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“Dose reduction potential of using gold fiducial markers for kilovoltage image-guided radiotherapy”
Extract from abstract: This study aimed to evaluate the possibility of reducing the imaging dose for image-guided radiotherapy by using planar kilovoltage orthogonal imaging and [Gold Anchor] fiducial markers (kV-FM). We tested kilovoltage planar images under clinical imaging conditions for the pelvis (75 kVp, 200 mA, 50 ms) at a decreasing tube current (from 200 to 10 mA). The visibility of the kV-FM, aspects of image quality (spatial resolution, low contrast resolution), and the resultant image registration reproducibility were evaluated. The imaging doses with 200 and 10 mA were approximately 0.74 and 0.04 mGy. Regardless of the marker’s shape, the GA phantom ensured visibility even when the tube current was reduced to the minimum value (10 mA). The low contrast resolution was gradually decreased at less than 50 mA, but the spatial resolution did not change. Manual-registration could be achieved with an accuracy of within 1 mm, even when the imaging dose was reduced to 1/20 of the clinical imaging condition for the pelvis.
“Radiotherapy for prostate cancer: Effect of gold fiducial markers on diffusion-weighted magnetic resonance imaging”
Summary: The effect on diffusion-weighted (DWI) MRI was evaluated of 0.28×10 mm Gold Anchor fiducial markers, implanted with a line shape.
Conclusions: Gold fiducial markers demonstrated negligible effect on DWI quality. Therefore, it appears that the use of these markers does not preclude the optimal utilization of MRI, particularly DWI, during follow-up in prostate cancer patients.
“Intrafractional fiducial marker position variations in stereotactic liver radiotherapy during voluntary deep inspiration breath-hold”
Objectives: To evaluate intrafractional fiducial marker position variations during stereotactic body radiotherapy (SBRT) in patients treated for liver metastases in visually guided, voluntary deep inspiration breath-hold (DIBH).
Comment on methods: 10 patients with implanted fiducial markers were studied. Three DIBH CTs were acquired for treatment planning. Pre- and post-treatment CBCTs were acquired for each of the three treatment fractions. Per-fraction marker position was evaluated on planar 2D kV images acquired during treatment fractions for 4 patients that each had three Gold Anchor markers implanted.
Results: The median difference in marker position was 0.3 cm (range, 0.0-0.9 cm) between the three DIBH CTs and 0.3 cm (range, 0.1 to 1.4 cm) between pre- and post-treatment CBCTs. The maximum intrafractional variation in marker position in craniocaudal (CC) direction on planar kV images was 0.7 to 1.3 cm and up to 1.0 cm during a single DIBH.
Conclusion: In order to increase treatment accuracy, it is necessary to apply real-time monitoring of the tumour or a reliable internal surrogate when delivering liver SBRT in visually guided, voluntary DIBH.
“Endoscopic ultrasound-guided fiducial marker placement for neoadjuvant chemoradiation therapy for resectable pancreatic cancer”
Background: Preoperative neoadjuvant chemoradiation therapy (NACRT) is applied for resectable pancreatic cancer (RPC). To maximize the efficacy of NACRT, it is essential to ensure the accurate placement of fiducial markers for image-guided radiation. However, no standard method for delivering fiducial markers has been established to date, and the nature of RPC during NACRT remains unclear.
Methods: This was a prospective case series of 29 patients (mean age, 67.5 years; 62.1% male) with RPC referred to our facility for NACRT. Under EUS guidance, a single gold marker was placed into the tumor using either a 19- or 22-gauge fine-needle aspiration needle. The differences in daily marker positioning were measured by comparing simulation computed tomography and treatment computed tomography.
Conclusion: EUS fiducial marker placement following NACRT for RPC is feasible and safe. The RPC is mobile and is affected by not only aspiration, but also food and fluid intake and bowel condition.
“Utilizing the TrueBeam Advanced Imaging Package to monitor intrafraction motion with periodic kV imaging and automatic marker detection during VMAT prostate treatments”
Background: Fiducial markers are frequently used before treatment for imageguided patient setup in radiation therapy (RT), but can also be used during treatment for image‐guided intrafraction motion detection. This report describes our implementation of automatic marker detection with periodic kV imaging (TrueBeam v2.5) to monitor and correct intrafraction motion during prostate RT.
