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Messner IM, Keuschnigg P, Stöllinger B, Kraihamer M, Coste-Marin J, Huber P, Kellner D, Kreuzeder EM, Steininger P, Deutschmann H. Investigating focal spot position drift in a mobile imaging system equipped with a monobloc-based x-ray generator. Med Phys 2024; 51:3578-3589. [PMID: 38014777 DOI: 10.1002/mp.16859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023] Open
Abstract
BACKGROUND Misalignment or double-contouring artifacts can appear in high-resolution 3D cone beam computed tomography (CBCT) images, potentially indicating geometric accuracy issues in the projection data. Such artifacts may go unnoticed in low-resolution images and could be associated with changes in the focal spot (FS) position. PURPOSE High-resolution 3D-CBCT imaging by a mobile imaging device with a large gantry clearance offers more versatility for clinical workflows in image-guided brachytherapy (IGBT), intraoperative radiation therapy (IORT), and spinal, as well as maxillofacial surgery. However, misalignment or double-contouring artifacts hinder workflow advancements in these domains. This paper introduces intrinsic calibration and geometrical correction methods as extensions to a well-established technique for addressing geometrical deviations resulting from factors such as gravity or mechanical inconsistencies. These extensions cover shifts and drifts of the FS depending on FS size selection, temperature, tube current, and tube potential. The proposed methods effectively mitigate artifacts in high-resolution CBCT images stemming from geometrical inaccuracies in projection data, without requiring additional equipment like a pinhole device. METHODS Geometrical offsets and drifts of the x-ray tube FS were characterized on a mobile multi-purpose imaging system, the ImagingRing-m. A pinhole-like experiment was simulated by adjusting the movable collimation unit to a small rectangular aperture within the FS size range. The influence of filament selection, that is, FS size, temperature, the relatively low tube currents, as well as tube potential settings have been studied on two different monobloc types sharing the same x-ray tube insert. The Catphan 504 and an Alderson head phantom were used to assess resulting image artifacts. RESULTS Switching the FS size to one different from what was used for geometrical (gravitation, mechanical variations) calibration induced the most notable position changes of the x-ray FS, resulting in double-contouring artifacts and blurring of high-resolution 3D-CBCT images. Incorporating these shifts into a geometrical correction method effectively minimized these artifacts. Thermal drifts exhibited the second largest geometrical changes, comparable to FS size shifts across the thermal operating conditions of the x-ray system. The proposed thermal drift compensation markedly reduced thermal drift effects. Tube current and potential had little impact within the range of available tube currents, eliminating the need for compensation in current applications. CONCLUSIONS Augmenting the geometrical calibration pipeline with proposed FS drift compensations yielded significant enhancements in image quality for high-resolution reconstructions. While compensation for thermal effects posed challenges, it proved achievable. The roles of tube current and potential were found to be negligible.
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Affiliation(s)
- Ivan Michael Messner
- Institute for Research and Development on Advanced Radiation Technologies (radART), Paracelsus Medical University, Salzburg, Austria
- medPhoton GmbH, Salzburg, Austria
| | | | | | | | | | | | | | | | - Philipp Steininger
- Institute for Research and Development on Advanced Radiation Technologies (radART), Paracelsus Medical University, Salzburg, Austria
- medPhoton GmbH, Salzburg, Austria
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Bindels BJJ, Dronkers BEG, Smits MLJ, Verlaan JJ. Accurate Placement and Revisions for Cervical Pedicle Screws Placed With or Without Navigation: A Systematic Review and Meta-Analysis. Global Spine J 2024; 14:1018-1037. [PMID: 37596998 PMCID: PMC11192121 DOI: 10.1177/21925682231196456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/21/2023] Open
Abstract
STUDY DESIGN Systematic review and meta-analysis. OBJECTIVES To evaluate the accuracy of placement for cervical pedicle screws with and without the use of spinal navigation. METHODS A structured search was conducted in electronic databases without any language or date restrictions. Eligible studies reported the proportion of accurately placed cervical pedicle screws measured on intraoperative or postoperative 3D imaging, and reported whether intraoperative navigation was used during screw placement. Randomized Studies (MINORS) criteria were used to evaluate the methodological quality of how accuracy was assessed for cervical pedicle screws. RESULTS After screening and critical appraisal, 4697 cervical pedicle screws from 18 studies were included in the meta-analysis. The pooled proportion for cervical pedicle screws with a breach up to 2 mm was 94% for navigated screws and did not differ from the pooled proportion for non-navigated screws (96%). The pooled proportion for cervical pedicle screws placed completely in the pedicle was 76% for navigated screws and did not differ from the pooled proportion for non-navigated screws (82%). Intraoperative screw reposition rates and screw revision rates as a result of postoperative imaging also did not differ between navigated and non-navigated screw placement. CONCLUSIONS This systematic review and meta-analysis found that the use of spinal navigation systems does not significantly improve the accuracy of placement of cervical pedicle screws compared to screws placed without navigation. Future studies evaluating intraoperative navigation for cervical pedicle screw placement should focus on the learning curve, postoperative complications, and the complexity of surgical cases.
