated according to institutional policy. Information obtained from these investigations led to surgeon education consisting of personalized instruction and a 1-hour lecture focused on reducing patient dose. Points addressed included increasing table height, using collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance. Procedural RAK doses and operating factors were compared 8 months before and 8 months after the educational intervention using analysis of variance with Tukey pairwise comparisons and t tests. Peak skin dose (PSD) distributions were calculated using custom software using input data from fluoroscopic machine logs. Of 447 procedures performed, 300 FGI had sufficient data to be included in the analysis (54% lower extremity, 11% TEVAR, 10% cerebral, 8% FEVAR, 7% EVAR, 5% visceral, and 5% embolization). Twenty cases were further investigated for exceeding 6 Gy RAK (14 FEVAR, 3 embolization, 1 EVAR, 1 TEVAR, 1 visceral). FEVAR represented only 8% of cases performed; however, FEVAR comprised 70% of the cases investigated for reaching 6 Gy RAK and had five times the average RAK dose compared with all other FGI performed (P < .0001). Degree of fenestration ranged from one to four vessels, and there was no difference in RAK dose based on number of vessels fenestrated. The effect of surgeon education on radiation dose was seen in all cases, regardless of complexity. Compared with the pre-education data set, the posteducation table height was 10 cm higher on average (P < .0001) per case, resulting in an estimated 15% reduction in PSD. Additionally, the use of collimation also increased from 25% to 40% (P < .001) for all cases, further reducing PSD. There was no observable change in other operating factors, including the use of magnification or angulation. The number of cases that exceeded 6 Gy RAK did not change after education; however, the proportion of non-FEVAR cases that exceeded 6 Gy decreased from 40% to 20%. These data show that radiation doses associated with FEVAR are significantly greater than doses associated with all other FGI. Surgeon education focused on good fluoroscopic operating factors can lower patient PSD; therefore, vascular surgeons must not only be aware of the potential for high radiation dose in CEP but also be vigilant in efforts to reduce exposure to themselves and the patient.

Comparison of visibility for four self-expanding nitinol bare stents in vitro

Sufficient radiopacity of stents is a prerequisite for safe interventions and minimization of the radiation dose for the patient and the interventionist. Modern nitinol stents are considered less radiopaque compared to formerly used stents. To evaluate the objective detection rate (ODR) and the subjective radiopacity score (SRS) of four self-expanding nitinol stents with their markers on a phantom human pelvis. We evaluated the ODR (as a percentage of correctly identified stents) and the SRS (on a scale from 0 = not visible to 4 = excellent visibility) for four self-expanding nitinol stents (SinusSuperflex, SMART, Luminexx, Zilver) with 8 mm diameter and 40 mm length. Stents were placed on a phantom human pelvis and images of the stents were taken in four different positions (right and left lumbosacral joint and near the right and left limbus acetabuli) using the following modes: spotfilm, pulsed fluoroscopy (4, 7.5, 15, and 30 pulses/min) and at three different digital magnification modes. Dose area products (DAPs) were assessed. ODR and SRS, respectively, were significantly increased for the SMART stent compared to all other tested stents (P < 0.05): SMART 93.53% and 2.43, SinusSuperflex 90.81% and 2.21, Luminexx 90.39% and 2.20, and Zilver 89.28% and 2.21. ODR was significantly reduced in position 3 where the bone overlap was more pronounced for all stents (detection rates 77.14-79.56%). An increase in magnification significantly improved the ODR and SRS for all stents (70.33-99.25% and 1.07-3.28, respectively, P < 0.05). Increased pulsing frequency did not improve the ODR of the various stents but did increase the DAP. The SMART stent had the best overall performance. In the presence of bone overlap, all self-expanding nitinol stents had poor results. Increased pulsing frequency did not improve ODR or SRS but did increase the DAP. Use of digital magnification modes had no effect on DAP increasing ODR and SRS.

SU-E-I-32: Sterile Radiation Reduction Gloves May Be Contraindicated in Fluoroscopically Guided Interventions.

Sterile radiation reduction gloves have been widely used in the past decade to provide modest decreases in operator hand dose when the hands are placed in the field of view (FOV). While multiple publications have quantified the potential dose reduction from the use of such gloves, possible effects on the patient have not yet been assessed. The aim of this study was to determine if radiation reduction gloves can Result in a significant increase in patient dose and increased risk of radiation induced skin injury when used in interventional radiology. The effect of radiation reduction gloves when used in the FOV was determined by measurement of patient entrance exposure rate (EER) for a variety of patient sizes and varying operating and magnification modes. EERs were measured with no glove in the FOV, with one glove and, to replicate the actions of many dose-conscious radiologists, with double gloves in the FOV. Compared to an ungloved hand, the use of a single radiation reduction glove near the center of the FOV results in a 2-fold average increase in patient EER. The use of double radiation reduction gloves results in a 3-fold average increase in EER. In both cases, this increase was only weakly dependent on the size of the patient and on the operating and magnification modes used. In fact, patient thicknesses ranging from 6-14 inches and operating modes ranging from low-dose fluoroscopy to DSA produced less than a 20% deviation from the increases in EER quoted above. When used in the FOV, radiation reduction gloves can substantially increase patient EER. This increase in patient dose, when compared with the relatively small published reduction in extremity dose provided to the operator, may make their use contraindicated in cases where radiation induced skin injury is a possible risk.

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.