Image intensifier distortion influences a surgeon’s ability to aim guidewires during orthopaedic procedures

Ward, Thomas; Schwarz, B; Le, Brian; Smith, Greg T.; Molnar, Robert; Smith, Paul N.

doi:10.1007/s00256-019-03171-7

Cited by 7 publications

(8 citation statements)

References 14 publications

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“…Both central and peripheral S‐distortion artifacts are numerically calculated, and, if interested, the maximum deviated distance can be estimated by multiplying the D/L ratio with the length (L) of the 200‐mm rod phantom. The results will be close to the reported deviation of approximately 1 cm at the peripheral of 12‐inch fluoroscopic images 5,12 …”

Section: Discussionsupporting

confidence: 88%

“…The results will be close to the reported deviation of approximately 1 cm at the peripheral of 12-inch fluoroscopic images. 5,12 Using the magnetic flux density at an II's entrance surface as the representative magnetic field experienced by the II, the fitted linear regression equations of Sdistortion quantification metrics in response to magnetic flux density can be used to anticipate the degree of 'unpredictable' S-distortion with high confidence, and determine if further S-distortion mitigation strategies are necessary before any undesirable surgical outcomes happen.…”

Section: Discussionmentioning

confidence: 99%

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Quantitative assessments of image intensifier distortion induced by weak (Sub‐Gauss) magnetic fields during fluoroscopically‐guided procedures

et al. 2022

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Background: Fluoroscopically-guided procedures at our hospital have been aborted due to sigmoidal distortion (S-distortion) when an image intensifier (II) system is used in a surgical environment distant from any apparent sources of strong magnetic fields, such as a nearby magnetic resonance imaging (MRI) scanner. Clearly, current clinical practice fails to account for the impact of ambient weak magnetic fields and/or other contributing factors on S-distortion induction.Purpose: This study attempts to quantitatively assess the threshold level of magnetic field, along with other potential factors, that can induce intolerable S-distortion during image-intensified fluoroscopically-guided procedures. We will also discover the origins of such level of magnetic field in typical surgical facilities and provide our practical mitigation strategies accordingly. Methods: Ten surgical facilities and their accessory equipment (e.g., surgical tables) were screened using an AC/DC gaussmeter for the distribution and magnitude of magnetic field (magnetic flux density). A 'hot spot' of magnetic field was identified to further investigate the induction of S-distortion by scanning a titanium rod phantom using a GE OEC 9900 Elite II system placed at increasing distance from the 'hot spot' corresponding to decreasing magnetic field experienced by the II. The measurements were compared to that on a 'cold spot', and a GE flat panel detector (FPD) fluoroscopy was used as the negative control. Rod phantoms made of various magnetic susceptible materials (titanium, steel, aluminium, and copper) were scanned to explore the potential effects of implant material on S-distortion. An upper extremity anthropomorphic phantom was imaged on various surgical tables to mimic clinical sceneries. The GE II model and Siemens ARCADIS Orbic II model were compared to evaluate if S-distortion induction varied among different II models. Two metrics, angle of rotation (θ) and deviation/length ratio, were used to quantify the degree of S-distortion. Three designs of external magnetic shielding were evaluated for mitigating S-distortion. Results: We identified static magnetic fields up to 2500 µT and 70 µT on the floor and at 1-meter height, respectively, in random locations of surgical facilities. A large variation of magnetic field (64 ± 20 µT) was detected on the surface of surgical tables, with background magnetic fields of ∼35 µT. Quantitative assessments demonstrated that even weak magnetic fields at sub-Gauss level (<100 µT) could induce noticeable distortion artifacts, deemed unacceptable (θ > 4 • ).S-distortion was independent of the implant material being imaged but dependent on the II model -the threshold magnetic fields (4 • distortion induction) were as low as 47 µT and 94 µT for the GE and Siemens II models.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Quantitative assessments of image intensifier distortion induced by weak (Sub‐Gauss) magnetic fields during fluoroscopically‐guided procedures

et al. 2022

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“…The slight deviation of the measured MP values relative to the direct measurements may be due to incomplete orthogonal rendering of the reference ring as it is only depicted partially on the intensifier images. Another reason for the measurement deviation might be explained by the problem of image intensifier distortion that occurs with intraoperative imaging [ 25 ]. The obtained images in this study were not corrected for distortion.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of radiographic measurement techniques for the Taylor spatial frame mounting parameters

