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1.
Phys Med ; 100: 135-141, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35816942

RESUMO

PURPOSE: Within the STRA-MI-VT phase Ib/II trial (NCT04066517), the aim of this phantom study was to explore the feasibility of Cyberknife treatments on cardiac lesions by tracking as a single marker the lead tip of an implantable cardioverter defibrillator. The residual displacement of the lesion during the tracking was studied, planning margins were found and the dosimetric accuracy of the treatment was checked. MATERIALS AND METHODS: A lead was inserted into a phantom (EasyCube phantom, Sun Nuclear Co, USA) and then placed on the translating ExacTrac Gating System (BrainLAB AG, Germany). The phantom was rotated, a virtual lesion was identified and its displacement during the tracking was studied. Two plans were compared, calculated on the unrotated volume and on the envelope of the unrotated and the rotated volumes. The plans were delivered using the Cyberknife System (Accuray Inc, USA) and their dosimetric accuracy verified by gamma analysis with gafchromic films. RESULTS: The residual margin increases enhancing the distance between the lead and the lesion. It is 4 mm for distance 0 cm and 5 mm for distance 5 cm. The coverage is reduced by 3.8% (interquartile range 2.5%-4.7%) when the dose is prescribed on the unrotated volume. All treatment plans are accurate and 3% 3 mm gamma analysis results are greater than 94%. CONCLUSIONS: Results showed that tracking with a single marker is feasible considering adequate residual planning margins. The volumes could be further reduced by using additional markers, for example by placing them on the patient's skin.


Assuntos
Radiocirurgia , Taquicardia Ventricular , Marcadores Fiduciais , Humanos , Imagens de Fantasmas , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos
2.
J Appl Clin Med Phys ; 23(6): e13596, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35377962

RESUMO

PURPOSE: Real-time tracking systems of moving respiratory targets such as CyberKnife, Radixact, or Vero4DRT are an advanced robotic radiotherapy device used to deliver stereotactic body radiotherapy (SBRT). The internal target volume (ITV) of lung tumors is assessed through a fiducial marker fusion using four-dimensional computed tomography (CT). It is important to minimize the ITV to protect normal lung tissue from exposure to radiation and the associated side effects post SBRT. However, the ITV may alter if there is a change in the position of the fiducial marker with respect to the tumor. This study investigated the relationship between fiducial marker position and the ITV in order to prevent radiation exposure of normal lung tissue, and correct target coverage. MATERIALS AND METHODS: This study retrospectively reviewed 230 lung cancer patients who received a fiducial marker for SBRT between April 2015 and September 2021. The distance of the fiducial marker to the gross tumor volume (GTV) in the expiratory (dex ) and inspiratory (din ) CT, and the ratio of the ITV/V(GTVex ), were investigated. RESULTS: Upon comparing each lobe, although there was no significant difference in the ddiff and the ITV/V(GTVex ) between all lobes for dex  < 10 mm, there was significant difference in the ddiff and the ITV/V(GTVex ) between the lower and upper lobes for dex ≥ 10 mm (p < 0.05). Moreover, there was significant difference in the ddiff and the ITV/V(GTVex ) between dex ≥10 mm and dex  < 10 mm in all lung regions (p < 0.05). CONCLUSION: The ITV that had no margin from GTVs increased when dex was ≥10 mm for all lung regions (p < 0.05). Furthermore, the increase in ITV tended to be greater in the lower lung lobe. These findings can help decrease the possibility of adverse events post SBRT, and correct target coverage.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Marcadores Fiduciais , Tomografia Computadorizada Quadridimensional/métodos , Humanos , Pulmão/diagnóstico por imagem , Pulmão/patologia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/cirurgia , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Estudos Retrospectivos
3.
Eur Rev Med Pharmacol Sci ; 26(5): 1674-1682, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35302216

