Qualitative Evaluation of Fiducial Markers for Radiotherapy Imaging

Chan, M; Cohen, Gilad; Deasy, Joseph O.

doi:10.1177/1533034614547447

Cited by 49 publications

(61 citation statements)

References 24 publications

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“…The fiducial markers are introduced in the prostate in order to improve the accuracy of EBRT. They facilitate the localization of the prostate, enable motion and deformation tracking and act as reference points for distance measurements as well as for registering images obtained from different imaging modalities . Typically 3 radio‐opaque markers are implanted in the prostate before the patient undergoes EBRT planning and remain permanently in the prostate after the completion of the treatment .…”

Section: Introductionmentioning

confidence: 99%

“…They facilitate the localization of the prostate, enable motion and deformation tracking and act as reference points for distance measurements as well as for registering images obtained from different imaging modalities. 30,31,34,35 Typically 3 radio-opaque markers are implanted in the prostate before the patient undergoes EBRT planning and remain permanently in the prostate after the completion of the treatment. 36,37 The markers are placed within the prostate gland using a transperineal or transrectal approach with a needle holding one or two markers, under the guidance of transrectal ultrasound (TRUS) in a procedure similar to that of a biopsy.…”

Section: Introductionmentioning

confidence: 99%

“…There is a large range of commercially available markers made from a variety of materials in different shapes and dimensions. 30,34,35,41 The most commonly used markers are made of gold, making them visible in a variety of imaging modalities, and have a cylindrical shape with their surface appropriately shaped to minimize migration. 30 Although less frequent, spherical gold markers are also utilized.…”

Section: Introductionmentioning

confidence: 99%

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Beam distortion due to gold fiducial markers during salvage high‐intensity focused ultrasound in the prostate

et al. 2017

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The copyright line for this article was changed on March 17, 2017, after original online publication.Purpose: High intensity focused ultrasound (HIFU) provides a non-invasive salvage treatment option for patients with recurrence after external beam radiation therapy (EBRT). As part of EBRT the prostate is frequently implanted with permanent fiducial markers. To date, the impact of these markers on subsequent HIFU treatment is unknown. The objective of this work was to systematically investigate, using computational simulations, how these fiducial markers affect the delivery of HIFU treatment. Methods: A series of simulations was performed modelling the propagation of ultrasound pressure waves in the prostate with a single spherical or cylindrical gold marker at different positions and orientations. For each marker configuration, a set of metrics (spatial-peak temporal-average intensity, focus shift, focal volume) was evaluated to quantify the distortion introduced at the focus. An analytical model was also developed describing the marker effect on the intensity at the focus. The model was used to examine the marker's impact in a clinical setting through case studies. Results: The simulations show that the presence of the marker in the pre-focal region causes reflections which induce a decrease in the focal intensity and focal volume, and a shift of the maximum pressure point away from the transducer's focus. These effects depend on the shape and orientation of the marker and become more pronounced as its distance from the transducer's focus decreases, with the distortion introduced by the marker greatly increasing when placed within 5 mm of the focus. The analytical model approximates the marker's effect and can be used as an alternative method to the computationally intensive and time consuming simulations for quickly estimating the intensity at the focus. A retrospective review of a small patient cohort selected for focal HIFU after failed EBRT indicates that the presence of the marker may affect HIFU treatment delivery. Conclusions: The distortion introduced by the marker to the HIFU beam when positioned close to the focus may result in an undertreated region beyond the marker due to less energy arriving at the focus, and an overtreated region due to reflections. Further work is necessary to investigate whether the results presented here justify the revision of the patient selection criteria or the markers' placement protocol.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Beam distortion due to gold fiducial markers during salvage high‐intensity focused ultrasound in the prostate

et al. 2017

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“…5 and 6), no significant dose shadow effect seems to appear. Finally, all OrthoCT images deemed useful have shown no artifacts whatsoever, which is a remarkable advantage in respect to other imaging techniques utilized in concomitance with FMs [21].…”