Methods: We evaluated the reproducibility and accuracy of software fiducial detection using a phantom with 3 implanted [Gold Anchor] fiducial markers. Clinical implementation for patients with intraprostatic fiducials receiving volumetric modulated arc therapy (VMAT) utilized periodic on‐board kV imaging with 10 s intervals during treatment delivery. For each image, the software automatically identified fiducial locations and determined whether their distance relative to planned locations were within a 3 mm tolerance. Motion was corrected if either ≥2 fiducials in a single image or ≥1 fiducial in sequential images were out of tolerance.
Conclusion: Periodic kV imaging with automatic detection of motion during VMAT prostate treatments is commercially available and can be successfully implemented to mitigate effects of intrafraction motion with careful attention to software settings.
“Safety and efficacy of fiducial marker implantation for robotic stereotactic body radiation therapy with fiducial tracking”
Summary: Gold Anchors were implanted percutaneously via the trans-thoracic route in lung in 80 patients for CyberKnife treatments at the Hartmann Radiotherapy Institute in France. This led to 9 cases (11%) of pneumothorax, out of which 2 cases (2.5%) required a drain. All implanted fiducials were effectively tracked by CyberKnife.
“Rectal Culture and Sensitivity Analysis for Reducing Sepsis Risk After Fiducial Marker Placement”
Summary: Between 2015 and 2017, 96 patients had 3 Gold Anchor fiducial markers placed in conjunction with transperineal SpaceOar placement into the prostate at the University of Florida Health Proton Therapy Institute (UFPTI). None of these patients developed sepsis.
The authors write in their discussion “Bacterial UTI following fiducial placement to facilitate treatment planning and delivery for patients undergoing definitive RT for prostate cancer is a potentially life-threatening complication that can often result in sepsis, hospitalization, intensive care unit, and sometimes death. The incidence of this complication is rising, probably due to the widespread use of antibiotics and the consequential development of antibiotic resistant organisms”.
“[OA126] Intrafractional imaging during volumetric modulated arc therapy (VMAT) prostate treatment in combination with gold anchor fiducials”
Purpose: Triggered imaging is the use of kV image acquisition during treatment delivery to monitor intrafractional motion of implanted fiducials. An automatically identified fiducial point on the kV image is compared to its expected position predetermined from the treatment planning CT, and the treatment can be paused if the difference exceeds a user-definable tolerance.
Conclusion: Triggered imaging seems to perform satisfactorily when used in combination with well-separated and compressed Gold Anchor fiducials.
“MRI visibility of gold fiducial markers for image-guided radiotherapy of rectal cancer”
Background and purpose: A GTV boost is suggested to result in higher complete response rates in rectal cancer patients, which is attractive for organ preservation. Fiducials may offer GTV position verification on (CB)CT, if the fiducial-GTV spatial relationship can be accurately defined on MRI. The study aim was to evaluate the MRI visibility of fiducials inserted in the rectum.
Conclusion: The Visicoil 0.75 and Gold Anchor fiducials were the most visible fiducials on MRI as they were most consistently identified. The use of a registered (CB)CT and a T1 3D GRE MRI sequence is recommended.
“Low Infection Rate After Transrectal Implantation of Gold Anchor ™ Fiducial Markers in Prostate Cancer Patients After Non-broad-spectrum Antibiotic Prophylaxis”
Abstract: In 621 consecutive prostate cancer patients, the frequency of urinary tract infections (UTI) and marker loss was evaluated. They prophylactically received a single dose of non-broad-spectrum antibiotics and transrectal implantation of three thin needle fiducial markers, Gold Anchor ™ (GA). The occurrence of UTIs, sepsis, hospitalization due to infection, and marker loss after implantation was assessed from the medical records containing notes from physicians and nurses from the day of implantation to the end of 29 fractions. UTIs occurred in two (0.3%) of the 621 patients. Neither sepsis nor hospitalization was noted. Loss/drop-out of three markers was noted among 1,863 markers implanted.