RESUMO

OBJECTIVE: This prospective study compared the accuracy of two different company-specific registration methods (Fiagon GmbH, Hennigsdorf, Germany) in the electromagnetic navigation of the frontal skull base. A newly developed photo registration technology (Fiagon tracey©) promises an increase in accuracy and user-friendliness, but there is no phantom-based prospective study comparing the new method with the classic approach of tactile surface registration. MATERIALS AND METHODS: A phantom skull was prepared with 27 markers in the sagittal, axial and coronary planes, and their reference coordinates were determined using a navigational CT (low dose, slice 0.6 mm). Subsequently, 20 runs of automatic photo registration and tactile surface registration were carried out, and the resulting marker coordinates were compared with the reference coordinates. The target registration error (TRE) of the 27 markers was assessed and compared between the two methods using a 2-factor ANOVA with repeated measures. RESULTS: The mean TRE using surface registration was 1.97 mm ± 0.57, while the mean TRE of the automatic photo registration was 1.54 mm ± 0.24 (p < 0.001). In a subgroup analysis limited to markers in anatomical regions of clinical relevance in terms of paranasal sinus surgery, the mean TRE for the photo registration procedure can even be reduced to 1.29 mm (± 0.43) compared to tactile registration (1.80 mm; ±0.50; p=0.01). CONCLUSIONS: Photo registration is a promising new technology in the field of electromagnetic navigation in paranasal sinus surgery. This prospective phantom-based study showed that the photo registration method achieves a significantly lower target registration error (1.29 mm) compared to the surface-based tactile registration procedure (1.80 mm).


Assuntos
Marcadores Fiduciais , Cirurgia Assistida por Computador , Estudos Prospectivos , Base do Crânio/diagnóstico por imagem , Base do Crânio/cirurgia , Cirurgia Assistida por Computador/métodos , Tecnologia
4.
Med Phys ; 49(5): 2914-2930, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35305271

RESUMO

PURPOSE: Fiducial markers are commonly used in navigation-assisted minimally invasive spine surgery and they help transfer image coordinates into real-world coordinates. In practice, these markers might be located outside the field-of-view (FOV) of C-arm cone-beam computed tomography (CBCT) systems used in intraoperative surgeries, due to the limited detector sizes. As a consequence, reconstructed markers in CBCT volumes suffer from artifacts and have distorted shapes, which sets an obstacle for navigation. METHODS: In this work, we propose two fiducial marker detection methods: direct detection from distorted markers (direct method) and detection after marker recovery (recovery method). For direct detection from distorted markers in reconstructed volumes, an efficient automatic marker detection method using two neural networks and a conventional circle detection algorithm is proposed. For marker recovery, a task-specific data preparation strategy is proposed to recover markers from severely truncated data. Afterwards, a conventional marker detection algorithm is applied for position detection. The networks in both methods are trained based on simulated data. For the direct method, 6800 images and 10 000 images are generated, respectively, to train the U-Net and ResNet50. For the recovery method, the training set includes 1360 images for FBPConvNet and Pix2pixGAN. The simulated data set with 166 markers and four cadaver cases with real fiducials are used for evaluation. RESULTS: The two methods are evaluated on simulated data and real cadaver data. The direct method achieves 100% detection rates within 1 mm detection error on simulated data with normal truncation and simulated data with heavier noise, but only detect 94.6% markers in extremely severe truncation case. The recovery method detects all the markers successfully in three test data sets and around 95% markers are detected within 0.5 mm error. For real cadaver data, both methods achieve 100% marker detection rates with mean registration error below 0.2 mm. CONCLUSIONS: Our experiments demonstrate that the direct method is capable of detecting distorted markers accurately and the recovery method with the task-specific data preparation strategy has high robustness and generalizability on various data sets. The task-specific data preparation is able to reconstruct structures of interest outside the FOV from severely truncated data better than conventional data preparation.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Marcadores Fiduciais , Algoritmos , Artefatos , Cadáver , Tomografia Computadorizada de Feixe Cônico/métodos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagens de Fantasmas
5.
Comput Biol Med ; 145: 105406, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35339847

RESUMO

Laparoscopic vision-based ultrasound probe tracking systems have gained considerable attention in ultrasound-guided laparoscopic surgeries as replacements for external tracking systems (e.g. optical tracking and electromagnetic tracking systems), which increase cost and setting time, require additional operation space, and introduce new limitations. Most existing laparoscopic ultrasound (LUS) probe tracking systems rely on fiducial markers, which cannot easily realise fast and robust vision-based tracking in laparoscopic surgery owing to their design limitations. Therefore, we propose a novel binary dot array marker to realise a robust and fast LUS probe tracking system. The binary dot array marker comprises two dots (green and blue), which form multiple unique identification dot subarrays in the binary dot array. The binary dot array marker can be tracked when one of the identification dot subarrays is detected and identified; this novel design makes the binary dot array marker-based probe tracking system robust against occlusions during surgery. The evaluation results indicate that the proposed binary dot marker performs better in terms of robustness, computational efficiency, and tracking accuracy compared to the state-of-the-art fiducial markers used for vision-based probe tracking.