Geßmann

Frieler

Königshausen

et al. 2021

BMC Musculoskelet Disord

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Aim The correction accuracy of the Taylor Spatial Frame (TSF) fixator depends considerably on the precise determination of the mounting parameters (MP). Incorrect parameters result in secondary deformities that require subsequent corrections. Different techniques have been described to improve the precision of MP measurement, although exact calculation is reportedly impossible radiologically. The aim of this study was to investigate the accuracy of intraoperative and postoperative radiographic measurement methods compared to direct MP measurement from TSF bone mounting. Methods A tibial Sawbone® model was established with different origins and reference ring positions. First, reference MPs for each origin were measured directly on the frame and bone using a calibrated, digital vernier calliper. In total 150 MPs measured with three different radiographic measurement techniques were compared to the reference MPs: digital radiographic measurements were performed using soft-copy PACS images without (method A) and with (method B) calibration and calibrated image intensifier images (method C). Results MPs measured from a non-calibrated X-ray image (method A) showed the highest variance compared to the reference MPs. A greater distance between the origin and the reference ring corresponded to less accurate MP measurements with method A. However, the MPs measured from calibrated X-ray images (method B) and calibrated image intensifier images (method C) were intercomparable (p = 0.226) and showed only minor differences compared to the reference values but significant differences to method A (p < 0,001). Conclusion The results demonstrate that MPs can be accurately measured with radiographic techniques when using calibration markers and a software calibration tool, thus minimizing the source of error and improving the quality of correction.

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“…for each projection angle in the images series corrected using a static approach. Figure obtained from Sanctorum et al [17] Next, different values of 𝑁 ∈ [3,360] were chosen to estimate the dynamic distortion behavior of the platform. For each choice of 𝑁 , the corresponding number of frames were selected from the series of the DIC pattern, which were consecutively used in the DIC analysis to obtain the distorted coordinate surfaces.…”

Section: A) Residual Error In Projectionsmentioning

confidence: 99%

“…Although x-ray image intensifier (XRII) distortion is a long-known and well-studied issue [1,2] , it remains an important problem in XRII-based imaging to this day [3] . In small animal related biomechanical research, for example, the number of stereoscopic x-ray imaging facilities is rising exponentially [4] , where XRIIs are preferred over flat-panel detectors because of their ability to be combined with high-speed cameras, necessary to monitor fast movements [5] .…”

Section: Introductionmentioning

confidence: 99%

Projection-angle-dependent distortion correction in high-speed image-intensifier-based x-ray computed tomography

Sanctorum¹,

Wassenbergh²,

Nguyen³

et al. 2020

Meas. Sci. Technol.

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Geometric distortion is inevitable in facilities using x-ray image intensifiers. When the induced distortion pattern varies over time, each recorded frame should be corrected accordingly, which is the case in conventional C-arm imaging, for example. This demonstrates the need for reliable and easy-to-use, projection-angle-dependent correction methods. In the present work, we demonstrate such a dynamic approach, based on digital image correlation (DIC). We validate the method in a set-up for high-speed x-ray tomography, where the variable distortion is induced by an inhomogeneous distribution of ferromagnetic components in the sample rotation stage. By comparing the ideal positions of metal beads in a rectilinear pattern and their positions in the corrected radiographs of that pattern, we deduced the minimum number of frames required to estimate the varying distortion behavior during a full revolution of the stage. Next, this method was validated in a geometry calibration algorithm for a tomographic set-up, as well as in a tomographic reconstruction. Before the application of any distortion correction, the recorded images suffer from, on average, a mean and maximum distortion of 11.12 pixels (1.56 mm) and 42.79 pixels (6.10 mm), respectively. From our experiments, we conclude that three projections, sampled with a 120° interval, are sufficient to correct any frame recorded under an intermediate angle, with mean and maximum residual errors respectively below 0.48 pixels (0.068 mm) and 1.68 pixels (0.240 mm) while using a 14” image intensifier covering a 292 mm × 292 mm field of view. These results imply a decrease of the mean and maximum distortion errors of at least 96%, regardless of the projection angle. Next, the results showed improved accuracy in the system’s geometry calibration, which resulted in a reduced blurring of edges and better contrast, as well as shape preservation in the tomographic reconstruction. This demonstrates that the new method is accurate and reliable and, due to the common availability of DIC software, it is very accessible and easy to use.

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Image intensifier distortion influences a surgeon’s ability to aim guidewires during orthopaedic procedures

Cited by 7 publications

References 14 publications

Quantitative assessments of image intensifier distortion induced by weak (Sub‐Gauss) magnetic fields during fluoroscopically‐guided procedures

Quantitative assessments of image intensifier distortion induced by weak (Sub‐Gauss) magnetic fields during fluoroscopically‐guided procedures

Accuracy of radiographic measurement techniques for the Taylor spatial frame mounting parameters

Projection-angle-dependent distortion correction in high-speed image-intensifier-based x-ray computed tomography

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