Conclusion: The use of thin needles for the implantation of fiducials appears to reduce the rate of infection despite the use of a single dose of non-broad-spectrum antibiotics as prophylaxis. The marker construct appears to provide stability in the tissues.
“Percutaneous ultrasound-guided fiducial marker placement for liver cancer robotic stereotactic radio-surgery treatment: A comparative analysis of three types of markers and needles”
Summary: In Italy, ultrasound guided implantation in liver was performed in 50 patients of 68 gold grain markers 1×4 mm through 17-gauge needles, 78 Gold Anchors 0.4×10 mm through 22-gauge needles, and 17 Gold Anchors 0.28×10 mm through 25-gauge needles. The use of 17-gauge needles resulted in five patients developing abdominal pain and the migration of 4 gold seeds (5.9%). One vagal syndrome occurred when using 22-gauge needle. No complications were reported with the use of the 25-gauge needle. None of the Gold Anchor markers migrated.
“Clinical Implications of a Novel, Iron-containing Fiducial Marker in Radiotherapy for Liver Tumors: An Initial Experience”
Summary: Gold Anchors were implanted percutaneously under local anesthesia close to liver tumors in four patients at the Meiwa Hospital in Japan. All implantations were successfully performed with no complications. The markers were more visible than the uptake of lipiodol emulsion. The markers were also well detected in CB-CT images in all fractions.
“The advantage of iron-containing fiducial markers placed with a thin needle for radiotherapy of liver cancer in terms of visualization on MRI: an initial experience of Gold Anchor”
Summary: Gold Anchors were implanted through 22-gauge needle in two liver cancer patients at the Gifu Municipal Hospital in Japan. This caused little pain during placement under local anesthesia with xylocaine. No complication occurred in either patient. The iron-containing fiducial marker composed of 99.5% gold and 0.5% iron made visualization in MRI easy, which helped registering planning CT and MRI easily and precisely.
“Usefulness of Iron-Containing Fiducial Marker for Prostate Radiotherapy”
Abstract: Visualization of markers is critical for imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). However, the size of the marker varies according to the imaging technique. While a large-sized marker is more useful for visualization in MRI, it results in artifacts on CT and causes substantial pain on administration. In contrast, a small-sized marker reduces the artifacts on CT but hampers MRI detection. Herein, we report a new iron-containing marker and compare its utility with that of non-iron-containing markers…
Conclusion: Our findings show that an iron-containing marker is extremely useful in image registration. Bleeding and pain can be avoided by using a thin needle, and the marker can be recognized on prostatic MRI even when using a thin 22 G needle. The present findings suggest that the Gold Anchor will indeed be useful in daily practice.
“Assessment of the feasibility and complications of implanting “Gold Anchor 25 G” fiducial markers by transparietal puncture under scanner before Cyberknife radiotherapy of lung nodules”
Summary: This is the largest series reporting the feasibility and complications of the use of the Gold Anchor 25G system for percutaneous puncture in the lung. This is a quick procedure, performed under local anesthesia. A single marker per lesion minimizes the risk of complications related to the implementation: with a pneumothorax rate of 25% versus 40-82% according to the series for 17 to 19G needles a rate of only 1.5% hemoptysis for the Gold Anchor 25G system.
“Visibility and artifacts of gold fiducial markers used for IGRT of pancreatic cancer on MRI”
Summary: The authors selected ten different markers suitable for endoscopic placement in the pancreas and tested the visibility and artifacts of these markers on magnetic resonance imaging (MRI). They conclude that when visibility of the markers is most important, markers that contain iron [Gold Anchor] are optimal, preferably in a folded configuration.
“Establishing adequately visible endoscopically implantable gold markers for CT, cone-beam CT and MRI”
Summary: Users interested in seeing the markers for CT-MRI registration purposes should use 0.28×10 mm Gold Anchor markers.