Assuntos
Laparoscopia , Cirurgia Assistida por Computador , Fenômenos Eletromagnéticos , Marcadores Fiduciais , Laparoscopia/métodos , Cirurgia Assistida por Computador/métodos , Ultrassonografia/métodos
6.
J Appl Clin Med Phys ; 23(6): e13593, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35338574

RESUMO

PURPOSE: Motion management is critical for prostate stereotactic body radiotherapy (SBRT) due to its high fractional dose and proximity to organs at risk. This study seeks to quantify the advantages of MV-kV tracking over kV imaging alone through a retrospective analysis of over 300 patients who underwent prostate SBRT treatment using MV-kV tracking. METHODS: An MV-kV imaging-based fiducial tracking technique has been developed at our institute and become a standard clinical practice. This technique calculates three-dimensional (3D) fiducial displacement in real time from orthogonal kV and MV images acquired simultaneously. The patient will be repositioned if for two consecutive MV-kV data points, the motion is larger than a tolerance of 1.5 mm in any of the lateral, superior-inferior, and/or anterior-posterior directions. This study retrospectively analyzed detected 3D motions using an MV-kV approach of 324 patients who recently underwent prostate SBRT treatments. An algorithm was developed to recover the 2D motion components as if they were detected by kV or MV imaging alone. RESULTS: Our results indicated that out-of-tolerance motions were primarily limited to the range of 1.5-3 mm (>95%). The motions are primarily anterior-posterior and superior-inferior, with less than 14.8% of the occurrences in the lateral direction. Compared to out-of-tolerance occurrences detected by MV-kV approach, kV alone caught 46.6% of motions in all three directions, and MV alone caught 46.7%. kV alone shows an overall missing rate of 45.8% for superior-inferior motions and 38.6% for lateral motions. It is also demonstrated that the detectability of motion in specific directions greatly depends on gantry angles, as does the missing rate. CONCLUSIONS: Our study demonstrated that MV-kV imaging-based intrafraction motion tracking is superior to single kV imaging for prostate SBRT in clinical practice.


Assuntos
Radiocirurgia , Algoritmos , Marcadores Fiduciais , Humanos , Masculino , Movimento , Próstata/diagnóstico por imagem , Próstata/cirurgia , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Estudos Retrospectivos
7.
Med Phys ; 49(5): 3041-3052, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35319790

RESUMO

PURPOSE: Mobile lung tumors are increasingly being treated with ablative radiotherapy, for which precise motion management is essential. In-room stereoscopic radiography systems are able to guide ablative radiotherapy for stationary cranial lesions but not optimally for lung tumors unless fiducial markers are inserted. We propose augmenting stereoscopic radiographic systems with multiple small x-ray sources to provide the capability of imaging with stereoscopic, single frame tomosynthesis. METHODS: In single frame tomosynthesis, nine x-ray sources are placed in a 3 × 3 configuration and energized simultaneously. The beams from these sources are collimated so that they converge on the tumor and then diverge to illuminate nine non-overlapping sectors on the detector. These nine sector images are averaged together and filtered to create the tomosynthesis effect. Single frame tomosynthesis is intended to be an alternative imaging mode for existing stereoscopic systems with a field of view that is three times smaller and a temporal resolution equal to the frame rate of the detector. We simulated stereoscopic tomosynthesis and radiography using Monte Carlo techniques on 60 patients with early-stage lung cancer from the NSCLC-Radiomics dataset. Two board-certified radiation oncologists reviewed these simulated images and rated them on a 4-point scale (1: tumor not visible; 2: tumor visible but inadequate for motion management; 3: tumor visible and adequate for motion management; 4: tumor visibility excellent). Each tumor was independently presented four times (two viewing angles from radiography and two viewing angles from tomosynthesis) in a blinded fashion over two reading sessions. RESULTS: The fraction of tumors that were rated as adequate or excellent for motion management (scores 3 or 4) from at least one viewing angle was 53% using radiography and 90% using tomosynthesis. From both viewing angles, the corresponding fractions were 7% for radiography and 48% for tomosynthesis. Readers agreed exactly on 62% of images and within 1 point on 98% of images. The acquisition technique was estimated to be 75 mAs at 120 kVp per treatment fraction assuming one verification image per breath, approximately one order of magnitude less than a standard dose cone beam CT. CONCLUSIONS: Stereoscopic tomosynthesis may provide a noninvasive, low dose, intrafraction motion verification technique for lung tumors treated by ablative radiotherapy. The system architecture is compatible with real-time video capture at 30 frames per second. Simulations suggest that most, but not all, lung tumors can be adequately visualized from at least one viewing angle.