Section: Discussionmentioning

confidence: 79%

Patient Compton Scattered Radiation for Monitoring Prostate Radiotherapy with Gold Fiducial Markers: A Simulation Study

Lopes¹,

Simoes²,

Travassos³

et al. 2017

IJPMBS

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Abstract-Orthogonal ray imaging is a new low-dose imaging technology under study aimed at assist externalbeam radiotherapy (EBRT) treatments. It consists in detecting radiation scattered in the patient and emitted perpendicularly to the incident beam. Such radiation can be collected by positioning a multi-sliced, collimator-based, 1D detector system parallel to the beam axis, hence collecting such orthogonal rays, or by using a pinhole-like detector system positioned above or below the patient. This system can potentially be useful for on-board imaging, or real-time EBRT monitoring. In terms of prostate cancer irradiation, the use of implanted fiducial markers allows a more precise verification of the gland position relative to the bony anatomy. The prostate target normally exhibits intra-and interfraction motion induced by the daily variation in rectal and bladder filling. In order to solve this issue, three gold fiducial markers are inserted into the prostate. In the present study, the imaging capability provided by utilizing X-rays escaping the patient/fiducial markers orthogonally in respect to the incoming beam direction is studied by GEANT4 simulation. The results allow concluding that the signal provided by such X-rays is highly coincident with the position of the gold fiducial markers, even in situations where these have been deviated by as little as 3.0 mm.  Index Terms-image-guided radiotherapy, OrthoCT, Monte Carlo simulation, gold fiducial markers, prostate cancer

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“…The precision of radiotherapy for prostate cancer has been improving, and intensity-modulated radiotherapy (IMRT) is commonly performed using fiducial markers [1][2][3], because the treatment is repeated and markers capable of being depicted on magnetic resonance imaging (MRI) are necessary. However, there are many fiducial markers in the world and they can sometimes be difficult to recognize on MR.…”

Section: Introductionmentioning

confidence: 99%

Initial experience of using an iron-containing fiducial marker for radiotherapy of prostate cancer: Advantages in the visualization of markers in Computed Tomography and Magnetic Resonance Imaging

Tanaka

Iida

Komeda

et al. 2016

Polish Journal of Medical Physics and Engineering

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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 ironcontaining marker and compare its utility with that of non-iron-containing markers. Five patients underwent CT/MRI fusion-based intensity-modulated radiotherapy, and the markers were placed by urologists. A Gold Anchor™ (GA; diameter, 0.28 mm; length, 10 mm) was placed using a 22G needle on the right side of the prostate. A VISICOIL™ (VIS; diameter, 0.35 mm; length, 10 mm) was placed using a 19G needle on the left side. MRI was performed using T2*-weighted imaging. Three observers evaluated and scored the visual qualities of the acquired images. The mean score of visualization was almost identical between the GA and VIS in radiography and cone-beam CT (Novalis Tx). The artifacts in planning CT were slightly larger using the GA than using the VIS. The visualization of the marker on MRI using the GA was superior to that using the VIS. In conclusion, the visualization quality of radiography, conebeam CT, and planning CT was roughly equal between the GA and VIS. However, the GA was more strongly visualized than was the VIS on MRI due to iron containing.

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Qualitative Evaluation of Fiducial Markers for Radiotherapy Imaging

Cited by 49 publications

References 24 publications

Beam distortion due to gold fiducial markers during salvage high‐intensity focused ultrasound in the prostate

Beam distortion due to gold fiducial markers during salvage high‐intensity focused ultrasound in the prostate

Patient Compton Scattered Radiation for Monitoring Prostate Radiotherapy with Gold Fiducial Markers: A Simulation Study

Initial experience of using an iron-containing fiducial marker for radiotherapy of prostate cancer: Advantages in the visualization of markers in Computed Tomography and Magnetic Resonance Imaging

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