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Affiliation(s)
- B. J. J. Bindels
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - B. E. G. Dronkers
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - M. L. J. Smits
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - J. J. Verlaan
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
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Lakomkin N, Eastlack RK, Uribe JS, Park P, Ryu SI, Kretzer R, Mimran RI, Holman P, Veeravagu A, Hassanzadeh H, Johnson MM, Sullivan L, Clark A, Mundis GM. An Integrated 3-Dimentional Navigation System Increases the Accuracy, Efficiency, and Safety of Percutaneous Thoracolumbar Pedicle Screw Placement in Minimally Invasive Approaches: A Randomized Cadaveric Study. Global Spine J 2024:21925682231224394. [PMID: 38165219 DOI: 10.1177/21925682231224394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2024] Open
Abstract
STUDY DESIGN Cadaveric study. OBJECTIVES The purpose of this study was to compare a novel, integrated 3D navigational system (NAV) and conventional fluoroscopy in the accuracy, efficiency, and radiation exposure of thoracolumbar percutaneous pedicle screw (PPS) placement. METHODS Twelve skeletally mature cadaveric specimens were obtained for twelve individual surgeons. Each participant placed bilateral PS at 11 segments, from T8 to S1. Prior to insertion, surgeons were randomized to the sequence of techniques and the side (left or right). Following placement, a CT scan of the spine was obtained for each cadaver, and an independent reviewer assessed the accuracy of screw placement using the Gertzbein grading system. Outcome metrics of interest included a comparison of breach incidence/severity, screw placement time, total procedure time, and radiation exposure between the techniques. Bivariate statistics were employed to compare outcomes at each level. RESULTS A total of 262 screws (131 using each technique) were placed. The incidence of cortical breaches was significantly lower with NAV compared to FG (9% vs 18%; P = .048). Of breaches with NAV, 25% were graded as moderate or severe compared to 39% in the FG subgroup (P = .034). Median time for screw placement was significantly lower with NAV (2.7 vs 4.1 min/screw; P = .012), exclusive of registration time. Cumulative radiation exposure to the surgeon was significantly lower for NAV-guided placement (9.4 vs 134 μGy, P = .02). CONCLUSIONS The use of NAV significantly decreased the incidence of cortical breaches, the severity of screw breeches, screw placement time, and radiation exposure to the surgeon when compared to traditional FG.
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Affiliation(s)
| | - Robert K Eastlack
- Department of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA
| | - Juan S Uribe
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Paul Park
- Department of Neurosurgery, Semmes-Murphey Clinic, Memphis, TN, USA
| | - Stephen I Ryu
- Department of Neurosurgery, Sutter Health, Palo Alto, CA, USA
| | - Ryan Kretzer
- Department of Neurosurgery, Western Neuro, Phoenix, AZ, USA
| | - Ronnie I Mimran
- Department of Neurosurgery, Sutter Health, Palo Alto, CA, USA
| | - Paul Holman
- Department of Neurosurgery, Houston Methodist, Houston, TX, USA
| | - Anand Veeravagu
- Department of Neurosurgery, Stanford University, Palo Alto, CA, USA
| | - Hamid Hassanzadeh
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, USA
| | - Michele M Johnson
- Department of Neurosurgery, Atlanta Brain and Spine, Atlanta, GA, USA
| | - Linda Sullivan
- Medical writing and Biostatistics, NuVasive, San Diego, CA, USA
| | - Aaron Clark
- Department of Neurosurgery, University of California, San Francisco, CA, USA
| | - Gregory M Mundis
- Department of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA
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