Assuntos
Marcadores Fiduciais , Neoplasias Pulmonares , Tomografia Computadorizada de Feixe Cônico/métodos , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/radioterapia , Movimento (Física) , Radiografia
8.
Sci Rep ; 12(1): 4486, 2022 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296720

RESUMO

Augmented reality (AR) offers a new medical treatment approach. We aimed to evaluate frameless (mask) fixation navigation using a 3D-printed patient model with fixed-AR technology for gamma knife radiosurgery (GKRS). Fixed-AR navigation was developed using the inside-out method with visual inertial odometry algorithms, and the flexible Quick Response marker was created for object-feature recognition. Virtual 3D-patient models for AR-rendering were created via 3D-scanning utilizing TrueDepth and cone-beam computed tomography (CBCT) to generate a new GammaKnife Icon™ model. A 3D-printed patient model included fiducial markers, and virtual 3D-patient models were used to validate registration accuracy. Registration accuracy between initial frameless fixation and re-fixation navigated fixed-AR was validated through visualization and quantitative method. The quantitative method was validated through set-up errors, fiducial marker coordinates, and high-definition motion management (HDMM) values. A 3D-printed model and virtual models were correctly overlapped under frameless fixation. Virtual models from both 3D-scanning and CBCT were enough to tolerate the navigated frameless re-fixation. Although the CBCT virtual model consistently delivered more accurate results, 3D-scanning was sufficient. Frameless re-fixation accuracy navigated in virtual models had mean set-up errors within 1 mm and 1.5° in all axes. Mean fiducial marker differences from coordinates in virtual models were within 2.5 mm in all axes, and mean 3D errors were within 3 mm. Mean HDMM difference values in virtual models were within 1.5 mm of initial HDMM values. The variability from navigation fixed-AR is enough to consider repositioning frameless fixation without CBCT scanning for treating patients fractionated with large multiple metastases lesions (> 3 cm) who have difficulty enduring long beam-on time. This system could be applied to novel GKRS navigation for frameless fixation with reduced preparation time.


Assuntos
Realidade Aumentada , Radiocirurgia , Tomografia Computadorizada de Feixe Cônico/métodos , Marcadores Fiduciais , Humanos , Movimento (Física) , Radiocirurgia/métodos
9.
ACS Appl Bio Mater ; 5(3): 1259-1266, 2022 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-35175735

RESUMO

Image-guided radiation therapy (IGRT) has emerged as a promising technique for cancer treatment to improve radiation precision and accuracy, thereby reducing the treatment toxicity and optimizing therapeutic efficacy. In IGRT, fiducial markers are required to be inserted near the tumor to get the spatial information of the tumor. Currently used metal fiducial markers with large sizes would be highly invasive; therefore, it is critical to develop minimally invasive alternatives to these markers. In this work, an injectable marker based on Biopex-supported Au NPs with adequate radio-opacity for X-ray visualization was developed. Biopex can function as a substrate for the growth of Au NPs and avoid excessive reaction-induced aggregation and precipitation. The self-curing property of Biopex prevents the leakage and elimination of isolated Au NPs, enabling long-term X-ray observation and radiotherapy. The effect of Biopex amount, gold precursor concentration, and reaction time were evaluated. The visibility of samples prepared by the optimized formula was also examined. The developed Biopex-Au NPs could be injected through a 21 G needle and exhibit great visibility in the X-ray visualization test, showing great potential as a fiducial marker for image-guided radiation therapy.


Assuntos
Nanopartículas Metálicas , Radioterapia Guiada por Imagem , Sulfatos de Condroitina , Marcadores Fiduciais , Ouro/química , Hidroxiapatitas , Nanopartículas Metálicas/uso terapêutico , Radioterapia Guiada por Imagem/métodos , Succinatos
10.
Technol Cancer Res Treat ; 21: 15330338221078464, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35167403

