Fiducial Markers in Image-guided Radiotherapy of the Prostate

Fuller, C.D.; Scarbrough, Todd J.

doi:10.17925/ohr.2006.00.02.75

Cited by 7 publications

(19 citation statements)

References 38 publications

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“…In particular, the minimum mass thickness of a carbon-coated ZrO 2 required for maintaining good visibility would be of interest since thinner fiducials cause lower dose perturbations. The general recommendations that can be extracted from this study (mid-Z material, minimize mass thickness while maintaining good radiographic visibility) as well as the proposed figure of merit can be applied to the design of more exotic fiducials, such as strings of fiducial markers on a bio-absorbable strand or coiled fiducials (Fuller and Scarbrough, 2006), as well as novel applications of fiducials, such as implanting fiducial markers along with source seeds for image guidance in prostate brachytherapy followed by external beam radiation (Welsh et al ., 2004). …”

Section: Discussionmentioning

confidence: 99%

“…With increasingly conformal treatment options, such as 3-D conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), and proton therapy, dose escalation is possible while simultaneously decreasing margins around the target volume and thus reducing normal tissue toxicities. For prostate therapy, increased dose to the tumor is associated with better outcomes (Fuller and Scarbrough, 2006). However, decreased margins necessitate more accurate and reproducible patient positioning and target alignment.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

et al. 2011

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Image guidance using implanted fiducial markers is commonly used to ensure accurate and reproducible target positioning in radiation therapy for prostate cancer. The ideal fiducial marker is clearly visible in kV imaging, does not perturb the therapeutic dose in the target volume, and does not cause any artifacts on the CT images used for treatment planning. As yet, ideal markers that fully meet all three of these criteria have not been reported. In this study, twelve fiducial markers were evaluated for their potential clinical utility in proton radiation therapy for prostate cancer. In order to identify the good candidates, each fiducial was imaged using a CT scanner as well as a kV imaging system. Additionally, the dose perturbation caused by each fiducial was quantified using radiochromic film and a clinical proton beam. Based on the results, three fiducials were identified as good candidates for use in proton radiotherapy of prostate cancer.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

et al. 2011

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“…However, the positive effect of the new treatment parameters introduced in some of the studies for post‐EBRT salvage‐HIFU demonstrates that there is significant opportunity for improving both the delivery of salvage‐HIFU treatment as well as patient selection. An aspect of salvage HIFU that has been overlooked so far, and which may affect the treatment's safety and efficacy as well as patient selection, is the presence of fiducial markers that are increasingly introduced in the prostate as part of modern image‐guided radiotherapy (IGRT) . To the best of our knowledge, there are no studies investigating the effect of these markers on the delivery of salvage‐HIFU after EBRT, with the exception of a small number of studies reporting on the effect of permanent BT seeds on HIFU .…”

Section: Introductionmentioning

confidence: 99%

“…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%

“…Second, metallic coils and strings of markers on an absorbable strand, which may offer better stability and localization since they stretch across the whole gland. Finally, a new family of markers with a transponder built‐in to allow wireless tracking of their position in real‐time without the need for additional imaging of the prostate …”

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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Computer‐assisted implantology: historical background and potential outcomes—a review

Azari

Nikzad

2008

Robotics Computer Surgery

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Fiducial Markers in Image-guided Radiotherapy of the Prostate

Cited by 7 publications

References 38 publications

Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

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

Computer‐assisted implantology: historical background and potential outcomes—a review

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