Critical assessment of intramodality 3D ultrasound imaging for prostate IGRT compared to fiducial markers

Meer, Skadi van der; Gurp, Esther Bloemen-van; Hermans, J; Voncken, Robert; Heuvelmans, D.; Gubbels, C; Fontanarosa, Davide; Visser, P.; Lutgens, Ludy; Gils, Francis van; Verhaegen, Frank

doi:10.1118/1.4808359

Cited by 42 publications

(55 citation statements)

References 71 publications

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“…For scenarios where it is not feasible to reproduce the probe position (e.g., in cases with large day-to-day patient setup errors, anatomy changes, or relatively unconstrained organs), alternative methods might be necessary. For example, US image information could be used to adjust the couch and place the organ at the treatment isocenter, 40 as is currently implemented with the Clarity 26,41 and BAT 27,28 US-based systems. In these cases, a robot could reduce interuser variability and reproduce simulation day probe-induced deformations by using image feedback or visual servoing to control probe placement (e.g., based on landmarks in the US image acquired on the simulation day).…”

Section: Discussionmentioning

confidence: 99%

In vivo reproducibility of robotic probe placement for a novel ultrasound-guided radiation therapy system

et al. 2014

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Abstract. Ultrasound can provide real-time image guidance of radiation therapy, but the probe-induced tissue deformations cause local deviations from the treatment plan. If placed during treatment planning, the probe causes streak artifacts in required computed tomography (CT) images. To overcome these challenges, we propose robot-assisted placement of an ultrasound probe, followed by replacement with a geometrically identical, CT-compatible model probe. In vivo reproducibility was investigated by implanting a canine prostate, liver, and pancreas with three 2.38-mm spherical markers in each organ. The real probe was placed to visualize the markers and subsequently replaced with the model probe. Each probe was automatically removed and returned to the same position or force. Under position control, the median three-dimensional reproducibility of marker positions was 0.6 to 0.7 mm, 0.3 to 0.6 mm, and 1.1 to 1.6 mm in the prostate, liver, and pancreas, respectively. Reproducibility was worse under force control. Probe substitution errors were smallest for the prostate (0.2 to 0.6 mm) and larger for the liver and pancreas (4.1 to 6.3 mm), where force control generally produced larger errors than position control. Results indicate that position control is better than force control for this application, and the robotic approach has potential, particularly for relatively constrained organs and reproducibility errors that are smaller than established treatment margins.

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Section: Discussionmentioning

confidence: 99%

In vivo reproducibility of robotic probe placement for a novel ultrasound-guided radiation therapy system

et al. 2014

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“…Several image guidance methods have been investigated in recent years, including tumor tracking with intraprostatic fiducial markers, cone‐beam computed tomography (CBCT), and ultrasound‐based imaging (US‐image guidance) 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . Ultrasound‐based systems are volumetric and offer better soft‐tissue visualization compared to CBCT, without additional exposure to ionizing radiations (9) . Several studies have shown that US‐based IGRT represents a reliable system for image guidance; 3 , 7 , 8 various other technical solutions may be used for ultrasound IGRT in clinical practice, either based on intramodality or cross‐modality verification methods (3) .…”

Section: Introductionmentioning

confidence: 99%

Impact of the observers' experience on daily prostate localization accuracy in ultrasound‐based IGRT with the Clarity platform

Fiandra

Guarneri

Muñoz

et al. 2014

J Applied Clin Med Phys

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The aim of this study is to evaluate the accuracy of daily prostate localization with ultrasound imaging of various radiation oncologists with nonhomogeneous expertise. For ten patients who underwent radical radiotherapy for localized prostate cancer, 11 radiation oncologists reviewed daily ultrasound scans acquired during three different treatment sessions. The average values of two senior radiation oncologists, considered to be expert observers, were selected as reference. The remaining nine observers were divided into two groups, Group 1 and Group 2, with more and less than one year of experience, respectively. The recorded shifts in prostate position were divided in three classes: <3 mm, 3–5 mm, and > 5 mm. Deviations from reference were less than 3 mm in all directions in 91% and 81% of measurements in Groups 1 and 2, respectively. The maximum difference in terms of root mean square error (RMSE) was reported for superior‐inferior (SI) direction, in particular a mean difference of 3.24 mm was observed for Group 2 in respect to the reference; moreover RMSE was 1 and 1.3 mm higher for Group 2 for anterior‐posterior (AP) and left‐right (LR) directions, respectively. The difference between Groups 1 and 2 was significant (p < 0.01) for all directions. The mean values for the shifts in all three directions between Group 1 and the references were 0.235 mm, 0.385 mm, and 0.009 mm for the LR, SI, and AP directions, respectively. The position of the prostate gland is more easily detectable (p.15em=.15em0.02) in the AP direction, while the visibility is lower for LR (p.15em=.15em0.02) and SI boundaries (p < 0.05). The observers' experience is essential for positioning the target correctly; therefore, a training period is recommended before putting the system into clinical practice.PACS number: 87.63.dh

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“…For the intramodality matching, the interoperator variability was found to be 1.3 , 1.4 , and 1.8, respectively, in the left-right, anterior-posterior, and superiorinferior direction. 10 For manual intermodality matching, this variability is not expected to be smaller since the tissue boundaries in CT and US are depicted very differently. [16][17][18][19] Although some of these errors might be intercepted by the safety margins used for treatment planning, and therefore will not always propagate to actual dose delivery errors, the recommended procedure in case of patient motion is always to rescan the patient with both CT and US ref .…”

Section: Resultsmentioning

confidence: 99%

Consequences of Intermodality Registration Errors for Intramodality 3D Ultrasound IGRT

Meer

Seravalli

Fontanarosa

et al. 2016

Technol Cancer Res Treat

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Intramodality ultrasound image-guided radiotherapy systems compare daily ultrasound to reference ultrasound images. Nevertheless, because the actual treatment planning is based on a reference computed tomography image, and not on a reference ultrasound image, their accuracy depends partially on the correct intermodality registration of the reference ultrasound and computed tomography images for treatment planning. The error propagation in daily patient positioning due to potential registration errors at the planning stage was assessed in this work. Five different scenarios were simulated involving shifts or rotations of ultrasound or computed tomography images. The consequences of several workflow procedures were tested with a phantom setup. As long as the reference ultrasound and computed tomography images are made to match, the patient will be in the correct treatment position. In an example with a phantom measurement, the accuracy of the performed manual fusion was found to be 2 mm. In clinical practice, manual registration of patient images is expected to be more difficult. Uncorrected mismatches will lead to a systematically incorrect final patient position because there will be no indication that there was a misregistration between the computed tomography and reference ultrasound images. In the treatment room, the fusion with the computed tomography image will not be visible and based on the ultrasound images the patient position seems correct.

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Critical assessment of intramodality 3D ultrasound imaging for prostate IGRT compared to fiducial markers

Cited by 42 publications

References 71 publications

In vivo reproducibility of robotic probe placement for a novel ultrasound-guided radiation therapy system

In vivo reproducibility of robotic probe placement for a novel ultrasound-guided radiation therapy system

Impact of the observers' experience on daily prostate localization accuracy in ultrasound‐based IGRT with the Clarity platform

Consequences of Intermodality Registration Errors for Intramodality 3D Ultrasound IGRT

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