RESUMO

Purpose: Various deformable image registration (DIR) methods have been used to evaluate organ deformations in 4-dimensional computed tomography (4D CT) images scanned during the respiratory motions of a patient. This study assesses the performance of 10 DIR algorithms using 4D CT images of 5 patients with fiducial markers (FMs) implanted during the postoperative radiosurgery of multiple lung metastases. Methods: To evaluate DIR algorithms, 4D CT images of 5 patients were used, and ground-truths of FMs and tumors were generated by physicians based on their medical expertise. The positions of FMs and tumors in each 4D CT phase image were determined using 10 DIR algorithms, and the deformed results were compared with ground-truth data. Results: The target registration errors (TREs) between the FM positions estimated by optical flow algorithms and the ground-truth ranged from 1.82 ± 1.05 to 1.98 ± 1.17 mm, which is within the uncertainty of the ground-truth position. Two algorithm groups, namely, optical flow and demons, were used to estimate tumor positions with TREs ranging from 1.29 ± 1.21 to 1.78 ± 1.75 mm. With respect to the deformed position for tumors, for the 2 DIR algorithm groups, the maximum differences of the deformed positions for gross tumor volume tracking were approximately 4.55 to 7.55 times higher than the mean differences. Errors caused by the aforementioned difference in the Hounsfield unit values were also observed. Conclusions: We quantitatively evaluated 10 DIR algorithms using 4D CT images of 5 patients and compared the results with ground-truth data. The optical flow algorithms showed reasonable FM-tracking results in patient 4D CT images. The iterative optical flow method delivered the best performance in this study. With respect to the tumor volume, the optical flow and demons algorithms delivered the best performance.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Algoritmos , Marcadores Fiduciais , Tomografia Computadorizada Quadridimensional/métodos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Neoplasias Pulmonares/diagnóstico por imagem
11.
Int J Med Robot ; 18(3): e2373, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35133715

RESUMO

BACKGROUND: Fiducial marker-based image-to-patient registration is the most common way in image-guided neurosurgery, which is labour-intensive, time consuming, invasive and error prone. METHODS: We proposed a method of facial landmark-guided surface matching for image-to-patient registration using an RGB-D camera. Five facial landmarks are localised from preoperative magnetic resonance (MR) images using deep learning and RGB image using Adaboost with multi-scale block local binary patterns, respectively. The registration of two facial surface point clouds derived from MR images and RGB-D data is initialised by aligning these five landmarks and further refined by weighted iterative closest point algorithm. RESULTS: Phantom experiment results show the target registration error is less than 3 mm when the distance from the camera to the phantom is less than 1000 mm. The registration takes less than 10 s. CONCLUSIONS: The proposed method is comparable to the state-of-the-arts in terms of the accuracy yet more time-saving and non-invasive.


Assuntos
Cirurgia Assistida por Computador , Algoritmos , Marcadores Fiduciais , Humanos , Imageamento por Ressonância Magnética , Procedimentos Neurocirúrgicos/métodos , Imagens de Fantasmas , Cirurgia Assistida por Computador/métodos
12.
Eur Respir Rev ; 31(163)2022 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-35022258

RESUMO

Stereotactic body radiation therapy is an alternative to surgery for early-stage, inoperable peripheral non-small cell lung cancer. As opposed to linear accelerator (linac)-based (e.g. gating) and free-breathing techniques, CyberKnife® with Synchrony® technology allows accurate radiation delivery by means of a real-time respiratory motion tracking system using, in most cases, metal fiducial markers (FMs) placed in the vicinity of the target. The aims of this review are as follows. First, to describe the safety and efficacy of the transthoracic, endovascular and endobronchial FM insertion techniques for peripheral pulmonary lesions (PPLs). Second, to analyse performance in terms of the migration and tracking rates of different FM types. Recent developments in FM tracking for central lesions will also be reviewed. In conclusion, for PPLs, the endobronchial approach provides a low rate of pneumothorax, offers the possibility of concurrent diagnostic sampling for both the PPL and the lymph nodes, and, finally, reduces the intervention time compared to other techniques. In this context, coil-tailed and coil-spring FMs have shown the lowest migration rate with a consequently high tracking rate.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Radiocirurgia , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Marcadores Fiduciais , Humanos , Pulmão/diagnóstico por imagem , Pulmão/cirurgia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/cirurgia , Radiocirurgia/efeitos adversos
13.
Int J Med Robot ; 18(3): e2376, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35100492

RESUMO

BACKGROUND: Markerless registration is required for image-guided surgery; it has limited accuracy due to the ambiguity of the correspondence point set. In this study, we proposed a registration framework to improve registration accuracy for markerless registration using a dynamic touchable region model (DTRM). METHODS: The DTRM is defined using the geometric characteristics of the surface around the fiducial area using Intrinsic Shape Signature keypoints. The new registration procedure, which combines the DTRM with iterative closest point-based registration (ICDTP) was implemented and verified with phantom experiments for a single-user and multi-user study. RESULTS: The ICDTP registration framework provides improved performance over the paired-point registration for surgeries, where it is inappropriate to construct the corresponding positions with adhesive fiducial markers. CONCLUSION: The proposed method can be an alternative approach for image-guided surgery in operations for which itis not appropriate to set up markers for registration.