“CyberKnife Markers Visible on CT and MRI”
Conclusion: We describe the use of the Gold Anchor fiducial markers in this poster. They have the advantage that a small amount of ferromagnetic material is mixed in the gold alloy to allow better visibility on MRI imaging than gold alloy fiducials alone. There are other markers that have been described (ref. 1) that also have a good signal on MRI imaging. One of the additional advantages of the Gold Anchor markers, however, is their crumpling effect that keeps them in position in soft tissue and low-density lung tissues.
“Investigation of dosimetric effects of radiopaque fiducial markers for use in proton beam therapy with film measurements and Monte Carlo simulations”
Summary: The purpose was to estimate the dose perturbation introduced by implanted radiopaque fiducial markers in proton beam therapy (PBT) and to compare cylindrical 1.2 x 3.0 mm and 0.6 x 4.0 mm gold markers to 0.28×20 mm Gold Anchor markers. Radiochromic film measurements of a phantom showed that the Gold Anchor marker causes the least dose perturbations in proton beams. It is concluded that the major advantages of the Gold Anchor marker makes it superior and may be used in future PBT.
“Spatial Accuracy and Visibility Studies of a MRI Compatible Gold Anchor™ Fine Needle Fiducial Marker”
Conclusion: The new MRI compatible Gold Anchor™ adds new features on top of the existing advantages. For specific anatomical targets treatment planning with fiducial marker information can be performed based only on MR images. For other targets images from both MRI and CT can be matched through the information from the fiducials. The content of iron may be changed to optimize the best signal to disturbance ratio.
“Assessment of stability of Gold Anchor™ fiducial marker implants in the prostate”
Conclusion: The position of the Gold Anchor™ fiducial marker in the prostate gland is stable, the marker remaining within the gland volume. The period of marker stabilization is less than the 7 days recommended by the manufacturer. We suggest that virtual simulation of the patient can be performed immediately after marker implantation.
“Comparison of the SBRT frame procedure versus Gold Anchor fiducial marker IGRT on Accuracy, Precision and Economy”
Conclusion: Positioning of the target with orthogonal images or CBCT with the Gold Anchor fiducial marker insertion is intuitive and easily accomplished for safe positioning. Excellent accuracy and precision can be achieved without the need of positioning patients in stereotactic whole body frames. The total cost of treatments with the Gold Anchor technique is less than with the use of the stereotactic coordinate set up due to less time needed in the treatment room and for preparations. However, a fixation system may be essential to minimize body movements during treatment.
“Using Foldable Gold Anchor Markers for Fiducial Tracking with the CyberKnife”
Conclusion: It is feasible to use gold anchor marker for Cyberknife. Ball shape or Tadpole gold anchor markers are recommended. Visual confirmation of lock-on is important due to the irregular shape of gold anchor markers. More study is needed to evaluate clinical effect.
“An assessment of inter and intrafraction prostate mobility using Gold Anchors during prostate cancer patients volumetric modulated arc radiotherapy (RapidArc)”
Conclusion: The patient positioning using 2D/2D kV and Gold Anchors increases the setup precision and enables to reduce margins. Because the prostate motion during the course of radiotherapy can be significant, margins for the PTV should include the intrafraction prostate mobility.
“Gold Anchor™ marker for IGRT, a new fiducial for high-precision radiotherapy”
Conclusion: Increasingly, we must be certain of exact localization of tumor targets by using markers and IGRT. The fine-needle marker presented here allows implantation into almost any tumor site with minimal risks of internal bleeding, infection or pneumothorax and can be implanted safely and precisely using guidance with ultrasound or CT. The Gold Anchor™ is developed for visualization with kilo voltage equipment during radiotherapy.
“XVI Gold Anchor Seed Project”
Conclusion: The gold seed markers can be seen clearly using the clinical 3DCBCT and 4DCBCT protocol which means the seeds can be used clinically to track the tumour position using XVI at the point of treatment delivery.
“An evaluation of side effects after gold markers (Gold Anchor™) implantation to prostate gland in patients with prostate cancer”
Conclusion: The Gold Anchors implantation is small invasive and safe method. The risk of side effects appearance is low.
“Stereotactic radiotherapy of malignant tumors of the liver with golden markers application”
“Zastosowanie złotych znaczników w radioterapii kierowanej obrazem u chorych na raka gruczołu krokowego”