Assuntos
Imageamento Tridimensional , Cirurgia Assistida por Computador , Algoritmos , Marcadores Fiduciais , Humanos , Imageamento Tridimensional/métodos , Imagens de Fantasmas , Cirurgia Assistida por Computador/métodos
14.
Biomed Phys Eng Express ; 8(2)2022 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-35026743

RESUMO

Objective. Synchrony®is a motion management system on the Radixact®that uses planar kV radiographs to locate the target during treatment. The purpose of this work is to quantify the visibility of fiducials on these radiographs.Approach. A custom acrylic slab was machined to hold 8 gold fiducials of various lengths, diameters, and orientations with respect to the imaging axis. The slab was placed on the couch at the imaging isocenter and planar radiographs were acquired perpendicular to the custom slab with varying thicknesses of acrylic on each side. Fiducial signal to noise ratio (SNR) and detected fiducial position error in millimeters were quantified.Main Results. The minimum output protocol (100 kVp, 0.8 mAs) was sufficient to detect all fiducials on both Radixact configurations when the thickness of the phantom was 20 cm. However, no fiducials for any protocol were detected when the phantom was 50 cm thick. The algorithm accurately detected fiducials on the image when the SNR was larger than 4. The MV beam was observed to cause RFI artifacts on the kV images and to decrease SNR by an average of 10%.Significance. This work provides the first data on fiducial visibility on kV radiographs from Radixact Synchrony treatments. The Synchrony fiducial detection algorithm was determined to be very accurate when sufficient SNR is achieved. However, a higher output protocol may need to be added for use with larger patients. This work provided groundwork for investigating visibility of fiducial-free solid targets in future studies and provided a direct comparison of fiducial visibility on the two Radixact configurations, which will allow for intercomparison of results between configurations.


Assuntos
Radioterapia de Intensidade Modulada , Artefatos , Marcadores Fiduciais , Humanos , Movimento (Física) , Imagens de Fantasmas , Radioterapia de Intensidade Modulada/métodos
15.
Phys Med ; 95: 9-15, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35063796

RESUMO

PURPOSE: Gold fiducial markers are used to guide liver stereotactic body radiation therapy (SBRT) and are hard to detect by magnetic resonance imaging (MRI). In this study, the parameters of the three-dimensional T1-weighted turbo gradient-echo (3D T1W-GRE) sequence were optimized for gold marker detection without degrading tumor delineation. METHODS: Custom-made phantoms mimicking tumor and normal liver parenchyma were prepared and embedded with a gold marker. The 3D T1W-GRE was scanned by varying echo time (TE), bandwidth (BW), flip angle (FA), and base matrix size. The signal-to-noise ratio (SNR), contrast ratio (CR), and relative standard deviation (RSD) of the signal intensity in the area including the gold marker were evaluated, and the parameters were optimized accordingly. The modified 3D T1W-GRE (called HYBRID) was compared with the conventional T1W-GRE- and T2*-sequences in both phantom and clinical studies. In the clinical study of six patients with primary liver tumors, two observers visually assessed marker detection, tumor delineation, and overall image quality on a four-point scale. RESULTS: In the phantom study, HYBRID showed significantly higher SNR and RSD than those of conventional T1W-GRE (P < 0.001). In the clinical study, HYBRID yielded significantly higher scores than conventional T1W-GRE did in terms of marker detection (P < 0.001). The scores of both sequences were not statistically different in terms of tumor delineation and overall image quality (P = 0.56 and P = 0.32). CONCLUSIONS: The proposed HYBRID sequence improved gold fiducial marker detection without degrading tumor delineation in MRI for SBRT of primary liver tumor.


Assuntos
Neoplasias Hepáticas , Radiocirurgia , Meios de Contraste , Marcadores Fiduciais , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/radioterapia , Imageamento por Ressonância Magnética/métodos
16.
Br J Surg ; 109(3): 274-282, 2022 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-35089321

RESUMO

BACKGROUND: Wire localization is historically the most common method for guiding excision of non-palpable breast lesions, but there are limitations to the technique. Newer technologies such as magnetic seeds may allow some of these challenges to be overcome. The aim was to compare safety and effectiveness of wire and magnetic seed localization techniques. METHODS: Women undergoing standard wire or magnetic seed localization for non-palpable lesions between August 2018 and August 2020 were recruited prospectively to this IDEAL stage 2a/2b platform cohort study. The primary outcome was effectiveness defined as accurate localization and removal of the index lesion. Secondary endpoints included safety, specimen weight and reoperation rate for positive margins. RESULTS: Data were accrued from 2300 patients in 35 units; 2116 having unifocal, unilateral breast lesion localization. Identification of the index lesion in magnetic-seed-guided (946 patients) and wire-guided excisions (1170 patients) was 99.8 versus 99.1 per cent (P = 0.048). There was no difference in overall complication rate. For a subset of patients having a single lumpectomy only for lesions less than 50 mm (1746 patients), there was no difference in median closest margin (2 mm versus 2 mm, P = 0.342), re-excision rate (12 versus 13 per cent, P = 0.574) and specimen weight in relation to lesion size (0.15 g/mm2versus 0.138 g/mm2, P = 0.453). CONCLUSION: Magnetic seed localization demonstrated similar safety and effectiveness to those of wire localization. This study has established a robust platform for the comparative evaluation of new localization devices.


Assuntos
Neoplasias da Mama/cirurgia , Imãs , Mastectomia Segmentar/métodos , Idoso , Neoplasias da Mama/patologia , Feminino , Marcadores Fiduciais , Humanos , Imãs/efeitos adversos , Margens de Excisão , Mastectomia Segmentar/efeitos adversos , Mastectomia Segmentar/instrumentação , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Complicações Pós-Operatórias , Estudos Prospectivos
17.
ACS Biomater Sci Eng ; 8(2): 859-870, 2022 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-35020357

RESUMO

This study aimed to evaluate, for the first time, implantable, biodegradable fiducial markers (FMs), which were designed for bimodal, near-infrared fluorescence-based (NIRF) and X-ray-based imaging. The developed FMs had poly(l-lactide-co-caprolactone)-based core-shell structures made of radiopaque (core) and fluorescent (shell) composites with a poly(l-lactide-co-caprolactone) matrix. The approved for human use contrast agents were utilized as fillers. Indocyanine green was applied to the shell material, whereas in the core materials, iohexol and barium sulfate were compared. Moreover, the possibility of tailoring the stability of the properties of the core materials by the addition of hydroxyapatite (HAp) was examined. The performed in situ (porcine tissue) and in vivo experiment (rat model) confirmed that the developed FMs possessed pronounced contrasting properties in NIRF and X-ray imaging. The presence of HAp improved the radiopacity of FMs at the initial state. It was also proved that, in iohexol-containing FMs, the presence of HAp slightly decreased the stability of contrasting properties, while in BaSO4-containing ones, changes were less pronounced. A comprehensive material analysis explaining the differences in the stability of the contrasting properties was also presented. The tissue response around the FMs with composite cores was comparable to that of the FMs with a pristine polymeric core. The developed composite FMs did not cause serious adverse effects on the surrounding tissues even when irradiated in vivo. The developed FMs ensured good visibility for NIRF image-supported tumor surgery and the following X-ray image-guided radiotherapy. Moreover, this study replenishes a scanty report regarding similar biodegradable composite materials with a high potential for application.


Assuntos
Marcadores Fiduciais , Radioterapia Guiada por Imagem , Animais , Durapatita/química , Polímeros , Radioterapia Guiada por Imagem/métodos , Ratos , Suínos , Raios X
18.
BMJ Open ; 12(1): e057135, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-35058267

RESUMO

INTRODUCTION: In radiotherapy, tumour tracking leads the radiation beam to accurately target the tumour while it moves in a complex and unpredictable way due to respiration. Several tumour tracking techniques require the implantation of fiducial markers around the tumour, a procedure that involves unnecessary risks and costs. Markerless tumour tracking (MTT) negates the need for implanted markers, potentially enabling accurate and optimal radiotherapy in a non-invasive way. METHODS AND ANALYSIS: We will perform a phase I interventional trial called MArkerless image Guidance using Intrafraction Kilovoltage x-ray imaging (MAGIK) to investigate the technical feasibility of the MTT technology developed at the University of Sydney (sponsor). 30 participants will undergo the current standard of care lung stereotactic ablative radiation therapy, with the exception that kilovoltage X-ray images will be acquired continuously during treatment delivery to enable MTT. If MTT indicates that the mean lung tumour position has shifted >3 mm, a warning message will be displayed to indicate the need for a treatment intervention. The radiation therapist will then pause the treatment, shift the treatment couch to account for the shift in tumour position and resume the treatment. Participants will be implanted with fiducial markers, which act as the ground truth for evaluating the accuracy of MTT. MTT is considered feasible if the tracking accuracy is <3 mm in each dimension for >80% of the treatment time. ETHICS AND DISSEMINATION: The MAGIK trial has received ethical approval from The Alfred Human Research Ethics Committee and has been registered with ClinicalTrials.gov with the Identifier: NCT04086082. Estimated time of first recruitment is early 2022. The study recruitment and data analysis phases will be performed concurrently. Treatment for all 30 participants is expected to be completed within 2 years and participant follow-up within a total duration of 7 years. Findings will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: NCT04086082; Pre-result.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Marcadores Fiduciais , Humanos , Pulmão/patologia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/radioterapia , Radiocirurgia/métodos , Raios X
19.
Jpn J Radiol ; 40(3): 318-325, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34655387

RESUMO

Real-time tumor tracking radiotherapy (RTRT) systems typically use fiducial markers implanted near the tumor to track the target using X-ray fluoroscopy. Template pattern matching, used in tracking, is often used to automatically localize the fiducial markers. In radiotherapy of the liver, the thickness of the body that can recognize the fiducial markers must be clinically assessed. The purpose of this study was to quantify the recognition of fiducial markers according to body thickness in stereotactic body radiotherapy of the liver using clinical images obtained using SyncTraX FX4. The recognition scores of fiducial markers were examined in relation to water equivalent length (WEL), tube current, and each flat panel detector. The relationship between the contrast ratio of the fiducial marker and the background and the WEL was also investigated. The average recognition score was found to be less than 20 when the WEL was greater than 25 cm. The probability of successful tracking of image recognition was mostly smaller than 0.8 when the WEL was over 30 cm. The relationship between WEL and tube current did not significantly differ between 100 and 140 mA, but there was a significant difference (p < 0.05) for all other combinations. To ensure tracking of fiducial markers during SBRT, if the WEL representing body thickness is longer than 25 cm, the X-ray fluoroscopy arrangement should be determined based on the WEL.


Assuntos
Neoplasias , Radiocirurgia , Marcadores Fiduciais , Humanos , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Água
20.
Br J Radiol ; 95(1130): 20210594, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34762499

RESUMO

OBJECTIVE: To determine the feasibility of using radiopaque (RO) beads as direct tumour surrogates for image-guided radiotherapy (IGRT) in patients with liver tumours after transarterial chemoembolisation (TACE). METHODS: A novel vandetanib-eluting RO bead was delivered via TACE as part of a first-in-human clinical trial in patients with either hepatocellular carcinoma or liver metastases from colorectal cancer. Following TACE, patients underwent simulated radiotherapy imaging with four-dimensional computed tomography (4D-CT) and cone-beam CT (CBCT) imaging. RO beads were contoured using automated thresholding, and feasibility of matching between the simulated radiotherapy planning dataset (AVE-IP image from 4D data) and CBCT scans assessed. Additional kV, MV, helical CT and CBCT images of RO beads were obtained using an in-house phantom. Stability of RO bead position was assessed by comparing 4D-CT imaging to CT scans taken 6-20 days following TACE. RESULTS: Eight patients were treated and 4D-CT and CBCT images acquired. RO beads were visible on 4D-CT and CBCT images in all cases and matching successfully performed. Differences in centre of mass of RO beads between CBCT and simulated radiotherapy planning scans (AVE-IP dataset) were 2.0 mm mediolaterally, 1.7 mm anteroposteriorally and 3.5 mm craniocaudally. RO beads in the phantom were visible on all imaging modalities assessed. RO bead position remained stable up to 29 days post TACE. CONCLUSION: RO beads are visible on IGRT imaging modalities, showing minimal artefact. They can be used for on-set matching with CBCT and remain stable over time. ADVANCES IN KNOWLEDGE: The role of RO beads as fiducial markers for stereotactic liver radiotherapy is feasible and warrants further exploration as a combination therapy approach.


Assuntos
Carcinoma Hepatocelular/radioterapia , Embolização Terapêutica/métodos , Marcadores Fiduciais , Neoplasias Hepáticas/radioterapia , Radiocirurgia/métodos , Radioterapia Guiada por Imagem/métodos , Carcinoma Hepatocelular/diagnóstico por imagem , Carcinoma Hepatocelular/terapia , Neoplasias Colorretais/patologia , Tomografia Computadorizada de Feixe Cônico , Estudos de Viabilidade , Tomografia Computadorizada Quadridimensional , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/terapia , Microesferas , Imagens de Fantasmas , Projetos Piloto
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